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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "utils/threads.h"
//--------------------------------------------------------------------------------------------------
namespace android {
class CallbackProtector : public RefBase {
public:
CallbackProtector();
virtual ~CallbackProtector();
/**
* Indicates whether the CallbackProtector is non-NULL and it's safe to enter the callback.
*/
static bool enterCbIfOk(const sp<CallbackProtector> &protector);
/**
* Indicates whether it's safe to enter the callback. It would typically return false
* if the associated object (AudioTrack, AudioPlayer, MediaPlayer) is about to be destroyed.
*/
bool enterCb();
/**
* This method must be paired to each call to enterCb() or enterCbIfOk(),
* only it returned that it is safe enter the callback;
*/
void exitCb();
/**
* Called to signal the associated object is about to be destroyed, so whenever a callback is
* entered (see enterCb) it will be notified it is pointless to process the callback. This will
* return immediately if there are no callbacks, and will block until current callbacks exit.
*/
void requestCbExitAndWait();
/**
* Similar to requestCbExitAndWait, but does not wait for current callbacks to exit.
*/
void requestCbExit();
private:
Mutex mLock;
Condition mCbExitedCondition;
bool mSafeToEnterCb;
/** Counts the number of callbacks actively locking the associated AudioPlayer */
unsigned int mCbCount;
#ifdef USE_DEBUG
pthread_t mCallbackThread;
pid_t mCallbackTid;
pthread_t mRequesterThread;
pid_t mRequesterTid;
#endif
// disallow "evil" constructors
CallbackProtector(const CallbackProtector &);
CallbackProtector &operator=(const CallbackProtector &);
};
} // namespace android