modules/cache/cache_cache.c

   1 /* Licensed to the Apache Software Foundation (ASF) under one or more
   2  * contributor license agreements.  See the NOTICE file distributed with
   3  * this work for additional information regarding copyright ownership.
   4  * The ASF licenses this file to You under the Apache License, Version 2.0
   5  * (the "License"); you may not use this file except in compliance with
   6  * the License.  You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include "apr_general.h"
  18
  19 #include "mod_cache.h"
  20 #include "cache_hash.h"
  21 #include "cache_pqueue.h"
  22 #include "cache_cache.h"
  23
  24 #if APR_HAVE_STDLIB_H
  25 #include <stdlib.h>
  26 #endif
  27 #if APR_HAVE_STRING_H
  28 #include <string.h>
  29 #endif
  30
  31 struct cache_cache_t  {
  32     int             max_entries;
  33     apr_size_t      max_size;
  34     apr_size_t      current_size;
  35     int             total_purges;
  36     long            queue_clock;
  37     cache_hash_t   *ht;
  38     cache_pqueue_t *pq;
  39     cache_pqueue_set_priority set_pri;
  40     cache_pqueue_get_priority get_pri;
  41     cache_cache_inc_frequency *inc_entry;
  42     cache_cache_get_size *size_entry;
  43     cache_cache_get_key *key_entry;
  44     cache_cache_free *free_entry;
  45 };
  46
  47 cache_cache_t* cache_init(int max_entries,
  48                                          apr_size_t max_size,
  49                                          cache_pqueue_get_priority get_pri,
  50                                          cache_pqueue_set_priority set_pri,
  51                                          cache_pqueue_getpos get_pos,
  52                                          cache_pqueue_setpos set_pos,
  53                                          cache_cache_inc_frequency *inc_entry,
  54                                          cache_cache_get_size *size_entry,
  55                                          cache_cache_get_key* key_entry,
  56                                          cache_cache_free *free_entry)
  57 {
  58     cache_cache_t *tmp;
  59     tmp = malloc(sizeof(cache_cache_t));
  60     tmp->max_entries = max_entries;
  61     tmp->max_size = max_size;
  62     tmp->current_size = 0;
  63     tmp->total_purges = 0;
  64     tmp->queue_clock = 0;
  65     tmp->get_pri = get_pri;
  66     tmp->set_pri = set_pri;
  67     tmp->inc_entry = inc_entry;
  68     tmp->size_entry = size_entry;
  69     tmp->key_entry = key_entry;
  70     tmp->free_entry = free_entry;
  71
  72     tmp->ht = cache_hash_make(max_entries);
  73     tmp->pq = cache_pq_init(max_entries, get_pri, get_pos, set_pos);
  74
  75     return tmp;
  76 }
  77
  78 void cache_free(cache_cache_t *c)
  79 {
  80     cache_pq_free(c->pq);
  81     cache_hash_free(c->ht);
  82     free(c);
  83 }
  84
  85
  86 void* cache_find(cache_cache_t* c, const char *key)
  87 {
  88     return cache_hash_get(c->ht, key, CACHE_HASH_KEY_STRING);
  89 }
  90
  91 void cache_update(cache_cache_t* c, void *entry)
  92 {
  93     long old_priority;
  94     long new_priority;
  95
  96     old_priority = c->set_pri(c->queue_clock, entry);
  97     c->inc_entry(entry);
  98     new_priority = c->set_pri(c->queue_clock, entry);
  99     cache_pq_change_priority(c->pq, old_priority, new_priority, entry);
 100 }
 101
 102 void cache_insert(cache_cache_t* c, void *entry)
 103 {
 104     void *ejected = NULL;
 105     long priority;
 106
 107     c->set_pri(c->queue_clock, entry);
 108     /* FIX: check if priority of bottom item is greater than inserted one */
 109     while ((cache_pq_size(c->pq) >= c->max_entries) ||
 110             ((c->current_size + c->size_entry(entry)) > c->max_size)) {
 111
 112         ejected = cache_pq_pop(c->pq);
 113         /* FIX: If ejected is NULL, we'll segfault here */
 114         priority = c->get_pri(ejected);
 115
 116         if (c->queue_clock > priority)
 117             c->queue_clock = priority;
 118
 119         cache_hash_set(c->ht,
 120                        c->key_entry(ejected),
 121                        CACHE_HASH_KEY_STRING,
 122                        NULL);
 123
 124         ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL, "Cache Purge of %s",c->key_entry(ejected));
 125         c->current_size -= c->size_entry(ejected);
 126         c->free_entry(ejected);
 127         c->total_purges++;
 128     }
 129     c->current_size += c->size_entry(entry);
 130
 131     cache_pq_insert(c->pq, entry);
 132     cache_hash_set(c->ht, c->key_entry(entry), CACHE_HASH_KEY_STRING, entry);
 133 }
 134
 135 void* cache_pop(cache_cache_t *c)
 136 {
 137     void *entry;
 138
 139     if (!c)
 140         return NULL;
 141
 142     entry = cache_pq_pop(c->pq);
 143
 144     if (!entry)
 145         return NULL;
 146
 147     c->current_size -= c->size_entry(entry);
 148     cache_hash_set(c->ht, c->key_entry(entry), CACHE_HASH_KEY_STRING, NULL);
 149
 150     return entry;
 151 }
 152
 153 apr_status_t cache_remove(cache_cache_t *c, void *entry)
 154 {
 155     apr_size_t entry_size = c->size_entry(entry);
 156     apr_status_t rc;
 157     rc = cache_pq_remove(c->pq, entry);
 158     if (rc != APR_SUCCESS)
 159         return rc;
 160
 161     cache_hash_set(c->ht, c->key_entry(entry), CACHE_HASH_KEY_STRING, NULL);
 162     c->current_size -= entry_size;
 163
 164     return APR_SUCCESS;
 165 }