157 lines
4.4 KiB
C++
157 lines
4.4 KiB
C++
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef _LIBS_UTILS_MUTEX_H
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#define _LIBS_UTILS_MUTEX_H
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#include <stdint.h>
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#include <sys/types.h>
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#include <time.h>
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#if !defined(_WIN32)
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# include <pthread.h>
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#endif
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#include <utils/Errors.h>
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#include <utils/Timers.h>
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// ---------------------------------------------------------------------------
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namespace android {
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// ---------------------------------------------------------------------------
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class Condition;
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/*
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* Simple mutex class. The implementation is system-dependent.
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*
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* The mutex must be unlocked by the thread that locked it. They are not
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* recursive, i.e. the same thread can't lock it multiple times.
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*/
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class Mutex {
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public:
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enum {
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PRIVATE = 0,
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SHARED = 1
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};
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Mutex();
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Mutex(const char* name);
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Mutex(int type, const char* name = NULL);
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~Mutex();
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// lock or unlock the mutex
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status_t lock();
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void unlock();
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// lock if possible; returns 0 on success, error otherwise
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status_t tryLock();
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#if HAVE_ANDROID_OS
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// lock the mutex, but don't wait longer than timeoutMilliseconds.
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// Returns 0 on success, TIMED_OUT for failure due to timeout expiration.
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//
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// OSX doesn't have pthread_mutex_timedlock() or equivalent. To keep
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// capabilities consistent across host OSes, this method is only available
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// when building Android binaries.
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status_t timedLock(nsecs_t timeoutMilliseconds);
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#endif
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// Manages the mutex automatically. It'll be locked when Autolock is
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// constructed and released when Autolock goes out of scope.
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class Autolock {
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public:
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inline Autolock(Mutex& mutex) : mLock(mutex) { mLock.lock(); }
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inline Autolock(Mutex* mutex) : mLock(*mutex) { mLock.lock(); }
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inline ~Autolock() { mLock.unlock(); }
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private:
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Mutex& mLock;
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};
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private:
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friend class Condition;
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// A mutex cannot be copied
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Mutex(const Mutex&);
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Mutex& operator = (const Mutex&);
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#if !defined(_WIN32)
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pthread_mutex_t mMutex;
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#else
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void _init();
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void* mState;
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#endif
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};
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// ---------------------------------------------------------------------------
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#if !defined(_WIN32)
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inline Mutex::Mutex() {
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pthread_mutex_init(&mMutex, NULL);
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}
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inline Mutex::Mutex(__attribute__((unused)) const char* name) {
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pthread_mutex_init(&mMutex, NULL);
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}
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inline Mutex::Mutex(int type, __attribute__((unused)) const char* name) {
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if (type == SHARED) {
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pthread_mutexattr_t attr;
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pthread_mutexattr_init(&attr);
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pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
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pthread_mutex_init(&mMutex, &attr);
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pthread_mutexattr_destroy(&attr);
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} else {
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pthread_mutex_init(&mMutex, NULL);
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}
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}
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inline Mutex::~Mutex() {
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pthread_mutex_destroy(&mMutex);
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}
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inline status_t Mutex::lock() {
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return -pthread_mutex_lock(&mMutex);
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}
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inline void Mutex::unlock() {
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pthread_mutex_unlock(&mMutex);
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}
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inline status_t Mutex::tryLock() {
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return -pthread_mutex_trylock(&mMutex);
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}
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#if HAVE_ANDROID_OS
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inline status_t Mutex::timedLock(nsecs_t timeoutNs) {
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const struct timespec ts = {
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/* .tv_sec = */ static_cast<time_t>(timeoutNs / 1000000000),
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/* .tv_nsec = */ static_cast<long>(timeoutNs % 1000000000),
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};
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return -pthread_mutex_timedlock(&mMutex, &ts);
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}
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#endif
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#endif // !defined(_WIN32)
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// ---------------------------------------------------------------------------
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/*
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* Automatic mutex. Declare one of these at the top of a function.
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* When the function returns, it will go out of scope, and release the
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* mutex.
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*/
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typedef Mutex::Autolock AutoMutex;
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// ---------------------------------------------------------------------------
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}; // namespace android
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// ---------------------------------------------------------------------------
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#endif // _LIBS_UTILS_MUTEX_H
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