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Annotation of embedaddon/strongswan/src/libstrongswan/threading/semaphore.h, revision 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_ @} */