87 lines
2.5 KiB
C
87 lines
2.5 KiB
C
/*
|
|
* Copyright (C) 2011 Tobias Brunner
|
|
* Hochschule fuer Technik Rapperswil
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify it
|
|
* under the terms of the GNU General Public License as published by the
|
|
* Free Software Foundation; either version 2 of the License, or (at your
|
|
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
* for more details.
|
|
*/
|
|
|
|
/**
|
|
* @defgroup semaphore semaphore
|
|
* @{ @ingroup threading
|
|
*/
|
|
|
|
#ifndef THREADING_SEMAPHORE_H_
|
|
#define THREADING_SEMAPHORE_H_
|
|
|
|
#include <utils/utils.h>
|
|
|
|
typedef struct semaphore_t semaphore_t;
|
|
|
|
/**
|
|
* A semaphore is basically an integer whose value is never allowed to be
|
|
* lower than 0. Two operations can be performed on it: increment the
|
|
* value by one, and decrement the value by one. If the value is currently
|
|
* zero, then the decrement operation will blcok until the value becomes
|
|
* greater than zero.
|
|
*/
|
|
struct semaphore_t {
|
|
|
|
/**
|
|
* Decrease the value by one, if it is greater than zero. Otherwise the
|
|
* current thread is blocked and it waits until the value increases.
|
|
*/
|
|
void (*wait)(semaphore_t *this);
|
|
|
|
/**
|
|
* Decrease the value by one, if it is greater than zero. Otherwise the
|
|
* current thread is blocked and it waits until the value increases, or the
|
|
* call times out.
|
|
*
|
|
* @param timeout timeout im ms
|
|
* @return TRUE if timed out, FALSE otherwise
|
|
*/
|
|
bool (*timed_wait)(semaphore_t *this, u_int timeout);
|
|
|
|
/**
|
|
* Decrease the value by one, if it is greater than zero. Otherwise the
|
|
* current thread is blocked and it waits until the value increases, or the
|
|
* call times out.
|
|
*
|
|
* The passed timeval should be calculated based on the time_monotonic()
|
|
* function.
|
|
*
|
|
* @param tv absolute time until timeout
|
|
* @return TRUE if timed out, FALSE otherwise
|
|
*/
|
|
bool (*timed_wait_abs)(semaphore_t *this, timeval_t tv);
|
|
|
|
/**
|
|
* Increase the value by one. If the value becomes greater than zero, then
|
|
* another thread waiting will be woken up.
|
|
*/
|
|
void (*post)(semaphore_t *this);
|
|
|
|
/**
|
|
* Destroy a semaphore and free its resources.
|
|
*/
|
|
void (*destroy)(semaphore_t *this);
|
|
};
|
|
|
|
/**
|
|
* Create a semaphore instance.
|
|
*
|
|
* @param value initial value (typically 0)
|
|
* @return semaphore instance
|
|
*/
|
|
semaphore_t *semaphore_create(u_int value);
|
|
|
|
#endif /** THREADING_SEMAPHORE_H_ @} */
|