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_ @} */
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