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101 lines
3.4 KiB
101 lines
3.4 KiB
/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_SERVICE_UTILS_SCOPED_CONDITION_H
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#define ANDROID_SERVICE_UTILS_SCOPED_CONDITION_H
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#include <utils/Timers.h>
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#include <utils/Condition.h>
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#include <utils/Errors.h>
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#include <utils/Mutex.h>
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#include <memory>
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namespace android {
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/**
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* WaitableMutexWrapper can be used with AutoConditionLock to construct scoped locks for the
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* wrapped Mutex with timeouts for lock acquisition.
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*/
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class WaitableMutexWrapper {
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friend class AutoConditionLock;
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public:
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/**
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* Construct the ConditionManger with the given Mutex.
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*/
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explicit WaitableMutexWrapper(Mutex* mutex);
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virtual ~WaitableMutexWrapper();
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private:
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Mutex* mMutex;
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bool mState;
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Condition mCondition;
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};
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/**
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* AutoConditionLock is a scoped lock similar to Mutex::Autolock, but allows timeouts to be
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* specified for lock acquisition.
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*
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* AutoConditionLock is used with a WaitableMutexWrapper to lock/unlock the WaitableMutexWrapper's
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* wrapped Mutex, and wait/set/signal the WaitableMutexWrapper's wrapped condition. To use this,
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* call AutoConditionLock::waitAndAcquire to get an instance. This will:
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* - Lock the given WaitableMutexWrapper's mutex.
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* - Wait for the WaitableMutexWrapper's condition to become false, or timeout.
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* - Set the WaitableMutexWrapper's condition to true.
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*
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* When the AutoConditionLock goes out of scope and is destroyed, this will:
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* - Set the WaitableMutexWrapper's condition to false.
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* - Signal threads waiting on this condition to wakeup.
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* - Release WaitableMutexWrapper's mutex.
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*/
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class AutoConditionLock final {
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public:
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AutoConditionLock() = delete;
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AutoConditionLock(const AutoConditionLock& other) = delete;
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AutoConditionLock & operator=(const AutoConditionLock&) = delete;
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~AutoConditionLock();
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/**
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* Make a new AutoConditionLock from a given WaitableMutexWrapper, waiting up to waitTime
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* nanoseconds to acquire the WaitableMutexWrapper's wrapped lock.
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*
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* Return an empty unique_ptr if this fails, or a timeout occurs.
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*/
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static std::unique_ptr<AutoConditionLock> waitAndAcquire(
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const std::shared_ptr<WaitableMutexWrapper>& manager, nsecs_t waitTime);
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/**
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* Make a new AutoConditionLock from a given WaitableMutexWrapper, waiting indefinitely to
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* acquire the WaitableMutexWrapper's wrapped lock.
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*
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* Return an empty unique_ptr if this fails.
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*/
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static std::unique_ptr<AutoConditionLock> waitAndAcquire(
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const std::shared_ptr<WaitableMutexWrapper>& manager);
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private:
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explicit AutoConditionLock(const std::shared_ptr<WaitableMutexWrapper>& manager);
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std::shared_ptr<WaitableMutexWrapper> mManager;
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Mutex::Autolock mAutoLock;
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bool mAcquired;
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};
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}; // namespace android
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#endif // ANDROID_SERVICE_UTILS_SCOPED_CONDITION_H
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