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 * University of Illinois, Urbana-Champaign.
 */

#ifndef APR_QUEUE_H
#define APR_QUEUE_H
#if APR_HAS_THREADS
/**
 * @file apr_queue.h
 * @brief Thread Safe FIFO bounded queue
 */
/**
 * @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_capacity maximum size of the queue
 * @pool to use
 */
apr_status_t apr_queue_create(apr_queue_t **queue, 
                            int queue_capacity, 
                            apr_pool_t *a);

/**
 * push/add a object to the queue, blocking if the queue is already full
 *
 * @param queue the queue
 * @param the data
 * @returns APR_EINTR the blocking was interrupted (try again)
 * @returns APR_EOF the queue has been terminated
 * @returns APR_SUCCESS on a successfull push
 */
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 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 successfull pop
 */
apr_status_t apr_queue_pop(apr_queue_t *queue, void **data);

/**
 * push/add a object to the queue, returning immediatly if the queue is full
 *
 * @param queue the queue
 * @param 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 successfull push
 */
apr_status_t apr_queue_trypush(apr_queue_t *queue, void *data);

/**
 * pop/get an object to the queue, returning immediatly if the queue is empty
 *
 * @param queue the queue
 * @param 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 successfull push
 */
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
 */
int apr_queue_size(apr_queue_t *queue);

/**
 * interrupt all the threads blocking on this queue.
 *
 * @param queue the queue
 */
apr_status_t apr_queue_interrupt_all(apr_queue_t *queue);

/**
 * terminate all queue, sendinging a interupt to all the
 * blocking threads
 *
 * @param queue the queue
 */
apr_status_t apr_queue_term(apr_queue_t *queue);

#endif /*  APR_HAS_THREADS */
#endif /* APRQUEUE_H */
