1 /* cache.c - routines to maintain an in-core cache of entries */
13 #include "back-ldbm.h"
15 static int cache_delete_entry_internal(struct cache *cache, Entry *e);
17 static void lru_print(struct cache *cache);
21 * the cache has three entry points (ways to find things):
23 * by entry e.g., if you already have an entry from the cache
24 * and want to delete it. (really by entry ptr)
25 * by dn e.g., when looking for the base object of a search
26 * by id e.g., for search candidates
28 * these correspond to three different avl trees that are maintained.
32 cache_entry_cmp( Entry *e1, Entry *e2 )
34 return( e1 < e2 ? -1 : (e1 > e2 ? 1 : 0) );
38 cache_entrydn_cmp( Entry *e1, Entry *e2 )
40 /* compare their normalized UPPERCASED dn's */
41 return( strcmp( e1->e_ndn, e2->e_ndn ) );
45 cache_entryid_cmp( Entry *e1, Entry *e2 )
47 return( e1->e_id < e2->e_id ? -1 : (e1->e_id > e2->e_id ? 1 : 0) );
51 cache_set_state( struct cache *cache, Entry *e, int state )
54 ldap_pvt_thread_mutex_lock( &cache->c_mutex );
58 /* free cache mutex */
59 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
63 cache_return_entry_rw( struct cache *cache, Entry *e, int rw )
65 Debug( LDAP_DEBUG_TRACE, "====> cache_return_entry_%s\n",
66 rw ? "w" : "r", 0, 0);
69 ldap_pvt_thread_mutex_lock( &cache->c_mutex );
71 entry_rdwr_unlock(e, rw);
73 if ( --e->e_refcnt == 0 && e->e_state == ENTRY_STATE_DELETED ) {
77 /* free cache mutex */
78 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
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 - 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
135 /* set cache mutex */
136 ldap_pvt_thread_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 %lu already in dn cache\n",
143 e->e_dn, e->e_id, 0 );
145 /* free cache mutex */
146 ldap_pvt_thread_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 %lu 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 ldap_pvt_thread_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 /* check for active readers/writer lock */
202 assert(!ldap_pvt_thread_rdwr_active( &e->e_rdwr ));
205 /* delete from cache and lru q */
206 rc = cache_delete_entry_internal( cache, e );
212 /* free cache mutex */
213 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
218 * cache_update_entry - update an entry in the cache
219 * returns: 0 entry has been created and locked
220 * 1 entry already existed
221 * -1 something bad happened
232 /* set cache mutex */
233 ldap_pvt_thread_mutex_lock( &cache->c_mutex );
235 if ( avl_insert( &cache->c_dntree, (caddr_t) e,
236 cache_entrydn_cmp, avl_dup_error ) != 0 )
238 Debug( LDAP_DEBUG_TRACE,
239 "====> cache_add_entry lock: entry %20s id %lu already in dn cache\n",
240 e->e_dn, e->e_id, 0 );
242 /* free cache mutex */
243 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
248 if ( avl_insert( &cache->c_idtree, (caddr_t) e,
249 cache_entryid_cmp, avl_dup_error ) != 0 )
251 Debug( LDAP_DEBUG_ANY,
252 "====> entry %20s id %lu already in id cache\n",
253 e->e_dn, e->e_id, 0 );
255 /* delete from dn tree inserted above */
256 if ( avl_delete( &cache->c_dntree, (caddr_t) e,
257 cache_entrydn_cmp ) == NULL )
259 Debug( LDAP_DEBUG_ANY, "====> can't delete from dn cache\n",
263 /* free cache mutex */
264 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
272 if ( ++cache->c_cursize > cache->c_maxsize ) {
274 * find the lru entry not currently in use and delete it.
275 * in case a lot of entries are in use, only look at the
276 * first 10 on the tail of the list.
279 while ( cache->c_lrutail != NULL && cache->c_lrutail->e_refcnt
281 /* move this in-use entry to the front of the q */
282 ee = cache->c_lrutail;
283 LRU_DELETE( cache, ee );
284 LRU_ADD( cache, ee );
289 * found at least one to delete - try to get back under
290 * the max cache size.
292 while ( cache->c_lrutail != NULL && cache->c_lrutail->e_refcnt
293 == 0 && cache->c_cursize > cache->c_maxsize ) {
294 e = cache->c_lrutail;
296 /* check for active readers/writer lock */
298 assert(!ldap_pvt_thread_rdwr_active( &e->e_rdwr ));
301 /* delete from cache and lru q */
302 rc = cache_delete_entry_internal( cache, e );
308 /* free cache mutex */
309 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
314 * cache_find_entry_dn2id - find an entry in the cache, given dn
318 cache_find_entry_dn2id(
324 struct ldbminfo *li = (struct ldbminfo *) be->be_private;
328 /* set cache mutex */
329 ldap_pvt_thread_mutex_lock( &cache->c_mutex );
332 e.e_ndn = dn_normalize_case( ch_strdup( dn ) );
334 if ( (ep = (Entry *) avl_find( cache->c_dntree, (caddr_t) &e,
335 cache_entrydn_cmp )) != NULL )
338 * ep now points to an unlocked entry
339 * we do not need to lock the entry if we only
340 * check the state, refcnt, LRU, and id.
344 Debug(LDAP_DEBUG_TRACE, "====> cache_find_entry_dn2id: found dn: %s\n",
348 * entry is deleted or not fully created yet
350 if ( ep->e_state == ENTRY_STATE_DELETED ||
351 ep->e_state == ENTRY_STATE_CREATING )
353 /* free cache mutex */
354 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
359 LRU_DELETE( cache, ep );
360 LRU_ADD( cache, ep );
365 /* free cache mutex */
366 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
373 /* free cache mutex */
374 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
380 * cache_find_entry_id - find an entry in the cache, given id
396 /* set cache mutex */
397 ldap_pvt_thread_mutex_lock( &cache->c_mutex );
399 if ( (ep = (Entry *) avl_find( cache->c_idtree, (caddr_t) &e,
400 cache_entryid_cmp )) != NULL )
402 Debug(LDAP_DEBUG_TRACE,
403 "====> cache_find_entry_dn2id: found id: %ld rw: %d\n",
407 * entry is deleted or not fully created yet
409 if ( ep->e_state == ENTRY_STATE_DELETED ||
410 ep->e_state == ENTRY_STATE_CREATING )
412 /* free cache mutex */
413 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
417 /* acquire reader lock */
418 if ( entry_rdwr_trylock(ep, rw) == LDAP_PVT_THREAD_EBUSY ) {
419 /* could not acquire entry lock...
420 * owner cannot free as we have the cache locked.
421 * so, unlock the cache, yield, and try again.
424 /* free cache mutex */
425 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
426 ldap_pvt_thread_yield();
431 LRU_DELETE( cache, ep );
432 LRU_ADD( cache, ep );
436 /* free cache mutex */
437 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
442 /* free cache mutex */
443 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
449 * cache_delete_entry - delete the entry e from the cache. the caller
450 * should have obtained e (increasing its ref count) via a call to one
451 * of the cache_find_* routines. the caller should *not* call the
452 * cache_return_entry() routine prior to calling cache_delete_entry().
453 * it performs this function.
455 * returns: 0 e was deleted ok
456 * 1 e was not in the cache
457 * -1 something bad happened
467 Debug( LDAP_DEBUG_TRACE, "====> cache_delete_entry:\n", 0, 0, 0 );
469 /* set cache mutex */
470 ldap_pvt_thread_mutex_lock( &cache->c_mutex );
472 /* XXX check for writer lock - should also check no readers pending */
474 assert(ldap_pvt_thread_rdwr_writers( &e->e_rdwr ) == 1);
477 rc = cache_delete_entry_internal( cache, e );
479 /* free cache mutex */
480 ldap_pvt_thread_mutex_unlock( &cache->c_mutex );
485 cache_delete_entry_internal(
490 int rc = 0; /* return code */
493 if ( avl_delete( &cache->c_dntree, (caddr_t) e, cache_entrydn_cmp )
500 if ( avl_delete( &cache->c_idtree, (caddr_t) e, cache_entryid_cmp )
511 LRU_DELETE( cache, e );
515 * flag entry to be freed later by a call to cache_return_entry()
517 e->e_state = ENTRY_STATE_DELETED;
525 lru_print( struct cache *cache )
529 fprintf( stderr, "LRU queue (head to tail):\n" );
530 for ( e = cache->c_lruhead; e != NULL; e = e->e_lrunext ) {
531 fprintf( stderr, "\tdn %20s id %lu refcnt %d\n", e->e_dn,
532 e->e_id, e->e_refcnt );
534 fprintf( stderr, "LRU queue (tail to head):\n" );
535 for ( e = cache->c_lrutail; e != NULL; e = e->e_lruprev ) {
536 fprintf( stderr, "\tdn %20s id %lu refcnt %d\n", e->e_dn,
537 e->e_id, e->e_refcnt );