native_client_sdk/src/libraries/sdk_util/thread_pool.h

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // Simple thread pool class
   6
   7 #ifndef LIBRARIES_SDK_UTIL_THREAD_POOL_H_
   8 #define LIBRARIES_SDK_UTIL_THREAD_POOL_H_
   9
  10 #include <pthread.h>
  11 #include <semaphore.h>
  12
  13 #include "sdk_util/atomicops.h"
  14
  15 namespace sdk_util {
  16
  17 // typdef helper for work function
  18 typedef void (*WorkFunction)(int task_index, void* data);
  19
  20 // ThreadPool is a class to manage num_threads and assign
  21 // them num_tasks of work at a time. Each call
  22 // to Dispatch(..) will block until all tasks complete.
  23 // If 0 is passed in for num_threads, all tasks will be
  24 // issued on the dispatch thread.
  25
  26 class ThreadPool {
  27  public:
  28   void Dispatch(int num_tasks, WorkFunction work, void* data);
  29   explicit ThreadPool(int num_threads);
  30   ~ThreadPool();
  31  private:
  32   int DecCounter();
  33   void Setup(int counter, WorkFunction work, void* data);
  34   void DispatchMany(int num_tasks, WorkFunction work, void* data);
  35   void DispatchHere(int num_tasks, WorkFunction work, void* data);
  36   void WorkLoop();
  37   static void* WorkerThreadEntry(void* data);
  38   void PostExitAndJoinAll();
  39   pthread_t* threads_;
  40   Atomic32 counter_;
  41   const int num_threads_;
  42   bool exiting_;
  43   void* user_data_;
  44   WorkFunction user_work_function_;
  45   sem_t work_sem_;
  46   sem_t done_sem_;
  47 };
  48
  49 }  // namespace sdk_util
  50
  51 #endif  // LIBRARIES_SDK_UTIL_THREAD_POOL_H_
  52