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         GETWD_CACHE,
  37         GETPWNAM_CACHE,         /* talloc */
  38         MANGLE_HASH2_CACHE,
  39         PDB_GETPWSID_CACHE,     /* talloc */
  40         SINGLETON_CACHE_TALLOC, /* talloc */
  41         SINGLETON_CACHE,
  42         SMB1_SEARCH_OFFSET_MAP
  43 };
  44
  45 /*
  46  * Create a memcache structure. max_size is in bytes, if you set it 0 it will
  47  * not forget anything.
  48  */
  49
  50 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size);
  51
  52 /*
  53  * If you set this global memcache, use it as the default cache when NULL is
  54  * passed to the memcache functions below. This is a workaround for many
  55  * situations where passing the cache everywhere would be a big hassle.
  56  */
  57
  58 void memcache_set_global(struct memcache *cache);
  59
  60 /*
  61  * Add a data blob to the cache
  62  */
  63
  64 void memcache_add(struct memcache *cache, enum memcache_number n,
  65                   DATA_BLOB key, DATA_BLOB value);
  66
  67 /*
  68  * Add a talloc object to the cache. The difference to memcache_add() is that
  69  * when the objects is to be discared, talloc_free is called for it. Also
  70  * talloc_move() ownership of the object to the cache.
  71  *
  72  * Please note that the current implementation has a fixed relationship
  73  * between what cache subtypes store talloc objects and which ones store plain
  74  * blobs. We can fix this, but for now we don't have a mixed use of blobs vs
  75  * talloc objects in the cache types.
  76  */
  77
  78 void memcache_add_talloc(struct memcache *cache, enum memcache_number n,
  79                          DATA_BLOB key, void *ptr);
  80
  81 /*
  82  * Delete an object from the cache
  83  */
  84
  85 void memcache_delete(struct memcache *cache, enum memcache_number n,
  86                      DATA_BLOB key);
  87
  88 /*
  89  * Look up an object from the cache. Memory still belongs to the cache, so
  90  * make a copy of it if needed.
  91  */
  92
  93 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
  94                      DATA_BLOB key, DATA_BLOB *value);
  95
  96 /*
  97  * Look up an object from the cache. Memory still belongs to the cache, so
  98  * make a copy of it if needed.
  99  */
 100
 101 void *memcache_lookup_talloc(struct memcache *cache, enum memcache_number n,
 102                              DATA_BLOB key);
 103
 104 /*
 105  * Flush a complete cache subset.
 106  */
 107
 108 void memcache_flush(struct memcache *cache, enum memcache_number n);
 109
 110 #endif