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Pass task by universal reference and variadics
As suggested by daniel-j-h tasks are now taken by universal reference and forwarded with std::forward. Also enqueue takes a variadic argument list and binds the arguments to the task.
1 parent 5d0ca72 commit 41355c0

2 files changed

Lines changed: 9 additions & 7 deletions

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‎ThreadPool.h‎

Lines changed: 8 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -26,8 +26,8 @@ class Worker {
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class ThreadPool {
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public:
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ThreadPool(size_t);
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template<class T, class F>
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std::future<T> enqueue(F f);
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template<class F, class... Args>
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auto enqueue(F&& f, Args&&... args) -> std::future<decltype(std::forward<F>(f)(std::forward<Args>(args)...))>;
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~ThreadPool();
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private:
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friend class Worker;
@@ -68,15 +68,17 @@ ThreadPool::ThreadPool(size_t threads)
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}
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// add new work item to the pool
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template<class T, class F>
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std::future<T> ThreadPool::enqueue(F f)
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template<class F, class... Args>
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auto ThreadPool::enqueue(F&& f, Args&&... args) -> std::future<decltype(std::forward<F>(f)(std::forward<Args>(args)...))>
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{
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typedef decltype(std::forward<F>(f)(std::forward<Args>(args)...)) return_type;
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// don't allow enqueueing after stopping the pool
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if(stop)
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throw std::runtime_error("enqueue on stopped ThreadPool");
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auto task = std::make_shared< std::packaged_task<T()> >(f);
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std::future<T> res = task->get_future();
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auto task = std::make_shared< std::packaged_task<return_type()> >(std::bind(std::forward<F>(f), std::forward<Args>(args)...));
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std::future<return_type> res = task->get_future();
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{
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std::unique_lock<std::mutex> lock(queue_mutex);
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tasks.push([task](){ (*task)(); });

‎example.cpp‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@ int main()
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for(int i = 0; i < 8; ++i) {
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results.push_back(
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pool.enqueue<int>([i] {
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pool.enqueue([i] {
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std::cout << "hello " << i << std::endl;
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std::this_thread::sleep_for(std::chrono::seconds(1));
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std::cout << "world " << i << std::endl;

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