1 /* cache.c - routines to maintain an in-core cache of entries */
10 #include "back-ldbm.h"
12 static int cache_delete_entry_internal();
14 static void lru_print();
18 * the cache has three entry points (ways to find things):
20 * by entry e.g., if you already have an entry from the cache
21 * and want to delete it. (really by entry ptr)
22 * by dn e.g., when looking for the base object of a search
23 * by id e.g., for search candidates
25 * these correspond to three different avl trees that are maintained.
29 cache_entry_cmp( Entry *e1, Entry *e2 )
31 return( e1 < e2 ? -1 : (e1 > e2 ? 1 : 0) );
35 cache_entrydn_cmp( Entry *e1, Entry *e2 )
37 return( strcasecmp( e1->e_dn, e2->e_dn ) );
41 cache_entryid_cmp( Entry *e1, Entry *e2 )
43 return( e1->e_id < e2->e_id ? -1 : (e1->e_id > e2->e_id ? 1 : 0) );
47 cache_set_state( struct cache *cache, Entry *e, int state )
50 pthread_mutex_lock( &cache->c_mutex );
54 /* free cache mutex */
55 pthread_mutex_unlock( &cache->c_mutex );
59 cache_return_entry( struct cache *cache, Entry *e )
62 pthread_mutex_lock( &cache->c_mutex );
64 if ( --e->e_refcnt == 0 && e->e_state == ENTRY_STATE_DELETED ) {
68 /* free cache mutex */
69 pthread_mutex_unlock( &cache->c_mutex );
73 cache_return_entry_rw( struct cache *cache, Entry *e, int rw )
75 Debug( LDAP_DEBUG_TRACE, "====> cache_return_entry_%s\n",
76 rw ? "w" : "r", 0, 0);
77 entry_rdwr_unlock(e, rw);;
78 cache_return_entry(cache, e);
82 cache_return_entry_r( struct cache *cache, Entry *e )
84 cache_return_entry_rw(cache, e, 0);
88 cache_return_entry_w( struct cache *cache, Entry *e )
90 cache_return_entry_rw(cache, e, 1);
94 #define LRU_DELETE( cache, e ) { \
95 if ( e->e_lruprev != NULL ) { \
96 e->e_lruprev->e_lrunext = e->e_lrunext; \
98 cache->c_lruhead = e->e_lrunext; \
100 if ( e->e_lrunext != NULL ) { \
101 e->e_lrunext->e_lruprev = e->e_lruprev; \
103 cache->c_lrutail = e->e_lruprev; \
107 #define LRU_ADD( cache, e ) { \
108 e->e_lrunext = cache->c_lruhead; \
109 if ( e->e_lrunext != NULL ) { \
110 e->e_lrunext->e_lruprev = e; \
112 cache->c_lruhead = e; \
113 e->e_lruprev = NULL; \
114 if ( cache->c_lrutail == NULL ) { \
115 cache->c_lrutail = e; \
120 * cache_create_entry_lock - create an entry in the cache, and lock it.
121 * returns: 0 entry has been created and locked
122 * 1 entry already existed
123 * -1 something bad happened
126 cache_add_entry_lock(
135 /* set cache mutex */
136 pthread_mutex_lock( &cache->c_mutex );
138 if ( avl_insert( &cache->c_dntree, (caddr_t) e,
139 cache_entrydn_cmp, avl_dup_error ) != 0 )
141 Debug( LDAP_DEBUG_TRACE,
142 "====> cache_add_entry lock: entry %20s id %d already in dn cache\n",
143 e->e_dn, e->e_id, 0 );
145 /* free cache mutex */
146 pthread_mutex_unlock( &cache->c_mutex );
151 if ( avl_insert( &cache->c_idtree, (caddr_t) e,
152 cache_entryid_cmp, avl_dup_error ) != 0 )
154 Debug( LDAP_DEBUG_ANY,
155 "====> entry %20s id %d already in id cache\n",
156 e->e_dn, e->e_id, 0 );
158 /* delete from dn tree inserted above */
159 if ( avl_delete( &cache->c_dntree, (caddr_t) e,
160 cache_entrydn_cmp ) == NULL )
162 Debug( LDAP_DEBUG_ANY, "====> can't delete from dn cache\n",
166 /* free cache mutex */
167 pthread_mutex_unlock( &cache->c_mutex );
176 if ( ++cache->c_cursize > cache->c_maxsize ) {
178 * find the lru entry not currently in use and delete it.
179 * in case a lot of entries are in use, only look at the
180 * first 10 on the tail of the list.
183 while ( cache->c_lrutail != NULL && cache->c_lrutail->e_refcnt
185 /* move this in-use entry to the front of the q */
186 ee = cache->c_lrutail;
187 LRU_DELETE( cache, ee );
188 LRU_ADD( cache, ee );
193 * found at least one to delete - try to get back under
194 * the max cache size.
196 while ( cache->c_lrutail != NULL && cache->c_lrutail->e_refcnt
197 == 0 && cache->c_cursize > cache->c_maxsize ) {
198 e = cache->c_lrutail;
200 /* XXX check for writer lock - should also check no readers pending */
202 assert(pthread_rdwr_wchk_np(&e->e_rdwr));
205 /* delete from cache and lru q */
206 rc = cache_delete_entry_internal( cache, e );
212 /* free cache mutex */
213 pthread_mutex_unlock( &cache->c_mutex );
218 * cache_find_entry_dn2id - find an entry in the cache, given dn
222 cache_find_entry_dn2id(
228 struct ldbminfo *li = (struct ldbminfo *) be->be_private;
232 /* set cache mutex */
233 pthread_mutex_lock( &cache->c_mutex );
237 if ( (ep = (Entry *) avl_find( cache->c_dntree, (caddr_t) &e,
238 cache_entrydn_cmp )) != NULL )
240 Debug(LDAP_DEBUG_TRACE, "====> cache_find_entry_dn2id: found dn: %s\n",
244 * entry is deleted or not fully created yet
246 if ( ep->e_state == ENTRY_STATE_DELETED ||
247 ep->e_state == ENTRY_STATE_CREATING )
249 /* free cache mutex */
250 pthread_mutex_unlock( &cache->c_mutex );
254 /* XXX is this safe without writer lock? */
258 LRU_DELETE( cache, ep );
259 LRU_ADD( cache, ep );
261 /* acquire reader lock */
262 entry_rdwr_lock(ep, 0);
265 if ( ep->e_state == ENTRY_STATE_DELETED ||
266 ep->e_state == ENTRY_STATE_CREATING )
268 /* XXX check that is is required */
271 /* free reader lock */
272 entry_rdwr_unlock(ep, 0);
273 /* free cache mutex */
274 pthread_mutex_unlock( &cache->c_mutex );
282 /* free reader lock */
283 entry_rdwr_unlock(ep, 0);
285 /* free cache mutex */
286 pthread_mutex_unlock( &cache->c_mutex );
288 cache_return_entry( &li->li_cache, ep );
293 /* free cache mutex */
294 pthread_mutex_unlock( &cache->c_mutex );
300 * cache_find_entry_id - find an entry in the cache, given id
313 /* set cache mutex */
314 pthread_mutex_lock( &cache->c_mutex );
318 if ( (ep = (Entry *) avl_find( cache->c_idtree, (caddr_t) &e,
319 cache_entryid_cmp )) != NULL )
321 Debug(LDAP_DEBUG_TRACE,
322 "====> cache_find_entry_dn2id: found id: %ld rw: %d\n",
326 * entry is deleted or not fully created yet
328 if ( ep->e_state == ENTRY_STATE_DELETED ||
329 ep->e_state == ENTRY_STATE_CREATING )
331 /* free cache mutex */
332 pthread_mutex_unlock( &cache->c_mutex );
335 /* XXX is this safe without writer lock? */
339 LRU_DELETE( cache, ep );
340 LRU_ADD( cache, ep );
342 /* acquire reader lock */
343 entry_rdwr_lock(ep, 0);
346 if ( ep->e_state == ENTRY_STATE_DELETED ||
347 ep->e_state == ENTRY_STATE_CREATING ) {
349 /* XXX check that is is required */
352 /* free reader lock */
353 entry_rdwr_unlock(ep, 0);
355 /* free cache mutex */
356 pthread_mutex_unlock( &cache->c_mutex );
361 entry_rdwr_unlock(ep, 0);
362 entry_rdwr_lock(ep, 1);
365 /* free cache mutex */
366 pthread_mutex_unlock( &cache->c_mutex );
371 /* free cache mutex */
372 pthread_mutex_unlock( &cache->c_mutex );
378 * cache_delete_entry - delete the entry e from the cache. the caller
379 * should have obtained e (increasing its ref count) via a call to one
380 * of the cache_find_* routines. the caller should *not* call the
381 * cache_return_entry() routine prior to calling cache_delete_entry().
382 * it performs this function.
384 * returns: 0 e was deleted ok
385 * 1 e was not in the cache
386 * -1 something bad happened
396 Debug( LDAP_DEBUG_TRACE, "====> cache_delete_entry:\n", 0, 0, 0 );
398 /* XXX check for writer lock - should also check no readers pending */
400 assert(pthread_rdwr_wchk_np(&e->e_rdwr));
403 /* set cache mutex */
404 pthread_mutex_lock( &cache->c_mutex );
406 rc = cache_delete_entry_internal( cache, e );
408 /* free cache mutex */
409 pthread_mutex_unlock( &cache->c_mutex );
414 cache_delete_entry_internal(
420 if ( avl_delete( &cache->c_dntree, (caddr_t) e, cache_entrydn_cmp )
427 if ( avl_delete( &cache->c_idtree, (caddr_t) e, cache_entryid_cmp )
434 LRU_DELETE( cache, e );
438 * flag entry to be freed later by a call to cache_return_entry()
440 e->e_state = ENTRY_STATE_DELETED;
448 lru_print( struct cache *cache )
452 fprintf( stderr, "LRU queue (head to tail):\n" );
453 for ( e = cache->c_lruhead; e != NULL; e = e->e_lrunext ) {
454 fprintf( stderr, "\tdn %20s id %d refcnt %d\n", e->e_dn,
455 e->e_id, e->e_refcnt );
457 fprintf( stderr, "LRU queue (tail to head):\n" );
458 for ( e = cache->c_lrutail; e != NULL; e = e->e_lruprev ) {
459 fprintf( stderr, "\tdn %20s id %d refcnt %d\n", e->e_dn,
460 e->e_id, e->e_refcnt );