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