lib/util/memcache.h

   1 /*
   2    Unix SMB/CIFS implementation.
   3    In-memory cache
   4    Copyright (C) Volker Lendecke 2007-2008
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #ifndef __MEMCACHE_H__
  21 #define __MEMCACHE_H__
  22
  23 struct memcache;
  24
  25 /*
  26  * A memcache can store different subkeys with overlapping keys, the
  27  * memcache_number becomes part of the key. Feel free to add caches of your
  28  * own here.
  29  *
  30  * If you add talloc type caches, also note this in the switch statement in
  31  * memcache_is_talloc().
  32  */
  33
  34 enum memcache_number {
  35         STAT_CACHE,
  36         GENCACHE_RAM,
  37         GETWD_CACHE,
  38         GETPWNAM_CACHE,         /* talloc */
  39         MANGLE_HASH2_CACHE,
  40         PDB_GETPWSID_CACHE,     /* talloc */
  41         SINGLETON_CACHE_TALLOC, /* talloc */
  42         SINGLETON_CACHE,
  43         SMB1_SEARCH_OFFSET_MAP
  44 };
  45
  46 /*
  47  * Create a memcache structure. max_size is in bytes, if you set it 0 it will
  48  * not forget anything.
  49  */
  50
  51 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size);
  52
  53 /*
  54  * If you set this global memcache, use it as the default cache when NULL is
  55  * passed to the memcache functions below. This is a workaround for many
  56  * situations where passing the cache everywhere would be a big hassle.
  57  */
  58
  59 void memcache_set_global(struct memcache *cache);
  60
  61 /*
  62  * Add a data blob to the cache
  63  */
  64
  65 void memcache_add(struct memcache *cache, enum memcache_number n,
  66                   DATA_BLOB key, DATA_BLOB value);
  67
  68 /*
  69  * Add a talloc object to the cache. The difference to memcache_add() is that
  70  * when the objects is to be discared, talloc_free is called for it. Also
  71  * talloc_move() ownership of the object to the cache.
  72  *
  73  * Please note that the current implementation has a fixed relationship
  74  * between what cache subtypes store talloc objects and which ones store plain
  75  * blobs. We can fix this, but for now we don't have a mixed use of blobs vs
  76  * talloc objects in the cache types.
  77  */
  78
  79 void memcache_add_talloc(struct memcache *cache, enum memcache_number n,
  80                          DATA_BLOB key, void *ptr);
  81
  82 /*
  83  * Delete an object from the cache
  84  */
  85
  86 void memcache_delete(struct memcache *cache, enum memcache_number n,
  87                      DATA_BLOB key);
  88
  89 /*
  90  * Look up an object from the cache. Memory still belongs to the cache, so
  91  * make a copy of it if needed.
  92  */
  93
  94 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
  95                      DATA_BLOB key, DATA_BLOB *value);
  96
  97 /*
  98  * Look up an object from the cache. Memory still belongs to the cache, so
  99  * make a copy of it if needed.
 100  */
 101
 102 void *memcache_lookup_talloc(struct memcache *cache, enum memcache_number n,
 103                              DATA_BLOB key);
 104
 105 /*
 106  * Flush a complete cache subset.
 107  */
 108
 109 void memcache_flush(struct memcache *cache, enum memcache_number n);
 110
 111 #endif