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
WaitableMutexWrapper(Mutex * mutex)21 WaitableMutexWrapper::WaitableMutexWrapper(Mutex* mutex) : mMutex{mutex}, mState{false} {}
22
~WaitableMutexWrapper()23 WaitableMutexWrapper::~WaitableMutexWrapper() {}
24
25 // Locks manager-owned mutex
AutoConditionLock(const std::shared_ptr<WaitableMutexWrapper> & manager)26 AutoConditionLock::AutoConditionLock(const std::shared_ptr<WaitableMutexWrapper>& manager) :
27 mManager{manager}, mAutoLock{manager->mMutex}, mAcquired(false) {}
28
29 // Unlocks manager-owned mutex
~AutoConditionLock()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
waitAndAcquire(const std::shared_ptr<WaitableMutexWrapper> & manager,nsecs_t waitTime)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
waitAndAcquire(const std::shared_ptr<WaitableMutexWrapper> & manager)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