1 /* 2 * Copyright (C) 2015 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 "AutoConditionLock.h" 18 19 namespace android { 20 21 WaitableMutexWrapper::WaitableMutexWrapper(Mutex* mutex) : mMutex{mutex}, mState{false} {} 22 23 WaitableMutexWrapper::~WaitableMutexWrapper() {} 24 25 // Locks manager-owned mutex 26 AutoConditionLock::AutoConditionLock(const std::shared_ptr<WaitableMutexWrapper>& manager) : 27 mManager{manager}, mAutoLock{manager->mMutex}, mAcquired(false) {} 28 29 // Unlocks manager-owned mutex 30 AutoConditionLock::~AutoConditionLock() { 31 // Unset the condition and wake everyone up before releasing lock 32 if (mAcquired) { 33 mManager->mState = false; 34 mManager->mCondition.broadcast(); 35 } 36 } 37 38 std::unique_ptr<AutoConditionLock> AutoConditionLock::waitAndAcquire( 39 const std::shared_ptr<WaitableMutexWrapper>& manager, nsecs_t waitTime) { 40 41 if (manager == nullptr || manager->mMutex == nullptr) { 42 // Bad input, return null 43 return std::unique_ptr<AutoConditionLock>{nullptr}; 44 } 45 46 // Acquire scoped lock 47 std::unique_ptr<AutoConditionLock> scopedLock(new AutoConditionLock(manager)); 48 49 // Figure out what time in the future we should hit the timeout 50 nsecs_t failTime = systemTime(SYSTEM_TIME_MONOTONIC) + waitTime; 51 52 // Wait until we timeout, or success 53 while(manager->mState) { 54 status_t ret = manager->mCondition.waitRelative(*(manager->mMutex), waitTime); 55 if (ret != NO_ERROR) { 56 // Timed out or whatever, return null 57 return std::unique_ptr<AutoConditionLock>{nullptr}; 58 } 59 waitTime = failTime - systemTime(SYSTEM_TIME_MONOTONIC); 60 } 61 62 // Set the condition and return 63 manager->mState = true; 64 scopedLock->mAcquired = true; 65 return scopedLock; 66 } 67 68 std::unique_ptr<AutoConditionLock> AutoConditionLock::waitAndAcquire( 69 const std::shared_ptr<WaitableMutexWrapper>& manager) { 70 71 if (manager == nullptr || manager->mMutex == nullptr) { 72 // Bad input, return null 73 return std::unique_ptr<AutoConditionLock>{nullptr}; 74 } 75 76 // Acquire scoped lock 77 std::unique_ptr<AutoConditionLock> scopedLock(new AutoConditionLock(manager)); 78 79 // Wait until we timeout, or success 80 while(manager->mState) { 81 status_t ret = manager->mCondition.wait(*(manager->mMutex)); 82 if (ret != NO_ERROR) { 83 // Timed out or whatever, return null 84 return std::unique_ptr<AutoConditionLock>{nullptr}; 85 } 86 } 87 88 // Set the condition and return 89 manager->mState = true; 90 scopedLock->mAcquired = true; 91 return scopedLock; 92 } 93 94 }; // namespace android 95
