content/common/gpu/media/video_accelerator_unittest_helpers.h

   1 // Copyright 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 // This file contains helper classes for video accelerator unittests.
   6
   7 #ifndef CONTENT_COMMON_GPU_MEDIA_VIDEO_ACCELERATOR_UNITTEST_HELPERS_H_
   8 #define CONTENT_COMMON_GPU_MEDIA_VIDEO_ACCELERATOR_UNITTEST_HELPERS_H_
   9
  10 #include <queue>
  11
  12 #include "base/synchronization/condition_variable.h"
  13 #include "base/synchronization/lock.h"
  14
  15 namespace content {
  16
  17 // Helper class allowing one thread to wait on a notification from another.
  18 // If notifications come in faster than they are Wait()'d for, they are
  19 // accumulated (so exactly as many Wait() calls will unblock as Notify() calls
  20 // were made, regardless of order).
  21 template <typename StateEnum>
  22 class ClientStateNotification {
  23  public:
  24   ClientStateNotification();
  25   ~ClientStateNotification();
  26
  27   // Used to notify a single waiter of a ClientState.
  28   void Notify(StateEnum state);
  29   // Used by waiters to wait for the next ClientState Notification.
  30   StateEnum Wait();
  31
  32  private:
  33   base::Lock lock_;
  34   base::ConditionVariable cv_;
  35   std::queue<StateEnum> pending_states_for_notification_;
  36 };
  37
  38 template <typename StateEnum>
  39 ClientStateNotification<StateEnum>::ClientStateNotification() : cv_(&lock_) {}
  40
  41 template <typename StateEnum>
  42 ClientStateNotification<StateEnum>::~ClientStateNotification() {}
  43
  44 template <typename StateEnum>
  45 void ClientStateNotification<StateEnum>::Notify(StateEnum state) {
  46   base::AutoLock auto_lock(lock_);
  47   pending_states_for_notification_.push(state);
  48   cv_.Signal();
  49 }
  50
  51 template <typename StateEnum>
  52 StateEnum ClientStateNotification<StateEnum>::Wait() {
  53   base::AutoLock auto_lock(lock_);
  54   while (pending_states_for_notification_.empty())
  55     cv_.Wait();
  56   StateEnum ret = pending_states_for_notification_.front();
  57   pending_states_for_notification_.pop();
  58   return ret;
  59 }
  60
  61 }  // namespace content
  62
  63 #endif  // CONTENT_COMMON_GPU_MEDIA_VIDEO_ACCELERATOR_UNITTEST_HELPERS_H_