1 /*
2  * Copyright 2022 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 #pragma once
18 
19 #include <log/log.h>
20 #include <utils/Mutex.h>
21 
22 namespace android {
23 
24 struct SCOPED_CAPABILITY ConditionalLock {
ConditionalLockConditionalLock25     ConditionalLock(Mutex& mutex, bool lock) ACQUIRE(mutex) : mutex(mutex), lock(lock) {
26         if (lock) mutex.lock();
27     }
28 
RELEASEConditionalLock29     ~ConditionalLock() RELEASE() {
30         if (lock) mutex.unlock();
31     }
32 
33     Mutex& mutex;
34     const bool lock;
35 };
36 
37 struct SCOPED_CAPABILITY TimedLock {
TimedLockTimedLock38     TimedLock(Mutex& mutex, nsecs_t timeout, const char* whence) ACQUIRE(mutex)
39           : mutex(mutex), status(mutex.timedLock(timeout)) {
40         ALOGE_IF(!locked(), "%s timed out locking: %s (%d)", whence, strerror(-status), status);
41     }
42 
RELEASETimedLock43     ~TimedLock() RELEASE() {
44         if (locked()) mutex.unlock();
45     }
46 
lockedTimedLock47     bool locked() const { return status == NO_ERROR; }
48 
49     Mutex& mutex;
50     const status_t status;
51 };
52 
53 // Require, under penalty of compilation failure, that the compiler thinks that a mutex is held.
54 #define REQUIRE_MUTEX(expr) ([]() REQUIRES(expr) {})()
55 
56 // Tell the compiler that we know that a mutex is held.
57 #define ASSERT_MUTEX(expr) ([]() ASSERT_CAPABILITY(expr) {})()
58 
59 // Specify that one mutex is an alias for another.
60 // (e.g. SurfaceFlinger::mStateLock and Layer::mFlinger->mStateLock)
61 #define MUTEX_ALIAS(held, alias) (REQUIRE_MUTEX(held), ASSERT_MUTEX(alias))
62 
63 } // namespace android
64