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