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/* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef APR_QUEUE_H
#define APR_QUEUE_H
/**
* @file apr_queue.h
* @brief Thread Safe FIFO bounded queue
* @note Since most implementations of the queue are backed by a condition
* variable implementation, it isn't available on systems without threads.
* Although condition variables are some times available without threads.
*/
#include "apu.h"
#include "apr_errno.h"
#include "apr_pools.h"
#if APR_HAS_THREADS
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/**
* @defgroup APR_Util_FIFO Thread Safe FIFO bounded queue
* @ingroup APR_Util
* @{
*/
/**
* opaque structure
*/
typedef struct apr_queue_t apr_queue_t;
/**
* create a FIFO queue
* @param queue The new queue
* @param queue_capacity maximum size of the queue
* @param a pool to allocate queue from
*/
APU_DECLARE(apr_status_t) apr_queue_create(apr_queue_t **queue,
unsigned int queue_capacity,
apr_pool_t *a);
/**
* push/add an object to the queue, blocking if the queue is already full
*
* @param queue the queue
* @param data the data
* @returns APR_EINTR the blocking was interrupted (try again)
* @returns APR_EOF the queue has been terminated
* @returns APR_SUCCESS on a successful push
*/
APU_DECLARE(apr_status_t) apr_queue_push(apr_queue_t *queue, void *data);
/**
* pop/get an object from the queue, blocking if the queue is already empty
*
* @param queue the queue
* @param data the data
* @returns APR_EINTR the blocking was interrupted (try again)
* @returns APR_EOF if the queue has been terminated
* @returns APR_SUCCESS on a successful pop
*/
APU_DECLARE(apr_status_t) apr_queue_pop(apr_queue_t *queue, void **data);
/**
* push/add an object to the queue, returning immediately if the queue is full
*
* @param queue the queue
* @param data the data
* @returns APR_EINTR the blocking operation was interrupted (try again)
* @returns APR_EAGAIN the queue is full
* @returns APR_EOF the queue has been terminated
* @returns APR_SUCCESS on a successful push
*/
APU_DECLARE(apr_status_t) apr_queue_trypush(apr_queue_t *queue, void *data);
/**
* pop/get an object to the queue, returning immediately if the queue is empty
*
* @param queue the queue
* @param data the data
* @returns APR_EINTR the blocking operation was interrupted (try again)
* @returns APR_EAGAIN the queue is empty
* @returns APR_EOF the queue has been terminated
* @returns APR_SUCCESS on a successful push
*/
APU_DECLARE(apr_status_t) apr_queue_trypop(apr_queue_t *queue, void **data);
/**
* returns the size of the queue.
*
* @warning this is not threadsafe, and is intended for reporting/monitoring
* of the queue.
* @param queue the queue
* @returns the size of the queue
*/
APU_DECLARE(unsigned int) apr_queue_size(apr_queue_t *queue);
/**
* interrupt all the threads blocking on this queue.
*
* @param queue the queue
*/
APU_DECLARE(apr_status_t) apr_queue_interrupt_all(apr_queue_t *queue);
/**
* terminate the queue, sending an interrupt to all the
* blocking threads
*
* @param queue the queue
*/
APU_DECLARE(apr_status_t) apr_queue_term(apr_queue_t *queue);
#ifdef __cplusplus
}
#endif
/** @} */
#endif /* APR_HAS_THREADS */
#endif /* APRQUEUE_H */
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