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/* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* @file cache_pqueue.h
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* @brief Cache Priority Queue function declarations
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* @defgroup MOD_CACHE_QUEUE Priority Queue
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#ifndef CACHE_PQUEUE_H
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#define CACHE_PQUEUE_H
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#include <apr_errno.h>
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/** the cache priority queue handle */
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typedef struct cache_pqueue_t cache_pqueue_t;
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* callback function to assign a priority for a element
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* @param a the element
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* @return the score (the lower the score the longer it is kept int the queue)
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typedef long (*cache_pqueue_set_priority)(long queue_clock, void *a);
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typedef long (*cache_pqueue_get_priority)(void *a);
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/** callback function to get a position of a element */
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typedef apr_ssize_t (*cache_pqueue_getpos)(void *a);
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* callback function to set a position of a element
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* @param a the element
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* @param pos the position to set it to
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typedef void (*cache_pqueue_setpos)(void *a, apr_ssize_t pos);
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/** debug callback function to print a entry */
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typedef void (*cache_pqueue_print_entry)(FILE *out, void *a);
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* initialize the queue
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* @param n the initial estimate of the number of queue items for which memory
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* should be preallocated
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* @param pri the callback function to run to assign a score to a element
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* @param get the callback function to get the current element's position
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* @param set the callback function to set the current element's position
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* @Return the handle or NULL for insufficent memory
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cache_pqueue_t *cache_pq_init(apr_ssize_t n,
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cache_pqueue_get_priority pri,
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cache_pqueue_getpos get,
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cache_pqueue_setpos set);
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* free all memory used by the queue
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void cache_pq_free(cache_pqueue_t *q);
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* return the size of the queue.
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apr_ssize_t cache_pq_size(cache_pqueue_t *q);
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* insert an item into the queue.
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* @return APR_SUCCESS on success
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apr_status_t cache_pq_insert(cache_pqueue_t *q, void *d);
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* move a existing entry to a different priority
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* @param old the old priority
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void cache_pq_change_priority(cache_pqueue_t *q,
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* pop the highest-ranking item from the queue.
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* @param d where to copy the entry to
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* @return NULL on error, otherwise the entry
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void *cache_pq_pop(cache_pqueue_t *q);
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* remove an item from the queue.
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* @return APR_SUCCESS on success
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apr_status_t cache_pq_remove(cache_pqueue_t *q, void *d);
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* access highest-ranking item without removing it.
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* @return NULL on error, otherwise the entry
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void *cache_pq_peek(cache_pqueue_t *q);
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* DEBUG function only
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* @param out the output handle
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* @param the callback function to print the entry
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void cache_pq_print(cache_pqueue_t *q,
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cache_pqueue_print_entry print);
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* dump the queue and it's internal structure
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* debug function only
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* @param out the output handle
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* @param the callback function to print the entry
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void cache_pq_dump(cache_pqueue_t *q,
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cache_pqueue_print_entry print);
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* checks that the pq is in the right order, etc
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* debug function only
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int cache_pq_is_valid(cache_pqueue_t *q);
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#endif /* !CACHE_PQUEUE_H */