mutex.h
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/*
* Copyright (C) 2015 Kaspar Schleiser <kaspar@schleiser.de>
* 2013, 2014 Freie Universität Berlin
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @defgroup core_sync Synchronization
* @brief Mutex for thread synchronization
* @ingroup core
* @{
*
* @file
* @brief RIOT synchronization API
*
* @author Kaspar Schleiser <kaspar@schleiser.de>
*/
#ifndef MUTEX_H
#define MUTEX_H
#include <stddef.h>
#include "list.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* @brief Mutex structure. Must never be modified by the user.
*/
typedef struct {
/**
* @brief The process waiting queue of the mutex. **Must never be changed
* by the user.**
* @internal
*/
list_node_t queue;
} mutex_t;
/**
* @brief Static initializer for mutex_t.
* @details This initializer is preferable to mutex_init().
*/
#define MUTEX_INIT { { NULL } }
/**
* @brief Static initializer for mutex_t with a locked mutex
*/
#define MUTEX_INIT_LOCKED { { MUTEX_LOCKED } }
/**
* @cond INTERNAL
* @brief This is the value of the mutex when locked and no threads are waiting
* for it
*/
#define MUTEX_LOCKED ((void *)-1)
/**
* @endcond
*/
/**
* @brief Initializes a mutex object.
* @details For initialization of variables use MUTEX_INIT instead.
* Only use the function call for dynamically allocated mutexes.
* @param[out] mutex pre-allocated mutex structure, must not be NULL.
*/
static inline void mutex_init(mutex_t *mutex)
{
mutex->queue.next = NULL;
}
/**
* @brief Lock a mutex, blocking or non-blocking.
*
* @details For commit purposes you should probably use mutex_trylock() and
* mutex_lock() instead.
*
* @param[in] mutex Mutex object to lock. Has to be initialized first.
* Must not be NULL.
* @param[in] blocking if true, block until mutex is available.
*
* @return 1 if mutex was unlocked, now it is locked.
* @return 0 if the mutex was locked.
*/
int _mutex_lock(mutex_t *mutex, int blocking);
/**
* @brief Tries to get a mutex, non-blocking.
*
* @param[in] mutex Mutex object to lock. Has to be initialized first. Must not
* be NULL.
*
* @return 1 if mutex was unlocked, now it is locked.
* @return 0 if the mutex was locked.
*/
static inline int mutex_trylock(mutex_t *mutex)
{
return _mutex_lock(mutex, 0);
}
/**
* @brief Locks a mutex, blocking.
*
* @param[in] mutex Mutex object to lock. Has to be initialized first. Must not be NULL.
*/
static inline void mutex_lock(mutex_t *mutex)
{
_mutex_lock(mutex, 1);
}
/**
* @brief Unlocks the mutex.
*
* @param[in] mutex Mutex object to unlock, must not be NULL.
*/
void mutex_unlock(mutex_t *mutex);
/**
* @brief Unlocks the mutex and sends the current thread to sleep
*
* @param[in] mutex Mutex object to unlock, must not be NULL.
*/
void mutex_unlock_and_sleep(mutex_t *mutex);
#ifdef __cplusplus
}
#endif
#endif /* MUTEX_H */
/** @} */