pthread_mutex.c

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/*
 * Copyright (c) 2013-2019 Huawei Technologies Co., Ltd. All rights reserved.
 * Copyright (c) 2020-2021 Huawei Device Co., Ltd. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 *    conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list
 *    of conditions and the following disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors may be used
 *    to endorse or promote products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#include "pthread.h"
/****************************************************************************
 
****************************************************************************/
/*!
* @file pthread_mutex.c
* @brief 对鸿蒙轻内核互斥锁的封装
* @verbatim 
    当 pthread_mutex_lock() 返回时，该互斥锁已被锁定。调用线程是该互斥锁的属主。
    如果该互斥锁已被另一个线程锁定和拥有，则调用线程将阻塞，直到该互斥锁变为可用为止。
 
    如果互斥锁类型为 PTHREAD_MUTEX_NORMAL，则不提供死锁检测。尝试重新锁定互斥锁会导致死锁。
    如果某个线程尝试解除锁定的互斥锁不是由该线程锁定或未锁定，则将产生不确定的行为。
 
    如果互斥锁类型为 PTHREAD_MUTEX_ERRORCHECK，则会提供错误检查。如果某个线程尝试重新锁定的互斥锁已经由该线程锁定，
    则将返回错误。如果某个线程尝试解除锁定的互斥锁不是由该线程锁定或者未锁定，则将返回错误。
 
    如果互斥锁类型为 PTHREAD_MUTEX_RECURSIVE，则该互斥锁会保留锁定计数这一概念。线程首次成功获取互斥锁时，
    锁定计数会设置为 1。线程每重新锁定该互斥锁一次，锁定计数就增加 1。线程每解除锁定该互斥锁一次，锁定计数就减小 1。 
    锁定计数达到 0 时，该互斥锁即可供其他线程获取。如果某个线程尝试解除锁定的互斥锁不是由该线程锁定或者未锁定，则将返回错误。
 
    如果互斥锁类型是 PTHREAD_MUTEX_DEFAULT，则尝试以递归方式锁定该互斥锁将产生不确定的行为。
    对于不是由调用线程锁定的互斥锁，如果尝试解除对它的锁定，则会产生不确定的行为。如果尝试解除锁定尚未锁定的互斥锁，
    则会产生不确定的行为。
    参考链接: https://docs.oracle.com/cd/E19253-01/819-7051/sync-12/index.html
* @endverbatim 
*/
 
/**
 * @brief 初始化互斥锁属性
 * @param attr 
 * @return int 
 */
int pthread_mutexattr_init(pthread_mutexattr_t *attr)
{//如果互斥锁已初始化，则它会处于未锁定状态。互斥锁可以位于进程之间共享的内存中或者某个进程的专用内存中。
    unsigned int ret = LOS_MuxAttrInit(attr);
    if (ret != LOS_OK) {
        return (int)ret;
    }
///当其他线程正在使用某个互斥锁时，请勿重新初始化或销毁该互斥锁。如果任一操作没有正确完成，将会导致程序失败。如果要重新初始化或销毁某个互斥锁，则应用程序必须确保当前未使用该互斥锁。
#if defined POSIX_MUTEX_DEFAULT_INHERIT
    attr->protocol    = PTHREAD_PRIO_INHERIT;
#elif defined POSIX_MUTEX_DEFAULT_PROTECT
    attr->protocol    = PTHREAD_PRIO_PROTECT;
#else
    attr->protocol    = PTHREAD_PRIO_NONE;
#endif
    attr->type = PTHREAD_MUTEX_NORMAL;
    return LOS_OK;
}
 
int pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
{
    return LOS_MuxAttrDestroy(attr);
}
 
int pthread_mutexattr_setprotocol(pthread_mutexattr_t *attr, int protocol)
{
    return LOS_MuxAttrSetProtocol(attr, protocol);
}
 
int pthread_mutexattr_getprotocol(const pthread_mutexattr_t *attr, int *protocol)
{
    return LOS_MuxAttrGetProtocol(attr, protocol);
}
 
int pthread_mutexattr_setprioceiling(pthread_mutexattr_t *attr, int prioceiling)
{
    return LOS_MuxAttrSetPrioceiling(attr, prioceiling);
}
 
int pthread_mutexattr_getprioceiling(const pthread_mutexattr_t *attr, int *prioceiling)
{
    return LOS_MuxAttrGetPrioceiling(attr, prioceiling);
}
 
int pthread_mutex_setprioceiling(pthread_mutex_t *mutex, int prioceiling, int *oldPrioceiling)
{
    return LOS_MuxSetPrioceiling(mutex, prioceiling, oldPrioceiling);
}
 
int pthread_mutex_getprioceiling(const pthread_mutex_t *mutex, int *prioceiling)
{
    return LOS_MuxGetPrioceiling(mutex, prioceiling);
}
 
int pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *outType)
{
    return LOS_MuxAttrGetType(attr, outType);
}
 
int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type)
{
    return LOS_MuxAttrSetType(attr, type);
}
/* Initialize mutex. If mutexAttr is NULL, use default attributes. */
/**
 * @brief 初始化互斥锁。 如果 mutexAttr 为 NULL，则使用默认属性。
 * @param mutex 
 * @param mutexAttr 
 * @return int 
 */
int pthread_mutex_init(pthread_mutex_t *mutex, const pthread_mutexattr_t *mutexAttr)
{
    unsigned int ret = LOS_MuxInit(mutex, mutexAttr);
    if ((ret == LOS_OK) && (mutexAttr == NULL)) {
#if defined POSIX_MUTEX_DEFAULT_INHERIT
        mutex->attr.protocol    = PTHREAD_PRIO_INHERIT;
#elif defined POSIX_MUTEX_DEFAULT_PROTECT
        mutex->attr.protocol    = PTHREAD_PRIO_PROTECT;
#else
        mutex->attr.protocol    = PTHREAD_PRIO_NONE;
#endif
        mutex->attr.type = PTHREAD_MUTEX_NORMAL;
    }
 
    return (int)ret;
}
///销毁互斥锁
int pthread_mutex_destroy(pthread_mutex_t *mutex)
{
    return LOS_MuxDestroy(mutex);
}
///互斥锁加锁操作
/* Lock mutex, waiting for it if necessary. */
int pthread_mutex_lock(pthread_mutex_t *mutex)
{
    return LOS_MuxLock(mutex, LOS_WAIT_FOREVER);
}
///互斥锁尝试加锁操作
int pthread_mutex_trylock(pthread_mutex_t *mutex)
{
    return LOS_MuxTrylock(mutex);
}
///解锁互斥锁
int pthread_mutex_unlock(pthread_mutex_t *mutex)
{
    return LOS_MuxUnlock(mutex);
}