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/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2000-2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
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* distribution.
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* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
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* not be used to endorse or promote products derived from this
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* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
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*/
#ifndef APR_THREAD_COND_H
#define APR_THREAD_COND_H
/**
* @file apr_thread_cond.h
* @brief APR Condition Variable Routines
*/
#include "apr.h"
#include "apr_pools.h"
#include "apr_errno.h"
#include "apr_time.h"
#include "apr_thread_mutex.h"
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
#if APR_HAS_THREADS || defined(DOXYGEN)
/**
* @defgroup apr_thread_cond Condition Variable Routines
* @ingroup APR
* @{
*/
/** Opaque structure for thread condition variables */
typedef struct apr_thread_cond_t apr_thread_cond_t;
/**
* Create and initialize a condition variable that can be used to signal
* and schedule threads in a single process.
* @param cond the memory address where the newly created condition variable
* will be stored.
* @param pool the pool from which to allocate the mutex.
*/
APR_DECLARE(apr_status_t) apr_thread_cond_create(apr_thread_cond_t **cond,
apr_pool_t *pool);
/**
* Put the active calling thread to sleep until signaled to wake up. Each
* condition variable must be associated with a mutex, and that mutex must
* be locked before calling this function, or the behavior will be
* undefined. As the calling thread is put to sleep, the given mutex
* will be simultaneously released; and as this thread wakes up the lock
* is again simultaneously acquired.
* @param cond the condition variable on which to block.
* @param mutex the mutex that must be locked upon entering this function,
* is released while the thread is asleep, and is again acquired before
* returning from this function.
*/
APR_DECLARE(apr_status_t) apr_thread_cond_wait(apr_thread_cond_t *cond,
apr_thread_mutex_t *mutex);
/**
* Put the active calling thread to sleep until signaled to wake up or
* the timeout is reached. Each condition variable must be associated
* with a mutex, and that mutex must be locked before calling this
* function, or the behavior will be undefined. As the calling thread
* is put to sleep, the given mutex will be simultaneously released;
* and as this thread wakes up the lock is again simultaneously acquired.
* @param cond the condition variable on which to block.
* @param mutex the mutex that must be locked upon entering this function,
* is released while the thread is asleep, and is again acquired before
* returning from this function.
* @param timeout The amount of time in microseconds to wait. This is
* a maximum, not a minimum. If the condition is signaled, we
* will wake up before this time, otherwise the error APR_TIMEUP
* is returned.
*/
APR_DECLARE(apr_status_t) apr_thread_cond_timedwait(apr_thread_cond_t *cond,
apr_thread_mutex_t *mutex,
apr_interval_time_t timeout);
/**
* Signals a singla thread, if one exists, that is blocking on the given
* condition variable. That thread is then scheduled to wake up and acquire
* the associated mutex. Although it is not required, if predictible schedule
* is desired, that mutex must be locked while calling this function.
* @param cond the condition variable on which to produce the signal.
*/
APR_DECLARE(apr_status_t) apr_thread_cond_signal(apr_thread_cond_t *cond);
/**
* Signals all threads blocking on the given condition variable.
* Each thread that was signaled is then schedule to wake up and acquire
* the associated mutex. This will happen in a serialized manner.
* @param cond the condition variable on which to produce the broadcast.
*/
APR_DECLARE(apr_status_t) apr_thread_cond_broadcast(apr_thread_cond_t *cond);
/**
* Destroy the condition variable and free the associated memory.
* @param cond the condition variable to destroy.
*/
APR_DECLARE(apr_status_t) apr_thread_cond_destroy(apr_thread_cond_t *cond);
/**
* Get the pool used by this thread_cond.
* @return apr_pool_t the pool
*/
APR_POOL_DECLARE_ACCESSOR(thread_cond);
#endif /* APR_HAS_THREADS */
/** @} */
#ifdef __cplusplus
}
#endif
#endif /* ! APR_THREAD_COND_H */
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