• Home
  • History
  • Annotate
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1  /*
2   * Copyright (C) 2011 The Android Open Source Project
3   *
4   * Licensed under the Apache License, Version 2.0 (the "License");
5   * you may not use this file except in compliance with the License.
6   * You may obtain a copy of the License at
7   *
8   *      http://www.apache.org/licenses/LICENSE-2.0
9   *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  #include "Configuration.h"
18  #include "utils/threads.h"
19  
20  //--------------------------------------------------------------------------------------------------
21  namespace android {
22  
23  class CallbackProtector : public RefBase {
24  
25  public:
26      CallbackProtector();
27      virtual ~CallbackProtector();
28  
29      /**
30       * Indicates whether the CallbackProtector is non-NULL and it's safe to enter the callback.
31       */
32      static bool enterCbIfOk(const sp<CallbackProtector> &protector);
33  
34      /**
35       * Indicates whether it's safe to enter the callback. It would typically return false
36       * if the associated object (AudioTrack, AudioPlayer, MediaPlayer) is about to be destroyed.
37       */
38      bool enterCb();
39  
40      /**
41       * This method must be paired to each call to enterCb() or enterCbIfOk(),
42       * only it returned that it is safe enter the callback;
43       */
44      void exitCb();
45  
46      /**
47       * Called to signal the associated object is about to be destroyed, so whenever a callback is
48       * entered (see enterCb) it will be notified it is pointless to process the callback. This will
49       * return immediately if there are no callbacks, and will block until current callbacks exit.
50       */
51      void requestCbExitAndWait();
52  
53      /**
54       * Similar to requestCbExitAndWait, but does not wait for current callbacks to exit.
55       */
56      void requestCbExit();
57  
58  private:
59      Mutex mLock;
60      Condition mCbExitedCondition;
61  
62      bool mSafeToEnterCb;
63  
64      /** Counts the number of callbacks actively locking the associated AudioPlayer */
65      unsigned int mCbCount;
66  
67  #ifdef USE_DEBUG
68      pthread_t mCallbackThread;
69      pid_t mCallbackTid;
70      pthread_t mRequesterThread;
71      pid_t mRequesterTid;
72  #endif
73  
74      // disallow "evil" constructors
75      CallbackProtector(const CallbackProtector &);
76      CallbackProtector &operator=(const CallbackProtector &);
77  };
78  
79  } // namespace android
80