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 static struct memcache *global_cache;
25 struct memcache_element {
26 struct rb_node rb_node;
27 struct memcache_element *prev, *next;
28 size_t keylength, valuelength;
29 uint8 n; /* This is really an enum, but save memory */
30 char data[1]; /* placeholder for offsetof */
34 struct memcache_element *mru, *lru;
40 static void memcache_element_parse(struct memcache_element *e,
41 DATA_BLOB *key, DATA_BLOB *value);
43 static bool memcache_is_talloc(enum memcache_number n)
59 static int memcache_destructor(struct memcache *cache) {
60 struct memcache_element *e, *next;
62 for (e = cache->mru; e != NULL; e = next) {
64 if (memcache_is_talloc(e->n)
65 && (e->valuelength == sizeof(void *))) {
68 memcache_element_parse(e, &key, &value);
69 memcpy(&ptr, value.data, sizeof(ptr));
77 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size)
79 struct memcache *result;
81 result = TALLOC_ZERO_P(mem_ctx, struct memcache);
85 result->max_size = max_size;
86 talloc_set_destructor(result, memcache_destructor);
90 void memcache_set_global(struct memcache *cache)
92 TALLOC_FREE(global_cache);
96 static struct memcache_element *memcache_node2elem(struct rb_node *node)
98 return (struct memcache_element *)
99 ((char *)node - offsetof(struct memcache_element, rb_node));
102 static void memcache_element_parse(struct memcache_element *e,
103 DATA_BLOB *key, DATA_BLOB *value)
105 key->data = ((uint8 *)e) + offsetof(struct memcache_element, data);
106 key->length = e->keylength;
107 value->data = key->data + e->keylength;
108 value->length = e->valuelength;
111 static size_t memcache_element_size(size_t key_length, size_t value_length)
113 return sizeof(struct memcache_element) - 1 + key_length + value_length;
116 static int memcache_compare(struct memcache_element *e, enum memcache_number n,
119 DATA_BLOB this_key, this_value;
121 if ((int)e->n < (int)n) return -1;
122 if ((int)e->n > (int)n) return 1;
124 if (e->keylength < key.length) return -1;
125 if (e->keylength > key.length) return 1;
127 memcache_element_parse(e, &this_key, &this_value);
128 return memcmp(this_key.data, key.data, key.length);
131 static struct memcache_element *memcache_find(
132 struct memcache *cache, enum memcache_number n, DATA_BLOB key)
134 struct rb_node *node;
136 node = cache->tree.rb_node;
138 while (node != NULL) {
139 struct memcache_element *elem = memcache_node2elem(node);
142 cmp = memcache_compare(elem, n, key);
146 node = (cmp < 0) ? node->rb_left : node->rb_right;
152 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
153 DATA_BLOB key, DATA_BLOB *value)
155 struct memcache_element *e;
158 cache = global_cache;
164 e = memcache_find(cache, n, key);
169 if (cache->size != 0) {
171 * Do LRU promotion only when we will ever shrink
173 if (e == cache->lru) {
174 cache->lru = e->prev;
176 DLIST_PROMOTE(cache->mru, e);
177 if (cache->mru == NULL) {
182 memcache_element_parse(e, &key, value);
186 void *memcache_lookup_talloc(struct memcache *cache, enum memcache_number n,
192 if (!memcache_lookup(cache, n, key, &value)) {
196 if (value.length != sizeof(result)) {
200 memcpy(&result, value.data, sizeof(result));
205 static void memcache_delete_element(struct memcache *cache,
206 struct memcache_element *e)
208 rb_erase(&e->rb_node, &cache->tree);
210 if (e == cache->lru) {
211 cache->lru = e->prev;
213 DLIST_REMOVE(cache->mru, e);
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) && (cache->lru != NULL)) {
227 memcache_delete_element(cache, cache->lru);
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) {
278 * We can reuse the existing record
280 memcpy(cache_value.data, value.data, value.length);
281 e->valuelength = value.length;
285 memcache_delete_element(cache, e);
288 element_size = memcache_element_size(key.length, value.length);
291 e = (struct memcache_element *)SMB_MALLOC(element_size);
294 DEBUG(0, ("malloc failed\n"));
299 e->keylength = key.length;
300 e->valuelength = value.length;
302 memcache_element_parse(e, &cache_key, &cache_value);
303 memcpy(cache_key.data, key.data, key.length);
304 memcpy(cache_value.data, value.data, value.length);
307 p = &cache->tree.rb_node;
310 struct memcache_element *elem = memcache_node2elem(*p);
315 cmp = memcache_compare(elem, n, key);
317 p = (cmp < 0) ? &(*p)->rb_left : &(*p)->rb_right;
320 rb_link_node(&e->rb_node, parent, p);
321 rb_insert_color(&e->rb_node, &cache->tree);
323 DLIST_ADD(cache->mru, e);
324 if (cache->lru == NULL) {
328 cache->size += element_size;
329 memcache_trim(cache);
332 void memcache_add_talloc(struct memcache *cache, enum memcache_number n,
333 DATA_BLOB key, void *ptr)
335 return memcache_add(cache, n, key, data_blob_const(&ptr, sizeof(ptr)));
338 void memcache_flush(struct memcache *cache, enum memcache_number n)
340 struct rb_node *node;
343 cache = global_cache;
350 * Find the smallest element of number n
353 node = cache->tree.rb_node;
359 struct memcache_element *elem = memcache_node2elem(node);
360 struct rb_node *next;
362 if ((int)elem->n < (int)n) {
363 next = node->rb_right;
366 next = node->rb_left;
374 node = rb_next(node);
379 while (node != NULL) {
380 struct memcache_element *e = memcache_node2elem(node);
381 struct rb_node *next = rb_next(node);
383 memcache_delete_element(cache, e);