Make stack allocator selectable by templated constructor.

I am not sure if this is appropriate, but it works and is no focus of this project.

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

@@ -5,6 +5,7 @@
 #include <atomic>
 #include <thread>
 #include <vector>
+#include <memory>
 
 #include "pls/internal/helpers/profiler.h"
 
@@ -38,7 +39,17 @@ class scheduler {
    *
    * @param num_threads The number of worker threads to be created.
    */
-  explicit scheduler(unsigned int num_threads, size_t computation_depth, size_t stack_size, bool reuse_thread = true);
+  explicit scheduler(unsigned int num_threads,
+                     size_t computation_depth,
+                     size_t stack_size,
+                     bool reuse_thread = true);
+
+  template<typename ALLOC>
+  explicit scheduler(unsigned int num_threads,
+                     size_t computation_depth,
+                     size_t stack_size,
+                     bool reuse_thread,
+                     ALLOC &&stack_allocator);
 
   /**
    * The scheduler is implicitly terminated as soon as it leaves the scope.
@@ -105,8 +116,7 @@ class scheduler {
 
   bool terminated_;
 
-  // TODO: remove this into a public wrapper class with templating
-  base::mmap_stack_allocator stack_allocator_{};
+  std::shared_ptr<base::stack_allocator> stack_allocator_;
 };
 
 }

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

@@ -14,6 +14,46 @@
 
 namespace pls::internal::scheduling {
 
+template<typename ALLOC>
+scheduler::scheduler(unsigned int num_threads,
+                     size_t computation_depth,
+                     size_t stack_size,
+                     bool reuse_thread,
+                     ALLOC &&stack_allocator) :
+    num_threads_{num_threads},
+    reuse_thread_{reuse_thread},
+    sync_barrier_{num_threads + 1 - reuse_thread},
+    worker_threads_{},
+    thread_states_{},
+    main_thread_starter_function_{nullptr},
+    work_section_done_{false},
+    terminated_{false},
+    stack_allocator_{std::make_shared<ALLOC>(std::forward<ALLOC>(stack_allocator))} {
+
+  worker_threads_.reserve(num_threads);
+  task_managers_.reserve(num_threads);
+  thread_states_.reserve(num_threads);
+  for (unsigned int i = 0; i < num_threads_; i++) {
+    auto &this_task_manager =
+        task_managers_.emplace_back(std::make_unique<task_manager>(i,
+                                                                   computation_depth,
+                                                                   stack_size,
+                                                                   stack_allocator_));
+    auto &this_thread_state = thread_states_.emplace_back(std::make_unique<thread_state>(*this, i, *this_task_manager));
+
+    if (reuse_thread && i == 0) {
+      worker_threads_.emplace_back();
+      continue; // Skip over first/main thread when re-using the users thread, as this one will replace the first one.
+    }
+
+    auto *this_thread_state_pointer = this_thread_state.get();
+    worker_threads_.emplace_back([this_thread_state_pointer] {
+      thread_state::set(this_thread_state_pointer);
+      work_thread_main_loop();
+    });
+  }
+}
+
 class scheduler::init_function {
  public:
   virtual void run() = 0;

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

@@ -26,7 +26,7 @@ class task_manager {
   explicit task_manager(unsigned thread_id,
                         size_t num_tasks,
                         size_t stack_size,
-                        stack_allocator &stack_allocator);
+                        std::shared_ptr<stack_allocator> stack_allocator);
   ~task_manager();
 
   void push_resource_on_task(task *target_task, task *spare_task_chain);
@@ -51,14 +51,29 @@ class task_manager {
 
   bool try_clean_return(context_switcher::continuation &result_cont);
 
+  /**
+   * Helper to check if a task chain is correctly chained forward form the given starting task.
+   *
+   * @param start_task The start of the 'to be clean' chain
+   * @return true if the chain is clean/consistent.
+   */
   bool check_task_chain_forward(task *start_task);
+  /**
+   * Helper to check if a task chain is correctly chained backward form the given starting task.
+   *
+   * @param start_task The end of the 'to be clean' chain
+   * @return true if the chain was is clean/consistent.
+   */
   bool check_task_chain_backward(task *start_task);
+  /**
+   * Check the task chain maintained by this task manager.
+   *
+   * @return true if the chain is in a clean/consistent state.
+   */
   bool check_task_chain();
 
  private:
-  size_t num_tasks_;
-
-  stack_allocator &stack_allocator_;
+  std::shared_ptr<stack_allocator> stack_allocator_;
   std::vector<std::unique_ptr<task>> tasks_;
   task *active_task_;
 

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

@@ -7,41 +7,19 @@
 
 namespace pls::internal::scheduling {
 
-scheduler::scheduler(unsigned int num_threads, size_t computation_depth, size_t stack_size, bool reuse_thread) :
-    num_threads_{num_threads},
-    reuse_thread_{reuse_thread},
-    sync_barrier_{num_threads + 1 - reuse_thread},
-    worker_threads_{},
-    thread_states_{},
-    main_thread_starter_function_{nullptr},
-    work_section_done_{false},
-    terminated_{false} {
-
-  worker_threads_.reserve(num_threads);
-  task_managers_.reserve(num_threads);
-  thread_states_.reserve(num_threads);
-  for (unsigned int i = 0; i < num_threads_; i++) {
-    auto &this_task_manager =
-        task_managers_.emplace_back(std::make_unique<task_manager>(i, computation_depth, stack_size, stack_allocator_));
-    auto &this_thread_state = thread_states_.emplace_back(std::make_unique<thread_state>(*this, i, *this_task_manager));
-
-    if (reuse_thread && i == 0) {
-      worker_threads_.emplace_back();
-      continue; // Skip over first/main thread when re-using the users thread, as this one will replace the first one.
-    }
+scheduler::scheduler(unsigned int num_threads,
+                     size_t computation_depth,
+                     size_t stack_size,
+                     bool reuse_thread) : scheduler(num_threads,
+                                                    computation_depth,
+                                                    stack_size,
+                                                    reuse_thread,
+                                                    base::mmap_stack_allocator{}) {}
 
-    auto *this_thread_state_pointer = this_thread_state.get();
-    worker_threads_.emplace_back([this_thread_state_pointer] {
-      thread_state::set(this_thread_state_pointer);
-      work_thread_main_loop();
-    });
-  }
-}
 
 scheduler::~scheduler() {
   terminate();
 }
-
 void scheduler::work_thread_main_loop() {
   auto &scheduler = thread_state::get().get_scheduler();
   while (true) {

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

@@ -9,14 +9,13 @@ namespace pls::internal::scheduling {
 task_manager::task_manager(unsigned thread_id,
                            size_t num_tasks,
                            size_t stack_size,
-                           stack_allocator &stack_allocator) : num_tasks_{num_tasks},
-                                                               stack_allocator_{stack_allocator},
-                                                               tasks_{},
-                                                               deque_{thread_id, num_tasks_} {
+                           std::shared_ptr<stack_allocator> stack_allocator) : stack_allocator_{stack_allocator},
+                                                                               tasks_{},
+                                                                               deque_{thread_id, num_tasks} {
   tasks_.reserve(num_tasks);
 
   for (size_t i = 0; i < num_tasks - 1; i++) {
-    char *stack_memory = stack_allocator.allocate_stack(stack_size);
+    char *stack_memory = stack_allocator->allocate_stack(stack_size);
     tasks_.emplace_back(std::make_unique<task>(stack_memory, stack_size, i, thread_id));
 
     if (i > 0) {
@@ -29,7 +28,7 @@ task_manager::task_manager(unsigned thread_id,
 
 task_manager::~task_manager() {
   for (auto &task : tasks_) {
-    stack_allocator_.free_stack(task->stack_size_, task->stack_memory_);
+    stack_allocator_->free_stack(task->stack_size_, task->stack_memory_);
   }
 }
 

test/scheduling_tests.cpp

@@ -10,7 +10,6 @@
 
 using namespace pls::internal::scheduling;
 
-constexpr int MAX_NUM_THREADS = 8;
 constexpr int MAX_NUM_TASKS = 32;
 constexpr int MAX_STACK_SIZE = 1024 * 8;