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/>.
23 struct memcache_element {
24 struct rb_node rb_node;
25 struct memcache_element *prev, *next;
26 size_t keylength, valuelength;
27 uint8 n; /* This is really an enum, but save memory */
28 char data[1]; /* placeholder for offsetof */
32 struct memcache_element *mru, *lru;
38 static int memcache_destructor(struct memcache *cache) {
39 struct memcache_element *e, *next;
41 for (e = cache->mru; e != NULL; e = next) {
48 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size)
50 struct memcache *result;
52 result = TALLOC_ZERO_P(mem_ctx, struct memcache);
56 result->max_size = max_size;
57 talloc_set_destructor(result, memcache_destructor);
61 static struct memcache_element *memcache_node2elem(struct rb_node *node)
63 return (struct memcache_element *)
64 ((char *)node - offsetof(struct memcache_element, rb_node));
67 static void memcache_element_parse(struct memcache_element *e,
68 DATA_BLOB *key, DATA_BLOB *value)
70 key->data = ((uint8 *)e) + offsetof(struct memcache_element, data);
71 key->length = e->keylength;
72 value->data = key->data + e->keylength;
73 value->length = e->valuelength;
76 static size_t memcache_element_size(size_t key_length, size_t value_length)
78 return sizeof(struct memcache_element) - 1 + key_length + value_length;
81 static int memcache_compare(struct memcache_element *e, enum memcache_number n,
84 DATA_BLOB this_key, this_value;
86 if ((int)e->n < (int)n) return -1;
87 if ((int)e->n > (int)n) return 1;
89 if (e->keylength < key.length) return -1;
90 if (e->keylength > key.length) return 1;
92 memcache_element_parse(e, &this_key, &this_value);
93 return memcmp(this_key.data, key.data, key.length);
96 static struct memcache_element *memcache_find(
97 struct memcache *cache, enum memcache_number n, DATA_BLOB key)
101 node = cache->tree.rb_node;
103 while (node != NULL) {
104 struct memcache_element *elem = memcache_node2elem(node);
107 cmp = memcache_compare(elem, n, key);
111 node = (cmp < 0) ? node->rb_left : node->rb_right;
117 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
118 DATA_BLOB key, DATA_BLOB *value)
120 struct memcache_element *e;
122 e = memcache_find(cache, n, key);
127 if (cache->size != 0) {
129 * Do LRU promotion only when we will ever shrink
131 if (e == cache->lru) {
132 cache->lru = e->prev;
134 DLIST_PROMOTE(cache->mru, e);
135 if (cache->mru == NULL) {
140 memcache_element_parse(e, &key, value);
144 static void memcache_delete_element(struct memcache *cache,
145 struct memcache_element *e)
147 rb_erase(&e->rb_node, &cache->tree);
149 if (e == cache->lru) {
150 cache->lru = e->prev;
152 DLIST_REMOVE(cache->mru, e);
154 cache->size -= memcache_element_size(e->keylength, e->valuelength);
159 static void memcache_trim(struct memcache *cache)
161 if (cache->max_size == 0) {
165 while ((cache->size > cache->max_size) && (cache->lru != NULL)) {
166 memcache_delete_element(cache, cache->lru);
170 void memcache_delete(struct memcache *cache, enum memcache_number n,
173 struct memcache_element *e;
175 e = memcache_find(cache, n, key);
180 memcache_delete_element(cache, e);
183 void memcache_add(struct memcache *cache, enum memcache_number n,
184 DATA_BLOB key, DATA_BLOB value)
186 struct memcache_element *e;
188 struct rb_node *parent;
189 DATA_BLOB cache_key, cache_value;
192 if (key.length == 0) {
196 e = memcache_find(cache, n, key);
199 memcache_element_parse(e, &cache_key, &cache_value);
201 if (value.length <= cache_value.length) {
203 * We can reuse the existing record
205 memcpy(cache_value.data, value.data, value.length);
206 e->valuelength = value.length;
210 memcache_delete_element(cache, e);
213 element_size = memcache_element_size(key.length, value.length);
216 e = (struct memcache_element *)SMB_MALLOC(element_size);
219 DEBUG(0, ("malloc failed\n"));
224 e->keylength = key.length;
225 e->valuelength = value.length;
227 memcache_element_parse(e, &cache_key, &cache_value);
228 memcpy(cache_key.data, key.data, key.length);
229 memcpy(cache_value.data, value.data, value.length);
232 p = &cache->tree.rb_node;
235 struct memcache_element *elem = memcache_node2elem(*p);
240 cmp = memcache_compare(elem, n, key);
242 p = (cmp < 0) ? &(*p)->rb_left : &(*p)->rb_right;
245 rb_link_node(&e->rb_node, parent, p);
246 rb_insert_color(&e->rb_node, &cache->tree);
248 DLIST_ADD(cache->mru, e);
249 if (cache->lru == NULL) {
253 cache->size += element_size;
254 memcache_trim(cache);
257 void memcache_flush(struct memcache *cache, enum memcache_number n)
259 struct rb_node *node;
262 * Find the smallest element of number n
265 node = cache->tree.rb_node;
271 struct memcache_element *elem = memcache_node2elem(node);
272 struct rb_node *next;
274 if ((int)elem->n < (int)n) {
275 next = node->rb_right;
278 next = node->rb_left;
286 node = rb_next(node);
291 while (node != NULL) {
292 struct memcache_element *e = memcache_node2elem(node);
293 struct rb_node *next = rb_next(node);
295 memcache_delete_element(cache, e);