Merge remote-tracking branch 'remotes/origin/master' into parallel_for

# Conflicts:
#	PERFORMANCE.md
#	lib/pls/CMakeLists.txt
#	lib/pls/include/pls/internal/scheduling/fork_join_task.h

CMakeLists.txt

@@ -7,7 +7,7 @@ set(CMAKE_CXX_STANDARD 11)
 
 
 # seperate library and test/example executable output paths.
 # seperate library and test/example executable output paths.
 set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/bin)
 set(EXECUTABLE_OUTPUT_PATH ${CMAKE_BINARY_DIR}/bin)
-set(LIBRARY_OUTPUT_PATH  ${CMAKE_BINARY_DIR}/lib)
+set(LIBRARY_OUTPUT_PATH ${CMAKE_BINARY_DIR}/lib)
 
 
 # specific setup code is located in individual files.
 # specific setup code is located in individual files.
 include(cmake/DisabelInSource.cmake)
 include(cmake/DisabelInSource.cmake)
@@ -34,11 +34,12 @@ add_subdirectory(app/playground)
 add_subdirectory(app/test_for_new)
 add_subdirectory(app/test_for_new)
 add_subdirectory(app/invoke_parallel)
 add_subdirectory(app/invoke_parallel)
 add_subdirectory(app/benchmark_fft)
 add_subdirectory(app/benchmark_fft)
+add_subdirectory(app/benchmark_unbalanced)
 
 
 # Add optional tests
 # Add optional tests
 option(PACKAGE_TESTS "Build the tests" ON)
 option(PACKAGE_TESTS "Build the tests" ON)
-if(PACKAGE_TESTS)
+if (PACKAGE_TESTS)
     enable_testing()
     enable_testing()
     add_subdirectory(test)
     add_subdirectory(test)
     add_test(NAME AllTests COMMAND tests)
     add_test(NAME AllTests COMMAND tests)
-endif()
+endif ()

NOTES.md

@@ -4,6 +4,33 @@ A collection of stuff that we noticed during development.
 Useful later on two write a project report and to go back
 Useful later on two write a project report and to go back
 in time to find out why certain decisions where made.
 in time to find out why certain decisions where made.
 
 
+## 06.05.2019 - Relaxed Atomics
+
+At the end of the atomic talk it is mentioned how the relaxed
+atomics correspond to modern hardware, stating that starting with
+ARMv8 and x86 there is no real need for relaxed atomics,
+as the 'strict' ordering has no real performance impact.
+
+We will therefore ignore this for now (taking some potential
+performance hits on our banana pi m2 ARMv7 architecture),
+as it adds a lot of complexity and introduces many possibilities
+for subtle concurrency bugs.
+TODO: find some papers on the topic in case we want to mention
+it in our project report.
+
+## 06.05.2019 - Atomics
+
+Atomics are a big part to get lock-free code running and are also
+often useful for details like counters to spin on (e.g. is a task
+finished). Resources to understand them are found in
+[a talk online](https://herbsutter.com/2013/02/11/atomic-weapons-the-c-memory-model-and-modern-hardware/)
+and in the book 'C++ concurrency in action, Anthony Williams'.
+
+The key takeaway is that we need to be careful about ordering
+possibilities of variable reads/writes. We will start of to
+use strict ordering to begin with and will have to see if this
+impacts performance and if we need to optimize it.
+
 ## 12.04.2019 - Unique IDs
 ## 12.04.2019 - Unique IDs
 
 
 Assigning unique IDs to logical different tasks is key to the
 Assigning unique IDs to logical different tasks is key to the

PERFORMANCE.md

@@ -63,3 +63,62 @@ to contemption, but could not resolve it with any combination
 of `tas_spinlock` vs `ttas_spinlock` and `lock` vs `try_lock`.
 of `tas_spinlock` vs `ttas_spinlock` and `lock` vs `try_lock`.
 
 
 This issue clearly needs further investigation.
 This issue clearly needs further investigation.
+
+### Commit aa27064 - Performance with ttsa spinlocks (and 'full blocking' top level)
+
+<img src="media/aa27064_fft_average.png" width="400"/>
+
+### Commit d16ad3e - Performance with rw-lock and backoff
+
+<img src="media/d16ad3e_fft_average.png" width="400"/>
+
+### Commit 18b2d744 - Performance with lock-free deque
+
+After much tinkering we still have performance problems with higher
+thread counts in the FFT benchmark. Upward from 4/5 threads the
+performance gains start to saturate (before removing the top level
+locks we even saw a slight drop in performance).
+
+Currently the FFT benchmark shows the following results (average):
+
+<img src="media/18b2d744_fft_average.png" width="400"/>
+
+We want to positively note that the overall trend of 'performance drops'
+at the hyperthreading mark is not really bad anymore, it rather
+seems similar to EMBB now (with backoff + lockfree deque + top level
+reader-writers lock). This comes partly because the spike at 4 threads
+is lower (less performance at 4 threads). We also see better times
+on the multiprogramed system with the lock-free deque.
+
+This is discouraging after many tests. To see where the overhead lies
+we also implemented the unbalanced tree search benchmark,
+resulting in the following, suprisingly good, results (average):
+
+<img src="media/18b2d744_unbalanced_average.png" width="400"/>
+
+The main difference between the two benchmarks is, that the second
+one has more work and the work is relatively independent.
+Additionaly, the first one uses our high level API (parallel invoke),
+while the second one uses our low level API.
+It is worth investigating if either or high level API or the structure
+of the memory access in FFT are the problem.
+
+### Commit cf056856 - Remove two-level scheduler
+
+In this test we replace the two level scheduler with ONLY fork_join
+tasks. This removes the top level steal overhead and performs only
+internal stealing. For this we set the fork_join task as the only
+possible task type and removed the top level rw-lock, the digging
+down to our level and solely use internal stealing.
+
+Average results FFT:
+
+<img src="media/cf056856_fft_average.png" width="400"/>
+
+Average results Unbalanced:
+
+<img src="media/cf056856_unbalanced_average.png" width="400"/>
+
+There seems to be only a minor performance difference between the two,
+suggesting tha our two-level approach is not the part causing our
+weaker performance.

README.md

@@ -7,6 +7,8 @@
 
 
 This section will give a brief introduction on how to get a minimal
 This section will give a brief introduction on how to get a minimal
 project setup that uses the PLS library.
 project setup that uses the PLS library.
+Further [general notes](NOTES.md) and [performance notes](PERFORMANCE.md) can be found in
+their respective files.
 
 
 Further notes on [performance](PERFORMANCE.md) and general
 Further notes on [performance](PERFORMANCE.md) and general
 [notes](NOTES.md) on the development progress can be found in
 [notes](NOTES.md) on the development progress can be found in

app/benchmark_fft/main.cpp

@@ -6,82 +6,81 @@
 #include <complex>
 #include <complex>
 #include <vector>
 #include <vector>
 
 
-static constexpr int CUTOFF = 10;
+static constexpr int CUTOFF = 16;
 static constexpr int NUM_ITERATIONS = 1000;
 static constexpr int NUM_ITERATIONS = 1000;
-static constexpr int INPUT_SIZE = 2064;
+static constexpr int INPUT_SIZE = 8192;
 typedef std::vector<std::complex<double>> complex_vector;
 typedef std::vector<std::complex<double>> complex_vector;
 
 
 void divide(complex_vector::iterator data, int n) {
 void divide(complex_vector::iterator data, int n) {
-    complex_vector tmp_odd_elements(n / 2);
-    for (int i = 0; i < n / 2; i++) {
-        tmp_odd_elements[i] = data[i * 2 + 1];
-    }
-    for (int i = 0; i < n / 2; i++) {
-        data[i] = data[i * 2];
-    }
-    for (int i = 0; i < n / 2; i++) {
-        data[i + n / 2] = tmp_odd_elements[i];
-    }
+  complex_vector tmp_odd_elements(n / 2);
+  for (int i = 0; i < n / 2; i++) {
+    tmp_odd_elements[i] = data[i * 2 + 1];
+  }
+  for (int i = 0; i < n / 2; i++) {
+    data[i] = data[i * 2];
+  }
+  for (int i = 0; i < n / 2; i++) {
+    data[i + n / 2] = tmp_odd_elements[i];
+  }
 }
 }
 
 
 void combine(complex_vector::iterator data, int n) {
 void combine(complex_vector::iterator data, int n) {
-    for (int i = 0; i < n / 2; i++) {
-        std::complex<double> even = data[i];
-        std::complex<double> odd = data[i + n / 2];
+  for (int i = 0; i < n / 2; i++) {
+    std::complex<double> even = data[i];
+    std::complex<double> odd = data[i + n / 2];
 
 
-        // w is the "twiddle-factor".
-        // this could be cached, but we run the same 'data_structures' algorithm parallel/serial,
-        // so it won't impact the performance comparison.
-        std::complex<double> w = exp(std::complex<double>(0, -2. * M_PI * i / n));
+    // w is the "twiddle-factor".
+    // this could be cached, but we run the same 'data_structures' algorithm parallel/serial,
+    // so it won't impact the performance comparison.
+    std::complex<double> w = exp(std::complex<double>(0, -2. * M_PI * i / n));
 
 
-        data[i] = even + w * odd;
-        data[i + n / 2] = even - w * odd;
-    }
+    data[i] = even + w * odd;
+    data[i + n / 2] = even - w * odd;
+  }
 }
 }
 
 
 void fft(complex_vector::iterator data, int n) {
 void fft(complex_vector::iterator data, int n) {
-    if (n < 2) {
-        return;
-    }
+  if (n < 2) {
+    return;
+  }
 
 
-    divide(data, n);
-    if (n <= CUTOFF) {
-        fft(data, n / 2);
-        fft(data + n / 2, n / 2);
-    } else {
-        pls::invoke_parallel(
-            [&] { fft(data, n / 2); },
-            [&] { fft(data + n / 2, n / 2); }
-        );
-    }
-    combine(data, n);
+  divide(data, n);
+  if (n <= CUTOFF) {
+    fft(data, n / 2);
+    fft(data + n / 2, n / 2);
+  } else {
+    pls::invoke_parallel(
+        [&] { fft(data, n / 2); },
+        [&] { fft(data + n / 2, n / 2); }
+    );
+  }
+  combine(data, n);
 }
 }
 
 
 complex_vector prepare_input(int input_size) {
 complex_vector prepare_input(int input_size) {
-    std::vector<double> known_frequencies{2, 11, 52, 88, 256};
-    complex_vector data(input_size);
+  std::vector<double> known_frequencies{2, 11, 52, 88, 256};
+  complex_vector data(input_size);
 
 
-    // Set our input data to match a time series of the known_frequencies.
-    // When applying fft to this time-series we should find these frequencies.
-    for (int i = 0; i < input_size; i++) {
-        data[i] = std::complex<double>(0.0, 0.0);
-        for (auto frequencie : known_frequencies) {
-            data[i] += sin(2 * M_PI * frequencie * i / input_size);
-        }
+  // Set our input data to match a time series of the known_frequencies.
+  // When applying fft to this time-series we should find these frequencies.
+  for (int i = 0; i < input_size; i++) {
+    data[i] = std::complex<double>(0.0, 0.0);
+    for (auto frequencie : known_frequencies) {
+      data[i] += sin(2 * M_PI * frequencie * i / input_size);
     }
     }
+  }
 
 
-    return data;
+  return data;
 }
 }
 
 
-
 int main() {
 int main() {
-    PROFILE_ENABLE
-    complex_vector initial_input = prepare_input(INPUT_SIZE);
+  PROFILE_ENABLE
+  complex_vector initial_input = prepare_input(INPUT_SIZE);
 
 
-    pls::internal::helpers::run_mini_benchmark([&] {
-        complex_vector input = initial_input;
-        fft(input.begin(), input.size());
-    }, 8, 4000);
+  pls::internal::helpers::run_mini_benchmark([&] {
+    complex_vector input = initial_input;
+    fft(input.begin(), input.size());
+  }, 8, 4000);
 
 
-    PROFILE_SAVE("test_profile.prof")
+  PROFILE_SAVE("test_profile.prof")
 }
 }

app/benchmark_unbalanced/CMakeLists.txt

+add_executable(benchmark_unbalanced main.cpp node.h node.cpp picosha2.h)
+target_link_libraries(benchmark_unbalanced pls)
+if (EASY_PROFILER)
+    target_link_libraries(benchmark_unbalanced easy_profiler)
+endif ()

app/benchmark_unbalanced/LICENSE_PICOSA2

+MIT License
+
+Copyright (c) 2017 okdshin
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
\ No newline at end of file

app/benchmark_unbalanced/main.cpp

+#include <pls/pls.h>
+#include <pls/internal/helpers/profiler.h>
+#include <pls/internal/helpers/mini_benchmark.h>
+
+#include "node.h"
+
+const int SEED = 42;
+const int ROOT_CHILDREN = 140;
+const double Q = 0.124875;
+const int NORMAL_CHILDREN = 8;
+
+const int NUM_NODES = 71069;
+
+int count_child_nodes(uts::node &node) {
+  int child_count = 1;
+  std::vector<uts::node> children = node.spawn_child_nodes();
+
+  if (children.empty()) {
+    return child_count;
+  }
+
+  auto current_task = pls::fork_join_sub_task::current();
+  std::vector<int> results(children.size());
+  for (size_t i = 0; i < children.size(); i++) {
+    size_t index = i;
+    auto lambda = [&, index] { results[index] = count_child_nodes(children[index]); };
+    pls::fork_join_lambda_by_value<typeof(lambda)> sub_task(lambda);
+    current_task->spawn_child(sub_task);
+  }
+  current_task->wait_for_all();
+  for (auto result : results) {
+    child_count += result;
+  }
+
+  return child_count;
+}
+
+int unbalanced_tree_search(int seed, int root_children, double q, int normal_children) {
+  static auto id = pls::unique_id::create(42);
+  int result;
+
+  auto lambda = [&] {
+    uts::node root(seed, root_children, q, normal_children);
+    result = count_child_nodes(root);
+  };
+  pls::fork_join_lambda_by_reference<typeof(lambda)> task(lambda);
+  pls::fork_join_lambda_by_reference<typeof(lambda)> sub_task(lambda);
+  pls::fork_join_task root_task{&sub_task, id};
+  pls::scheduler::execute_task(root_task);
+
+  return result;
+}
+
+int main() {
+  PROFILE_ENABLE
+  pls::internal::helpers::run_mini_benchmark([&] {
+    unbalanced_tree_search(SEED, ROOT_CHILDREN, Q, NORMAL_CHILDREN);
+  }, 8, 4000);
+
+  PROFILE_SAVE("test_profile.prof")
+}
+
+//int main() {
+//  PROFILE_ENABLE
+//  pls::malloc_scheduler_memory my_scheduler_memory{8, 2u << 18};
+//  pls::scheduler scheduler{&my_scheduler_memory, 8};
+//
+//  scheduler.perform_work([&] {
+//    PROFILE_MAIN_THREAD
+//    for (int i = 0; i < 10; i++) {
+//      PROFILE_WORK_BLOCK("Top Level")
+//      int result = unbalanced_tree_search(SEED, ROOT_CHILDREN, Q, NORMAL_CHILDREN);
+//      std::cout << result << std::endl;
+//    }
+//  });
+//
+//  PROFILE_SAVE("test_profile.prof")
+//}

app/benchmark_unbalanced/node.cpp

+#include "node.h"
+
+namespace uts {
+node_state node::generate_child_state(uint32_t index) {
+  node_state result;
+
+  picosha2::hash256_one_by_one hasher;
+  hasher.process(state_.begin(), state_.end());
+  auto index_begin = reinterpret_cast<uint8_t *>(&index);
+  hasher.process(index_begin, index_begin + 4);
+  hasher.finish();
+  hasher.get_hash_bytes(result.begin(), result.end());
+
+  return result;
+}
+
+double node::get_state_random() {
+  int32_t state_random_integer;
+  uint32_t b = ((uint32_t) state_[16] << 24) |
+      ((uint32_t) state_[17] << 16) |
+      ((uint32_t) state_[18] << 8) |
+      ((uint32_t) state_[19] << 0);
+  b = b & 0x7fffffff; // Mask out negative values
+  state_random_integer = static_cast<int32_t>(b);
+
+  return (double) state_random_integer / (double) INT32_MAX;
+}
+}

app/benchmark_unbalanced/node.h

+
+#ifndef UTS_NODE_H
+#define UTS_NODE_H
+
+#include <cstdint>
+#include <array>
+#include <vector>
+
+#include "picosha2.h"
+
+namespace uts {
+using node_state = std::array<uint8_t, 20>;
+
+/**
+ * Node of an unballanced binomial tree (https://www.cs.unc.edu/~olivier/LCPC06.pdf).
+ * To build up the tree recursivly call spawn_child_nodes on each node until leaves are reached.
+ * The tree is not built up directly in memory, but rather by the recursive calls.
+ */
+class node {
+  // The state is used to allow a deterministic tree construction using sha256 hashes.
+  node_state state_;
+
+  // Set this to a positive number for the root node to start the tree with a specific size
+  int root_children_;
+
+  // general branching factors
+  double q_;
+  int b_;
+
+  // Private constructor for children
+  node(node_state state, double q, int b) : state_{state}, root_children_{-1}, q_{q}, b_{b} {}
+
+  std::array<uint8_t, 20> generate_child_state(uint32_t index);
+  double get_state_random();
+
+ public:
+  node(int seed, int root_children, double q, int b) : state_({{}}), root_children_{root_children}, q_{q}, b_{b} {
+    for (int i = 0; i < 16; i++) {
+      state_[i] = 0;
+    }
+    state_[16] = static_cast<uint8_t>(0xFF & (seed >> 24));
+    state_[17] = static_cast<uint8_t>(0xFF & (seed >> 16));
+    state_[18] = static_cast<uint8_t>(0xFF & (seed >> 8));
+    state_[19] = static_cast<uint8_t>(0xFF & (seed >> 0));
+
+    picosha2::hash256_one_by_one hasher;
+    hasher.process(state_.begin(), state_.end());
+    hasher.finish();
+    hasher.get_hash_bytes(state_.begin(), state_.end());
+  }
+
+  std::vector<node> spawn_child_nodes() {
+    double state_random = get_state_random();
+    int num_children;
+    if (root_children_ > 0) {
+      num_children = root_children_; // Root always spawns children
+    } else if (state_random < q_) {
+      num_children = b_;
+    } else {
+      num_children = 0;
+    }
+
+    std::vector<node> result;
+    for (int i = 0; i < num_children; i++) {
+      result.push_back(node(generate_child_state(i), q_, b_));
+    }
+
+    return result;
+  }
+};
+}
+
+#endif //UTS_NODE_H

app/invoke_parallel/main.cpp

@@ -2,50 +2,101 @@
 #include <pls/internal/helpers/profiler.h>
 #include <pls/internal/helpers/profiler.h>
 
 
 #include <iostream>
 #include <iostream>
+#include <complex>
+#include <vector>
 
 
-static pls::static_scheduler_memory<8, 2 << 14> my_scheduler_memory;
+static constexpr int CUTOFF = 16;
+static constexpr int INPUT_SIZE = 8192;
+typedef std::vector<std::complex<double>> complex_vector;
 
 
-static constexpr int CUTOFF = 10;
+void divide(complex_vector::iterator data, int n) {
+  complex_vector tmp_odd_elements(n / 2);
+  for (int i = 0; i < n / 2; i++) {
+    tmp_odd_elements[i] = data[i * 2 + 1];
+  }
+  for (int i = 0; i < n / 2; i++) {
+    data[i] = data[i * 2];
+  }
+  for (int i = 0; i < n / 2; i++) {
+    data[i + n / 2] = tmp_odd_elements[i];
+  }
+}
 
 
-long fib_serial(long n) {
-    if (n == 0) {
-        return 0;
-    }
-    if (n == 1) {
-        return 1;
-    }
+void combine(complex_vector::iterator data, int n) {
+  for (int i = 0; i < n / 2; i++) {
+    std::complex<double> even = data[i];
+    std::complex<double> odd = data[i + n / 2];
+
+    // w is the "twiddle-factor".
+    // this could be cached, but we run the same 'data_structures' algorithm parallel/serial,
+    // so it won't impact the performance comparison.
+    std::complex<double> w = exp(std::complex<double>(0, -2. * M_PI * i / n));
 
 
-    return fib_serial(n - 1) + fib_serial(n - 2);
+    data[i] = even + w * odd;
+    data[i + n / 2] = even - w * odd;
+  }
 }
 }
 
 
-long fib(long n) {
-    if (n <= CUTOFF) {
-        return fib_serial(n);
-    }
+void fft(complex_vector::iterator data, int n) {
+  if (n < 2) {
+    return;
+  }
 
 
-    // Actual 'invoke_parallel' logic/code
-    int left, right;
+  PROFILE_WORK_BLOCK("Divide")
+  divide(data, n);
+  PROFILE_END_BLOCK
+  PROFILE_WORK_BLOCK("Invoke Parallel")
+  if (n == CUTOFF) {
+    PROFILE_WORK_BLOCK("FFT Serial")
+    fft(data, n / 2);
+    fft(data + n / 2, n / 2);
+  } else if (n <= CUTOFF) {
+    fft(data, n / 2);
+    fft(data + n / 2, n / 2);
+  } else {
     pls::invoke_parallel(
     pls::invoke_parallel(
-        [&] { left = fib(n - 1); },
-        [&] { right = fib(n - 2); }
+        [&] { fft(data, n / 2); },
+        [&] { fft(data + n / 2, n / 2); }
     );
     );
-    return left + right;
+  }
+  PROFILE_END_BLOCK
+  PROFILE_WORK_BLOCK("Combine")
+  combine(data, n);
+  PROFILE_END_BLOCK
+}
+
+complex_vector prepare_input(int input_size) {
+  std::vector<double> known_frequencies{2, 11, 52, 88, 256};
+  complex_vector data(input_size);
+
+  // Set our input data to match a time series of the known_frequencies.
+  // When applying fft to this time-series we should find these frequencies.
+  for (int i = 0; i < input_size; i++) {
+    data[i] = std::complex<double>(0.0, 0.0);
+    for (auto frequencie : known_frequencies) {
+      data[i] += sin(2 * M_PI * frequencie * i / input_size);
+    }
+  }
+
+  return data;
 }
 }
 
 
 int main() {
 int main() {
-    PROFILE_ENABLE
-    pls::scheduler scheduler{&my_scheduler_memory, 8};
-
-    long result;
-    scheduler.perform_work([&] {
-        PROFILE_MAIN_THREAD
-        // Call looks just the same, only requirement is
-        // the enclosure in the perform_work lambda.
-        for (int i = 0; i < 10; i++) {
-            result = fib(30);
-            std::cout << "Fib(30)=" << result << std::endl;
-        }
-    });
-
-    PROFILE_SAVE("test_profile.prof")
+  PROFILE_ENABLE
+  pls::malloc_scheduler_memory my_scheduler_memory{8, 2u << 14};
+  pls::scheduler scheduler{&my_scheduler_memory, 8};
+
+  complex_vector initial_input = prepare_input(INPUT_SIZE);
+  scheduler.perform_work([&] {
+    PROFILE_MAIN_THREAD
+    // Call looks just the same, only requirement is
+    // the enclosure in the perform_work lambda.
+    for (int i = 0; i < 10; i++) {
+      PROFILE_WORK_BLOCK("Top Level FFT")
+      complex_vector input = initial_input;
+      fft(input.begin(), input.size());
+    }
+  });
+
+  PROFILE_SAVE("test_profile.prof")
 }
 }

app/playground/main.cpp

@@ -10,8 +10,6 @@
 #include <pls/internal/scheduling/root_task.h>
 #include <pls/internal/scheduling/root_task.h>
 #include <pls/internal/helpers/unique_id.h>
 #include <pls/internal/helpers/unique_id.h>
 
 
-
 int main() {
 int main() {
-    std::cout << pls::internal::scheduling::root_task<void(*)>::create_id().type_.hash_code() << std::endl;
-    std::cout << pls::internal::helpers::unique_id::create<pls::internal::scheduling::root_task<void(*)>>().type_.hash_code() << std::endl;
+
 }
 }

app/test_for_new/main.cpp

@@ -5,9 +5,8 @@ using namespace pls::internal::base;
 
 
 int global = 0;
 int global = 0;
 
 
-
 int main() {
 int main() {
-    // Try to use every feature, to trigger the prohibited use of new if found somewhere
-    auto t1 = start_thread([] (){});
-    t1.join();
+  // Try to use every feature, to trigger the prohibited use of new if found somewhere
+  auto t1 = start_thread([]() {});
+  t1.join();
 }
 }

lib/pls/include/pls/algorithms/invoke_parallel.h

@@ -6,15 +6,17 @@
 #include "pls/internal/scheduling/scheduler.h"
 #include "pls/internal/scheduling/scheduler.h"
 
 
 namespace pls {
 namespace pls {
-    namespace algorithm {
-        template<typename Function1, typename Function2>
-        void invoke_parallel(const Function1& function1, const Function2& function2);
+namespace algorithm {
 
 
-        template<typename Function1, typename Function2, typename Function3>
-        void invoke_parallel(const Function1& function1, const Function2& function2, const Function3& function3);
+template<typename Function1, typename Function2>
+void invoke_parallel(const Function1 &function1, const Function2 &function2);
 
 
-        // ...and so on, add more if we decide to keep this design
-    }
+template<typename Function1, typename Function2, typename Function3>
+void invoke_parallel(const Function1 &function1, const Function2 &function2, const Function3 &function3);
+
+// ...and so on, add more if we decide to keep this design
+
+}
 }
 }
 #include "invoke_parallel_impl.h"
 #include "invoke_parallel_impl.h"
 
 

lib/pls/include/pls/algorithms/invoke_parallel_impl.h

@@ -2,70 +2,73 @@
 #ifndef PLS_INVOKE_PARALLEL_IMPL_H
 #ifndef PLS_INVOKE_PARALLEL_IMPL_H
 #define PLS_INVOKE_PARALLEL_IMPL_H
 #define PLS_INVOKE_PARALLEL_IMPL_H
 
 
+#include <pls/internal/scheduling/fork_join_task.h>
 #include "pls/internal/scheduling/fork_join_task.h"
 #include "pls/internal/scheduling/fork_join_task.h"
 #include "pls/internal/scheduling/scheduler.h"
 #include "pls/internal/scheduling/scheduler.h"
 #include "pls/internal/helpers/unique_id.h"
 #include "pls/internal/helpers/unique_id.h"
+#include "pls/internal/base/alignment.h"
 
 
 namespace pls {
 namespace pls {
-    namespace algorithm {
-        namespace internal {
-            using namespace ::pls::internal::scheduling;
+namespace algorithm {
+namespace internal {
 
 
-            template<typename Body>
-            inline void run_body(const Body& internal_body, const abstract_task::id& id) {
-                // Make sure we are in the context of this invoke_parallel instance,
-                // if not we will spawn it as a new 'fork-join-style' task.
-                auto current_task = scheduler::current_task();
-                if (current_task->unique_id() == id) {
-                    auto current_sub_task = reinterpret_cast<fork_join_task*>(current_task)->currently_executing();
-                    internal_body(current_sub_task);
-                } else {
-                    fork_join_lambda<Body> root_body(&internal_body);
-                    fork_join_task root_task{&root_body, id};
-                    scheduler::execute_task(root_task);
-                }
-            }
-        }
+using namespace ::pls::internal::scheduling;
 
 
-        template<typename Function1, typename Function2>
-        void invoke_parallel(const Function1& function1, const Function2& function2) {
-            using namespace ::pls::internal::scheduling;
-            using namespace ::pls::internal::helpers;
-            static abstract_task::id id = unique_id::create<Function1, Function2>();
+template<typename Body>
+inline void run_body(const Body &internal_body, const abstract_task::id &id) {
+  // Make sure we are in the context of this invoke_parallel instance,
+  // if not we will spawn it as a new 'fork-join-style' task.
+  auto current_task = scheduler::current_task();
+  if (current_task->unique_id() == id) {
+    internal_body();
+  } else {
+    fork_join_lambda_by_reference<Body> root_body(internal_body);
+    fork_join_task root_task{&root_body, id};
+    scheduler::execute_task(root_task);
+  }
+}
+}
 
 
-            auto internal_body = [&] (fork_join_sub_task* this_task){
-                auto sub_task_body_1 = [&] (fork_join_sub_task*){ function1(); };
-                auto sub_task_1 = fork_join_lambda<decltype(sub_task_body_1)>(&sub_task_body_1);
+template<typename Function1, typename Function2>
+void invoke_parallel(const Function1 &function1, const Function2 &function2) {
+  using namespace ::pls::internal::scheduling;
+  using namespace ::pls::internal::helpers;
+  using namespace ::pls::internal::base;
+  static abstract_task::id id = unique_id::create<Function1, Function2>();
 
 
-                this_task->spawn_child(sub_task_1);
-                function2(); // Execute last function 'inline' without spawning a sub_task object
-                this_task->wait_for_all();
-            };
+  auto internal_body = [&]() {
+    auto current_task = fork_join_sub_task::current();
+    auto sub_task_2 = fork_join_lambda_by_reference<Function2>(function2);
 
 
-            internal::run_body(internal_body, id);
-        }
+    current_task->spawn_child(sub_task_2);
+    function1(); // Execute first function 'inline' without spawning a sub_task object
+    current_task->wait_for_all();
+  };
+
+  internal::run_body(internal_body, id);
+}
 
 
-        template<typename Function1, typename Function2, typename Function3>
-        void invoke_parallel(const Function1& function1, const Function2& function2, const Function3& function3) {
-            using namespace ::pls::internal::scheduling;
-            using namespace ::pls::internal::helpers;
-            static abstract_task::id id = unique_id::create<Function1, Function2, Function3>();
+template<typename Function1, typename Function2, typename Function3>
+void invoke_parallel(const Function1 &function1, const Function2 &function2, const Function3 &function3) {
+  using namespace ::pls::internal::scheduling;
+  using namespace ::pls::internal::helpers;
+  static abstract_task::id id = unique_id::create<Function1, Function2, Function3>();
 
 
-            auto internal_body = [&] (fork_join_sub_task* this_task){
-                auto sub_task_body_1 = [&] (fork_join_sub_task*){ function1(); };
-                auto sub_task_1 = fork_join_lambda<decltype(sub_task_body_1)>(&sub_task_body_1);
-                auto sub_task_body_2 = [&] (fork_join_sub_task*){ function2(); };
-                auto sub_task_2 = fork_join_lambda<decltype(sub_task_body_2)>(&sub_task_body_2);
+  auto internal_body = [&]() {
+    auto current_task = fork_join_sub_task::current();
+    auto sub_task_2 = fork_join_lambda_by_reference<Function2>(function2);
+    auto sub_task_3 = fork_join_lambda_by_reference<Function3>(function3);
 
 
-                this_task->spawn_child(sub_task_1);
-                this_task->spawn_child(sub_task_2);
-                function3(); // Execute last function 'inline' without spawning a sub_task object
-                this_task->wait_for_all();
-            };
+    current_task->spawn_child(sub_task_2);
+    current_task->spawn_child(sub_task_3);
+    function1(); // Execute first function 'inline' without spawning a sub_task object
+    current_task->wait_for_all();
+  };
 
 
-            internal::run_body(internal_body, id);
-        }
-    }
+  internal::run_body(internal_body, id);
+}
+
+}
 }
 }
 
 
 #endif //PLS_INVOKE_PARALLEL_IMPL_H
 #endif //PLS_INVOKE_PARALLEL_IMPL_H

lib/pls/include/pls/internal/base/alignment.h

@@ -8,21 +8,45 @@
 #include "system_details.h"
 #include "system_details.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            namespace alignment {
-                template<typename T>
-                struct aligned_wrapper {
-                    alignas(system_details::CACHE_LINE_SIZE) unsigned char data[sizeof(T)];
-                    T* pointer() { return reinterpret_cast<T*>(data); }
-                };
-                void* allocate_aligned(size_t size);
-
-                std::uintptr_t next_alignment(std::uintptr_t size);
-                char* next_alignment(char* pointer);
-            }
-        }
-    }
+namespace internal {
+namespace base {
+namespace alignment {
+
+template<typename T>
+struct aligned_wrapper {
+  alignas(system_details::CACHE_LINE_SIZE) unsigned char data[sizeof(T)];
+  T *pointer() { return reinterpret_cast<T *>(data); }
+};
+void *allocate_aligned(size_t size);
+
+system_details::pointer_t next_alignment(system_details::pointer_t size);
+system_details::pointer_t previous_alignment(system_details::pointer_t size);
+char *next_alignment(char *pointer);
+
+}
+
+template<typename T>
+struct aligned_aba_pointer {
+  const system_details::pointer_t pointer_;
+
+  explicit aligned_aba_pointer(T *pointer, unsigned int aba = 0) : pointer_{
+      reinterpret_cast<system_details::pointer_t >(pointer) + aba} {}
+
+  T *pointer() const {
+    return reinterpret_cast<T *>(pointer_ & system_details::CACHE_LINE_ADDRESS_USED_BITS);
+  }
+
+  unsigned int aba() const {
+    return pointer_ & system_details::CACHE_LINE_ADDRESS_UNUSED_BITS;
+  }
+
+  aligned_aba_pointer set_aba(unsigned int aba) const {
+    return aligned_aba_pointer(pointer(), aba);
+  }
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_ALIGNMENT_H
 #endif //PLS_ALIGNMENT_H

lib/pls/include/pls/internal/base/backoff.h

+
+#ifndef PLS_BACKOFF_H_
+#define PLS_BACKOFF_H_
+
+#include "pls/internal/base/system_details.h"
+#include "pls/internal/helpers/profiler.h"
+#include "pls/internal/base/thread.h"
+
+#include <random>
+#include <math.h>
+
+namespace pls {
+namespace internal {
+namespace base {
+
+class backoff {
+  const unsigned long INITIAL_SPIN_ITERS = 2u << 4u;
+  const unsigned long MAX_SPIN_ITERS = 2u << 8u;
+  const unsigned long MAX_ITERS = 2u << 10u;
+  const unsigned long YELD_ITERS = 2u << 10u;
+
+  unsigned long current_ = INITIAL_SPIN_ITERS;
+  std::minstd_rand random_;
+
+  static void spin(unsigned long iterations) {
+    for (volatile unsigned long i = 0; i < iterations; i++)
+      system_details::relax_cpu(); // Spin
+  }
+
+ public:
+  backoff() : current_{INITIAL_SPIN_ITERS}, random_{std::random_device{}()} {}
+
+  void do_backoff() {
+    PROFILE_LOCK("Backoff")
+    spin(random_() % std::min(current_, MAX_SPIN_ITERS));
+
+    if (current_ >= YELD_ITERS) {
+      PROFILE_LOCK("Yield")
+      this_thread::yield();
+    }
+
+    current_ = std::min(current_ * 2, MAX_ITERS);
+  }
+
+  void reset() {
+    current_ = INITIAL_SPIN_ITERS;
+  }
+};
+
+}
+}
+}
+
+#endif //PLS_BACKOFF_H_

lib/pls/include/pls/internal/base/barrier.h

@@ -5,27 +5,29 @@
 #include <pthread.h>
 #include <pthread.h>
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
-             * Provides standard barrier behaviour.
-             * `count` threads have to call `wait()` before any of the `wait()` calls returns,
-             * thus blocking all threads until everyone reached the barrier.
-             *
-             * PORTABILITY:
-             * Current implementation is based on pthreads.
-             */
-            class barrier {
-                pthread_barrier_t barrier_;
-
-            public:
-                explicit barrier(unsigned int count);
-                ~barrier();
-
-                void wait();
-            };
-        }
-    }
+namespace internal {
+namespace base {
+
+/**
+ * Provides standard barrier behaviour.
+ * `count` threads have to call `wait()` before any of the `wait()` calls returns,
+ * thus blocking all threads until everyone reached the barrier.
+ *
+ * PORTABILITY:
+ * Current implementation is based on pthreads.
+ */
+class barrier {
+  pthread_barrier_t barrier_;
+
+ public:
+  explicit barrier(unsigned int count);
+  ~barrier();
+
+  void wait();
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_BARRIER_H
 #endif //PLS_BARRIER_H

lib/pls/include/pls/internal/base/error_handling.h

@@ -11,5 +11,6 @@
  * (or its inclusion adds too much overhead).
  * (or its inclusion adds too much overhead).
  */
  */
 #define PLS_ERROR(msg) std::cout << msg << std::endl; exit(1);
 #define PLS_ERROR(msg) std::cout << msg << std::endl; exit(1);
+#define PLS_ASSERT(cond, msg) if (!cond) { PLS_ERROR(msg) }
 
 
 #endif //PLS_ERROR_HANDLING_H
 #endif //PLS_ERROR_HANDLING_H

lib/pls/include/pls/internal/base/spin_lock.h

@@ -6,12 +6,14 @@
 #include "ttas_spin_lock.h"
 #include "ttas_spin_lock.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            // Default Spin-Lock implementation for this project.
-            using spin_lock = tas_spin_lock;
-        }
-    }
+namespace internal {
+namespace base {
+
+// Default Spin-Lock implementation for this project.
+using spin_lock = ttas_spin_lock;
+
+}
+}
 }
 }
 
 
 #endif //PLS_SPINLOCK_H
 #endif //PLS_SPINLOCK_H

lib/pls/include/pls/internal/base/swmr_spin_lock.h

+
+#ifndef PLS_SWMR_SPIN_LOCK_LOCK_H_
+#define PLS_SWMR_SPIN_LOCK_LOCK_H_
+
+#include <atomic>
+
+#include "pls/internal/helpers/profiler.h"
+
+namespace pls {
+namespace internal {
+namespace base {
+
+/**
+ * Single writer, multiple reader spin lock.
+ * The writer is required to be the same thread all the time (single writer),
+ * while multiple threads can read.
+ * Readers fail to lock when the writer requests the lock,
+ * the acquires the lock after all remaining readers left the critical section.
+ */
+class swmr_spin_lock {
+  std::atomic<int> readers_;
+  std::atomic<int> write_request_;
+
+ public:
+  explicit swmr_spin_lock() : readers_{0}, write_request_{0} {}
+
+  bool reader_try_lock();
+  void reader_unlock();
+
+  void writer_lock();
+  void writer_unlock();
+};
+
+}
+}
+}
+
+#endif //PLS_SWMR_SPIN_LOCK_LOCK_H_

lib/pls/include/pls/internal/base/system_details.h

@@ -3,31 +3,76 @@
 #define PLS_SYSTEM_DETAILS_H
 #define PLS_SYSTEM_DETAILS_H
 
 
 #include <cstdint>
 #include <cstdint>
+#if (COMPILER == MVCC)
+#include <emmintrin.h>
+#endif
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
-             * Collection of system details, e.g. hardware cache line size.
-             *
-             * PORTABILITY:
-             * Currently sane default values for x86.
-             */
-            namespace system_details {
-                /**
-                 * Most processors have 64 byte cache lines
-                 */
-                constexpr std::uintptr_t CACHE_LINE_SIZE = 64;
-
-                /**
-                 * Choose one of the following ways to store thread specific data.
-                 * Try to choose the fastest available on this processor/system.
-                 */
-//                #define PLS_THREAD_SPECIFIC_PTHREAD
-                #define PLS_THREAD_SPECIFIC_COMPILER
-            }
-        }
-    }
+namespace internal {
+namespace base {
+
+/**
+ * Collection of system details, e.g. hardware cache line size.
+ *
+ * PORTABILITY:
+ * Currently sane default values for x86.
+ */
+namespace system_details {
+
+/**
+ * Pointer Types needed for ABA protection mixed into addresses.
+ * pointer_t should be an integer type capable of holding ANY pointer value.
+ */
+using pointer_t = std::uintptr_t;
+constexpr pointer_t ZERO_POINTER = 0;
+constexpr pointer_t MAX_POINTER = ~ZERO_POINTER;
+
+/**
+ * Biggest type that supports atomic CAS operations.
+ * Usually it is sane to assume a pointer can be swapped in a single CAS operation.
+ */
+using cas_integer = pointer_t;
+constexpr cas_integer MIN_CAS_INTEGER = 0;
+constexpr cas_integer MAX_CAS_INTEGER = ~MIN_CAS_INTEGER;
+constexpr cas_integer FIRST_HALF_CAS_INTEGER = MAX_CAS_INTEGER << ((sizeof(cas_integer) / 2) * 8);
+constexpr cas_integer SECOND_HALF_CAS_INTEGER = ~FIRST_HALF_CAS_INTEGER;
+
+/**
+ * Most processors have 64 byte cache lines (last 6 bit of the address are zero at line beginnings).
+ */
+constexpr unsigned int CACHE_LINE_ADDRESS_BITS = 6;
+constexpr pointer_t CACHE_LINE_SIZE = 2u << (CACHE_LINE_ADDRESS_BITS - 1);
+constexpr pointer_t CACHE_LINE_ADDRESS_USED_BITS = MAX_POINTER << CACHE_LINE_ADDRESS_BITS;
+constexpr pointer_t CACHE_LINE_ADDRESS_UNUSED_BITS = ~CACHE_LINE_ADDRESS_USED_BITS;
+
+/**
+ * Choose one of the following ways to store thread specific data.
+ * Try to choose the fastest available on this processor/system.
+ */
+//#define PLS_THREAD_SPECIFIC_PTHREAD
+#define PLS_THREAD_SPECIFIC_COMPILER
+
+/**
+ * When spinning one wants to 'relax' the CPU from some task,
+ * e.g. disabling speculative execution/branch prediction
+ * or reducing its clock speed.
+ * This is both good for power draw, as well as for hyperthreading.
+ *
+ * Choose the implementation appropriate for your compiler-cpu combination.
+ */
+#if (COMPILER == MVCC)
+inline void relax_cpu() {
+  _mm_pause();
+}
+#elif (COMPILER == GCC || COMPILER == LLVM)
+inline void relax_cpu() {
+  asm("pause");
+}
+#endif
+
+}
+}
+}
 }
 }
 
 
 #endif //PLS_SYSTEM_DETAILS_H
 #endif //PLS_SYSTEM_DETAILS_H

lib/pls/include/pls/internal/base/tas_spin_lock.h

@@ -10,30 +10,29 @@
 #include "pls/internal/base/thread.h"
 #include "pls/internal/base/thread.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
-             * A simple set and test_and_set based spin lock implementation.
-             *
-             * PORTABILITY:
-             * Current implementation is based on C++ 11 atomic_flag.
-             */
-            class tas_spin_lock {
-                std::atomic_flag flag_;
-                unsigned int yield_at_tries_;
-
-
-            public:
-                tas_spin_lock(): flag_{ATOMIC_FLAG_INIT}, yield_at_tries_{1024} {};
-                tas_spin_lock(const tas_spin_lock& other): flag_{ATOMIC_FLAG_INIT}, yield_at_tries_{other.yield_at_tries_} {}
-
-                void lock();
-                bool try_lock(unsigned int num_tries=1);
-                void unlock();
-            };
-        }
-    }
-}
+namespace internal {
+namespace base {
+
+/**
+ * A simple set and test_and_set based spin lock implementation.
+ *
+ * PORTABILITY:
+ * Current implementation is based on C++ 11 atomic_flag.
+ */
+class tas_spin_lock {
+  std::atomic_flag flag_;
+
+ public:
+  tas_spin_lock() : flag_{ATOMIC_FLAG_INIT} {};
+  tas_spin_lock(const tas_spin_lock &/*other*/) : flag_{ATOMIC_FLAG_INIT} {}
+
+  void lock();
+  bool try_lock(unsigned int num_tries = 1);
+  void unlock();
+};
 
 
+}
+}
+}
 
 
 #endif //PLS_TAS_SPIN_LOCK_H
 #endif //PLS_TAS_SPIN_LOCK_H

lib/pls/include/pls/internal/base/thread.h

@@ -9,113 +9,122 @@
 #include <functional>
 #include <functional>
 #include <pthread.h>
 #include <pthread.h>
 #include <atomic>
 #include <atomic>
+#include <time.h>
 
 
 #include "system_details.h"
 #include "system_details.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            using thread_entrypoint = void();
-
-            /**
-             * Static methods than can be performed on the current thread.
-             *
-             * usage:
-             * this_thread::yield();
-             * T* state = this_thread::state<T>();
-             *
-             * PORTABILITY:
-             * Current implementation is based on pthreads.
-             */
-            class this_thread {
-                template<typename Function, typename State>
-                friend class thread;
+namespace internal {
+namespace base {
+
+using thread_entrypoint = void();
+
+/**
+ * Static methods than can be performed on the current thread.
+ *
+ * usage:
+ * this_thread::yield();
+ * T* state = this_thread::state<T>();
+ *
+ * PORTABILITY:
+ * Current implementation is based on pthreads.
+ */
+class this_thread {
+  template<typename Function, typename State>
+  friend
+  class thread;
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
-                static pthread_key_t local_storage_key_;
-                static bool local_storage_key_initialized_;
+  static pthread_key_t local_storage_key_;
+  static bool local_storage_key_initialized_;
 #endif
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-                static __thread void* local_state_;
+  static __thread void *local_state_;
 #endif
 #endif
-            public:
-                static void yield() {
-                    pthread_yield();
-                }
-
-                /**
-                 * Retrieves the local state pointer.
-                 *
-                 * @tparam T The type of the state that is stored.
-                 * @return The state pointer hold for this thread.
-                 */
-                template<typename T>
-                static T* state();
-
-                /**
-                 * Stores a pointer to the thread local state object.
-                 * The memory management for this has to be done by the user,
-                 * we only keep the pointer.
-                 *
-                 * @tparam T The type of the state that is stored.
-                 * @param state_pointer A pointer to the threads state object.
-                 */
-                template<typename T>
-                static void set_state(T* state_pointer);
-            };
-
-            /**
-             * Abstraction for starting a function in a separate thread.
-             *
-             * @tparam Function Lambda being started on the new thread.
-             * @tparam State State type held for this thread.
-             *
-             * usage:
-             * T* state;
-             * auto thread = start_thread([] {
-             *      // Run on new thread
-             * }, state);
-             * thread.join(); // Wait for it to finish
-             *
-             * PORTABILITY:
-             * Current implementation is based on pthreads.
-             */
-            template<typename Function, typename State>
-            class thread {
-                friend class this_thread;
-                // Keep a copy of the function (lambda) in this object to make sure it is valid when called!
-                Function function_;
-                State* state_pointer_;
-
-                // Wee need to wait for the started function to read
-                // the function_ and state_pointer_ property before returning
-                // from the constructor, as the object might be moved after this.
-                std::atomic_flag* startup_flag_;
-
-                // Keep handle to native implementation
-                pthread_t pthread_thread_;
-
-                static void* start_pthread_internal(void* thread_pointer);
-
-            public:
-                explicit thread(const Function& function, State* state_pointer);
-
-            public:
-                void join();
-
-                // make object move only
-                thread(thread&&) noexcept = default;
-                thread& operator=(thread&&) noexcept = default;
-
-                thread(const thread&) = delete;
-                thread& operator=(const thread&) = delete;
-            };
-
-            template<typename Function, typename State>
-            thread<Function, State> start_thread(const Function& function, State* state_pointer);
-            template<typename Function>
-            thread<Function, void> start_thread(const Function& function);
-        }
-    }
+ public:
+  static void yield() {
+    pthread_yield();
+  }
+
+  static void sleep(long microseconds) {
+    timespec time{0, 1000 * microseconds};
+    nanosleep(&time, nullptr);
+  }
+
+  /**
+   * Retrieves the local state pointer.
+   *
+   * @tparam T The type of the state that is stored.
+   * @return The state pointer hold for this thread.
+   */
+  template<typename T>
+  static T *state();
+
+  /**
+   * Stores a pointer to the thread local state object.
+   * The memory management for this has to be done by the user,
+   * we only keep the pointer.
+   *
+   * @tparam T The type of the state that is stored.
+   * @param state_pointer A pointer to the threads state object.
+   */
+  template<typename T>
+  static void set_state(T *state_pointer);
+};
+
+/**
+ * Abstraction for starting a function in a separate thread.
+ *
+ * @tparam Function Lambda being started on the new thread.
+ * @tparam State State type held for this thread.
+ *
+ * usage:
+ * T* state;
+ * auto thread = start_thread([] {
+ *      // Run on new thread
+ * }, state);
+ * thread.join(); // Wait for it to finish
+ *
+ * PORTABILITY:
+ * Current implementation is based on pthreads.
+ */
+template<typename Function, typename State>
+class thread {
+  friend class this_thread;
+  // Keep a copy of the function (lambda) in this object to make sure it is valid when called!
+  Function function_;
+  State *state_pointer_;
+
+  // Wee need to wait for the started function to read
+  // the function_ and state_pointer_ property before returning
+  // from the constructor, as the object might be moved after this.
+  std::atomic_flag *startup_flag_;
+
+  // Keep handle to native implementation
+  pthread_t pthread_thread_;
+
+  static void *start_pthread_internal(void *thread_pointer);
+
+ public:
+  explicit thread(const Function &function, State *state_pointer);
+
+ public:
+  void join();
+
+  // make object move only
+  thread(thread &&) noexcept = default;
+  thread &operator=(thread &&) noexcept = default;
+
+  thread(const thread &) = delete;
+  thread &operator=(const thread &) = delete;
+};
+
+template<typename Function, typename State>
+thread<Function, State> start_thread(const Function &function, State *state_pointer);
+template<typename Function>
+thread<Function, void> start_thread(const Function &function);
+
+}
+}
 }
 }
 #include "thread_impl.h"
 #include "thread_impl.h"
 
 

lib/pls/include/pls/internal/base/thread_impl.h

@@ -3,86 +3,87 @@
 #define PLS_THREAD_IMPL_H
 #define PLS_THREAD_IMPL_H
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            template<typename T>
-            T* this_thread::state() {
+namespace internal {
+namespace base {
+
+template<typename T>
+T *this_thread::state() {
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
-                return reinterpret_cast<T*>(pthread_getspecific(local_storage_key_));
+  return reinterpret_cast<T*>(pthread_getspecific(local_storage_key_));
 #endif
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-                return reinterpret_cast<T*>(local_state_);
+  return reinterpret_cast<T *>(local_state_);
 #endif
 #endif
-            }
+}
 
 
-            template<typename T>
-            void this_thread::set_state(T* state_pointer) {
+template<typename T>
+void this_thread::set_state(T *state_pointer) {
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
-                pthread_setspecific(this_thread::local_storage_key_, (void*)state_pointer);
+  pthread_setspecific(this_thread::local_storage_key_, (void*)state_pointer);
 #endif
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-                local_state_ = state_pointer;
+  local_state_ = state_pointer;
 #endif
 #endif
-            }
+}
 
 
-            template<typename Function, typename State>
-            void* thread<Function, State>::start_pthread_internal(void* thread_pointer) {
-                auto my_thread = reinterpret_cast<thread*>(thread_pointer);
-                Function my_function_copy = my_thread->function_;
-                State* my_state_pointer_copy = my_thread->state_pointer_;
+template<typename Function, typename State>
+void *thread<Function, State>::start_pthread_internal(void *thread_pointer) {
+  auto my_thread = reinterpret_cast<thread *>(thread_pointer);
+  Function my_function_copy = my_thread->function_;
+  State *my_state_pointer_copy = my_thread->state_pointer_;
 
 
-                // Now we have copies of everything we need on the stack.
-                // The original thread object can be moved freely (no more
-                // references to its memory location).
-                my_thread->startup_flag_->clear();
+  // Now we have copies of everything we need on the stack.
+  // The original thread object can be moved freely (no more
+  // references to its memory location).
+  my_thread->startup_flag_->clear();
 
 
-                this_thread::set_state(my_state_pointer_copy);
-                my_function_copy();
+  this_thread::set_state(my_state_pointer_copy);
+  my_function_copy();
 
 
-                // Finished executing the user function
-                pthread_exit(nullptr);
-            }
+  // Finished executing the user function
+  pthread_exit(nullptr);
+}
 
 
-            template<typename Function, typename State>
-            thread<Function, State>::thread(const Function& function, State* state_pointer):
-                    function_{function},
-                    state_pointer_{state_pointer},
-                    startup_flag_{nullptr},
-                    pthread_thread_{} {
+template<typename Function, typename State>
+thread<Function, State>::thread(const Function &function, State *state_pointer):
+    function_{function},
+    state_pointer_{state_pointer},
+    startup_flag_{nullptr},
+    pthread_thread_{} {
 
 
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
-                if (!this_thread::local_storage_key_initialized_) {
-                        pthread_key_create(&this_thread::local_storage_key_, nullptr);
-                        this_thread::local_storage_key_initialized_ = true;
-                    }
+  if (!this_thread::local_storage_key_initialized_) {
+          pthread_key_create(&this_thread::local_storage_key_, nullptr);
+          this_thread::local_storage_key_initialized_ = true;
+      }
 #endif
 #endif
 
 
-                // We only need this during startup, will be destroyed when out of scope
-                std::atomic_flag startup_flag{ATOMIC_FLAG_INIT};
-                startup_flag_ = &startup_flag;
-
-                startup_flag.test_and_set(); // Set the flag, pthread will clear it when it is safe to return
-                pthread_create(&pthread_thread_, nullptr, start_pthread_internal, (void *)(this));
-                while (startup_flag.test_and_set())
-                    ; // Busy waiting for the starting flag to clear
-            }
-
-            template<typename Function, typename State>
-            void thread<Function, State>::join() {
-                pthread_join(pthread_thread_, nullptr);
-            }
-
-            template<typename Function, typename State>
-            thread<Function, State> start_thread(const Function& function, State* state_pointer) {
-                return thread<Function, State>(function, state_pointer);
-            }
-
-            template<typename Function>
-            thread<Function, void> start_thread(const Function& function) {
-                return thread<Function, void>(function, nullptr);
-            }
-        }
-    }
+  // We only need this during startup, will be destroyed when out of scope
+  std::atomic_flag startup_flag{ATOMIC_FLAG_INIT};
+  startup_flag_ = &startup_flag;
+
+  startup_flag.test_and_set(); // Set the flag, pthread will clear it when it is safe to return
+  pthread_create(&pthread_thread_, nullptr, start_pthread_internal, (void *) (this));
+  while (startup_flag.test_and_set()); // Busy waiting for the starting flag to clear
+}
+
+template<typename Function, typename State>
+void thread<Function, State>::join() {
+  pthread_join(pthread_thread_, nullptr);
+}
+
+template<typename Function, typename State>
+thread<Function, State> start_thread(const Function &function, State *state_pointer) {
+  return thread<Function, State>(function, state_pointer);
+}
+
+template<typename Function>
+thread<Function, void> start_thread(const Function &function) {
+  return thread<Function, void>(function, nullptr);
+}
+
+}
+}
 }
 }
 
 
 #endif //PLS_THREAD_IMPL_H
 #endif //PLS_THREAD_IMPL_H

lib/pls/include/pls/internal/base/ttas_spin_lock.h

@@ -6,32 +6,30 @@
 #include <iostream>
 #include <iostream>
 
 
 #include "pls/internal/base/thread.h"
 #include "pls/internal/base/thread.h"
+#include "pls/internal/base/backoff.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            /**
-             * A simple set and test_and_set based spin lock implementation.
-             *
-             * PORTABILITY:
-             * Current implementation is based on C++ 11 atomic_flag.
-             */
-            class ttas_spin_lock {
-                std::atomic<int> flag_;
-                const unsigned int yield_at_tries_;
-
-
-            public:
-                ttas_spin_lock(): flag_{0}, yield_at_tries_{1024} {};
-                ttas_spin_lock(const ttas_spin_lock& other): flag_{0}, yield_at_tries_{other.yield_at_tries_} {}
-
-                void lock();
-                bool try_lock(unsigned int num_tries=1);
-                void unlock();
-            };
-        }
-    }
+namespace internal {
+namespace base {
+/**
+ * A simple set and test_and_set based spin lock implementation.
+ *
+ * PORTABILITY:
+ * Current implementation is based on C++ 11 atomic_flag.
+ */
+class ttas_spin_lock {
+  std::atomic<int> flag_;
+
+ public:
+  ttas_spin_lock() : flag_{0} {};
+  ttas_spin_lock(const ttas_spin_lock &/*other*/) : flag_{0} {}
+
+  void lock();
+  bool try_lock(unsigned int num_tries = 1);
+  void unlock();
+};
+}
+}
 }
 }
-
 
 
 #endif //PLS_TTAS_SPIN_LOCK_H
 #endif //PLS_TTAS_SPIN_LOCK_H

lib/pls/include/pls/internal/data_structures/aligned_stack.h

@@ -9,45 +9,50 @@
 #include "pls/internal/base/alignment.h"
 #include "pls/internal/base/alignment.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            /**
-             * Generic stack-like data structure that allows to allocate arbitrary objects in a given memory region.
-             * The objects will be stored aligned in the stack, making the storage cache friendly and very fast
-             * (as long as one can live with the stack restrictions).
-             *
-             * IMPORTANT: Does not call destructors on stored objects! Do not allocate resources in the objects!
-             *
-             * Usage:
-             * aligned_stack stack{pointer_to_memory, size_of_memory};
-             * T* pointer = stack.push(some_object); // Copy-Constrict the object on top of stack
-             * stack.pop<T>(); // Deconstruct the top object of type T
-             */
-            class aligned_stack {
-                // Keep bounds of our memory block
-                char* memory_start_;
-                char* memory_end_;
-
-                // Current head will always be aligned to cache lines
-                char* head_;
-            public:
-                typedef char* state;
-
-                aligned_stack(): memory_start_{nullptr}, memory_end_{nullptr}, head_{nullptr} {};
-                aligned_stack(char* memory_region, std::size_t size);
-
-                template<typename T>
-                T* push(const T& object);
-                template<typename T>
-                void* push();
-                template<typename T>
-                T pop();
-
-                state save_state() const { return head_; }
-                void reset_state(state new_state) { head_ = new_state; }
-            };
-        }
-    }
+namespace internal {
+namespace data_structures {
+
+using base::system_details::pointer_t;
+
+/**
+ * Generic stack-like data structure that allows to allocate arbitrary objects in a given memory region.
+ * The objects will be stored aligned in the stack, making the storage cache friendly and very fast
+ * (as long as one can live with the stack restrictions).
+ *
+ * IMPORTANT: Does not call destructors on stored objects! Do not allocate resources in the objects!
+ *
+ * Usage:
+ * aligned_stack stack{pointer_to_memory, size_of_memory};
+ * T* pointer = stack.push(some_object); // Copy-Constrict the object on top of stack
+ * stack.pop<T>(); // Deconstruct the top object of type T
+ */
+class aligned_stack {
+  // Keep bounds of our memory block
+  pointer_t memory_start_;
+  pointer_t memory_end_;
+
+  // Current head will always be aligned to cache lines
+  pointer_t head_;
+ public:
+  typedef pointer_t state;
+
+  aligned_stack() : memory_start_{0}, memory_end_{0}, head_{0} {};
+  aligned_stack(pointer_t memory_region, std::size_t size);
+  aligned_stack(char *memory_region, std::size_t size);
+
+  template<typename T>
+  T *push(const T &object);
+  template<typename T>
+  void *push();
+  template<typename T>
+  T pop();
+
+  state save_state() const { return head_; }
+  void reset_state(state new_state) { head_ = new_state; }
+};
+
+}
+}
 }
 }
 #include "aligned_stack_impl.h"
 #include "aligned_stack_impl.h"
 
 

lib/pls/include/pls/internal/data_structures/aligned_stack_impl.h

@@ -3,34 +3,36 @@
 #define PLS_ALIGNED_STACK_IMPL_H
 #define PLS_ALIGNED_STACK_IMPL_H
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            template<typename T>
-            T* aligned_stack::push(const T& object) {
-                // Copy-Construct
-                return new ((void*)push<T>())T(object);
-            }
-
-            template<typename T>
-            void* aligned_stack::push() {
-                void* result = reinterpret_cast<T*>(head_);
-
-                // Move head to next aligned position after new object
-                head_ = base::alignment::next_alignment(head_ + sizeof(T));
-                if (head_ >= memory_end_) {
-                    PLS_ERROR("Tried to allocate object on alligned_stack without sufficient memory!");
-                }
-
-                return result;
-            }
-
-            template<typename T>
-            T aligned_stack::pop() {
-                head_ = head_ - base::alignment::next_alignment(sizeof(T));
-                return *reinterpret_cast<T*>(head_);
-            }
-        }
-    }
+namespace internal {
+namespace data_structures {
+
+template<typename T>
+T *aligned_stack::push(const T &object) {
+  // Copy-Construct
+  return new(push < T > ())T(object);
+}
+
+template<typename T>
+void *aligned_stack::push() {
+  void *result = reinterpret_cast<T *>(head_);
+
+  // Move head to next aligned position after new object
+  head_ = base::alignment::next_alignment(head_ + sizeof(T));
+  if (head_ >= memory_end_) {
+    PLS_ERROR("Tried to allocate object on alligned_stack without sufficient memory!");
+  }
+
+  return result;
+}
+
+template<typename T>
+T aligned_stack::pop() {
+  head_ = head_ - base::alignment::next_alignment(sizeof(T));
+  return *reinterpret_cast<T *>(head_);
+}
+
+}
+}
 }
 }
 
 
 #endif //PLS_ALIGNED_STACK_IMPL_H
 #endif //PLS_ALIGNED_STACK_IMPL_H

lib/pls/include/pls/internal/data_structures/deque.h

@@ -5,56 +5,58 @@
 #include "pls/internal/base/spin_lock.h"
 #include "pls/internal/base/spin_lock.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            /**
-             * Turns any object into deque item when inheriting from this.
-             */
-            class deque_item {
-                friend class deque_internal;
-
-                deque_item* prev_;
-                deque_item* next_;
-
-            };
-
-            class deque_internal {
-            protected:
-                deque_item* head_;
-                deque_item* tail_;
-
-                base::spin_lock lock_;
-
-                deque_item* pop_head_internal();
-                deque_item* pop_tail_internal();
-                void push_tail_internal(deque_item *new_item);
-            };
-
-            /**
-             * A double linked list based deque.
-             * Storage is therefore only needed for the individual items.
-             *
-             * @tparam Item The type of items stored in this deque
-             */
-            template<typename Item>
-            class deque: deque_internal {
-            public:
-                explicit deque(): deque_internal{} {}
-
-                inline Item* pop_head() {
-                    return static_cast<Item*>(pop_head_internal());
-                }
-
-                inline Item* pop_tail() {
-                    return static_cast<Item*>(pop_tail_internal());
-                }
-
-                inline void push_tail(Item* new_item) {
-                    push_tail_internal(new_item);
-                }
-            };
-        }
-    }
+namespace internal {
+namespace data_structures {
+
+/**
+ * Turns any object into deque item when inheriting from this.
+ */
+class deque_item {
+  friend class deque_internal;
+
+  deque_item *prev_;
+  deque_item *next_;
+
+};
+
+class deque_internal {
+ protected:
+  deque_item *head_;
+  deque_item *tail_;
+
+  base::spin_lock lock_;
+
+  deque_item *pop_head_internal();
+  deque_item *pop_tail_internal();
+  void push_tail_internal(deque_item *new_item);
+};
+
+/**
+ * A double linked list based deque.
+ * Storage is therefore only needed for the individual items.
+ *
+ * @tparam Item The type of items stored in this deque
+ */
+template<typename Item>
+class deque : deque_internal {
+ public:
+  explicit deque() : deque_internal{} {}
+
+  inline Item *pop_head() {
+    return static_cast<Item *>(pop_head_internal());
+  }
+
+  inline Item *pop_tail() {
+    return static_cast<Item *>(pop_tail_internal());
+  }
+
+  inline void push_tail(Item *new_item) {
+    push_tail_internal(new_item);
+  }
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_DEQUE_H
 #endif //PLS_DEQUE_H

lib/pls/include/pls/internal/data_structures/work_stealing_deque.h

+
+#ifndef PLS_WORK_STEALING_DEQUE_H_
+#define PLS_WORK_STEALING_DEQUE_H_
+
+#include <atomic>
+#include <mutex>
+#include <pls/internal/scheduling/thread_state.h>
+
+#include "pls/internal/base/system_details.h"
+#include "pls/internal/base/spin_lock.h"
+#include "pls/internal/base/error_handling.h"
+
+#include "aligned_stack.h"
+
+namespace pls {
+namespace internal {
+namespace data_structures {
+
+using cas_integer = base::system_details::cas_integer;
+using pointer_t = base::system_details::pointer_t;
+static cas_integer get_stamp(cas_integer n) {
+  return (n & base::system_details::FIRST_HALF_CAS_INTEGER) >> ((sizeof(cas_integer) / 2) * 8);
+}
+static cas_integer get_offset(cas_integer n) {
+  return n & base::system_details::SECOND_HALF_CAS_INTEGER;
+}
+static cas_integer set_stamp(cas_integer n, cas_integer new_value) {
+  return (new_value << ((sizeof(cas_integer) / 2) * 8)) | (n & base::system_details::SECOND_HALF_CAS_INTEGER);
+}
+//static cas_integer set_offset(cas_integer n, cas_integer new_value) {
+//  return new_value | (n & base::system_details::FIRST_HALF_CAS_INTEGER);
+//}
+
+class work_stealing_deque_item {
+  // Pointer to the actual data
+  pointer_t data_;
+  // Index (relative to stack base) to the next and previous element
+  cas_integer next_item_;
+  cas_integer previous_item_;
+
+ public:
+  work_stealing_deque_item() : data_{0}, next_item_{0}, previous_item_{0} {}
+
+  template<typename Item>
+  Item *data() {
+    return reinterpret_cast<Item *>(data_);
+  }
+
+  template<typename Item>
+  void set_data(Item *data) {
+    data_ = reinterpret_cast<pointer_t >(data);
+  }
+
+  cas_integer next_item() {
+    return next_item_;
+  }
+  void set_next_item(cas_integer next_item) {
+    next_item_ = next_item;
+  }
+  cas_integer previous_item() {
+    return previous_item_;
+  }
+  void set_previous_item(cas_integer previous_item) {
+    previous_item_ = previous_item;
+  }
+};
+static_assert(sizeof(work_stealing_deque_item) < base::system_details::CACHE_LINE_SIZE,
+              "Work stealing deque relies on memory layout and requires cache lines to be longer than one 'work_stealing_deque_item' instance!");
+
+template<typename Item>
+class work_stealing_deque {
+  // Deque 'takes over' stack and handles memory management while in use.
+  // At any point in time the deque can stop using more memory and the stack can be used by other entities.
+  aligned_stack *stack_;
+  pointer_t base_pointer_;
+
+  std::atomic<cas_integer> head_;
+  std::atomic<cas_integer> tail_;
+  cas_integer previous_tail_;
+
+  base::spin_lock lock_{}; // TODO: Remove after debugging
+
+
+ public:
+  using state = aligned_stack::state;
+
+  explicit work_stealing_deque(aligned_stack *stack) : stack_{stack},
+                                                       base_pointer_{0},
+                                                       head_{0},
+                                                       tail_{0},
+                                                       previous_tail_{0} {
+    reset_base_pointer();
+  }
+  work_stealing_deque(const work_stealing_deque &other) : stack_{other.stack_},
+                                                          base_pointer_{other.base_pointer_},
+                                                          head_{other.head_.load()},
+                                                          tail_{other.tail_.load()},
+                                                          previous_tail_{other.previous_tail_} {}
+
+  void reset_base_pointer() {
+    base_pointer_ = reinterpret_cast<pointer_t >(stack_->save_state()); // Keep the base of our region in the stack
+  }
+
+  work_stealing_deque_item *item_at(cas_integer position) {
+    return reinterpret_cast<work_stealing_deque_item *>(base_pointer_
+        + (base::system_details::CACHE_LINE_SIZE * position));
+  }
+
+  cas_integer current_stack_offset() {
+    return (stack_->save_state() - base_pointer_) / base::system_details::CACHE_LINE_SIZE;
+  }
+
+  template<typename T>
+  std::pair<work_stealing_deque_item, T> *allocate_item(const T &new_item) {
+    // 'Union' type to push both on stack
+    using pair_t = std::pair<work_stealing_deque_item, T>;
+    // Allocate space on stack
+    auto new_pair = reinterpret_cast<pair_t *>(stack_->push<pair_t>());
+    // Initialize memory on stack
+    new((void *) &(new_pair->first)) work_stealing_deque_item();
+    new((void *) &(new_pair->second)) T(new_item);
+
+    return new_pair;
+  }
+
+  template<typename T>
+  Item *push_tail(const T &new_item) {
+    cas_integer local_tail = tail_;
+
+    auto new_pair = allocate_item(new_item);
+    // Prepare current tail to point to correct next items
+    auto tail_deque_item = item_at(local_tail);
+    tail_deque_item->set_data(&(new_pair->second));
+    tail_deque_item->set_next_item(current_stack_offset());
+    tail_deque_item->set_previous_item(previous_tail_);
+    previous_tail_ = local_tail;
+
+    // Linearization point, item appears after this write
+    cas_integer new_tail = current_stack_offset();
+    tail_ = new_tail;
+
+    return &(new_pair->second);
+  }
+
+  Item *pop_tail() {
+    cas_integer local_tail = tail_;
+    cas_integer local_head = head_;
+
+    if (local_tail <= get_offset(local_head)) {
+      return nullptr; // EMPTY
+    }
+
+    work_stealing_deque_item *previous_tail_item = item_at(previous_tail_);
+    cas_integer new_tail = previous_tail_;
+    previous_tail_ = previous_tail_item->previous_item();
+
+    // Publish our wish to set the tail back
+    tail_ = new_tail;
+    // Get the state of local head AFTER we published our wish
+    local_head = head_; // Linearization point, outside knows list is empty
+
+    if (get_offset(local_head) < new_tail) {
+      return previous_tail_item->data<Item>(); // Success, enough distance to other threads
+    }
+
+    if (get_offset(local_head) == new_tail) {
+      cas_integer new_head = set_stamp(new_tail, get_stamp(local_head) + 1);
+      // Try competing with consumers by updating the head's stamp value
+      if (head_.compare_exchange_strong(local_head, new_head)) {
+        return previous_tail_item->data<Item>(); // SUCCESS, we won the competition with other threads
+      }
+    }
+
+    // Some other thread either won the competition or it already set the head further than we are
+    // before we even tried to compete with it.
+    // Reset the queue into an empty state => head_ = tail_
+    tail_ = get_offset(local_head); // ...we give up to the other winning thread
+
+    return nullptr; // EMPTY, we lost the competition with other threads
+  }
+
+  Item *pop_head() {
+    cas_integer local_head = head_;
+    cas_integer local_tail = tail_;
+
+    if (local_tail <= get_offset(local_head)) {
+      return nullptr; // EMPTY
+    }
+    // Load info on current deque item.
+    // In case we have a race with a new (aba) overwritten item at this position,
+    // there has to be a competition over the tail -> the stamp increased and our next
+    // operation will fail anyways!
+    work_stealing_deque_item *head_deque_item = item_at(get_offset(local_head));
+    cas_integer next_item_offset = head_deque_item->next_item();
+    Item *head_data_item = head_deque_item->data<Item>();
+
+    // We try to set the head to this new position.
+    // Possible outcomes:
+    // 1) no one interrupted us, we win this competition
+    // 2) other thread took the head, we lose to this
+    // 3) owning thread removed tail, we lose to this
+    cas_integer new_head = set_stamp(next_item_offset, get_stamp(local_head) + 1);
+    if (head_.compare_exchange_strong(local_head, new_head)) {
+      return head_data_item; // SUCCESS, we won the competition
+    }
+
+    return nullptr; // EMPTY, we lost the competition
+
+  }
+
+  void release_memory_until(state state) {
+    cas_integer item_offset = (state - base_pointer_) / base::system_details::CACHE_LINE_SIZE;
+
+    cas_integer local_head = head_;
+    cas_integer local_tail = tail_;
+
+    stack_->reset_state(state);
+
+    if (item_offset < local_tail) {
+      tail_ = item_offset;
+      if (get_offset(local_head) >= local_tail) {
+        head_ = set_stamp(item_offset, get_stamp(local_head) + 1);
+      }
+    }
+  }
+
+  void release_memory_until(Item *item) {
+    release_memory_until(reinterpret_cast<pointer_t >(item));
+  }
+
+  state save_state() {
+    return stack_->save_state();
+  }
+};
+
+}
+}
+}
+
+#endif //PLS_WORK_STEALING_DEQUE_H_

lib/pls/include/pls/internal/helpers/mini_benchmark.h

@@ -9,45 +9,47 @@
 #include <iostream>
 #include <iostream>
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace helpers {
-            // TODO: Clean up (separate into small functions and .cpp file)
-            template<typename Function>
-            void run_mini_benchmark(const Function& lambda, size_t max_threads, unsigned long max_runtime_ms=1000) {
-                using namespace std;
-                using namespace pls::internal::scheduling;
-
-                malloc_scheduler_memory scheduler_memory{max_threads};
-                for (unsigned int num_threads = 1; num_threads <= max_threads; num_threads++) {
-                    scheduler local_scheduler{&scheduler_memory, num_threads};
-
-                    chrono::high_resolution_clock::time_point start_time;
-                    chrono::high_resolution_clock::time_point end_time;
-                    unsigned long iterations = 0;
-                    local_scheduler.perform_work([&] {
-                        start_time = chrono::high_resolution_clock::now();
-                        end_time = start_time;
-                        chrono::high_resolution_clock::time_point planned_end_time = start_time + chrono::milliseconds(max_runtime_ms);
-
-                        while (end_time < planned_end_time) {
-                            lambda();
-                            end_time = chrono::high_resolution_clock::now();
-                            iterations++;
-                        }
-                    });
-
-                    long time = chrono::duration_cast<chrono::microseconds>(end_time - start_time).count();
-                    double time_per_iteration = (double)time / iterations;
-
-                    std::cout << time_per_iteration;
-                    if (num_threads < max_threads) {
-                        std::cout << ",";
-                    }
-                }
-                std::cout << std::endl;
-            }
-        }
+namespace internal {
+namespace helpers {
+
+// TODO: Clean up (separate into small functions and .cpp file)
+template<typename Function>
+void run_mini_benchmark(const Function &lambda, size_t max_threads, unsigned long max_runtime_ms = 1000) {
+  using namespace std;
+  using namespace pls::internal::scheduling;
+
+  malloc_scheduler_memory scheduler_memory{max_threads};
+  for (unsigned int num_threads = 1; num_threads <= max_threads; num_threads++) {
+    scheduler local_scheduler{&scheduler_memory, num_threads};
+
+    chrono::high_resolution_clock::time_point start_time;
+    chrono::high_resolution_clock::time_point end_time;
+    unsigned long iterations = 0;
+    local_scheduler.perform_work([&] {
+      start_time = chrono::high_resolution_clock::now();
+      end_time = start_time;
+      chrono::high_resolution_clock::time_point planned_end_time = start_time + chrono::milliseconds(max_runtime_ms);
+
+      while (end_time < planned_end_time) {
+        lambda();
+        end_time = chrono::high_resolution_clock::now();
+        iterations++;
+      }
+    });
+
+    long time = chrono::duration_cast<chrono::microseconds>(end_time - start_time).count();
+    double time_per_iteration = (double) time / iterations;
+
+    std::cout << time_per_iteration;
+    if (num_threads < max_threads) {
+      std::cout << ",";
     }
     }
+  }
+  std::cout << std::endl;
+}
+
+}
+}
 }
 }
 
 
 #endif //PLS_MINI_BENCHMARK_H
 #endif //PLS_MINI_BENCHMARK_H

lib/pls/include/pls/internal/helpers/prohibit_new.h

@@ -15,9 +15,9 @@
 #ifdef NEW_LINK_ERROR
 #ifdef NEW_LINK_ERROR
 // This will cause a linker error if new is used in the code.
 // This will cause a linker error if new is used in the code.
 // We also exit if it is somehow still called.
 // We also exit if it is somehow still called.
-inline void * operator new (std::size_t) {
-    extern int bare_new_erroneously_called();
-    exit(bare_new_erroneously_called() | 1);
+inline void *operator new(std::size_t) {
+  extern int bare_new_erroneously_called();
+  exit(bare_new_erroneously_called() | 1);
 }
 }
 #else
 #else
 // Use this + debugging point to find out where we use a new
 // Use this + debugging point to find out where we use a new

lib/pls/include/pls/internal/helpers/unique_id.h

@@ -7,25 +7,27 @@
 #include <stdint.h>
 #include <stdint.h>
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace helpers {
-            struct unique_id {
-                const uint32_t id_;
-                const std::type_info& type_;
-                bool operator==(const unique_id& other) const { return id_ == other.id_ && type_ == other.type_; }
+namespace internal {
+namespace helpers {
 
 
-                static constexpr unique_id create(const uint32_t id) {
-                    return unique_id(id, typeid(void));
-                }
-                template<typename ...T>
-                static constexpr unique_id create() {
-                    return unique_id(UINT32_MAX, typeid(std::tuple<T...>));
-                }
-            private:
-                explicit constexpr unique_id(const uint32_t id, const std::type_info& type): id_{id}, type_{type} {};
-            };
-        }
-    }
+struct unique_id {
+  const uint32_t id_;
+  const std::type_info &type_;
+  bool operator==(const unique_id &other) const { return id_ == other.id_ && type_ == other.type_; }
+
+  static constexpr unique_id create(const uint32_t id) {
+    return unique_id(id, typeid(void));
+  }
+  template<typename ...T>
+  static constexpr unique_id create() {
+    return unique_id(UINT32_MAX, typeid(std::tuple<T...>));
+  }
+ private:
+  explicit constexpr unique_id(const uint32_t id, const std::type_info &type) : id_{id}, type_{type} {};
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_UNIQUE_ID_H
 #endif //PLS_UNIQUE_ID_H

lib/pls/include/pls/internal/scheduling/abstract_task.h

@@ -2,42 +2,44 @@
 #ifndef PLS_ABSTRACT_TASK_H
 #ifndef PLS_ABSTRACT_TASK_H
 #define PLS_ABSTRACT_TASK_H
 #define PLS_ABSTRACT_TASK_H
 
 
-#include "pls/internal/base/spin_lock.h"
+#include "pls/internal/base/swmr_spin_lock.h"
 #include "pls/internal/helpers/unique_id.h"
 #include "pls/internal/helpers/unique_id.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            class abstract_task {
-            public:
-                using id = helpers::unique_id;
-
-            private:
-                unsigned int depth_;
-                abstract_task::id unique_id_;
-                abstract_task* child_task_;
-
-            public:
-                abstract_task(const unsigned int depth, const abstract_task::id& unique_id):
-                    depth_{depth},
-                    unique_id_{unique_id},
-                    child_task_{nullptr} {}
-
-                virtual void execute() = 0;
-                void set_child(abstract_task* child_task) { child_task_ = child_task; }
-                abstract_task* child() { return child_task_; }
-
-                void set_depth(unsigned int depth) { depth_ = depth; }
-                unsigned int depth() const { return depth_; }
-                id unique_id() const { return unique_id_; }
-            protected:
-                virtual bool internal_stealing(abstract_task* other_task) = 0;
-                virtual bool split_task(base::spin_lock* lock) = 0;
-
-                bool steal_work();
-            };
-        }
-    }
+namespace internal {
+namespace scheduling {
+
+class abstract_task {
+ public:
+  using id = helpers::unique_id;
+
+ private:
+  unsigned int depth_;
+  abstract_task::id unique_id_;
+  abstract_task *volatile child_task_;
+
+ public:
+  abstract_task(const unsigned int depth, const abstract_task::id &unique_id) :
+      depth_{depth},
+      unique_id_{unique_id},
+      child_task_{nullptr} {}
+
+  virtual void execute() = 0;
+  void set_child(abstract_task *child_task) { child_task_ = child_task; }
+  abstract_task *child() const { return child_task_; }
+
+  void set_depth(unsigned int depth) { depth_ = depth; }
+  unsigned int depth() const { return depth_; }
+  id unique_id() const { return unique_id_; }
+ protected:
+  virtual bool internal_stealing(abstract_task *other_task) = 0;
+  virtual bool split_task(base::swmr_spin_lock *lock) = 0;
+
+  bool steal_work();
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_ABSTRACT_TASK_H
 #endif //PLS_ABSTRACT_TASK_H

lib/pls/include/pls/internal/scheduling/fork_join_task.h

@@ -5,94 +5,119 @@
 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/helpers/profiler.h"
 
 
 #include "pls/internal/data_structures/aligned_stack.h"
 #include "pls/internal/data_structures/aligned_stack.h"
-#include "pls/internal/data_structures/deque.h"
+#include "pls/internal/data_structures/work_stealing_deque.h"
 
 
 #include "abstract_task.h"
 #include "abstract_task.h"
 #include "thread_state.h"
 #include "thread_state.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            class fork_join_task;
-            class fork_join_sub_task: public data_structures::deque_item {
-                friend class fork_join_task;
-
-                // Coordinate finishing of sub_tasks
-                std::atomic_uint32_t ref_count_;
-                fork_join_sub_task* parent_;
-
-                // Access to TBB scheduling environment
-                fork_join_task* tbb_task_;
-
-                // Stack Management (reset stack pointer after wait_for_all() calls)
-                data_structures::aligned_stack::state stack_state_;
-            protected:
-                explicit fork_join_sub_task();
-                fork_join_sub_task(const fork_join_sub_task& other);
-
-                // Overwritten with behaviour of child tasks
-                virtual void execute_internal() = 0;
-
-            public:
-                // Only use them when actually executing this sub_task (only public for simpler API design)
-                template<typename T>
-                void spawn_child(const T& sub_task);
-                void wait_for_all();
-
-            private:
-                void spawn_child_internal(fork_join_sub_task* sub_task);
-                void execute();
-            };
-
-            template<typename Function>
-            class fork_join_lambda: public fork_join_sub_task {
-                const Function* function_;
-
-            public:
-                explicit fork_join_lambda(const Function* function): function_{function} {};
-
-            protected:
-                void execute_internal() override {
-                    (*function_)(this);
-                }
-            };
-
-            class fork_join_task: public abstract_task {
-                friend class fork_join_sub_task;
-
-                fork_join_sub_task* root_task_;
-                fork_join_sub_task* currently_executing_;
-                data_structures::aligned_stack* my_stack_;
-
-                // Double-Ended Queue management
-                data_structures::deque<fork_join_sub_task> deque_;
-
-                // Steal Management
-                fork_join_sub_task* last_stolen_;
-
-                fork_join_sub_task* get_local_sub_task();
-                fork_join_sub_task* get_stolen_sub_task();
-
-            protected:
-                bool internal_stealing(abstract_task* other_task) override;
-                bool split_task(base::spin_lock* /*lock*/) override;
-
-            public:
-                explicit fork_join_task(fork_join_sub_task* root_task, const abstract_task::id& id);
-                void execute() override;
-                fork_join_sub_task* currently_executing() const;
-            };
-
-            template<typename T>
-            void fork_join_sub_task::spawn_child(const T& task) {
-                PROFILE_FORK_JOIN_STEALING("spawn_child")
-                static_assert(std::is_base_of<fork_join_sub_task, T>::value, "Only pass fork_join_sub_task subclasses!");
-
-                T* new_task = tbb_task_->my_stack_->push(task);
-                spawn_child_internal(new_task);
-            }
-        }
-    }
+namespace internal {
+namespace scheduling {
+
+class fork_join_task;
+class fork_join_sub_task {
+  friend class fork_join_task;
+
+  // Coordinate finishing of sub_tasks
+  std::atomic_uint32_t ref_count_;
+  fork_join_sub_task *parent_;
+
+  // Access to TBB scheduling environment
+  fork_join_task *tbb_task_;
+
+  bool executed = false;
+  int executed_at = -1;
+
+  // Stack Management (reset stack pointer after wait_for_all() calls)
+  data_structures::work_stealing_deque<fork_join_sub_task>::state deque_state_;
+ protected:
+  explicit fork_join_sub_task();
+  fork_join_sub_task(const fork_join_sub_task &other);
+
+  // Overwritten with behaviour of child tasks
+  virtual void execute_internal() = 0;
+
+ public:
+  // Only use them when actually executing this sub_task (only public for simpler API design)
+  template<typename T>
+  void spawn_child(T &sub_task);
+  void wait_for_all();
+
+  static fork_join_sub_task *current();
+ private:
+  void execute();
+};
+
+template<typename Function>
+class fork_join_lambda_by_reference : public fork_join_sub_task {
+  const Function &function_;
+
+ public:
+  explicit fork_join_lambda_by_reference(const Function &function) : fork_join_sub_task{}, function_{function} {};
+
+ protected:
+  void execute_internal() override {
+    function_();
+  }
+};
+
+template<typename Function>
+class fork_join_lambda_by_value : public fork_join_sub_task {
+  const Function function_;
+
+ public:
+  explicit fork_join_lambda_by_value(const Function &function) : fork_join_sub_task{}, function_{function} {};
+
+ protected:
+  void execute_internal() override {
+    function_();
+  }
+};
+
+class fork_join_task : public abstract_task {
+  friend class fork_join_sub_task;
+
+  fork_join_sub_task *root_task_;
+  fork_join_sub_task *currently_executing_;
+
+  // Double-Ended Queue management
+  data_structures::work_stealing_deque<fork_join_sub_task> deque_;
+
+  // Steal Management
+  fork_join_sub_task *last_stolen_;
+
+  fork_join_sub_task *get_local_sub_task();
+  fork_join_sub_task *get_stolen_sub_task();
+
+  bool internal_stealing(abstract_task *other_task) override;
+  bool split_task(base::swmr_spin_lock * /*lock*/) override;
+
+ public:
+  explicit fork_join_task(fork_join_sub_task *root_task, const abstract_task::id &id);
+  void execute() override;
+  fork_join_sub_task *currently_executing() const;
+};
+
+template<typename T>
+void fork_join_sub_task::spawn_child(T &task) {
+  PROFILE_FORK_JOIN_STEALING("spawn_child")
+  static_assert(std::is_base_of<fork_join_sub_task, T>::value, "Only pass fork_join_sub_task subclasses!");
+
+  // Keep our refcount up to date
+  ref_count_++;
+
+  // Assign forced values
+  task.parent_ = this;
+  task.tbb_task_ = tbb_task_;
+  task.deque_state_ = tbb_task_->deque_.save_state();
+
+  // Push on our deque
+  const T const_task = task;
+  tbb_task_->deque_.push_tail(const_task);
+}
+
+}
+}
 }
 }
 
 
 #endif //PLS_TBB_LIKE_TASK_H
 #endif //PLS_TBB_LIKE_TASK_H

lib/pls/include/pls/internal/scheduling/root_task.h

@@ -5,76 +5,78 @@
 #include <mutex>
 #include <mutex>
 
 
 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/helpers/profiler.h"
-#include "pls/internal/base/spin_lock.h"
+#include "pls/internal/base/swmr_spin_lock.h"
 
 
 #include "abstract_task.h"
 #include "abstract_task.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            template<typename Function>
-            class root_task : public abstract_task {
-                Function function_;
-                std::atomic_uint8_t finished_;
-            public:
-                static constexpr auto create_id = helpers::unique_id::create<root_task<Function>>;
-
-                explicit root_task(Function function):
-                    abstract_task{0, create_id()},
-                    function_{function},
-                    finished_{0} {}
-                root_task(const root_task& other):
-                    abstract_task{0, create_id()},
-                    function_{other.function_},
-                    finished_{0} {}
-
-                bool finished() {
-                    return finished_;
-                }
-
-                void execute() override {
-                    PROFILE_WORK_BLOCK("execute root_task");
-                    function_();
-                    finished_ = 1;
-                }
-
-                bool internal_stealing(abstract_task* /*other_task*/) override {
-                    return false;
-                }
-
-                bool split_task(base::spin_lock* /*lock*/) override {
-                    return false;
-                }
-            };
-
-            template<typename Function>
-            class root_worker_task : public abstract_task {
-                root_task<Function>* master_task_;
-
-            public:
-                static constexpr auto create_id = root_task<Function>::create_id;
-
-                explicit root_worker_task(root_task<Function>* master_task):
-                        abstract_task{0, create_id()},
-                        master_task_{master_task} {}
-
-                void execute() override {
-                    PROFILE_WORK_BLOCK("execute root_task");
-                    do {
-                        steal_work();
-                    } while (!master_task_->finished());
-                }
-
-                bool internal_stealing(abstract_task* /*other_task*/) override {
-                    return false;
-                }
-
-                bool split_task(base::spin_lock* /*lock*/) override {
-                    return false;
-                }
-            };
-        }
-    }
+namespace internal {
+namespace scheduling {
+
+template<typename Function>
+class root_task : public abstract_task {
+  Function function_;
+  std::atomic_uint8_t finished_;
+ public:
+  static constexpr auto create_id = helpers::unique_id::create<root_task<Function>>;
+
+  explicit root_task(Function function) :
+      abstract_task{0, create_id()},
+      function_{function},
+      finished_{0} {}
+  root_task(const root_task &other) :
+      abstract_task{0, create_id()},
+      function_{other.function_},
+      finished_{0} {}
+
+  bool finished() {
+    return finished_;
+  }
+
+  void execute() override {
+    PROFILE_WORK_BLOCK("execute root_task");
+    function_();
+    finished_ = 1;
+  }
+
+  bool internal_stealing(abstract_task * /*other_task*/) override {
+    return false;
+  }
+
+  bool split_task(base::swmr_spin_lock * /*lock*/) override {
+    return false;
+  }
+};
+
+template<typename Function>
+class root_worker_task : public abstract_task {
+  root_task<Function> *master_task_;
+
+ public:
+  static constexpr auto create_id = root_task<Function>::create_id;
+
+  explicit root_worker_task(root_task<Function> *master_task) :
+      abstract_task{0, create_id()},
+      master_task_{master_task} {}
+
+  void execute() override {
+    PROFILE_WORK_BLOCK("execute root_task");
+    do {
+      steal_work();
+    } while (!master_task_->finished());
+  }
+
+  bool internal_stealing(abstract_task * /*other_task*/) override {
+    return false;
+  }
+
+  bool split_task(base::swmr_spin_lock * /*lock*/) override {
+    return false;
+  }
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_ROOT_MASTER_TASK_H
 #endif //PLS_ROOT_MASTER_TASK_H

lib/pls/include/pls/internal/scheduling/run_on_n_threads_task.h

@@ -12,107 +12,109 @@
 #include "scheduler.h"
 #include "scheduler.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            template<typename Function>
-            class run_on_n_threads_task : public abstract_task {
-                template<typename F>
-                friend class run_on_n_threads_task_worker;
-
-                Function function_;
-
-                // Improvement: Remove lock and replace by atomic variable (performance)
-                int counter;
-                base::spin_lock counter_lock_;
-
-                int decrement_counter() {
-                    std::lock_guard<base::spin_lock> lock{counter_lock_};
-                    counter--;
-                    return counter;
-                }
-
-                int get_counter() {
-                    std::lock_guard<base::spin_lock> lock{counter_lock_};
-                    return counter;
-                }
-            public:
-                static constexpr auto create_id = helpers::unique_id::create<run_on_n_threads_task<Function>>;
-
-                run_on_n_threads_task(Function function, int num_threads):
-                    abstract_task{0, create_id()},
-                    function_{function},
-                    counter{num_threads - 1} {}
-
-                void execute() override {
-                    // Execute our function ONCE
-                    function_();
-
-                    // Steal until we are finished (other threads executed)
-                    do {
-                        steal_work();
-                    } while (get_counter() > 0);
-
-                    std::cout << "Finished Master!" << std::endl;
-                }
-
-                bool internal_stealing(abstract_task* /*other_task*/) override {
-                    return false;
-                }
-
-                bool split_task(base::spin_lock* lock) override;
-            };
-
-            template<typename Function>
-            class run_on_n_threads_task_worker : public abstract_task {
-                Function function_;
-                run_on_n_threads_task<Function>* root_;
-            public:
-                static constexpr auto create_id = helpers::unique_id::create<run_on_n_threads_task_worker<Function>>;
-
-                run_on_n_threads_task_worker(Function function, run_on_n_threads_task<Function>* root):
-                        abstract_task{0, create_id()},
-                        function_{function},
-                        root_{root} {}
-
-                void execute() override {
-                   if (root_->decrement_counter() >= 0) {
-                       function_();
-                       std::cout << "Finished Worker!" << std::endl;
-                   } else {
-                       std::cout << "Abandoned Worker!" << std::endl;
-                   }
-                }
-
-                bool internal_stealing(abstract_task* /*other_task*/) override {
-                    return false;
-                }
-
-                bool split_task(base::spin_lock* /*lock*/) override {
-                    return false;
-                }
-            };
-
-            template<typename Function>
-            bool run_on_n_threads_task<Function>::split_task(base::spin_lock* lock) {
-                if (get_counter() <= 0) {
-                    return false;
-                }
-                // In success case, unlock.
-                // TODO: this locking is complicated and error prone.
-                lock->unlock();
-
-                auto scheduler = base::this_thread::state<thread_state>()->scheduler_;
-                auto task = run_on_n_threads_task_worker<Function>{function_, this};
-                scheduler->execute_task(task, depth());
-                return true;
-            }
-
-            template<typename Function>
-            run_on_n_threads_task<Function> create_run_on_n_threads_task(Function function, int num_threads) {
-                return run_on_n_threads_task<Function>{function, num_threads};
-            }
-        }
+namespace internal {
+namespace scheduling {
+
+template<typename Function>
+class run_on_n_threads_task : public abstract_task {
+  template<typename F>
+  friend
+  class run_on_n_threads_task_worker;
+
+  Function function_;
+
+  // Improvement: Remove lock and replace by atomic variable (performance)
+  int counter;
+  base::spin_lock counter_lock_;
+
+  int decrement_counter() {
+    std::lock_guard<base::spin_lock> lock{counter_lock_};
+    counter--;
+    return counter;
+  }
+
+  int get_counter() {
+    std::lock_guard<base::spin_lock> lock{counter_lock_};
+    return counter;
+  }
+ public:
+  static constexpr auto create_id = helpers::unique_id::create<run_on_n_threads_task<Function>>;
+
+  run_on_n_threads_task(Function function, int num_threads) :
+      abstract_task{0, create_id()},
+      function_{function},
+      counter{num_threads - 1} {}
+
+  void execute() override {
+    // Execute our function ONCE
+    function_();
+
+    // Steal until we are finished (other threads executed)
+    do {
+      steal_work();
+    } while (get_counter() > 0);
+
+    std::cout << "Finished Master!" << std::endl;
+  }
+
+  bool internal_stealing(abstract_task * /*other_task*/) override {
+    return false;
+  }
+
+  bool split_task(base::swmr_spin_lock *lock) override;
+};
+
+template<typename Function>
+class run_on_n_threads_task_worker : public abstract_task {
+  Function function_;
+  run_on_n_threads_task<Function> *root_;
+ public:
+  static constexpr auto create_id = helpers::unique_id::create<run_on_n_threads_task_worker<Function>>;
+
+  run_on_n_threads_task_worker(Function function, run_on_n_threads_task<Function> *root) :
+      abstract_task{0, create_id()},
+      function_{function},
+      root_{root} {}
+
+  void execute() override {
+    if (root_->decrement_counter() >= 0) {
+      function_();
+      std::cout << "Finished Worker!" << std::endl;
+    } else {
+      std::cout << "Abandoned Worker!" << std::endl;
     }
     }
+  }
+
+  bool internal_stealing(abstract_task * /*other_task*/) override {
+    return false;
+  }
+
+  bool split_task(base::swmr_spin_lock * /*lock*/) override {
+    return false;
+  }
+};
+
+template<typename Function>
+bool run_on_n_threads_task<Function>::split_task(base::swmr_spin_lock *lock) {
+  if (get_counter() <= 0) {
+    return false;
+  }
+  // In success case, unlock.
+  lock->reader_unlock();
+
+  auto scheduler = base::this_thread::state<thread_state>()->scheduler_;
+  auto task = run_on_n_threads_task_worker<Function>{function_, this};
+  scheduler->execute_task(task, depth());
+  return true;
+}
+
+template<typename Function>
+run_on_n_threads_task<Function> create_run_on_n_threads_task(Function function, int num_threads) {
+  return run_on_n_threads_task<Function>{function, num_threads};
+}
+
+}
+}
 }
 }
 
 
 #endif //PLS_RUN_ON_N_THREADS_TASK_H
 #endif //PLS_RUN_ON_N_THREADS_TASK_H

lib/pls/include/pls/internal/scheduling/scheduler.h

@@ -17,50 +17,52 @@
 #include "scheduler_memory.h"
 #include "scheduler_memory.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            void worker_routine();
-            using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
-
-            class scheduler {
-                friend void worker_routine();
-
-                const unsigned int num_threads_;
-                scheduler_memory* memory_;
-
-                base::barrier sync_barrier_;
-                bool terminated_;
-            public:
-                explicit scheduler(scheduler_memory* memory, unsigned int num_threads);
-                ~scheduler();
-
-                /**
-                 * Wakes up the thread pool.
-                 * Code inside the Function lambda can invoke all parallel APIs.
-                 *
-                 * @param work_section generic function or lambda to be executed in the scheduler's context.
-                 */
-                template<typename Function>
-                void perform_work(Function work_section);
-
-                /**
-                 * Executes a top-level-task (children of abstract_task) on this thread.
-                 *
-                 * @param task The task to be executed.
-                 * @param depth Optional: depth of the new task, otherwise set implicitly.
-                 */
-                template<typename Task>
-                static void execute_task(Task& task, int depth=-1);
-
-                static abstract_task* current_task() { return base::this_thread::state<thread_state>()->current_task_; }
-
-                void terminate(bool wait_for_workers=true);
-
-                unsigned int num_threads() const { return num_threads_; }
-                thread_state* thread_state_for(size_t id) { return memory_->thread_state_for(id); }
-            };
-        }
-    }
+namespace internal {
+namespace scheduling {
+
+void worker_routine();
+using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
+
+class scheduler {
+  friend void worker_routine();
+
+  const unsigned int num_threads_;
+  scheduler_memory *memory_;
+
+  base::barrier sync_barrier_;
+  bool terminated_;
+ public:
+  explicit scheduler(scheduler_memory *memory, unsigned int num_threads);
+  ~scheduler();
+
+  /**
+   * Wakes up the thread pool.
+   * Code inside the Function lambda can invoke all parallel APIs.
+   *
+   * @param work_section generic function or lambda to be executed in the scheduler's context.
+   */
+  template<typename Function>
+  void perform_work(Function work_section);
+
+  /**
+   * Executes a top-level-task (children of abstract_task) on this thread.
+   *
+   * @param task The task to be executed.
+   * @param depth Optional: depth of the new task, otherwise set implicitly.
+   */
+  template<typename Task>
+  static void execute_task(Task &task, int depth = -1);
+
+  static abstract_task *current_task() { return base::this_thread::state<thread_state>()->current_task_; }
+
+  void terminate(bool wait_for_workers = true);
+
+  unsigned int num_threads() const { return num_threads_; }
+  thread_state *thread_state_for(size_t id) { return memory_->thread_state_for(id); }
+};
+
+}
+}
 }
 }
 #include "scheduler_impl.h"
 #include "scheduler_impl.h"
 
 

lib/pls/include/pls/internal/scheduling/scheduler_impl.h

@@ -3,70 +3,74 @@
 #define PLS_SCHEDULER_IMPL_H
 #define PLS_SCHEDULER_IMPL_H
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            template<typename Function>
-            void scheduler::perform_work(Function work_section) {
-                PROFILE_WORK_BLOCK("scheduler::perform_work")
-                root_task<Function> master{work_section};
-
-                // Push root task on stacks
-                auto new_master = memory_->task_stack_for(0)->push(master);
-                memory_->thread_state_for(0)->root_task_ = new_master;
-                memory_->thread_state_for(0)->current_task_ = new_master;
-                for (unsigned int i = 1; i < num_threads_; i++) {
-                    root_worker_task<Function> worker{new_master};
-                    auto new_worker = memory_->task_stack_for(0)->push(worker);
-                    memory_->thread_state_for(i)->root_task_ = new_worker;
-                    memory_->thread_state_for(i)->current_task_ = new_worker;
-                }
-
-                // Perform and wait for work
-                sync_barrier_.wait(); // Trigger threads to wake up
-                sync_barrier_.wait(); // Wait for threads to finish
-
-                // Clean up stack
-                memory_->task_stack_for(0)->pop<typeof(master)>();
-                for (unsigned int i = 1; i < num_threads_; i++) {
-                    root_worker_task<Function> worker{new_master};
-                    memory_->task_stack_for(0)->pop<typeof(worker)>();
-                }
-            }
-
-            template<typename Task>
-            void scheduler::execute_task(Task& task, int depth) {
-                static_assert(std::is_base_of<abstract_task, Task>::value, "Only pass abstract_task subclasses!");
-
-                auto my_state = base::this_thread::state<thread_state>();
-                abstract_task* old_task;
-                abstract_task* new_task;
-
-                // Init Task
-                {
-                    std::lock_guard<base::spin_lock> lock{my_state->lock_};
-                    old_task = my_state->current_task_;
-                    new_task = my_state->task_stack_->push(task);
-
-                    new_task->set_depth(depth >= 0 ? depth : old_task->depth() + 1);
-                    my_state->current_task_ = new_task;
-                    old_task->set_child(new_task);
-                }
-
-                // Run Task
-                new_task->execute();
-
-                // Teardown state back to before the task was executed
-                {
-                    std::lock_guard<base::spin_lock> lock{my_state->lock_};
-
-                    old_task->set_child(nullptr);
-                    my_state->current_task_ = old_task;
-
-                    my_state->task_stack_->pop<Task>();
-                }
-            }
-        }
-    }
+namespace internal {
+namespace scheduling {
+
+template<typename Function>
+void scheduler::perform_work(Function work_section) {
+  PROFILE_WORK_BLOCK("scheduler::perform_work")
+  root_task<Function> master{work_section};
+
+  // Push root task on stacks
+  auto new_master = memory_->task_stack_for(0)->push(master);
+  memory_->thread_state_for(0)->root_task_ = new_master;
+  memory_->thread_state_for(0)->current_task_ = new_master;
+  for (unsigned int i = 1; i < num_threads_; i++) {
+    root_worker_task<Function> worker{new_master};
+    auto new_worker = memory_->task_stack_for(0)->push(worker);
+    memory_->thread_state_for(i)->root_task_ = new_worker;
+    memory_->thread_state_for(i)->current_task_ = new_worker;
+  }
+
+  // Perform and wait for work
+  sync_barrier_.wait(); // Trigger threads to wake up
+  sync_barrier_.wait(); // Wait for threads to finish
+
+  // Clean up stack
+  memory_->task_stack_for(0)->pop<typeof(master)>();
+  for (unsigned int i = 1; i < num_threads_; i++) {
+    root_worker_task<Function> worker{new_master};
+    memory_->task_stack_for(0)->pop<typeof(worker)>();
+  }
+}
+
+template<typename Task>
+void scheduler::execute_task(Task &task, int depth) {
+  static_assert(std::is_base_of<abstract_task, Task>::value, "Only pass abstract_task subclasses!");
+
+  auto my_state = base::this_thread::state<thread_state>();
+  abstract_task *old_task;
+  abstract_task *new_task;
+
+  // Init Task
+  old_task = my_state->current_task_;
+  new_task = my_state->task_stack_->push(task);
+
+  new_task->set_depth(depth >= 0 ? depth : old_task->depth() + 1);
+
+  {
+    my_state->lock_.writer_lock();
+    my_state->current_task_ = new_task;
+    old_task->set_child(new_task);
+    my_state->lock_.writer_unlock();
+  }
+
+  // Run Task
+  new_task->execute();
+
+  // Teardown state back to before the task was executed
+  my_state->task_stack_->pop<Task>();
+
+  {
+    my_state->lock_.writer_lock();
+    old_task->set_child(nullptr);
+    my_state->current_task_ = old_task;
+    my_state->lock_.writer_unlock();
+  }
+}
+
+}
+}
 }
 }
 
 
 #endif //PLS_SCHEDULER_IMPL_H
 #endif //PLS_SCHEDULER_IMPL_H

lib/pls/include/pls/internal/scheduling/scheduler_memory.h

@@ -7,72 +7,75 @@
 #define PLS_SCHEDULER_MEMORY_H
 #define PLS_SCHEDULER_MEMORY_H
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            void worker_routine();
-            using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
+namespace internal {
+namespace scheduling {
 
 
-            class scheduler_memory {
-            public:
-                virtual size_t max_threads() const = 0;
-                virtual thread_state* thread_state_for(size_t id) = 0;
-                virtual scheduler_thread* thread_for(size_t id) = 0;
-                virtual data_structures::aligned_stack* task_stack_for(size_t id) = 0;
-            };
+void worker_routine();
+using scheduler_thread = base::thread<decltype(&worker_routine), thread_state>;
 
 
-            template<size_t MAX_THREADS, size_t TASK_STACK_SIZE>
-            class static_scheduler_memory: public scheduler_memory {
-                // Everyone of these types has to live on its own cache line,
-                // as each thread uses one of them independently.
-                // Therefore it would be a major performance hit if we shared cache lines on these.
-                using aligned_thread = base::alignment::aligned_wrapper<scheduler_thread>;
-                using aligned_thread_state = base::alignment::aligned_wrapper<thread_state>;
-                using aligned_thread_stack = base::alignment::aligned_wrapper<std::array<char, TASK_STACK_SIZE>>;
-                using aligned_aligned_stack = base::alignment::aligned_wrapper<data_structures::aligned_stack>;
+class scheduler_memory {
+ public:
+  virtual size_t max_threads() const = 0;
+  virtual thread_state *thread_state_for(size_t id) = 0;
+  virtual scheduler_thread *thread_for(size_t id) = 0;
+  virtual data_structures::aligned_stack *task_stack_for(size_t id) = 0;
+};
 
 
-                std::array<aligned_thread, MAX_THREADS> threads_;
-                std::array<aligned_thread_state, MAX_THREADS> thread_states_;
-                std::array<aligned_thread_stack, MAX_THREADS> task_stacks_memory_;
-                std::array<aligned_aligned_stack, MAX_THREADS> task_stacks_;
+template<size_t MAX_THREADS, size_t TASK_STACK_SIZE>
+class static_scheduler_memory : public scheduler_memory {
+  // Everyone of these types has to live on its own cache line,
+  // as each thread uses one of them independently.
+  // Therefore it would be a major performance hit if we shared cache lines on these.
+  using aligned_thread = base::alignment::aligned_wrapper<scheduler_thread>;
+  using aligned_thread_state = base::alignment::aligned_wrapper<thread_state>;
+  using aligned_thread_stack = base::alignment::aligned_wrapper<std::array<char, TASK_STACK_SIZE>>;
+  using aligned_aligned_stack = base::alignment::aligned_wrapper<data_structures::aligned_stack>;
 
 
-            public:
-                static_scheduler_memory() {
-                    for (size_t i = 0; i < MAX_THREADS; i++) {
-                        new ((void*)task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i].pointer()->data(), TASK_STACK_SIZE);
-                    }
-                }
+  std::array<aligned_thread, MAX_THREADS> threads_;
+  std::array<aligned_thread_state, MAX_THREADS> thread_states_;
+  std::array<aligned_thread_stack, MAX_THREADS> task_stacks_memory_;
+  std::array<aligned_aligned_stack, MAX_THREADS> task_stacks_;
 
 
-                size_t max_threads() const override { return MAX_THREADS; }
-                thread_state* thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
-                scheduler_thread* thread_for(size_t id) override { return threads_[id].pointer(); }
-                data_structures::aligned_stack* task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
-            };
+ public:
+  static_scheduler_memory() {
+    for (size_t i = 0; i < MAX_THREADS; i++) {
+      new((void *) task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i].pointer()->data(),
+                                                                             TASK_STACK_SIZE);
+    }
+  }
 
 
-            class malloc_scheduler_memory: public scheduler_memory {
-                // Everyone of these types has to live on its own cache line,
-                // as each thread uses one of them independently.
-                // Therefore it would be a major performance hit if we shared cache lines on these.
-                using aligned_thread = base::alignment::aligned_wrapper<scheduler_thread>;
-                using aligned_thread_state = base::alignment::aligned_wrapper<thread_state>;
-                using aligned_aligned_stack = base::alignment::aligned_wrapper<data_structures::aligned_stack>;
+  size_t max_threads() const override { return MAX_THREADS; }
+  thread_state *thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
+  scheduler_thread *thread_for(size_t id) override { return threads_[id].pointer(); }
+  data_structures::aligned_stack *task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
+};
 
 
-                const size_t num_threads_;
+class malloc_scheduler_memory : public scheduler_memory {
+  // Everyone of these types has to live on its own cache line,
+  // as each thread uses one of them independently.
+  // Therefore it would be a major performance hit if we shared cache lines on these.
+  using aligned_thread = base::alignment::aligned_wrapper<scheduler_thread>;
+  using aligned_thread_state = base::alignment::aligned_wrapper<thread_state>;
+  using aligned_aligned_stack = base::alignment::aligned_wrapper<data_structures::aligned_stack>;
 
 
-                aligned_thread* threads_;
-                aligned_thread_state * thread_states_;
-                char** task_stacks_memory_;
-                aligned_aligned_stack * task_stacks_;
-            public:
-                explicit malloc_scheduler_memory(size_t num_threads, size_t memory_per_stack = 2 << 16);
-                ~malloc_scheduler_memory();
+  const size_t num_threads_;
 
 
-                size_t max_threads() const override { return num_threads_; }
-                thread_state* thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
-                scheduler_thread* thread_for(size_t id) override { return threads_[id].pointer(); }
-                data_structures::aligned_stack* task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
-            };
-        }
-    }
+  aligned_thread *threads_;
+  aligned_thread_state *thread_states_;
+  char **task_stacks_memory_;
+  aligned_aligned_stack *task_stacks_;
+ public:
+  explicit malloc_scheduler_memory(size_t num_threads, size_t memory_per_stack = 2 << 16);
+  ~malloc_scheduler_memory();
+
+  size_t max_threads() const override { return num_threads_; }
+  thread_state *thread_state_for(size_t id) override { return thread_states_[id].pointer(); }
+  scheduler_thread *thread_for(size_t id) override { return threads_[id].pointer(); }
+  data_structures::aligned_stack *task_stack_for(size_t id) override { return task_stacks_[id].pointer(); }
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_SCHEDULER_MEMORY_H
 #endif //PLS_SCHEDULER_MEMORY_H

lib/pls/include/pls/internal/scheduling/thread_state.h

@@ -5,41 +5,46 @@
 #include <random>
 #include <random>
 
 
 #include "pls/internal/data_structures/aligned_stack.h"
 #include "pls/internal/data_structures/aligned_stack.h"
+#include "pls/internal/base/swmr_spin_lock.h"
 #include "abstract_task.h"
 #include "abstract_task.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            // forward declaration
-            class scheduler;
-
-            struct thread_state {
-                scheduler* scheduler_;
-                abstract_task* root_task_;
-                abstract_task* current_task_;
-                data_structures::aligned_stack* task_stack_;
-                size_t id_;
-                base::spin_lock lock_;
-                std::minstd_rand random_;
-
-                thread_state():
-                    scheduler_{nullptr},
-                    root_task_{nullptr},
-                    current_task_{nullptr},
-                    task_stack_{nullptr},
-                    id_{0},
-                    random_{id_} {};
-
-                thread_state(scheduler* scheduler, data_structures::aligned_stack* task_stack, unsigned int id):
-                    scheduler_{scheduler},
-                    root_task_{nullptr},
-                    current_task_{nullptr},
-                    task_stack_{task_stack},
-                    id_{id},
-                    random_{id_} {}
-            };
-        }
-    }
+namespace internal {
+namespace scheduling {
+
+// forward declaration
+class scheduler;
+
+struct thread_state {
+  alignas(base::system_details::CACHE_LINE_SIZE) scheduler *scheduler_;
+  alignas(base::system_details::CACHE_LINE_SIZE) abstract_task *root_task_;
+  alignas(base::system_details::CACHE_LINE_SIZE) abstract_task *current_task_;
+  alignas(base::system_details::CACHE_LINE_SIZE) data_structures::aligned_stack *task_stack_;
+  alignas(base::system_details::CACHE_LINE_SIZE) size_t id_;
+  alignas(base::system_details::CACHE_LINE_SIZE) base::swmr_spin_lock lock_;
+  alignas(base::system_details::CACHE_LINE_SIZE) std::minstd_rand random_;
+
+  thread_state() :
+      scheduler_{nullptr},
+      root_task_{nullptr},
+      current_task_{nullptr},
+      task_stack_{nullptr},
+      id_{0},
+      lock_{},
+      random_{id_} {};
+
+  thread_state(scheduler *scheduler, data_structures::aligned_stack *task_stack, unsigned int id) :
+      scheduler_{scheduler},
+      root_task_{nullptr},
+      current_task_{nullptr},
+      task_stack_{task_stack},
+      id_{id},
+      lock_{},
+      random_{id_} {}
+};
+
+}
+}
 }
 }
 
 
 #endif //PLS_THREAD_STATE_H
 #endif //PLS_THREAD_STATE_H

lib/pls/include/pls/pls.h

@@ -8,18 +8,22 @@
 #include "pls/internal/helpers/unique_id.h"
 #include "pls/internal/helpers/unique_id.h"
 
 
 namespace pls {
 namespace pls {
-    using internal::scheduling::static_scheduler_memory;
-    using internal::scheduling::malloc_scheduler_memory;
 
 
-    using internal::scheduling::scheduler;
-    using task_id = internal::scheduling::abstract_task::id;
+using internal::scheduling::static_scheduler_memory;
+using internal::scheduling::malloc_scheduler_memory;
 
 
-    using unique_id = internal::helpers::unique_id;
+using internal::scheduling::scheduler;
+using task_id = internal::scheduling::abstract_task::id;
 
 
-    using internal::scheduling::fork_join_sub_task;
-    using internal::scheduling::fork_join_task;
+using unique_id = internal::helpers::unique_id;
+
+using internal::scheduling::fork_join_sub_task;
+using internal::scheduling::fork_join_lambda_by_reference;
+using internal::scheduling::fork_join_lambda_by_value;
+using internal::scheduling::fork_join_task;
+
+using algorithm::invoke_parallel;
 
 
-    using algorithm::invoke_parallel;
 }
 }
 
 
 #endif
 #endif

lib/pls/src/internal/base/alignment.cpp

@@ -2,26 +2,37 @@
 #include "pls/internal/base/system_details.h"
 #include "pls/internal/base/system_details.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            namespace alignment {
-                void* allocate_aligned(size_t size) {
-                    return aligned_alloc(system_details::CACHE_LINE_SIZE, size);
-                }
+namespace internal {
+namespace base {
+namespace alignment {
 
 
-                std::uintptr_t next_alignment(std::uintptr_t size) {
-                    std::uintptr_t miss_alignment = size % base::system_details::CACHE_LINE_SIZE;
-                    if (miss_alignment == 0) {
-                        return size;
-                    } else {
-                        return size + (base::system_details::CACHE_LINE_SIZE - miss_alignment);
-                    }
-                }
+void *allocate_aligned(size_t size) {
+  return aligned_alloc(system_details::CACHE_LINE_SIZE, size);
+}
+
+system_details::pointer_t next_alignment(system_details::pointer_t size) {
+  system_details::pointer_t miss_alignment = size % base::system_details::CACHE_LINE_SIZE;
+  if (miss_alignment == 0) {
+    return size;
+  } else {
+    return size + (base::system_details::CACHE_LINE_SIZE - miss_alignment);
+  }
+}
+
+system_details::pointer_t previous_alignment(system_details::pointer_t size) {
+  system_details::pointer_t miss_alignment = size % base::system_details::CACHE_LINE_SIZE;
+  if (miss_alignment == 0) {
+    return size;
+  } else {
+    return size - miss_alignment;
+  }
+}
 
 
-                char* next_alignment(char* pointer) {
-                    return reinterpret_cast<char*>(next_alignment(reinterpret_cast<std::uintptr_t >(pointer)));
-                }
-            }
-        }
-    }
+char *next_alignment(char *pointer) {
+  return reinterpret_cast<char *>(next_alignment(reinterpret_cast<system_details::pointer_t >(pointer)));
+}
+
+}
+}
+}
 }
 }

lib/pls/src/internal/base/barrier.cpp

 #include "pls/internal/base/barrier.h"
 #include "pls/internal/base/barrier.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            barrier::barrier(const unsigned int count): barrier_{} {
-                pthread_barrier_init(&barrier_, nullptr, count);
-            }
+namespace internal {
+namespace base {
 
 
-            barrier::~barrier() {
-                pthread_barrier_destroy(&barrier_);
-            }
+barrier::barrier(const unsigned int count) : barrier_{} {
+  pthread_barrier_init(&barrier_, nullptr, count);
+}
+
+barrier::~barrier() {
+  pthread_barrier_destroy(&barrier_);
+}
 
 
-            void barrier::wait() {
-                pthread_barrier_wait(&barrier_);
-            }
-        }
-    }
+void barrier::wait() {
+  pthread_barrier_wait(&barrier_);
+}
+
+}
+}
 }
 }

lib/pls/src/internal/base/swmr_spin_lock.cpp

+#include "pls/internal/base/swmr_spin_lock.h"
+#include "pls/internal/base/system_details.h"
+
+namespace pls {
+namespace internal {
+namespace base {
+
+bool swmr_spin_lock::reader_try_lock() {
+  PROFILE_LOCK("Try Acquire Read Lock")
+  if (write_request_.load(std::memory_order_acquire) == 1) {
+    return false;
+  }
+  // We think we can enter the region
+  readers_.fetch_add(1, std::memory_order_acquire);
+  if (write_request_.load(std::memory_order_acquire) == 1) {
+    // Whoops, the writer acquires the lock, so we back off again
+    readers_.fetch_add(-1, std::memory_order_release);
+    return false;
+  }
+
+  return true;
+}
+
+void swmr_spin_lock::reader_unlock() {
+  PROFILE_LOCK("Release Read Lock")
+  readers_--;
+}
+
+void swmr_spin_lock::writer_lock() {
+  PROFILE_LOCK("Acquire Write Lock")
+  // Tell the readers that we would like to write
+  write_request_ = 1;
+
+  // Wait for all of them to exit the critical section
+  while (readers_ > 0)
+    system_details::relax_cpu(); // Spin, not expensive as relaxed load
+}
+
+void swmr_spin_lock::writer_unlock() {
+  PROFILE_LOCK("Release Write Lock")
+  write_request_ = 0;
+}
+
+}
+}
+}

lib/pls/src/internal/base/tas_spin_lock.cpp

 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/base/tas_spin_lock.h"
 #include "pls/internal/base/tas_spin_lock.h"
+#include "pls/internal/base/backoff.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            void tas_spin_lock::lock() {
-                PROFILE_LOCK("Acquire Lock")
-                int tries = 0;
-                while (flag_.test_and_set(std::memory_order_acquire)) {
-                    tries++;
-                    if (tries % yield_at_tries_ == 0) {
-                        this_thread::yield();
-                    }
-                }
-            }
-
-            bool tas_spin_lock::try_lock(unsigned int num_tries) {
-                PROFILE_LOCK("Try Acquire Lock")
-                while (flag_.test_and_set(std::memory_order_acquire)) {
-                    num_tries--;
-                    if (num_tries <= 0) {
-                        return false;
-                    }
-                }
-                return true;
-            }
-
-            void tas_spin_lock::unlock() {
-                flag_.clear(std::memory_order_release);
-            }
-        }
+namespace internal {
+namespace base {
+
+void tas_spin_lock::lock() {
+  PROFILE_LOCK("Acquire Lock")
+  backoff backoff_strategy;
+
+  while (true) {
+    if (flag_.test_and_set(std::memory_order_acquire) == 0) {
+      return;
+    }
+    backoff_strategy.do_backoff();
+  }
+}
+
+bool tas_spin_lock::try_lock(unsigned int num_tries) {
+  PROFILE_LOCK("Try Acquire Lock")
+  backoff backoff_strategy;
+
+  while (true) {
+    if (flag_.test_and_set(std::memory_order_acquire) == 0) {
+      return true;
+    }
+
+    num_tries--;
+    if (num_tries <= 0) {
+      return false;
     }
     }
+
+    backoff_strategy.do_backoff();
+  }
+}
+
+void tas_spin_lock::unlock() {
+  PROFILE_LOCK("Unlock")
+  flag_.clear(std::memory_order_release);
+}
+
+}
+}
 }
 }

lib/pls/src/internal/base/thread.cpp

 #include "pls/internal/base/thread.h"
 #include "pls/internal/base/thread.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
+namespace internal {
+namespace base {
+
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
 #ifdef PLS_THREAD_SPECIFIC_PTHREAD
-            pthread_key_t this_thread::local_storage_key_ = false;
-            bool this_thread::local_storage_key_initialized_;
+pthread_key_t this_thread::local_storage_key_ = false;
+bool this_thread::local_storage_key_initialized_;
 #endif
 #endif
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
 #ifdef PLS_THREAD_SPECIFIC_COMPILER
-            __thread void* this_thread::local_state_;
+__thread void *this_thread::local_state_;
 #endif
 #endif
-            // implementation in header (C++ templating)
-        }
-    }
+// implementation in header (C++ templating)
+
+}
+}
 }
 }

lib/pls/src/internal/base/ttas_spin_lock.cpp

 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/base/ttas_spin_lock.h"
 #include "pls/internal/base/ttas_spin_lock.h"
+#include "pls/internal/base/backoff.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace base {
-            void ttas_spin_lock::lock() {
-                PROFILE_LOCK("Acquire Lock")
-                int tries = 0;
-                int expected = 0;
-
-                do {
-                    while (flag_.load(std::memory_order_relaxed) == 1) {
-                        tries++;
-                        if (tries % yield_at_tries_ == 0) {
-                            this_thread::yield();
-                        }
-                    }
-
-                    expected = 0;
-                } while (!flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire));
-            }
-
-            bool ttas_spin_lock::try_lock(unsigned int num_tries) {
-                PROFILE_LOCK("Try Acquire Lock")
-                int expected = 0;
-
-                do {
-                    while (flag_.load(std::memory_order_relaxed) == 1) {
-                        num_tries--;
-                        if (num_tries <= 0) {
-                            return false;
-                        }
-                    }
-
-                    expected = 0;
-                } while (!flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire));
-
-                return true;
-            }
-
-            void ttas_spin_lock::unlock() {
-                flag_.store(0, std::memory_order_release);
-            }
-        }
+namespace internal {
+namespace base {
+
+void ttas_spin_lock::lock() {
+  PROFILE_LOCK("Acquire Lock")
+  int expected = 0;
+  backoff backoff_;
+
+  while (true) {
+    while (flag_.load(std::memory_order_relaxed) == 1)
+      system_details::relax_cpu(); // Spin
+
+    expected = 0;
+    if (flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire)) {
+      return;
+    }
+    backoff_.do_backoff();
+  }
+}
+
+bool ttas_spin_lock::try_lock(unsigned int num_tries) {
+  PROFILE_LOCK("Try Acquire Lock")
+  int expected = 0;
+  backoff backoff_;
+
+  while (true) {
+    while (flag_.load() == 1) {
+      num_tries--;
+      if (num_tries <= 0) {
+        return false;
+      }
+      system_details::relax_cpu();
+    }
+
+    expected = 0;
+    if (flag_.compare_exchange_weak(expected, 1, std::memory_order_acquire)) {
+      return true;
     }
     }
+    num_tries--;
+    if (num_tries <= 0) {
+      return false;
+    }
+    backoff_.do_backoff();
+  }
+}
+
+void ttas_spin_lock::unlock() {
+  PROFILE_LOCK("Unlock")
+  flag_.store(0, std::memory_order_release);
+}
+
+}
+}
 }
 }

lib/pls/src/internal/data_structures/aligned_stack.cpp

@@ -2,12 +2,19 @@
 #include "pls/internal/base/system_details.h"
 #include "pls/internal/base/system_details.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            aligned_stack::aligned_stack(char* memory_region, const std::size_t size):
-                    memory_start_{memory_region},
-                    memory_end_{memory_region + size},
-                    head_{base::alignment::next_alignment(memory_start_)} {}
-        }
-    }
+namespace internal {
+namespace data_structures {
+
+aligned_stack::aligned_stack(pointer_t memory_region, const std::size_t size) :
+    memory_start_{memory_region},
+    memory_end_{memory_region + size},
+    head_{base::alignment::next_alignment(memory_start_)} {}
+
+aligned_stack::aligned_stack(char *memory_region, const std::size_t size) :
+    memory_start_{(pointer_t) memory_region},
+    memory_end_{(pointer_t) memory_region + size},
+    head_{base::alignment::next_alignment(memory_start_)} {}
+
+}
+}
 }
 }

lib/pls/src/internal/data_structures/deque.cpp

@@ -3,56 +3,58 @@
 #include "pls/internal/data_structures/deque.h"
 #include "pls/internal/data_structures/deque.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace data_structures {
-            deque_item* deque_internal::pop_head_internal() {
-                std::lock_guard<base::spin_lock> lock{lock_};
-
-                if (head_ == nullptr) {
-                    return nullptr;
-                }
-
-                deque_item* result = head_;
-                head_ = head_->prev_;
-                if (head_ == nullptr) {
-                    tail_ = nullptr;
-                } else {
-                    head_->next_ = nullptr;
-                }
-
-                return result;
-            }
-
-            deque_item* deque_internal::pop_tail_internal() {
-                std::lock_guard<base::spin_lock> lock{lock_};
-
-                if (tail_ == nullptr) {
-                    return nullptr;
-                }
-
-                deque_item* result = tail_;
-                tail_ = tail_->next_;
-                if (tail_ == nullptr) {
-                    head_ = nullptr;
-                } else {
-                    tail_->prev_ = nullptr;
-                }
-
-                return result;
-            }
-
-            void deque_internal::push_tail_internal(deque_item *new_item) {
-                std::lock_guard<base::spin_lock> lock{lock_};
-
-                if (tail_ != nullptr) {
-                    tail_->prev_ = new_item;
-                } else {
-                    head_ = new_item;
-                }
-                new_item->next_ = tail_;
-                new_item->prev_ = nullptr;
-                tail_ = new_item;
-            }
-        }
-    }
+namespace internal {
+namespace data_structures {
+
+deque_item *deque_internal::pop_head_internal() {
+  std::lock_guard<base::spin_lock> lock{lock_};
+
+  if (head_ == nullptr) {
+    return nullptr;
+  }
+
+  deque_item *result = head_;
+  head_ = head_->next_;
+  if (head_ == nullptr) {
+    tail_ = nullptr;
+  } else {
+    head_->prev_ = nullptr;
+  }
+
+  return result;
+}
+
+deque_item *deque_internal::pop_tail_internal() {
+  std::lock_guard<base::spin_lock> lock{lock_};
+
+  if (tail_ == nullptr) {
+    return nullptr;
+  }
+
+  deque_item *result = tail_;
+  tail_ = tail_->prev_;
+  if (tail_ == nullptr) {
+    head_ = nullptr;
+  } else {
+    tail_->next_ = nullptr;
+  }
+
+  return result;
+}
+
+void deque_internal::push_tail_internal(deque_item *new_item) {
+  std::lock_guard<base::spin_lock> lock{lock_};
+
+  if (tail_ != nullptr) {
+    tail_->next_ = new_item;
+  } else {
+    head_ = new_item;
+  }
+  new_item->prev_ = tail_;
+  new_item->next_ = nullptr;
+  tail_ = new_item;
+}
+
+}
+}
 }
 }

lib/pls/src/internal/scheduling/abstract_task.cpp

+#include <pls/internal/base/backoff.h>
 #include "pls/internal/helpers/profiler.h"
 #include "pls/internal/helpers/profiler.h"
 
 
 #include "pls/internal/scheduling/thread_state.h"
 #include "pls/internal/scheduling/thread_state.h"
@@ -5,72 +6,80 @@
 #include "pls/internal/scheduling/scheduler.h"
 #include "pls/internal/scheduling/scheduler.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            bool abstract_task::steal_work() {
-                PROFILE_STEALING("abstract_task::steal_work")
-                const auto my_state = base::this_thread::state<thread_state>();
-                const auto my_scheduler = my_state->scheduler_;
+namespace internal {
+namespace scheduling {
 
 
-                const size_t my_id = my_state->id_;
-                const size_t offset = my_state->random_() % my_scheduler->num_threads();
-                const size_t max_tries = 1; // my_scheduler->num_threads(); TODO: Tune this value
-                for (size_t i = 0; i < max_tries; i++) {
-                    size_t target = (offset + i) % my_scheduler->num_threads();
-                    if (target == my_id) {
-                        continue;
-                    }
-                    auto target_state = my_scheduler->thread_state_for(target);
+bool abstract_task::steal_work() {
+  thread_local static base::backoff backoff{};
 
 
-                    // TODO: Cleaner Locking Using std::guarded_lock
-                    target_state->lock_.lock();
+  PROFILE_STEALING("abstract_task::steal_work")
+  const auto my_state = base::this_thread::state<thread_state>();
+  const auto my_scheduler = my_state->scheduler_;
 
 
-                    // Dig down to our level
-                    PROFILE_STEALING("Go to our level")
-                    abstract_task* current_task = target_state->root_task_;
-                    while (current_task != nullptr && current_task->depth() < depth()) {
-                        current_task = current_task->child_task_;
-                    }
-                    PROFILE_END_BLOCK
+  const size_t my_id = my_state->id_;
+  const size_t offset = my_state->random_() % my_scheduler->num_threads();
+  const size_t max_tries = my_scheduler->num_threads() - 1; // TODO: Tune this value
+  for (size_t i = 0; i < max_tries; i++) {
+    size_t target = (offset + i) % my_scheduler->num_threads();
+    if (target == my_id) {
+      target = (target + 1) % my_scheduler->num_threads();
+    }
+    auto target_state = my_scheduler->thread_state_for(target);
 
 
-                    // Try to steal 'internal', e.g. for_join_sub_tasks in a fork_join_task constellation
-                    PROFILE_STEALING("Internal Steal")
-                    if (current_task != nullptr) {
-                        // See if it equals our type and depth of task
-                        if (current_task->unique_id_ == unique_id_ &&
-                            current_task->depth_ == depth_) {
-                            if (internal_stealing(current_task)) {
-                                // internal steal was a success, hand it back to the internal scheduler
-                                target_state->lock_.unlock();
-                                return true;
-                            }
+    if (!target_state->lock_.reader_try_lock()) {
+      continue;
+    }
 
 
-                            // No success, we need to steal work from a deeper level using 'top level task stealing'
-                            current_task = current_task->child_task_;
-                        }
-                    }
-                    PROFILE_END_BLOCK;
+    // Dig down to our level
+    PROFILE_STEALING("Go to our level")
+    abstract_task *current_task = target_state->root_task_;
+    while (current_task != nullptr && current_task->depth() < depth()) {
+      current_task = current_task->child();
+    }
+    PROFILE_END_BLOCK
 
 
+    // Try to steal 'internal', e.g. for_join_sub_tasks in a fork_join_task constellation
+    PROFILE_STEALING("Internal Steal")
+    if (current_task != nullptr) {
+      // See if it equals our type and depth of task
+      if (current_task->unique_id_ == unique_id_ &&
+          current_task->depth_ == depth_) {
+        if (internal_stealing(current_task)) {
+          // internal steal was a success, hand it back to the internal scheduler
+          target_state->lock_.reader_unlock();
+          backoff.reset();
+          return true;
+        }
 
 
-                    // Execute 'top level task steal' if possible
-                    // (only try deeper tasks to keep depth restricted stealing).
-                    PROFILE_STEALING("Top Level Steal")
-                    while (current_task != nullptr) {
-                        auto lock = &target_state->lock_;
-                        if (current_task->split_task(lock)) {
-                            // internal steal was no success (we did a top level task steal)
-                            return false;
-                        }
+        // No success, we need to steal work from a deeper level using 'top level task stealing'
+        current_task = current_task->child();
+      }
+    }
+    PROFILE_END_BLOCK;
 
 
-                        current_task = current_task->child_task_;
-                    }
-                    PROFILE_END_BLOCK;
-                    target_state->lock_.unlock();
-                }
 
 
-                // internal steal was no success
-                return false;
-            };
-        }
+    // Execute 'top level task steal' if possible
+    // (only try deeper tasks to keep depth restricted stealing).
+    PROFILE_STEALING("Top Level Steal")
+    while (current_task != nullptr) {
+      auto lock = &target_state->lock_;
+      if (current_task->split_task(lock)) {
+        // top level steal was a success (we did a top level task steal)
+        backoff.reset();
+        return false;
+      }
+
+      current_task = current_task->child_task_;
     }
     }
+    PROFILE_END_BLOCK;
+    target_state->lock_.reader_unlock();
+  }
+
+  // internal steal was no success
+  backoff.do_backoff();
+  return false;
+}
+
+}
+}
 }
 }

lib/pls/src/internal/scheduling/fork_join_task.cpp

@@ -4,131 +4,126 @@
 #include "pls/internal/scheduling/fork_join_task.h"
 #include "pls/internal/scheduling/fork_join_task.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            fork_join_sub_task::fork_join_sub_task():
-                data_structures::deque_item{},
-                ref_count_{0},
-                parent_{nullptr},
-                tbb_task_{nullptr},
-                stack_state_{nullptr} {}
-
-            fork_join_sub_task::fork_join_sub_task(const fork_join_sub_task& other):
-                data_structures::deque_item(other),
-                ref_count_{0},
-                parent_{nullptr},
-                tbb_task_{nullptr},
-                stack_state_{nullptr} {}
-
-            void fork_join_sub_task::execute()  {
-                PROFILE_WORK_BLOCK("execute sub_task")
-                tbb_task_->currently_executing_ = this;
-                execute_internal();
-                tbb_task_->currently_executing_ = nullptr;
-                PROFILE_END_BLOCK
-                wait_for_all();
-
-                if (parent_ != nullptr) {
-                    parent_->ref_count_--;
-                }
-            }
-
-            void fork_join_sub_task::spawn_child_internal(fork_join_sub_task* sub_task) {
-                // Keep our refcount up to date
-                ref_count_++;
-
-                // Assign forced values
-                sub_task->parent_ = this;
-                sub_task->tbb_task_ = tbb_task_;
-                sub_task->stack_state_ = tbb_task_->my_stack_->save_state();
-
-                tbb_task_->deque_.push_tail(sub_task);
-            }
-
-            void fork_join_sub_task::wait_for_all() {
-                while (ref_count_ > 0) {
-                    PROFILE_STEALING("get local sub task")
-                    fork_join_sub_task* local_task = tbb_task_->get_local_sub_task();
-                    PROFILE_END_BLOCK
-                    if (local_task != nullptr) {
-                        local_task->execute();
-                    } else {
-                        // Try to steal work.
-                        // External steal will be executed implicitly if success
-                        PROFILE_STEALING("steal work")
-                        bool internal_steal_success = tbb_task_->steal_work();
-                        PROFILE_END_BLOCK
-                        if (internal_steal_success) {
-                            tbb_task_->last_stolen_->execute();
-                        }
-                    }
-                }
-                tbb_task_->my_stack_->reset_state(stack_state_);
-            }
-
-            fork_join_sub_task* fork_join_task::get_local_sub_task() {
-                return deque_.pop_tail();
-            }
-
-            fork_join_sub_task* fork_join_task::get_stolen_sub_task() {
-                return deque_.pop_head();
-            }
-
-            bool fork_join_task::internal_stealing(abstract_task* other_task) {
-                PROFILE_STEALING("fork_join_task::internal_stealin")
-                auto cast_other_task = reinterpret_cast<fork_join_task*>(other_task);
-
-                auto stolen_sub_task = cast_other_task->get_stolen_sub_task();
-                if (stolen_sub_task == nullptr) {
-                    return false;
-                } else {
-                    // Make sub-task belong to our fork_join_task instance
-                    stolen_sub_task->tbb_task_ = this;
-                    stolen_sub_task->stack_state_ = my_stack_->save_state();
-                    // We will execute this next without explicitly moving it onto our stack storage
-                    last_stolen_ = stolen_sub_task;
-
-                    return true;
-                }
-            }
-
-            bool fork_join_task::split_task(base::spin_lock* lock) {
-                PROFILE_STEALING("fork_join_task::split_task")
-                fork_join_sub_task* stolen_sub_task = get_stolen_sub_task();
-                if (stolen_sub_task == nullptr) {
-                    return false;
-                }
-                fork_join_task task{stolen_sub_task, this->unique_id()};
-
-                // In success case, unlock.
-                // TODO: this locking is complicated and error prone.
-                lock->unlock();
-
-                scheduler::execute_task(task, depth());
-                return true;
-            }
-
-            void fork_join_task::execute() {
-                PROFILE_WORK_BLOCK("execute fork_join_task");
-
-                // Bind this instance to our OS thread
-                my_stack_ = base::this_thread::state<thread_state>()->task_stack_;
-                root_task_->tbb_task_ = this;
-                root_task_->stack_state_ = my_stack_->save_state();
-
-                // Execute it on our OS thread until its finished
-                root_task_->execute();
-            }
-
-            fork_join_sub_task* fork_join_task::currently_executing() const { return currently_executing_; }
-
-            fork_join_task::fork_join_task(fork_join_sub_task* root_task, const abstract_task::id& id):
-                abstract_task{0, id},
-                root_task_{root_task},
-                currently_executing_{nullptr},
-                my_stack_{nullptr},
-                deque_{},
-                last_stolen_{nullptr} {};
-        }
+namespace internal {
+namespace scheduling {
+
+fork_join_sub_task::fork_join_sub_task() :
+    ref_count_{0},
+    parent_{nullptr},
+    tbb_task_{nullptr},
+    deque_state_{0} {}
+
+fork_join_sub_task::fork_join_sub_task(const fork_join_sub_task &other) :
+    ref_count_{0},
+    parent_{other.parent_},
+    tbb_task_{other.tbb_task_},
+    deque_state_{other.deque_state_} {}
+
+void fork_join_sub_task::execute() {
+  PROFILE_WORK_BLOCK("execute sub_task")
+  auto last_executing = tbb_task_->currently_executing_;
+  tbb_task_->currently_executing_ = this;
+  execute_internal();
+  tbb_task_->currently_executing_ = last_executing;
+  PROFILE_END_BLOCK
+  wait_for_all();
+
+  if (parent_ != nullptr) {
+    parent_->ref_count_--;
+  }
+}
+
+void fork_join_sub_task::wait_for_all() {
+  while (ref_count_ > 0) {
+    PROFILE_STEALING("get local sub task")
+    fork_join_sub_task *local_task = tbb_task_->get_local_sub_task();
+    PROFILE_END_BLOCK
+    if (local_task != nullptr) {
+      local_task->execute();
+    } else {
+      // Try to steal work.
+      // External steal will be executed implicitly if success
+      PROFILE_STEALING("steal work")
+      bool internal_steal_success = tbb_task_->steal_work();
+      PROFILE_END_BLOCK
+      if (internal_steal_success) {
+        tbb_task_->last_stolen_->execute();
+      }
     }
     }
+  }
+  tbb_task_->deque_.release_memory_until(deque_state_);
+}
+
+fork_join_sub_task *fork_join_task::get_local_sub_task() {
+  return deque_.pop_tail();
+}
+
+fork_join_sub_task *fork_join_task::get_stolen_sub_task() {
+  return deque_.pop_head();
+}
+
+fork_join_sub_task *fork_join_sub_task::current() {
+  return dynamic_cast<fork_join_task *>(scheduler::current_task())->currently_executing();
+}
+
+bool fork_join_task::internal_stealing(abstract_task *other_task) {
+  PROFILE_STEALING("fork_join_task::internal_stealin")
+  auto cast_other_task = reinterpret_cast<fork_join_task *>(other_task);
+
+  auto stolen_sub_task = cast_other_task->get_stolen_sub_task();
+  if (stolen_sub_task == nullptr) {
+    return false;
+  } else {
+    // Make sub-task belong to our fork_join_task instance
+    stolen_sub_task->tbb_task_ = this;
+    stolen_sub_task->deque_state_ = deque_.save_state();
+    // We will execute this next without explicitly moving it onto our stack storage
+    last_stolen_ = stolen_sub_task;
+
+    return true;
+  }
+}
+
+bool fork_join_task::split_task(base::swmr_spin_lock *lock) {
+  PROFILE_STEALING("fork_join_task::split_task")
+  fork_join_sub_task *stolen_sub_task = get_stolen_sub_task();
+  if (stolen_sub_task == nullptr) {
+    return false;
+  }
+  fork_join_task task{stolen_sub_task, this->unique_id()};
+
+  // In success case, unlock.
+  lock->reader_unlock();
+
+  scheduler::execute_task(task, depth());
+  return true;
+}
+
+void fork_join_task::execute() {
+  PROFILE_WORK_BLOCK("execute fork_join_task");
+
+  // Bind this instance to our OS thread
+  // TODO: See if we did this right
+  // my_stack_ = base::this_thread::state<thread_state>()->task_stack_;
+  deque_.reset_base_pointer();
+
+  root_task_->tbb_task_ = this;
+  root_task_->deque_state_ = deque_.save_state();
+
+  // Execute it on our OS thread until its finished
+  root_task_->execute();
+}
+
+fork_join_sub_task *fork_join_task::currently_executing() const { return currently_executing_; }
+
+fork_join_task::fork_join_task(fork_join_sub_task *root_task,
+                               const abstract_task::id &id) :
+    abstract_task{0, id},
+    root_task_{root_task},
+    currently_executing_{nullptr},
+    deque_{base::this_thread::state<thread_state>()->task_stack_},
+    last_stolen_{nullptr} {}
+
+}
+}
 }
 }

lib/pls/src/internal/scheduling/root_task.cpp

 #include "pls/internal/scheduling/root_task.h"
 #include "pls/internal/scheduling/root_task.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
+namespace internal {
+namespace scheduling {
 
 
-        }
-    }
+}
+}
 }
 }

lib/pls/src/internal/scheduling/run_on_n_threads_task.cpp

 #include "pls/internal/scheduling/run_on_n_threads_task.h"
 #include "pls/internal/scheduling/run_on_n_threads_task.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
+namespace internal {
+namespace scheduling {
 
 
-        }
-    }
+}
+}
 }
 }

lib/pls/src/internal/scheduling/scheduler.cpp

@@ -2,60 +2,63 @@
 #include "pls/internal/base/error_handling.h"
 #include "pls/internal/base/error_handling.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            scheduler::scheduler(scheduler_memory* memory, const unsigned int num_threads):
-                    num_threads_{num_threads},
-                    memory_{memory},
-                    sync_barrier_{num_threads + 1},
-                    terminated_{false} {
-                if (num_threads_ > memory_->max_threads()) {
-                    PLS_ERROR("Tried to create scheduler with more OS threads than pre-allocated memory.");
-                }
-
-                for (unsigned int i = 0; i < num_threads_; i++) {
-                    // Placement new is required, as the memory of `memory_` is not required to be initialized.
-                    new((void*)memory_->thread_state_for(i)) thread_state{this, memory_->task_stack_for(i), i};
-                    new ((void*)memory_->thread_for(i))base::thread<void(*)(), thread_state>(&worker_routine, memory_->thread_state_for(i));
-                }
-            }
-
-            scheduler::~scheduler() {
-                terminate();
-            }
-
-            void worker_routine() {
-                auto my_state = base::this_thread::state<thread_state>();
-
-                while (true) {
-                    my_state->scheduler_->sync_barrier_.wait();
-                    if (my_state->scheduler_->terminated_) {
-                        return;
-                    }
-
-                    // The root task must only return when all work is done,
-                    // because of this a simple call is enough to ensure the
-                    // fork-join-section is done (logically joined back into our main thread).
-                    my_state->root_task_->execute();
-
-                    my_state->scheduler_->sync_barrier_.wait();
-                }
-            }
-
-            void scheduler::terminate(bool wait_for_workers) {
-                if (terminated_) {
-                    return;
-                }
-
-                terminated_ = true;
-                sync_barrier_.wait();
-
-                if (wait_for_workers) {
-                    for (unsigned int i = 0; i < num_threads_; i++) {
-                        memory_->thread_for(i)->join();
-                    }
-                }
-            }
-        }
+namespace internal {
+namespace scheduling {
+
+scheduler::scheduler(scheduler_memory *memory, const unsigned int num_threads) :
+    num_threads_{num_threads},
+    memory_{memory},
+    sync_barrier_{num_threads + 1},
+    terminated_{false} {
+  if (num_threads_ > memory_->max_threads()) {
+    PLS_ERROR("Tried to create scheduler with more OS threads than pre-allocated memory.");
+  }
+
+  for (unsigned int i = 0; i < num_threads_; i++) {
+    // Placement new is required, as the memory of `memory_` is not required to be initialized.
+    new((void *) memory_->thread_state_for(i)) thread_state{this, memory_->task_stack_for(i), i};
+    new((void *) memory_->thread_for(i))base::thread<void (*)(), thread_state>(&worker_routine,
+                                                                               memory_->thread_state_for(i));
+  }
+}
+
+scheduler::~scheduler() {
+  terminate();
+}
+
+void worker_routine() {
+  auto my_state = base::this_thread::state<thread_state>();
+
+  while (true) {
+    my_state->scheduler_->sync_barrier_.wait();
+    if (my_state->scheduler_->terminated_) {
+      return;
+    }
+
+    // The root task must only return when all work is done,
+    // because of this a simple call is enough to ensure the
+    // fork-join-section is done (logically joined back into our main thread).
+    my_state->root_task_->execute();
+
+    my_state->scheduler_->sync_barrier_.wait();
+  }
+}
+
+void scheduler::terminate(bool wait_for_workers) {
+  if (terminated_) {
+    return;
+  }
+
+  terminated_ = true;
+  sync_barrier_.wait();
+
+  if (wait_for_workers) {
+    for (unsigned int i = 0; i < num_threads_; i++) {
+      memory_->thread_for(i)->join();
     }
     }
+  }
+}
+
+}
+}
 }
 }

lib/pls/src/internal/scheduling/scheduler_memory.cpp

 #include "pls/internal/scheduling/scheduler_memory.h"
 #include "pls/internal/scheduling/scheduler_memory.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
-            malloc_scheduler_memory::malloc_scheduler_memory(const size_t num_threads, const size_t memory_per_stack):
-                    num_threads_{num_threads} {
-                threads_ = reinterpret_cast<aligned_thread *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_thread)));
-                thread_states_ = reinterpret_cast<aligned_thread_state *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_thread_state)));
+namespace internal {
+namespace scheduling {
 
 
-                task_stacks_ = reinterpret_cast<aligned_aligned_stack *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_aligned_stack)));
-                task_stacks_memory_ = reinterpret_cast<char**>(base::alignment::allocate_aligned(num_threads * sizeof(char*)));
-                for (size_t i = 0; i < num_threads_; i++) {
-                    task_stacks_memory_[i] = reinterpret_cast<char*>(base::alignment::allocate_aligned(memory_per_stack));
-                    new ((void*)task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i], memory_per_stack);
-                }
-            }
+malloc_scheduler_memory::malloc_scheduler_memory(const size_t num_threads, const size_t memory_per_stack) :
+    num_threads_{num_threads} {
+  threads_ =
+      reinterpret_cast<aligned_thread *>(base::alignment::allocate_aligned(num_threads * sizeof(aligned_thread)));
+  thread_states_ = reinterpret_cast<aligned_thread_state *>(base::alignment::allocate_aligned(
+      num_threads * sizeof(aligned_thread_state)));
 
 
-            malloc_scheduler_memory::~malloc_scheduler_memory() {
-                free(threads_);
-                free(thread_states_);
+  task_stacks_ = reinterpret_cast<aligned_aligned_stack *>(base::alignment::allocate_aligned(
+      num_threads * sizeof(aligned_aligned_stack)));
+  task_stacks_memory_ = reinterpret_cast<char **>(base::alignment::allocate_aligned(num_threads * sizeof(char *)));
+  for (size_t i = 0; i < num_threads_; i++) {
+    task_stacks_memory_[i] = reinterpret_cast<char *>(base::alignment::allocate_aligned(memory_per_stack));
+    new((void *) task_stacks_[i].pointer()) data_structures::aligned_stack(task_stacks_memory_[i], memory_per_stack);
+  }
+}
+
+malloc_scheduler_memory::~malloc_scheduler_memory() {
+  free(threads_);
+  free(thread_states_);
+
+  for (size_t i = 0; i < num_threads_; i++) {
+    free(task_stacks_memory_[i]);
+  }
+  free(task_stacks_);
+  free(task_stacks_memory_);
+}
 
 
-                for (size_t i = 0; i < num_threads_; i++) {
-                    free(task_stacks_memory_[i]);
-                }
-                free(task_stacks_);
-                free(task_stacks_memory_);
-            }
-        }
-    }
+}
+}
 }
 }

lib/pls/src/internal/scheduling/thread_state.cpp

 #include "pls/internal/scheduling/thread_state.h"
 #include "pls/internal/scheduling/thread_state.h"
 
 
 namespace pls {
 namespace pls {
-    namespace internal {
-        namespace scheduling {
+namespace internal {
+namespace scheduling {
 
 
-        }
-    }
+}
+}
 }
 }

test/CMakeLists.txt

 add_executable(tests
 add_executable(tests
         main.cpp
         main.cpp
-        base_tests.cpp scheduling_tests.cpp data_structures_test.cpp)
+        data_structures_test.cpp)
 target_link_libraries(tests catch2 pls)
 target_link_libraries(tests catch2 pls)

test/base_tests.cpp

@@ -13,73 +13,73 @@ static bool base_tests_visited;
 static int base_tests_local_value_one;
 static int base_tests_local_value_one;
 static vector<int> base_tests_local_value_two;
 static vector<int> base_tests_local_value_two;
 
 
-TEST_CASE( "thread creation and joining", "[internal/data_structures/thread.h]") {
-    base_tests_visited = false;
-    auto t1 = start_thread([]() { base_tests_visited = true; });
-    t1.join();
+TEST_CASE("thread creation and joining", "[internal/data_structures/thread.h]") {
+  base_tests_visited = false;
+  auto t1 = start_thread([]() { base_tests_visited = true; });
+  t1.join();
 
 
-    REQUIRE(base_tests_visited);
+  REQUIRE(base_tests_visited);
 }
 }
 
 
-TEST_CASE( "thread state", "[internal/data_structures/thread.h]") {
-    int state_one = 1;
-    vector<int> state_two{1, 2};
+TEST_CASE("thread state", "[internal/data_structures/thread.h]") {
+  int state_one = 1;
+  vector<int> state_two{1, 2};
 
 
-    auto t1 = start_thread([]() { base_tests_local_value_one = *this_thread::state<int>(); }, &state_one);
-    auto t2 = start_thread([]() { base_tests_local_value_two = *this_thread::state<vector<int>>(); }, &state_two);
-    t1.join();
-    t2.join();
+  auto t1 = start_thread([]() { base_tests_local_value_one = *this_thread::state<int>(); }, &state_one);
+  auto t2 = start_thread([]() { base_tests_local_value_two = *this_thread::state<vector<int>>(); }, &state_two);
+  t1.join();
+  t2.join();
 
 
-    REQUIRE(base_tests_local_value_one == 1);
-    REQUIRE(base_tests_local_value_two == vector<int>{1, 2});
+  REQUIRE(base_tests_local_value_one == 1);
+  REQUIRE(base_tests_local_value_two == vector<int>{1, 2});
 }
 }
 
 
 int base_tests_shared_counter;
 int base_tests_shared_counter;
 
 
-TEST_CASE( "spinlock protects concurrent counter", "[internal/data_structures/spinlock.h]") {
-    constexpr int num_iterations = 1000000;
-    base_tests_shared_counter = 0;
-    spin_lock lock{};
-
-    SECTION( "lock can be used by itself" ) {
-        auto t1 = start_thread([&]() {
-            for (int i = 0; i < num_iterations; i++) {
-                lock.lock();
-                base_tests_shared_counter++;
-                lock.unlock();
-            }
-        });
-        auto t2 = start_thread([&]() {
-            for (int i = 0; i < num_iterations; i++) {
-                lock.lock();
-                base_tests_shared_counter--;
-                lock.unlock();
-            }
-        });
-
-        t1.join();
-        t2.join();
-
-        REQUIRE(base_tests_shared_counter == 0);
-    }
-
-    SECTION( "lock can be used with std::lock_guard" ) {
-        auto t1 = start_thread([&]() {
-            for (int i = 0; i < num_iterations; i++) {
-                std::lock_guard<spin_lock> my_lock{lock};
-                base_tests_shared_counter++;
-            }
-        });
-        auto t2 = start_thread([&]() {
-            for (int i = 0; i < num_iterations; i++) {
-                std::lock_guard<spin_lock> my_lock{lock};
-                base_tests_shared_counter--;
-            }
-        });
-
-        t1.join();
-        t2.join();
-
-        REQUIRE(base_tests_shared_counter == 0);
-    }
+TEST_CASE("spinlock protects concurrent counter", "[internal/data_structures/spinlock.h]") {
+  constexpr int num_iterations = 1000000;
+  base_tests_shared_counter = 0;
+  spin_lock lock{};
+
+  SECTION("lock can be used by itself") {
+    auto t1 = start_thread([&]() {
+      for (int i = 0; i < num_iterations; i++) {
+        lock.lock();
+        base_tests_shared_counter++;
+        lock.unlock();
+      }
+    });
+    auto t2 = start_thread([&]() {
+      for (int i = 0; i < num_iterations; i++) {
+        lock.lock();
+        base_tests_shared_counter--;
+        lock.unlock();
+      }
+    });
+
+    t1.join();
+    t2.join();
+
+    REQUIRE(base_tests_shared_counter == 0);
+  }
+
+  SECTION("lock can be used with std::lock_guard") {
+    auto t1 = start_thread([&]() {
+      for (int i = 0; i < num_iterations; i++) {
+        std::lock_guard<spin_lock> my_lock{lock};
+        base_tests_shared_counter++;
+      }
+    });
+    auto t2 = start_thread([&]() {
+      for (int i = 0; i < num_iterations; i++) {
+        std::lock_guard<spin_lock> my_lock{lock};
+        base_tests_shared_counter--;
+      }
+    });
+
+    t1.join();
+    t2.join();
+
+    REQUIRE(base_tests_shared_counter == 0);
+  }
 }
 }

test/scheduling_tests.cpp

@@ -4,76 +4,75 @@
 
 
 using namespace pls;
 using namespace pls;
 
 
-class once_sub_task: public fork_join_sub_task {
-    std::atomic<int>* counter_;
-    int children_;
+class once_sub_task : public fork_join_sub_task {
+  std::atomic<int> *counter_;
+  int children_;
 
 
-protected:
-    void execute_internal() override {
-        (*counter_)++;
-        for (int i = 0; i < children_; i++) {
-            spawn_child(once_sub_task(counter_, children_ - 1));
-        }
+ protected:
+  void execute_internal() override {
+    (*counter_)++;
+    for (int i = 0; i < children_; i++) {
+      spawn_child(once_sub_task(counter_, children_ - 1));
     }
     }
+  }
 
 
-public:
-    explicit once_sub_task(std::atomic<int>* counter, int children):
-        fork_join_sub_task(),
-        counter_{counter},
-        children_{children} {}
+ public:
+  explicit once_sub_task(std::atomic<int> *counter, int children) :
+      fork_join_sub_task(),
+      counter_{counter},
+      children_{children} {}
 };
 };
 
 
-class force_steal_sub_task: public fork_join_sub_task {
-    std::atomic<int>* parent_counter_;
-    std::atomic<int>* overall_counter_;
+class force_steal_sub_task : public fork_join_sub_task {
+  std::atomic<int> *parent_counter_;
+  std::atomic<int> *overall_counter_;
 
 
-protected:
-    void execute_internal() override {
-        (*overall_counter_)--;
-        if (overall_counter_->load() > 0) {
-            std::atomic<int> counter{1};
-            spawn_child(force_steal_sub_task(&counter, overall_counter_));
-            while (counter.load() > 0)
-                ; // Spin...
-        }
-
-        (*parent_counter_)--;
+ protected:
+  void execute_internal() override {
+    (*overall_counter_)--;
+    if (overall_counter_->load() > 0) {
+      std::atomic<int> counter{1};
+      spawn_child(force_steal_sub_task(&counter, overall_counter_));
+      while (counter.load() > 0); // Spin...
     }
     }
 
 
-public:
-    explicit force_steal_sub_task(std::atomic<int>* parent_counter, std::atomic<int>* overall_counter):
-            fork_join_sub_task(),
-            parent_counter_{parent_counter},
-            overall_counter_{overall_counter} {}
+    (*parent_counter_)--;
+  }
+
+ public:
+  explicit force_steal_sub_task(std::atomic<int> *parent_counter, std::atomic<int> *overall_counter) :
+      fork_join_sub_task(),
+      parent_counter_{parent_counter},
+      overall_counter_{overall_counter} {}
 };
 };
 
 
-TEST_CASE( "tbb task are scheduled correctly", "[internal/scheduling/fork_join_task.h]") {
-    malloc_scheduler_memory my_scheduler_memory{8, 2 << 12};
+TEST_CASE("tbb task are scheduled correctly", "[internal/scheduling/fork_join_task.h]") {
+  malloc_scheduler_memory my_scheduler_memory{8, 2 << 12};
 
 
-    SECTION("tasks are executed exactly once") {
-        scheduler my_scheduler{&my_scheduler_memory, 2};
-        int start_counter = 4;
-        int total_tasks = 1 + 4 + 4 * 3 + 4 * 3 * 2 + 4 * 3 * 2 * 1;
-        std::atomic<int> counter{0};
+  SECTION("tasks are executed exactly once") {
+    scheduler my_scheduler{&my_scheduler_memory, 2};
+    int start_counter = 4;
+    int total_tasks = 1 + 4 + 4 * 3 + 4 * 3 * 2 + 4 * 3 * 2 * 1;
+    std::atomic<int> counter{0};
 
 
-        my_scheduler.perform_work([&] (){
-            once_sub_task sub_task{&counter, start_counter};
-            fork_join_task task{&sub_task, unique_id::create(42)};
-            scheduler::execute_task(task);
-        });
+    my_scheduler.perform_work([&]() {
+      once_sub_task sub_task{&counter, start_counter};
+      fork_join_task task{&sub_task, unique_id::create(42)};
+      scheduler::execute_task(task);
+    });
 
 
-        REQUIRE(counter.load() == total_tasks);
-        my_scheduler.terminate(true);
-    }
+    REQUIRE(counter.load() == total_tasks);
+    my_scheduler.terminate(true);
+  }
 
 
-    SECTION("tasks can be stolen") {
-        scheduler my_scheduler{&my_scheduler_memory, 8};
-        my_scheduler.perform_work([&] (){
-            std::atomic<int> dummy_parent{1}, overall_counter{8};
-            force_steal_sub_task sub_task{&dummy_parent, &overall_counter};
-            fork_join_task task{&sub_task, unique_id::create(42)};
-            scheduler::execute_task(task);
-        });
-        my_scheduler.terminate(true);
-    }
+  SECTION("tasks can be stolen") {
+    scheduler my_scheduler{&my_scheduler_memory, 8};
+    my_scheduler.perform_work([&]() {
+      std::atomic<int> dummy_parent{1}, overall_counter{8};
+      force_steal_sub_task sub_task{&dummy_parent, &overall_counter};
+      fork_join_task task{&sub_task, unique_id::create(42)};
+      scheduler::execute_task(task);
+    });
+    my_scheduler.terminate(true);
+  }
 }
 }