2 Unix SMB/CIFS implementation.
4 Copyright (C) Volker Lendecke 2007
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.
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.
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/>.
22 #include "../lib/util/debug.h"
23 #include "../lib/util/samba_util.h"
24 #include "../lib/util/dlinklist.h"
25 #include "../lib/util/rbtree.h"
28 static struct memcache *global_cache;
30 struct memcache_element {
31 struct rb_node rb_node;
32 struct memcache_element *prev, *next;
33 size_t keylength, valuelength;
34 uint8_t n; /* This is really an enum, but save memory */
35 char data[1]; /* placeholder for offsetof */
39 struct memcache_element *mru;
45 static void memcache_element_parse(struct memcache_element *e,
46 DATA_BLOB *key, DATA_BLOB *value);
48 static bool memcache_is_talloc(enum memcache_number n)
54 case PDB_GETPWSID_CACHE:
55 case SINGLETON_CACHE_TALLOC:
56 case SHARE_MODE_LOCK_CACHE:
58 case VIRUSFILTER_SCAN_RESULTS_CACHE_TALLOC:
69 static int memcache_destructor(struct memcache *cache) {
70 struct memcache_element *e, *next;
72 for (e = cache->mru; e != NULL; e = next) {
79 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size)
81 struct memcache *result;
83 result = talloc_zero(mem_ctx, struct memcache);
87 result->max_size = max_size;
88 talloc_set_destructor(result, memcache_destructor);
92 void memcache_set_global(struct memcache *cache)
94 TALLOC_FREE(global_cache);
98 static struct memcache_element *memcache_node2elem(struct rb_node *node)
100 return (struct memcache_element *)
101 ((char *)node - offsetof(struct memcache_element, rb_node));
104 static void memcache_element_parse(struct memcache_element *e,
105 DATA_BLOB *key, DATA_BLOB *value)
107 key->data = ((uint8_t *)e) + offsetof(struct memcache_element, data);
108 key->length = e->keylength;
109 value->data = key->data + e->keylength;
110 value->length = e->valuelength;
113 static size_t memcache_element_size(size_t key_length, size_t value_length)
115 return sizeof(struct memcache_element) - 1 + key_length + value_length;
118 static int memcache_compare(struct memcache_element *e, enum memcache_number n,
121 DATA_BLOB this_key, this_value;
123 if ((int)e->n < (int)n) return 1;
124 if ((int)e->n > (int)n) return -1;
126 if (e->keylength < key.length) return 1;
127 if (e->keylength > key.length) return -1;
129 memcache_element_parse(e, &this_key, &this_value);
130 return memcmp(this_key.data, key.data, key.length);
133 static struct memcache_element *memcache_find(
134 struct memcache *cache, enum memcache_number n, DATA_BLOB key)
136 struct rb_node *node;
138 node = cache->tree.rb_node;
140 while (node != NULL) {
141 struct memcache_element *elem = memcache_node2elem(node);
144 cmp = memcache_compare(elem, n, key);
148 node = (cmp < 0) ? node->rb_left : node->rb_right;
154 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
155 DATA_BLOB key, DATA_BLOB *value)
157 struct memcache_element *e;
160 cache = global_cache;
166 e = memcache_find(cache, n, key);
171 if (cache->size != 0) {
172 DLIST_PROMOTE(cache->mru, e);
175 memcache_element_parse(e, &key, value);
179 void *memcache_lookup_talloc(struct memcache *cache, enum memcache_number n,
185 if (!memcache_lookup(cache, n, key, &value)) {
189 if (value.length != sizeof(result)) {
193 memcpy(&result, value.data, sizeof(result));
198 static void memcache_delete_element(struct memcache *cache,
199 struct memcache_element *e)
201 rb_erase(&e->rb_node, &cache->tree);
203 DLIST_REMOVE(cache->mru, e);
205 if (memcache_is_talloc(e->n)) {
206 DATA_BLOB cache_key, cache_value;
209 memcache_element_parse(e, &cache_key, &cache_value);
210 SMB_ASSERT(cache_value.length == sizeof(ptr));
211 memcpy(&ptr, cache_value.data, sizeof(ptr));
215 cache->size -= memcache_element_size(e->keylength, e->valuelength);
220 static void memcache_trim(struct memcache *cache)
222 if (cache->max_size == 0) {
226 while ((cache->size > cache->max_size) && DLIST_TAIL(cache->mru)) {
227 memcache_delete_element(cache, DLIST_TAIL(cache->mru));
231 void memcache_delete(struct memcache *cache, enum memcache_number n,
234 struct memcache_element *e;
237 cache = global_cache;
243 e = memcache_find(cache, n, key);
248 memcache_delete_element(cache, e);
251 void memcache_add(struct memcache *cache, enum memcache_number n,
252 DATA_BLOB key, DATA_BLOB value)
254 struct memcache_element *e;
256 struct rb_node *parent;
257 DATA_BLOB cache_key, cache_value;
261 cache = global_cache;
267 if (key.length == 0) {
271 e = memcache_find(cache, n, key);
274 memcache_element_parse(e, &cache_key, &cache_value);
276 if (value.length <= cache_value.length) {
277 if (memcache_is_talloc(e->n)) {
279 SMB_ASSERT(cache_value.length == sizeof(ptr));
280 memcpy(&ptr, cache_value.data, sizeof(ptr));
284 * We can reuse the existing record
286 memcpy(cache_value.data, value.data, value.length);
287 e->valuelength = value.length;
291 memcache_delete_element(cache, e);
294 element_size = memcache_element_size(key.length, value.length);
296 e = talloc_size(cache, element_size);
298 DEBUG(0, ("talloc failed\n"));
301 talloc_set_type(e, struct memcache_element);
304 e->keylength = key.length;
305 e->valuelength = value.length;
307 memcache_element_parse(e, &cache_key, &cache_value);
308 memcpy(cache_key.data, key.data, key.length);
309 memcpy(cache_value.data, value.data, value.length);
312 p = &cache->tree.rb_node;
315 struct memcache_element *elem = memcache_node2elem(*p);
320 cmp = memcache_compare(elem, n, key);
322 p = (cmp < 0) ? &(*p)->rb_left : &(*p)->rb_right;
325 rb_link_node(&e->rb_node, parent, p);
326 rb_insert_color(&e->rb_node, &cache->tree);
328 DLIST_ADD(cache->mru, e);
330 cache->size += element_size;
331 memcache_trim(cache);
334 void memcache_add_talloc(struct memcache *cache, enum memcache_number n,
335 DATA_BLOB key, void *pptr)
337 void **ptr = (void **)pptr;
341 cache = global_cache;
347 p = talloc_move(cache, ptr);
348 memcache_add(cache, n, key, data_blob_const(&p, sizeof(p)));
351 void memcache_flush(struct memcache *cache, enum memcache_number n)
353 struct rb_node *node;
356 cache = global_cache;
363 * Find the smallest element of number n
366 node = cache->tree.rb_node;
372 * First, find *any* element of number n
376 struct memcache_element *elem = memcache_node2elem(node);
377 struct rb_node *next;
379 if ((int)elem->n == (int)n) {
383 if ((int)elem->n < (int)n) {
384 next = node->rb_right;
387 next = node->rb_left;
396 * Then, find the leftmost element with number n
400 struct rb_node *prev = rb_prev(node);
401 struct memcache_element *elem;
406 elem = memcache_node2elem(prev);
407 if ((int)elem->n != (int)n) {
413 while (node != NULL) {
414 struct memcache_element *e = memcache_node2elem(node);
415 struct rb_node *next = rb_next(node);
421 memcache_delete_element(cache, e);