//===--------------------- TaskPool.h ---------------------------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #ifndef utility_TaskPool_h_ #define utility_TaskPool_h_ #include "llvm/ADT/STLExtras.h" #include // for bind, function #include #include #include // for make_shared #include // for mutex, unique_lock, condition_variable #include // for forward, result_of, move // Global TaskPool class for running tasks in parallel on a set of worker thread // created the first // time the task pool is used. The TaskPool provide no guarantee about the order // the task will be run // and about what tasks will run in parallel. None of the task added to the task // pool should block // on something (mutex, future, condition variable) what will be set only by the // completion of an // other task on the task pool as they may run on the same thread sequentally. class TaskPool { public: // Add a new task to the task pool and return a std::future belonging to the // newly created task. // The caller of this function has to wait on the future for this task to // complete. template static std::future::type> AddTask(F &&f, Args &&... args); // Run all of the specified tasks on the task pool and wait until all of them // are finished // before returning. This method is intended to be used for small number tasks // where listing // them as function arguments is acceptable. For running large number of tasks // you should use // AddTask for each task and then call wait() on each returned future. template static void RunTasks(T &&... tasks); private: TaskPool() = delete; template struct RunTaskImpl; static void AddTaskImpl(std::function &&task_fn); }; template std::future::type> TaskPool::AddTask(F &&f, Args &&... args) { auto task_sp = std::make_shared< std::packaged_task::type()>>( std::bind(std::forward(f), std::forward(args)...)); AddTaskImpl([task_sp]() { (*task_sp)(); }); return task_sp->get_future(); } template void TaskPool::RunTasks(T &&... tasks) { RunTaskImpl::Run(std::forward(tasks)...); } template struct TaskPool::RunTaskImpl { static void Run(Head &&h, Tail &&... t) { auto f = AddTask(std::forward(h)); RunTaskImpl::Run(std::forward(t)...); f.wait(); } }; template <> struct TaskPool::RunTaskImpl<> { static void Run() {} }; // Run 'func' on every value from begin .. end-1. Each worker will grab // 'batch_size' numbers at a time to work on, so for very fast functions, batch // should be large enough to avoid too much cache line contention. void TaskMapOverInt(size_t begin, size_t end, const llvm::function_ref &func); #endif // #ifndef utility_TaskPool_h_