Add merge and split nodes.

This makes the programming model a full dataflow implementation, as it allows for branching and recursion.

app/playground/main.cpp

@@ -9,7 +9,9 @@
 #include <pls/dataflow/internal/outputs.h>
 #include <pls/dataflow/internal/function_node.h>
 #include <pls/dataflow/internal/graph.h>
-#include <pls/dataflow/internal/out_port.h>
+#include <pls/dataflow/internal/switch_node.h>
+#include <pls/dataflow/internal/split_node.h>
+#include <pls/dataflow/internal/merge_node.h>
 
 int main() {
   using namespace pls::dataflow;
@@ -28,26 +30,48 @@ int main() {
   };
   function_node<inputs<int>, outputs<int>, decltype(minus_one)> minus_one_node{minus_one};
 
+  auto is_positive = [](const int &i1, bool &o1) {
+    o1 = i1 > 0;
+  };
+  function_node<inputs<int>, outputs<bool>, decltype(is_positive)> is_positive_node{is_positive};
+
   auto recursion = [&](const int &i1, const int &i2, int &o1) {
-    if (i1 > 0) {
     std::tuple<int> out;
     graph.run({i1, i2}, out);
     pls::scheduler::wait_for_all();
     o1 = std::get<0>(out);
-    } else {
-      o1 = i2;
-    }
   };
   function_node<inputs<int, int>, outputs<int>, decltype(recursion)> recursion_node{recursion};
 
+  split_node<int> minus_split;
+  split_node<bool> decision_split;
+  switch_node<int> recursion_split;
+  merge_node<int> recursion_merge;
+
   // Connect
-  graph.input<0>() >> minus_one_node.in_port<0>();
-  minus_one_node.out_port<0>() >> recursion_node.in_port<0>();
 
+  // Inputs to first processing step
+  graph.input<0>() >> minus_one_node.in_port<0>();
   graph.input<1>() >> triple_node.in_port<0>();
-  triple_node.out_port<0>() >> recursion_node.in_port<1>();
+  minus_one_node.out_port<0>() >> minus_split.value_in_port();
+
+  // Prepare decision...
+  minus_split.out_port_1() >> is_positive_node.in_port<0>();
+  is_positive_node.out_port<0>() >> decision_split.value_in_port();
+  triple_node.out_port<0>() >> recursion_split.value_in_port();
+  decision_split.out_port_1() >> recursion_split.condition_in_port();
+
+  // Connect true case (recursion)
+  minus_split.out_port_2() >> recursion_node.in_port<0>();
+  recursion_split.true_out_port() >> recursion_node.in_port<1>();
+  recursion_node.out_port<0>() >> recursion_merge.true_in_port();
+
+  // Connect false case (no recursion)
+  recursion_split.false_out_port() >> recursion_merge.false_in_port();
 
-  recursion_node.out_port<0>() >> graph.output<0>();
+  // Deliver final result (back from merge)
+  decision_split.out_port_2() >> recursion_merge.condition_in_port();
+  recursion_merge.value_out_port() >> graph.output<0>();
 
   // Build
   graph.build();

lib/pls/CMakeLists.txt

@@ -18,6 +18,11 @@ add_library(pls STATIC
         include/pls/dataflow/internal/function_node.h
         include/pls/dataflow/internal/node.h
         include/pls/dataflow/internal/graph.h
+        include/pls/dataflow/internal/build_state.h
+        include/pls/dataflow/internal/function_node_impl.h
+        include/pls/dataflow/internal/graph_impl.h
+        include/pls/dataflow/internal/switch_node.h
+        include/pls/dataflow/internal/merge_node.h
 
         include/pls/internal/base/spin_lock.h
         include/pls/internal/base/tas_spin_lock.h src/internal/base/tas_spin_lock.cpp
@@ -43,13 +48,15 @@ add_library(pls STATIC
         include/pls/internal/helpers/mini_benchmark.h
         include/pls/internal/helpers/unique_id.h
         include/pls/internal/helpers/range.h
+        include/pls/internal/helpers/seqence.h
 
         include/pls/internal/scheduling/thread_state.h
         include/pls/internal/scheduling/scheduler.h src/internal/scheduling/scheduler.cpp
         include/pls/internal/scheduling/scheduler_impl.h
         include/pls/internal/scheduling/task.h src/internal/scheduling/task.cpp
         include/pls/internal/scheduling/scheduler_memory.h src/internal/scheduling/scheduler_memory.cpp
-        include/pls/internal/scheduling/lambda_task.h include/pls/internal/helpers/seqence.h include/pls/dataflow/internal/build_state.h include/pls/dataflow/internal/function_node_impl.h include/pls/dataflow/internal/graph_impl.h)
+        include/pls/internal/scheduling/lambda_task.h
+        include/pls/dataflow/internal/split_node.h)
 # Add everything in `./include` to be in the include path of this project
 target_include_directories(pls
         PUBLIC

lib/pls/include/pls/dataflow/internal/in_port.h

@@ -68,13 +68,12 @@ class multi_in_port {
 };
 template<typename CB, int N, typename I0, typename ...I>
 class multi_in_port<CB, N, I0, I...> : public in_port<I0> {
- private:
+ public:
   // Helpers for managing recursive types
   using my_type = multi_in_port<CB, N, I0, I...>;
   using child_type = multi_in_port<CB, N + 1, I...>;
   using value_type = I0;
 
- public:
   explicit multi_in_port(node *owning_node, CB *cb) : in_port<I0>{owning_node}, cb_{cb}, rec_{owning_node, cb} {};
 
   void token_pushed(token<I0> token) override {
@@ -103,13 +102,13 @@ class multi_in_port<CB, N, I0, I...> : public in_port<I0> {
   using value_type_at = typename type_at<POS, I0, I...>::type;
 
   // Helper struct required for recursive access to input's by index
-  template<int POS, class RES_T, class MY_T>
+  template<int POS, typename RES_T, typename MY_T>
   struct get_at {
     static RES_T &get(MY_T &self) {
       return get_at<POS - 1, RES_T, typename MY_T::child_type>::get(self.rec_);
     }
   };
-  template<class RESULT, class CURRENT>
+  template<typename RESULT, typename CURRENT>
   struct get_at<0, RESULT, CURRENT> {
     static RESULT &get(CURRENT &self) {
       return self;
@@ -126,7 +125,6 @@ class multi_in_port<CB, N, I0, I...> : public in_port<I0> {
     return this->is_connected() && rec_.fully_connected();
   }
 
- private:
   child_type rec_;
   CB *cb_;
 };

lib/pls/include/pls/dataflow/internal/merge_node.h

+
+#ifndef PLS_DATAFLOW_INTERNAL_MERGE_NODE_H_
+#define PLS_DATAFLOW_INTERNAL_MERGE_NODE_H_
+
+#include <atomic>
+
+#include "in_port.h"
+#include "out_port.h"
+#include "node.h"
+#include "token.h"
+
+namespace pls {
+namespace dataflow {
+namespace internal {
+
+template<typename I>
+class merge_node : public node {
+  // Our own type
+  using self_type = merge_node<I>;
+
+  // Input-Output port types
+  using multi_in_port_type = multi_in_port<self_type, 0, I, I, bool>;
+  using multi_out_port_type = multi_out_port<I>;
+
+  // Input-Output tuples
+  using input_tuple = std::tuple<token < I>, token<I>, token<bool>>;
+
+  // Memory used for ONE active invocation of the dataflow-graph
+  struct invocation_memory {
+    std::atomic<unsigned int> inputs_missing_;
+    input_tuple input_buffer_;
+  };
+
+  // Encodings for current input state (needs to fit into an atomic)
+  static constexpr unsigned int IN_0_MISSING = 1u << 0u;
+  static constexpr unsigned int IN_1_MISSING = 1u << 1u;
+  static constexpr unsigned int COND_MISSING = 1u << 2u;
+  static constexpr unsigned int INITIAL_STATE = IN_0_MISSING + IN_1_MISSING + COND_MISSING;
+
+ public:
+  explicit merge_node() : in_port_{this, this}, out_port_{} {}
+
+  in_port<I> &true_in_port() {
+    return in_port_.template get<0>();
+  }
+
+  in_port<I> &false_in_port() {
+    return in_port_.template get<1>();
+  }
+
+  in_port<bool> &condition_in_port() {
+    return in_port_.template get<2>();
+  }
+
+  out_port<I> &value_out_port() {
+    return out_port_.template get<0>();
+  }
+
+  template<int POS, typename T>
+  void token_pushed(token<T> token) {
+    auto current_memory = get_invocation<invocation_memory>(token.invocation());
+
+    std::get<POS>(current_memory->input_buffer_) = token;
+
+    unsigned int remaining_inputs;
+    if (POS == 0) {
+      remaining_inputs = (current_memory->inputs_missing_).fetch_sub(IN_0_MISSING) - IN_0_MISSING;
+    } else if (POS == 1) {
+      remaining_inputs = (current_memory->inputs_missing_).fetch_sub(IN_1_MISSING) - IN_1_MISSING;
+    } else {
+      remaining_inputs = (current_memory->inputs_missing_).fetch_sub(COND_MISSING) - COND_MISSING;
+    }
+
+    if ((remaining_inputs & COND_MISSING) == 0) {
+      if ((remaining_inputs & IN_0_MISSING) == 0) {
+        auto &data = std::get<0>(current_memory->input_buffer_);
+        value_out_port().push_token(data);
+        current_memory->inputs_missing_ += IN_0_MISSING + COND_MISSING;
+      } else if ((remaining_inputs & IN_1_MISSING) == 0) {
+        auto &data = std::get<1>(current_memory->input_buffer_);
+        value_out_port().push_token(data);
+        current_memory->inputs_missing_ += IN_1_MISSING + COND_MISSING;
+      }
+    }
+  }
+
+  int num_successors() const override {
+    return 1;
+  }
+  node *successor_at(int pos) const override {
+    return out_port_.next_node_at(pos);
+  }
+
+  bool is_fully_connected() const override {
+    return in_port_.fully_connected() && out_port_.fully_connected();
+  }
+
+  int instance_buffer_size() const override {
+    return sizeof(invocation_memory);
+  }
+  void init_instance_buffer(void *memory) const override {
+    auto invocation = new(memory) invocation_memory{};
+    invocation->inputs_missing_ = INITIAL_STATE;
+  };
+
+ private:
+  multi_in_port_type in_port_;
+  multi_out_port_type out_port_;
+};
+
+}
+}
+}
+
+#endif //PLS_DATAFLOW_INTERNAL_MERGE_NODE_H_

lib/pls/include/pls/dataflow/internal/split_node.h

+
+#ifndef PLS_DATAFLOW_INTERNAL_SPLIT_NODE_H_
+#define PLS_DATAFLOW_INTERNAL_SPLIT_NODE_H_
+
+#include <atomic>
+
+#include "in_port.h"
+#include "out_port.h"
+#include "node.h"
+#include "token.h"
+
+namespace pls {
+namespace dataflow {
+namespace internal {
+
+template<typename I>
+class split_node : public node {
+  // Our own type
+  using self_type = split_node<I>;
+
+  // Input-Output port types
+  using multi_in_port_type = multi_in_port<self_type, 0, I>;
+  using multi_out_port_type = multi_out_port<I, I>;
+
+ public:
+  explicit split_node() : in_port_{this, this}, out_port_{} {}
+
+  in_port<I> &value_in_port() {
+    return in_port_.template get<0>();
+  }
+
+  out_port<I> &out_port_1() {
+    return out_port_.template get<0>();
+  }
+
+  out_port<I> &out_port_2() {
+    return out_port_.template get<1>();
+  }
+
+  template<int POS, typename T>
+  void token_pushed(token<T> token) {
+    out_port_1().push_token(token);
+    out_port_2().push_token(token);
+  }
+
+  int num_successors() const override {
+    return 2;
+  }
+  node *successor_at(int pos) const override {
+    return out_port_.next_node_at(pos);
+  }
+
+  bool is_fully_connected() const override {
+    return in_port_.fully_connected() && out_port_.fully_connected();
+  }
+
+  int instance_buffer_size() const override {
+    return 0;
+  }
+  void init_instance_buffer(void *memory) const override {
+    // No need for memory, we simply forward
+  };
+
+ private:
+  multi_in_port_type in_port_;
+  multi_out_port_type out_port_;
+};
+
+}
+}
+}
+
+#endif //PLS_DATAFLOW_INTERNAL_SPLIT_NODE_H_

lib/pls/include/pls/dataflow/internal/switch_node.h

+
+#ifndef PLS_DATAFLOW_INTERNAL_SWITCH_NODE_H_
+#define PLS_DATAFLOW_INTERNAL_SWITCH_NODE_H_
+
+#include <atomic>
+
+#include "in_port.h"
+#include "out_port.h"
+#include "node.h"
+#include "token.h"
+
+namespace pls {
+namespace dataflow {
+namespace internal {
+
+template<typename I>
+class switch_node : public node {
+  // Our own type
+  using self_type = switch_node<I>;
+
+  // Input-Output port types
+  using multi_in_port_type = multi_in_port<self_type, 0, I, bool>;
+  using multi_out_port_type = multi_out_port<I, I>;
+
+  // Input-Output tuples
+  using input_tuple = std::tuple<token < I>, token<bool>>;
+
+  // Memory used for ONE active invocation of the dataflow-graph
+  struct invocation_memory {
+    std::atomic<int> inputs_missing_;
+    input_tuple input_buffer_;
+  };
+
+ public:
+  explicit switch_node() : in_port_{this, this}, out_port_{} {}
+
+  in_port<I> &value_in_port() {
+    return in_port_.template get<0>();
+  }
+
+  in_port<bool> &condition_in_port() {
+    return in_port_.template get<1>();
+  }
+
+  out_port<I> &true_out_port() {
+    return out_port_.template get<0>();
+  }
+
+  out_port<I> &false_out_port() {
+    return out_port_.template get<1>();
+  }
+
+  template<int POS, typename T>
+  void token_pushed(token<T> token) {
+    auto current_memory = get_invocation<invocation_memory>(token.invocation());
+
+    std::get<POS>(current_memory->input_buffer_) = token;
+    auto remaining_inputs = --(current_memory->inputs_missing_);
+    if (remaining_inputs == 0) {
+      bool condition = std::get<1>(current_memory->input_buffer_).value();
+      auto &data = std::get<0>(current_memory->input_buffer_);
+      if (condition) {
+        true_out_port().push_token(data);
+      } else {
+        false_out_port().push_token(data);
+      }
+      current_memory->inputs_missing_ = 2;
+    }
+  }
+
+  int num_successors() const override {
+    return 2;
+  }
+  node *successor_at(int pos) const override {
+    return out_port_.next_node_at(pos);
+  }
+
+  bool is_fully_connected() const override {
+    return in_port_.fully_connected() && out_port_.fully_connected();
+  }
+
+  int instance_buffer_size() const override {
+    return sizeof(invocation_memory);
+  }
+  void init_instance_buffer(void *memory) const override {
+    auto invocation = new(memory) invocation_memory{};
+    invocation->inputs_missing_ = 2;
+  };
+
+ private:
+  multi_in_port_type in_port_;
+  multi_out_port_type out_port_;
+};
+
+}
+}
+}
+
+#endif //PLS_DATAFLOW_INTERNAL_SWITCH_NODE_H_