/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _LIBS_UTILS_MUTEX_H
#define _LIBS_UTILS_MUTEX_H
#include <stdint.h>
#include <sys/types.h>
#include <time.h>
#if !defined(_WIN32)
# include <pthread.h>
#endif
#include <utils/Errors.h>
#include <utils/Timers.h>
// Enable thread safety attributes only with clang.
// The attributes can be safely erased when compiling with other compilers.
#if defined(__clang__) && (!defined(SWIG))
#define THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x))
#else
#define THREAD_ANNOTATION_ATTRIBUTE__(x) // no-op
#endif
#define CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(capability(x))
#define SCOPED_CAPABILITY THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)
#define GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))
#define PT_GUARDED_BY(x) THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))
#define ACQUIRED_BEFORE(...) THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(__VA_ARGS__))
#define ACQUIRED_AFTER(...) THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(__VA_ARGS__))
#define REQUIRES(...) THREAD_ANNOTATION_ATTRIBUTE__(requires_capability(__VA_ARGS__))
#define REQUIRES_SHARED(...) THREAD_ANNOTATION_ATTRIBUTE__(requires_shared_capability(__VA_ARGS__))
#define ACQUIRE(...) THREAD_ANNOTATION_ATTRIBUTE__(acquire_capability(__VA_ARGS__))
#define ACQUIRE_SHARED(...) THREAD_ANNOTATION_ATTRIBUTE__(acquire_shared_capability(__VA_ARGS__))
#define RELEASE(...) THREAD_ANNOTATION_ATTRIBUTE__(release_capability(__VA_ARGS__))
#define RELEASE_SHARED(...) THREAD_ANNOTATION_ATTRIBUTE__(release_shared_capability(__VA_ARGS__))
#define TRY_ACQUIRE(...) THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_capability(__VA_ARGS__))
#define TRY_ACQUIRE_SHARED(...) \
THREAD_ANNOTATION_ATTRIBUTE__(try_acquire_shared_capability(__VA_ARGS__))
#define EXCLUDES(...) THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__))
#define ASSERT_CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(assert_capability(x))
#define ASSERT_SHARED_CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_capability(x))
#define RETURN_CAPABILITY(x) THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))
#define NO_THREAD_SAFETY_ANALYSIS THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)
// ---------------------------------------------------------------------------
namespace android {
// ---------------------------------------------------------------------------
class Condition;
/*
* NOTE: This class is for code that builds on Win32. Its usage is
* deprecated for code which doesn't build for Win32. New code which
* doesn't build for Win32 should use std::mutex and std::lock_guard instead.
*
* Simple mutex class. The implementation is system-dependent.
*
* The mutex must be unlocked by the thread that locked it. They are not
* recursive, i.e. the same thread can't lock it multiple times.
*/
class CAPABILITY("mutex") Mutex {
public:
enum {
PRIVATE = 0,
SHARED = 1
};
Mutex();
explicit Mutex(const char* name);
explicit Mutex(int type, const char* name = nullptr);
~Mutex();
// lock or unlock the mutex
status_t lock() ACQUIRE();
void unlock() RELEASE();
// lock if possible; returns 0 on success, error otherwise
status_t tryLock() TRY_ACQUIRE(0);
#if defined(__ANDROID__)
// Lock the mutex, but don't wait longer than timeoutNs (relative time).
// Returns 0 on success, TIMED_OUT for failure due to timeout expiration.
//
// OSX doesn't have pthread_mutex_timedlock() or equivalent. To keep
// capabilities consistent across host OSes, this method is only available
// when building Android binaries.
//
// FIXME?: pthread_mutex_timedlock is based on CLOCK_REALTIME,
// which is subject to NTP adjustments, and includes time during suspend,
// so a timeout may occur even though no processes could run.
// Not holding a partial wakelock may lead to a system suspend.
status_t timedLock(nsecs_t timeoutNs) TRY_ACQUIRE(0);
#endif
// Manages the mutex automatically. It'll be locked when Autolock is
// constructed and released when Autolock goes out of scope.
class SCOPED_CAPABILITY Autolock {
public:
inline explicit Autolock(Mutex& mutex) ACQUIRE(mutex) : mLock(mutex) { mLock.lock(); }
inline explicit Autolock(Mutex* mutex) ACQUIRE(mutex) : mLock(*mutex) { mLock.lock(); }
inline ~Autolock() RELEASE() { mLock.unlock(); }
private:
Mutex& mLock;
// Cannot be copied or moved - declarations only
Autolock(const Autolock&);
Autolock& operator=(const Autolock&);
};
private:
friend class Condition;
// A mutex cannot be copied
Mutex(const Mutex&);
Mutex& operator=(const Mutex&);
#if !defined(_WIN32)
pthread_mutex_t mMutex;
#else
void _init();
void* mState;
#endif
};
// ---------------------------------------------------------------------------
#if !defined(_WIN32)
inline Mutex::Mutex() {
pthread_mutex_init(&mMutex, nullptr);
}
inline Mutex::Mutex(__attribute__((unused)) const char* name) {
pthread_mutex_init(&mMutex, nullptr);
}
inline Mutex::Mutex(int type, __attribute__((unused)) const char* name) {
if (type == SHARED) {
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
pthread_mutex_init(&mMutex, &attr);
pthread_mutexattr_destroy(&attr);
} else {
pthread_mutex_init(&mMutex, nullptr);
}
}
inline Mutex::~Mutex() {
pthread_mutex_destroy(&mMutex);
}
inline status_t Mutex::lock() {
return -pthread_mutex_lock(&mMutex);
}
inline void Mutex::unlock() {
pthread_mutex_unlock(&mMutex);
}
inline status_t Mutex::tryLock() {
return -pthread_mutex_trylock(&mMutex);
}
#if defined(__ANDROID__)
inline status_t Mutex::timedLock(nsecs_t timeoutNs) {
timeoutNs += systemTime(SYSTEM_TIME_REALTIME);
const struct timespec ts = {
/* .tv_sec = */ static_cast<time_t>(timeoutNs / 1000000000),
/* .tv_nsec = */ static_cast<long>(timeoutNs % 1000000000),
};
return -pthread_mutex_timedlock(&mMutex, &ts);
}
#endif
#endif // !defined(_WIN32)
// ---------------------------------------------------------------------------
/*
* Automatic mutex. Declare one of these at the top of a function.
* When the function returns, it will go out of scope, and release the
* mutex.
*/
typedef Mutex::Autolock AutoMutex;
// ---------------------------------------------------------------------------
} // namespace android
// ---------------------------------------------------------------------------
#endif // _LIBS_UTILS_MUTEX_H