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/*
* 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>
// ---------------------------------------------------------------------------
namespace android {
// ---------------------------------------------------------------------------
class Condition;
/*
* 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 Mutex {
public:
enum {
PRIVATE = 0,
SHARED = 1
};
Mutex();
Mutex(const char* name);
Mutex(int type, const char* name = NULL);
~Mutex();
// lock or unlock the mutex
status_t lock();
void unlock();
// lock if possible; returns 0 on success, error otherwise
status_t tryLock();
#if defined(__ANDROID__)
// lock the mutex, but don't wait longer than timeoutMilliseconds.
// 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.
status_t timedLock(nsecs_t timeoutMilliseconds);
#endif
// Manages the mutex automatically. It'll be locked when Autolock is
// constructed and released when Autolock goes out of scope.
class Autolock {
public:
inline Autolock(Mutex& mutex) : mLock(mutex) { mLock.lock(); }
inline Autolock(Mutex* mutex) : mLock(*mutex) { mLock.lock(); }
inline ~Autolock() { mLock.unlock(); }
private:
Mutex& mLock;
};
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, NULL);
}
inline Mutex::Mutex(__attribute__((unused)) const char* name) {
pthread_mutex_init(&mMutex, NULL);
}
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, NULL);
}
}
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) {
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
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