rwlock.h

MANTIS是由科罗拉多大学开发的传感器网络嵌入式操作系统。 这是mantis的0.9.5版本的源码。

//  This file is part of MANTIS OS, Operating System
//  See http://mantis.cs.colorado.edu/
//
//  Copyright (C) 2003,2004,2005 University of Colorado, Boulder
//
//  This program is free software; you can redistribute it and/or
//  modify it under the terms of the mos license (see file LICENSE)

/** @file micro/include/rwlock.h
 * @brief Basic read-write locking support.
 *
 * @author Lane Phillips
 * @date Created: 02/25/2005
 */

#ifndef RWLOCK_H_
#define RWLOCK_H_

#include "mos.h"
#include "tlist.h"

/** @brief Rwlock is locked */
#define RWLOCK_LOCKED 1
/** @brief Rwlock is unlocked */
#define RWLOCK_OK 0

/** @brief Rwlock data structure */
typedef struct mos_rwlock_t {
   tlist_t rq;
   tlist_t wq;
   uint8_t rlocked;
   uint8_t wlocked;
} mos_rwlock_t;


/** @brief Initialize a read-write lock.
 *
 * Must init before use.
 * @param lock Read-write lock to init
 */
void rwlock_init(mos_rwlock_t *lock);

/** @brief Lock a read-write lock for reading.
 *
 * This lock may be shared with other threads that have called rwlock_rdlock().
 * Blocks the thread if the read-write lock is already locked for writing.
 * @param lock Read-write lock to lock
 */
void rwlock_rdlock(mos_rwlock_t *lock);

/** @brief Lock a read-write lock for reading if it is free.
 *
 * This lock may be shared with other threads that have called rwlock_rdlock().
 * Does not block.
 * @param lock Read-write lock to lock
 * @return RWLOCK_LOCKED if another thread already has a lock, else RWLOCK_OK
 */
uint8_t rwlock_tryrdlock(mos_rwlock_t *lock);

/** @brief Lock a read-write lock for writing.
 *
 * Only one thread will hold a write lock at a time.
 * Blocks the thread if the read-write lock is already locked for reading or writing.
 * @param lock Read-write lock to lock
 */
void rwlock_wrlock(mos_rwlock_t *lock);

/** @brief Lock a read-write lock for writing if it is free.
 *
 * Only one thread will hold a write lock at a time.
 * Does not block.
 * @param lock Read-write lock to lock
 * @return RWLOCK_LOCKED if another thread already has a lock, else RWLOCK_OK
 */
uint8_t rwlock_trywrlock(mos_rwlock_t *lock);

/** @brief Unlock a read-write lock.
 * 
 * Release both read and write locks.  Threads that are blocking on write locks
 * will wake up before threads blocking on read locks.
 * @param lock Read-write lock to unlock
 */
void rwlock_unlock(mos_rwlock_t *lock);

// Not implemented
/*void rwlock_timedrdlock(mos_rwlock_t *lock,
            const struct timespec *restrict);
void rwlock_timedwrlock(mos_rwlock_t *lock,
            const struct timespec *restrict);*/

#endif