Return to semaphore.h CVS log

Up to [ELWIX - Embedded LightWeight unIX -] / embedaddon / strongswan / src / libstrongswan / threading

Annotation of embedaddon/strongswan/src/libstrongswan/threading/semaphore.h, revision 1.1.1.1

1.1       misho       1: /*
                      2:  * Copyright (C) 2011 Tobias Brunner
                      3:  * HSR Hochschule fuer Technik Rapperswil
                      4:  *
                      5:  * This program is free software; you can redistribute it and/or modify it
                      6:  * under the terms of the GNU General Public License as published by the
                      7:  * Free Software Foundation; either version 2 of the License, or (at your
                      8:  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
                      9:  *
                     10:  * This program is distributed in the hope that it will be useful, but
                     11:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     12:  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
                     13:  * for more details.
                     14:  */
                     15: 
                     16: /**
                     17:  * @defgroup semaphore semaphore
                     18:  * @{ @ingroup threading
                     19:  */
                     20: 
                     21: #ifndef THREADING_SEMAPHORE_H_
                     22: #define THREADING_SEMAPHORE_H_
                     23: 
                     24: #include <utils/utils.h>
                     25: 
                     26: typedef struct semaphore_t semaphore_t;
                     27: 
                     28: /**
                     29:  * A semaphore is basically an integer whose value is never allowed to be
                     30:  * lower than 0.  Two operations can be performed on it: increment the
                     31:  * value by one, and decrement the value by one.  If the value is currently
                     32:  * zero, then the decrement operation will block until the value becomes
                     33:  * greater than zero.
                     34:  */
                     35: struct semaphore_t {
                     36: 
                     37:        /**
                     38:         * Decrease the value by one, if it is greater than zero. Otherwise the
                     39:         * current thread is blocked and it waits until the value increases.
                     40:         */
                     41:        void (*wait)(semaphore_t *this);
                     42: 
                     43:        /**
                     44:         * Decrease the value by one, if it is greater than zero. Otherwise the
                     45:         * current thread is blocked and it waits until the value increases, or the
                     46:         * call times out.
                     47:         *
                     48:         * @param timeout               timeout im ms
                     49:         * @return                              TRUE if timed out, FALSE otherwise
                     50:         */
                     51:        bool (*timed_wait)(semaphore_t *this, u_int timeout);
                     52: 
                     53:        /**
                     54:         * Decrease the value by one, if it is greater than zero. Otherwise the
                     55:         * current thread is blocked and it waits until the value increases, or the
                     56:         * call times out.
                     57:         *
                     58:         * The passed timeval should be calculated based on the time_monotonic()
                     59:         * function.
                     60:         *
                     61:         * @param tv                    absolute time until timeout
                     62:         * @return                              TRUE if timed out, FALSE otherwise
                     63:         */
                     64:        bool (*timed_wait_abs)(semaphore_t *this, timeval_t tv);
                     65: 
                     66:        /**
                     67:         * Increase the value by one. If the value becomes greater than zero, then
                     68:         * another thread waiting will be woken up.
                     69:         */
                     70:        void (*post)(semaphore_t *this);
                     71: 
                     72:        /**
                     73:         * Destroy a semaphore and free its resources.
                     74:         */
                     75:        void (*destroy)(semaphore_t *this);
                     76: };
                     77: 
                     78: /**
                     79:  * Create a semaphore instance.
                     80:  *
                     81:  * @param value                initial value (typically 0)
                     82:  * @return                     semaphore instance
                     83:  */
                     84: semaphore_t *semaphore_create(u_int value);
                     85: 
                     86: #endif /** THREADING_SEMAPHORE_H_ @} */