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/*
* Copyright (C) 2015 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.
*/
#ifndef ANDROID_SERVICE_UTILS_SCOPED_CONDITION_H
#define ANDROID_SERVICE_UTILS_SCOPED_CONDITION_H
#include <utils/Timers.h>
#include <utils/Condition.h>
#include <utils/Errors.h>
#include <utils/Mutex.h>
#include <memory>
namespace android {
/**
* WaitableMutexWrapper can be used with AutoConditionLock to construct scoped locks for the
* wrapped Mutex with timeouts for lock acquisition.
*/
class WaitableMutexWrapper {
friend class AutoConditionLock;
public:
/**
* Construct the ConditionManger with the given Mutex.
*/
WaitableMutexWrapper(Mutex* mutex);
virtual ~WaitableMutexWrapper();
private:
Mutex* mMutex;
bool mState;
Condition mCondition;
};
/**
* AutoConditionLock is a scoped lock similar to Mutex::Autolock, but allows timeouts to be
* specified for lock acquisition.
*
* AutoConditionLock is used with a WaitableMutexWrapper to lock/unlock the WaitableMutexWrapper's
* wrapped Mutex, and wait/set/signal the WaitableMutexWrapper's wrapped condition. To use this,
* call AutoConditionLock::waitAndAcquire to get an instance. This will:
* - Lock the given WaitableMutexWrapper's mutex.
* - Wait for the WaitableMutexWrapper's condition to become false, or timeout.
* - Set the WaitableMutexWrapper's condition to true.
*
* When the AutoConditionLock goes out of scope and is destroyed, this will:
* - Set the WaitableMutexWrapper's condition to false.
* - Signal threads waiting on this condition to wakeup.
* - Release WaitableMutexWrapper's mutex.
*/
class AutoConditionLock final {
public:
AutoConditionLock() = delete;
AutoConditionLock(const AutoConditionLock& other) = delete;
AutoConditionLock & operator=(const AutoConditionLock&) = delete;
~AutoConditionLock();
/**
* Make a new AutoConditionLock from a given WaitableMutexWrapper, waiting up to waitTime
* nanoseconds to acquire the WaitableMutexWrapper's wrapped lock.
*
* Return an empty unique_ptr if this fails, or a timeout occurs.
*/
static std::unique_ptr<AutoConditionLock> waitAndAcquire(
const std::shared_ptr<WaitableMutexWrapper>& manager, nsecs_t waitTime);
/**
* Make a new AutoConditionLock from a given WaitableMutexWrapper, waiting indefinitely to
* acquire the WaitableMutexWrapper's wrapped lock.
*
* Return an empty unique_ptr if this fails.
*/
static std::unique_ptr<AutoConditionLock> waitAndAcquire(
const std::shared_ptr<WaitableMutexWrapper>& manager);
private:
AutoConditionLock(const std::shared_ptr<WaitableMutexWrapper>& manager);
std::shared_ptr<WaitableMutexWrapper> mManager;
Mutex::Autolock mAutoLock;
};
}; // namespace android
#endif // ANDROID_SERVICE_UTILS_SCOPED_CONDITION_H
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