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/>.
21 #include "../lib/util/rbtree.h"
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)
49 case PDB_GETPWSID_CACHE:
50 case SINGLETON_CACHE_TALLOC:
61 static int memcache_destructor(struct memcache *cache) {
62 struct memcache_element *e, *next;
64 for (e = cache->mru; e != NULL; e = next) {
71 struct memcache *memcache_init(TALLOC_CTX *mem_ctx, size_t max_size)
73 struct memcache *result;
75 result = TALLOC_ZERO_P(mem_ctx, struct memcache);
79 result->max_size = max_size;
80 talloc_set_destructor(result, memcache_destructor);
84 void memcache_set_global(struct memcache *cache)
86 TALLOC_FREE(global_cache);
90 static struct memcache_element *memcache_node2elem(struct rb_node *node)
92 return (struct memcache_element *)
93 ((char *)node - offsetof(struct memcache_element, rb_node));
96 static void memcache_element_parse(struct memcache_element *e,
97 DATA_BLOB *key, DATA_BLOB *value)
99 key->data = ((uint8 *)e) + offsetof(struct memcache_element, data);
100 key->length = e->keylength;
101 value->data = key->data + e->keylength;
102 value->length = e->valuelength;
105 static size_t memcache_element_size(size_t key_length, size_t value_length)
107 return sizeof(struct memcache_element) - 1 + key_length + value_length;
110 static int memcache_compare(struct memcache_element *e, enum memcache_number n,
113 DATA_BLOB this_key, this_value;
115 if ((int)e->n < (int)n) return 1;
116 if ((int)e->n > (int)n) return -1;
118 if (e->keylength < key.length) return 1;
119 if (e->keylength > key.length) return -1;
121 memcache_element_parse(e, &this_key, &this_value);
122 return memcmp(this_key.data, key.data, key.length);
125 static struct memcache_element *memcache_find(
126 struct memcache *cache, enum memcache_number n, DATA_BLOB key)
128 struct rb_node *node;
130 node = cache->tree.rb_node;
132 while (node != NULL) {
133 struct memcache_element *elem = memcache_node2elem(node);
136 cmp = memcache_compare(elem, n, key);
140 node = (cmp < 0) ? node->rb_left : node->rb_right;
146 bool memcache_lookup(struct memcache *cache, enum memcache_number n,
147 DATA_BLOB key, DATA_BLOB *value)
149 struct memcache_element *e;
152 cache = global_cache;
158 e = memcache_find(cache, n, key);
163 if (cache->size != 0) {
165 * Do LRU promotion only when we will ever shrink
167 if (e == cache->lru) {
168 cache->lru = e->prev;
170 DLIST_PROMOTE(cache->mru, e);
171 if (cache->mru == NULL) {
176 memcache_element_parse(e, &key, value);
180 void *memcache_lookup_talloc(struct memcache *cache, enum memcache_number n,
186 if (!memcache_lookup(cache, n, key, &value)) {
190 if (value.length != sizeof(result)) {
194 memcpy(&result, value.data, sizeof(result));
199 static void memcache_delete_element(struct memcache *cache,
200 struct memcache_element *e)
202 rb_erase(&e->rb_node, &cache->tree);
204 if (e == cache->lru) {
205 cache->lru = e->prev;
207 DLIST_REMOVE(cache->mru, e);
209 if (memcache_is_talloc(e->n)) {
210 DATA_BLOB cache_key, cache_value;
213 memcache_element_parse(e, &cache_key, &cache_value);
214 SMB_ASSERT(cache_value.length == sizeof(ptr));
215 memcpy(&ptr, cache_value.data, sizeof(ptr));
219 cache->size -= memcache_element_size(e->keylength, e->valuelength);
224 static void memcache_trim(struct memcache *cache)
226 if (cache->max_size == 0) {
230 while ((cache->size > cache->max_size) && (cache->lru != NULL)) {
231 memcache_delete_element(cache, cache->lru);
235 void memcache_delete(struct memcache *cache, enum memcache_number n,
238 struct memcache_element *e;
241 cache = global_cache;
247 e = memcache_find(cache, n, key);
252 memcache_delete_element(cache, e);
255 void memcache_add(struct memcache *cache, enum memcache_number n,
256 DATA_BLOB key, DATA_BLOB value)
258 struct memcache_element *e;
260 struct rb_node *parent;
261 DATA_BLOB cache_key, cache_value;
265 cache = global_cache;
271 if (key.length == 0) {
275 e = memcache_find(cache, n, key);
278 memcache_element_parse(e, &cache_key, &cache_value);
280 if (value.length <= cache_value.length) {
281 if (memcache_is_talloc(e->n)) {
283 SMB_ASSERT(cache_value.length == sizeof(ptr));
284 memcpy(&ptr, cache_value.data, sizeof(ptr));
288 * We can reuse the existing record
290 memcpy(cache_value.data, value.data, value.length);
291 e->valuelength = value.length;
295 memcache_delete_element(cache, e);
298 element_size = memcache_element_size(key.length, value.length);
301 e = (struct memcache_element *)SMB_MALLOC(element_size);
304 DEBUG(0, ("malloc failed\n"));
309 e->keylength = key.length;
310 e->valuelength = value.length;
312 memcache_element_parse(e, &cache_key, &cache_value);
313 memcpy(cache_key.data, key.data, key.length);
314 memcpy(cache_value.data, value.data, value.length);
317 p = &cache->tree.rb_node;
320 struct memcache_element *elem = memcache_node2elem(*p);
325 cmp = memcache_compare(elem, n, key);
327 p = (cmp < 0) ? &(*p)->rb_left : &(*p)->rb_right;
330 rb_link_node(&e->rb_node, parent, p);
331 rb_insert_color(&e->rb_node, &cache->tree);
333 DLIST_ADD(cache->mru, e);
334 if (cache->lru == NULL) {
338 cache->size += element_size;
339 memcache_trim(cache);
342 void memcache_add_talloc(struct memcache *cache, enum memcache_number n,
343 DATA_BLOB key, void *pptr)
345 void **ptr = (void **)pptr;
349 cache = global_cache;
355 p = talloc_move(cache, ptr);
356 memcache_add(cache, n, key, data_blob_const(&p, sizeof(p)));
359 void memcache_flush(struct memcache *cache, enum memcache_number n)
361 struct rb_node *node;
364 cache = global_cache;
371 * Find the smallest element of number n
374 node = cache->tree.rb_node;
380 * First, find *any* element of number n
384 struct memcache_element *elem = memcache_node2elem(node);
385 struct rb_node *next;
387 if ((int)elem->n == (int)n) {
391 if ((int)elem->n < (int)n) {
392 next = node->rb_right;
395 next = node->rb_left;
408 * Then, find the leftmost element with number n
412 struct rb_node *prev = rb_prev(node);
413 struct memcache_element *elem;
418 elem = memcache_node2elem(prev);
419 if ((int)elem->n != (int)n) {
425 while (node != NULL) {
426 struct memcache_element *e = memcache_node2elem(node);
427 struct rb_node *next = rb_next(node);
433 memcache_delete_element(cache, e);