- new thread pool (no stucks anymore)

src/engine/helper/HL_ThreadPool.cpp

@@ -0,0 +1,51 @@
+#include "HL_ThreadPool.h"
+
+thread_pool::thread_pool(size_t num_of_threads, const std::string& name)
+{
+    this->name = name;
+    if (!num_of_threads)
+        num_of_threads = std::thread::hardware_concurrency();
+
+    for(size_t idx = 0; idx < num_of_threads; idx++)
+        this->workers.push_back(std::thread(&thread_pool::run_worker, this));
+}
+
+// Add new work item to the pool
+void thread_pool::enqueue(const thread_pool::task& t)
+{
+    {
+        std::unique_lock<std::mutex> lock(this->queue_mutex);
+        this->tasks.push(t);
+    }
+    this->condition.notify_one();
+}
+
+
+// the destructor joins all threads
+thread_pool::~thread_pool()
+{
+    {
+        std::unique_lock<std::mutex> lock(this->queue_mutex);
+        stop = true;
+    }
+    this->condition.notify_all();
+    for(std::thread &worker: workers)
+        worker.join();
+}
+
+void thread_pool::run_worker()
+{
+    ThreadHelper::setName(this->name);
+    task t;
+    while(!this->stop)
+    {
+        {
+            std::unique_lock<std::mutex> lock(this->queue_mutex);
+
+            this->condition.wait(lock, [this]{return !this->tasks.empty() || this->stop;});
+            t = this->tasks.front();
+            this->tasks.pop();
+        }
+        t(); // function<void()> type
+    }
+}

src/engine/helper/HL_ThreadPool.h

@@ -13,99 +13,31 @@
 #include <optional>
 #include "HL_Sync.h"
 
-class ThreadPool
+class thread_pool
 {
 public:
-    ThreadPool(size_t, const std::string&);
-    template<class F, class... Args>
-    auto enqueue(F&& f, Args&&... args)
-        -> std::future<typename std::result_of<F(Args...)>::type>;
-    ~ThreadPool();
-    void setPause(bool v) { this->pause = v;}
+    typedef std::function<void()> task;
+
+    thread_pool(size_t num_of_threads, const std::string&);
+    ~thread_pool();
+
+    void enqueue(const task& task);
+
 private:
     // need to keep track of threads so we can join them
     std::vector< std::thread > workers;
+
     // the task queue
-    std::queue< std::function<void()> > tasks;
+    std::queue< task > tasks;
     
     // synchronization
     std::mutex queue_mutex;
     std::condition_variable condition;
-    bool stop, pause;
+    bool stop = false;
+
+    // thread name prefix for worker threads
     std::string name;
+
+    void run_worker();
 };
- 
-// the constructor just launches some amount of workers
-inline ThreadPool::ThreadPool(size_t threads, const std::string& name)
-    :   stop(false), pause(false), name(name)
-{
-    for(size_t i = 0;i<threads;++i)
-        workers.emplace_back(
-            [this, i]
-            {
-                ThreadHelper::setName(this->name + std::to_string(i));
-                for(;;)
-                {
-                    std::function<void()> task; bool task_assigned = false;
-
-                    {
-                        std::unique_lock<std::mutex> lock(this->queue_mutex);
-                        this->condition.wait(lock,
-                            [this]{ return this->stop || !this->pause || !this->tasks.empty(); });
-                        if (this->tasks.empty())
-                            std::this_thread::sleep_for(std::chrono::milliseconds(10));
-                        if(this->stop && this->tasks.empty())
-                            return;
-                        if(this->pause)
-                            continue;
-                        if (this->tasks.size())
-                        {
-                            task = std::move(this->tasks.front()); task_assigned = true;
-                            this->tasks.pop();
-                        }
-                    }
-                    if (task_assigned)
-                        task();
-                }
-            }
-        );
-}
-
-// add new work item to the pool
-template<class F, class... Args>
-auto ThreadPool::enqueue(F&& f, Args&&... args)
-    -> std::future<typename std::result_of<F(Args...)>::type>
-{
-    using return_type = typename std::result_of<F(Args...)>::type;
-
-    auto task = std::make_shared< std::packaged_task<return_type()> >(
-            std::bind(std::forward<F>(f), std::forward<Args>(args)...)
-        );
-        
-    std::future<return_type> res = task->get_future();
-    {
-        std::unique_lock<std::mutex> lock(queue_mutex);
-
-        // don't allow enqueueing after stopping the pool
-        if(stop)
-            throw std::runtime_error("enqueue on stopped ThreadPool");
-
-        tasks.emplace([task](){ (*task)(); });
-    }
-    condition.notify_one();
-    return res;
-}
-
-// the destructor joins all threads
-inline ThreadPool::~ThreadPool()
-{
-    {
-        std::unique_lock<std::mutex> lock(queue_mutex);
-        stop = true;
-    }
-    condition.notify_all();
-    for(std::thread &worker: workers)
-        worker.join();
-}
-
 #endif