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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_RWLOCK_H
#define _LIBS_UTILS_RWLOCK_H
#include <stdint.h>
#include <sys/types.h>
#if defined(HAVE_PTHREADS)
# include <pthread.h>
#endif
#include <utils/Errors.h>
#include <utils/ThreadDefs.h>
// ---------------------------------------------------------------------------
namespace android {
// ---------------------------------------------------------------------------
#if defined(HAVE_PTHREADS)
/*
* 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 RWLock {
public:
enum {
PRIVATE = 0,
SHARED = 1
};
RWLock();
RWLock(const char* name);
RWLock(int type, const char* name = NULL);
~RWLock();
status_t readLock();
status_t tryReadLock();
status_t writeLock();
status_t tryWriteLock();
void unlock();
class AutoRLock {
public:
inline AutoRLock(RWLock& rwlock) : mLock(rwlock) { mLock.readLock(); }
inline ~AutoRLock() { mLock.unlock(); }
private:
RWLock& mLock;
};
class AutoWLock {
public:
inline AutoWLock(RWLock& rwlock) : mLock(rwlock) { mLock.writeLock(); }
inline ~AutoWLock() { mLock.unlock(); }
private:
RWLock& mLock;
};
private:
// A RWLock cannot be copied
RWLock(const RWLock&);
RWLock& operator = (const RWLock&);
pthread_rwlock_t mRWLock;
};
inline RWLock::RWLock() {
pthread_rwlock_init(&mRWLock, NULL);
}
inline RWLock::RWLock(const char* name) {
pthread_rwlock_init(&mRWLock, NULL);
}
inline RWLock::RWLock(int type, const char* name) {
if (type == SHARED) {
pthread_rwlockattr_t attr;
pthread_rwlockattr_init(&attr);
pthread_rwlockattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
pthread_rwlock_init(&mRWLock, &attr);
pthread_rwlockattr_destroy(&attr);
} else {
pthread_rwlock_init(&mRWLock, NULL);
}
}
inline RWLock::~RWLock() {
pthread_rwlock_destroy(&mRWLock);
}
inline status_t RWLock::readLock() {
return -pthread_rwlock_rdlock(&mRWLock);
}
inline status_t RWLock::tryReadLock() {
return -pthread_rwlock_tryrdlock(&mRWLock);
}
inline status_t RWLock::writeLock() {
return -pthread_rwlock_wrlock(&mRWLock);
}
inline status_t RWLock::tryWriteLock() {
return -pthread_rwlock_trywrlock(&mRWLock);
}
inline void RWLock::unlock() {
pthread_rwlock_unlock(&mRWLock);
}
#endif // HAVE_PTHREADS
// ---------------------------------------------------------------------------
}; // namespace android
// ---------------------------------------------------------------------------
#endif // _LIBS_UTILS_RWLOCK_H
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