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/samba_util.h"
23 #include "../lib/util/debug.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:
66 static int memcache_destructor(struct memcache *cache) {
67 struct memcache_element *e, *next;
69 for (e = cache->mru; e != NULL; e = next) {
76 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size)
78 struct memcache *result;
80 result = talloc_zero(mem_ctx, struct memcache);
84 result->max_size = max_size;
85 talloc_set_destructor(result, memcache_destructor);
89 void memcache_set_global(struct memcache *cache)
91 TALLOC_FREE(global_cache);
95 static struct memcache_element *memcache_node2elem(struct rb_node *node)
97 return (struct memcache_element *)
98 ((char *)node - offsetof(struct memcache_element, rb_node));
101 static void memcache_element_parse(struct memcache_element *e,
102 DATA_BLOB *key, DATA_BLOB *value)
104 key->data = ((uint8_t *)e) + offsetof(struct memcache_element, data);
105 key->length = e->keylength;
106 value->data = key->data + e->keylength;
107 value->length = e->valuelength;
110 static size_t memcache_element_size(size_t key_length, size_t value_length)
112 return sizeof(struct memcache_element) - 1 + key_length + value_length;
115 static int memcache_compare(struct memcache_element *e, enum memcache_number n,
118 DATA_BLOB this_key, this_value;
120 if ((int)e->n < (int)n) return 1;
121 if ((int)e->n > (int)n) return -1;
123 if (e->keylength < key.length) return 1;
124 if (e->keylength > key.length) return -1;
126 memcache_element_parse(e, &this_key, &this_value);
127 return memcmp(this_key.data, key.data, key.length);
130 static struct memcache_element *memcache_find(
131 struct memcache *cache, enum memcache_number n, DATA_BLOB key)
133 struct rb_node *node;
135 node = cache->tree.rb_node;
137 while (node != NULL) {
138 struct memcache_element *elem = memcache_node2elem(node);
141 cmp = memcache_compare(elem, n, key);
145 node = (cmp < 0) ? node->rb_left : node->rb_right;
151 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
152 DATA_BLOB key, DATA_BLOB *value)
154 struct memcache_element *e;
157 cache = global_cache;
163 e = memcache_find(cache, n, key);
168 if (cache->size != 0) {
169 DLIST_PROMOTE(cache->mru, e);
172 memcache_element_parse(e, &key, value);
176 void *memcache_lookup_talloc(struct memcache *cache, enum memcache_number n,
182 if (!memcache_lookup(cache, n, key, &value)) {
186 if (value.length != sizeof(result)) {
190 memcpy(&result, value.data, sizeof(result));
195 static void memcache_delete_element(struct memcache *cache,
196 struct memcache_element *e)
198 rb_erase(&e->rb_node, &cache->tree);
200 DLIST_REMOVE(cache->mru, e);
202 if (memcache_is_talloc(e->n)) {
203 DATA_BLOB cache_key, cache_value;
206 memcache_element_parse(e, &cache_key, &cache_value);
207 SMB_ASSERT(cache_value.length == sizeof(ptr));
208 memcpy(&ptr, cache_value.data, sizeof(ptr));
212 cache->size -= memcache_element_size(e->keylength, e->valuelength);
217 static void memcache_trim(struct memcache *cache)
219 if (cache->max_size == 0) {
223 while ((cache->size > cache->max_size) && DLIST_TAIL(cache->mru)) {
224 memcache_delete_element(cache, DLIST_TAIL(cache->mru));
228 void memcache_delete(struct memcache *cache, enum memcache_number n,
231 struct memcache_element *e;
234 cache = global_cache;
240 e = memcache_find(cache, n, key);
245 memcache_delete_element(cache, e);
248 void memcache_add(struct memcache *cache, enum memcache_number n,
249 DATA_BLOB key, DATA_BLOB value)
251 struct memcache_element *e;
253 struct rb_node *parent;
254 DATA_BLOB cache_key, cache_value;
258 cache = global_cache;
264 if (key.length == 0) {
268 e = memcache_find(cache, n, key);
271 memcache_element_parse(e, &cache_key, &cache_value);
273 if (value.length <= cache_value.length) {
274 if (memcache_is_talloc(e->n)) {
276 SMB_ASSERT(cache_value.length == sizeof(ptr));
277 memcpy(&ptr, cache_value.data, sizeof(ptr));
281 * We can reuse the existing record
283 memcpy(cache_value.data, value.data, value.length);
284 e->valuelength = value.length;
288 memcache_delete_element(cache, e);
291 element_size = memcache_element_size(key.length, value.length);
293 e = talloc_size(cache, element_size);
295 DEBUG(0, ("talloc failed\n"));
298 talloc_set_type(e, struct memcache_element);
301 e->keylength = key.length;
302 e->valuelength = value.length;
304 memcache_element_parse(e, &cache_key, &cache_value);
305 memcpy(cache_key.data, key.data, key.length);
306 memcpy(cache_value.data, value.data, value.length);
309 p = &cache->tree.rb_node;
312 struct memcache_element *elem = memcache_node2elem(*p);
317 cmp = memcache_compare(elem, n, key);
319 p = (cmp < 0) ? &(*p)->rb_left : &(*p)->rb_right;
322 rb_link_node(&e->rb_node, parent, p);
323 rb_insert_color(&e->rb_node, &cache->tree);
325 DLIST_ADD(cache->mru, e);
327 cache->size += element_size;
328 memcache_trim(cache);
331 void memcache_add_talloc(struct memcache *cache, enum memcache_number n,
332 DATA_BLOB key, void *pptr)
334 void **ptr = (void **)pptr;
338 cache = global_cache;
344 p = talloc_move(cache, ptr);
345 memcache_add(cache, n, key, data_blob_const(&p, sizeof(p)));
348 void memcache_flush(struct memcache *cache, enum memcache_number n)
350 struct rb_node *node;
353 cache = global_cache;
360 * Find the smallest element of number n
363 node = cache->tree.rb_node;
369 * First, find *any* element of number n
373 struct memcache_element *elem = memcache_node2elem(node);
374 struct rb_node *next;
376 if ((int)elem->n == (int)n) {
380 if ((int)elem->n < (int)n) {
381 next = node->rb_right;
384 next = node->rb_left;
393 * Then, find the leftmost element with number n
397 struct rb_node *prev = rb_prev(node);
398 struct memcache_element *elem;
403 elem = memcache_node2elem(prev);
404 if ((int)elem->n != (int)n) {
410 while (node != NULL) {
411 struct memcache_element *e = memcache_node2elem(node);
412 struct rb_node *next = rb_next(node);
418 memcache_delete_element(cache, e);