native_client_sdk/src/libraries/sdk_util/thread_safe_queue.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 #ifndef LIBRARIES_SDK_UTIL_THREAD_SAFE_QUEUE_H_
   6 #define LIBRARIES_SDK_UTIL_THREAD_SAFE_QUEUE_H_
   7
   8 #include <pthread.h>
   9
  10 #include <list>
  11
  12 #include "sdk_util/auto_lock.h"
  13 #include "sdk_util/macros.h"
  14
  15 namespace sdk_util {
  16
  17 // ThreadSafeQueue
  18 //
  19 // A simple template to support multithreaded and optionally blocking access
  20 // to a Queue of object pointers.
  21 //
  22 template<class T> class ThreadSafeQueue {
  23  public:
  24   ThreadSafeQueue() {
  25     pthread_cond_init(&cond_, NULL);
  26   }
  27
  28   ~ThreadSafeQueue() {
  29     pthread_cond_destroy(&cond_);
  30   }
  31
  32   void Enqueue(T* item) {
  33     AUTO_LOCK(lock_);
  34     list_.push_back(item);
  35
  36     pthread_cond_signal(&cond_);
  37   }
  38
  39   T* Dequeue(bool block) {
  40     AUTO_LOCK(lock_);
  41
  42     // If blocking enabled, wait until we queue is non-empty
  43     if (block) {
  44       while (list_.empty()) pthread_cond_wait(&cond_, lock_.mutex());
  45     }
  46
  47     if (list_.empty()) return NULL;
  48
  49     T* item = list_.front();
  50     list_.pop_front();
  51     return item;
  52   }
  53
  54  private:
  55   std::list<T*> list_;
  56   pthread_cond_t  cond_;
  57   SimpleLock lock_;
  58   DISALLOW_COPY_AND_ASSIGN(ThreadSafeQueue);
  59 };
  60
  61 }  // namespace sdk_util
  62
  63 #endif  // LIBRARIES_SDK_UTIL_THREAD_SAFE_QUEUE_H_
  64