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Cache-thrashing protection: if the DB has more entries than the cache,
don't allow large search operations that touch more entries churn the existing cached entries.
This commit is contained in:
Howard Chu
parent
eea5e60bf0
commit
b4bcc325ee
@ -117,6 +117,7 @@ typedef struct bdb_entry_info {
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#define CACHE_ENTRY_WALKING 0x20
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#define CACHE_ENTRY_ONELEVEL 0x40
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#define CACHE_ENTRY_REFERENCED 0x80
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#define CACHE_ENTRY_NOT_CACHED 0x100
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int bei_finders;
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/*
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@ -119,13 +119,13 @@ static void
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bdb_cache_lru_link( struct bdb_info *bdb, EntryInfo *ei )
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{
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/* Already linked, ignore */
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if ( ei->bei_lruprev )
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return;
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/* Insert into circular LRU list */
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ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_lru_mutex );
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/* Still linked, remove */
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if ( ei->bei_lruprev ) {
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LRU_DEL( &bdb->bi_cache, ei );
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}
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ei->bei_lruprev = bdb->bi_cache.c_lrutail;
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if ( bdb->bi_cache.c_lrutail ) {
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ei->bei_lrunext = bdb->bi_cache.c_lrutail->bei_lrunext;
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@ -250,6 +250,28 @@ bdb_cache_entry_db_unlock ( struct bdb_info *bdb, DB_LOCK *lock )
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#endif
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}
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void
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bdb_cache_return_entry_rw( struct bdb_info *bdb, Entry *e,
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int rw, DB_LOCK *lock )
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{
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EntryInfo *ei;
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int free = 0;
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ei = e->e_private;
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bdb_cache_entryinfo_lock( ei );
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if ( ei->bei_state & CACHE_ENTRY_NOT_CACHED ) {
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ei->bei_e = NULL;
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ei->bei_state ^= CACHE_ENTRY_NOT_CACHED;
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free = 1;
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}
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bdb_cache_entryinfo_unlock( ei );
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bdb_cache_entry_db_unlock( bdb, lock );
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if ( free ) {
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e->e_private = NULL;
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bdb_entry_return( e );
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}
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}
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static int
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bdb_cache_entryinfo_destroy( EntryInfo *e )
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{
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@ -541,6 +563,7 @@ hdb_cache_find_parent(
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/* Got the parent, link in and we're done. */
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if ( ei2 ) {
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bdb_cache_entryinfo_lock( eir );
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bdb_cache_entryinfo_lock( ei2 );
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ein->bei_parent = ei2;
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@ -553,7 +576,6 @@ hdb_cache_find_parent(
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ein->bei_state &= ~CACHE_ENTRY_NOT_LINKED;
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bdb_cache_entryinfo_unlock( ei2 );
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bdb_cache_entryinfo_lock( eir );
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*res = eir;
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break;
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@ -737,7 +759,7 @@ bdb_cache_find_info(
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/*
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* cache_find_id - find an entry in the cache, given id.
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* The entry is locked for Read upon return. Call with islocked TRUE if
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* The entry is locked for Read upon return. Call with flag ID_LOCKED if
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* the supplied *eip was already locked.
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*/
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@ -747,7 +769,7 @@ bdb_cache_find_id(
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DB_TXN *tid,
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ID id,
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EntryInfo **eip,
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int islocked,
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int flag,
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BDB_LOCKER locker,
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DB_LOCK *lock )
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{
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@ -789,7 +811,7 @@ again: ldap_pvt_thread_rdwr_rlock( &bdb->bi_cache.c_rwlock );
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ldap_pvt_thread_yield();
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goto again;
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}
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islocked = 1;
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flag |= ID_LOCKED;
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}
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ldap_pvt_thread_rdwr_runlock( &bdb->bi_cache.c_rwlock );
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}
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@ -801,7 +823,7 @@ again: ldap_pvt_thread_rdwr_rlock( &bdb->bi_cache.c_rwlock );
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if ( rc == 0 ) {
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rc = bdb_cache_find_ndn( op, tid,
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&ep->e_nname, eip );
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if ( *eip ) islocked = 1;
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if ( *eip ) flag |= ID_LOCKED;
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if ( rc ) {
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ep->e_private = NULL;
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#ifdef SLAP_ZONE_ALLOC
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@ -814,7 +836,7 @@ again: ldap_pvt_thread_rdwr_rlock( &bdb->bi_cache.c_rwlock );
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}
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#else
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rc = hdb_cache_find_parent(op, tid, locker, id, eip );
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if ( rc == 0 ) islocked = 1;
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if ( rc == 0 ) flag |= ID_LOCKED;
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#endif
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}
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@ -839,9 +861,18 @@ load1:
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(*eip)->bei_state |= CACHE_ENTRY_LOADING;
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}
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if ( islocked ) {
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/* If the entry was loaded before but uncached, and we need
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* it again, clear the uncached state
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*/
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if ( (*eip)->bei_state & CACHE_ENTRY_NOT_CACHED ) {
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(*eip)->bei_state ^= CACHE_ENTRY_NOT_CACHED;
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if ( flag & ID_NOCACHE )
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flag ^= ID_NOCACHE;
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}
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if ( flag & ID_LOCKED ) {
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bdb_cache_entryinfo_unlock( *eip );
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islocked = 0;
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flag ^= ID_LOCKED;
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}
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rc = bdb_cache_entry_db_lock( bdb, locker, *eip, load, 0, lock );
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if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
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@ -863,6 +894,11 @@ load1:
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#endif
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ep = NULL;
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bdb_cache_lru_link( bdb, *eip );
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if ( flag & ID_NOCACHE ) {
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bdb_cache_entryinfo_lock( *eip );
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(*eip)->bei_state |= CACHE_ENTRY_NOT_CACHED;
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bdb_cache_entryinfo_unlock( *eip );
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}
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}
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if ( rc == 0 ) {
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/* If we succeeded, downgrade back to a readlock. */
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@ -878,7 +914,7 @@ load1:
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*/
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bdb_cache_entry_db_unlock( bdb, lock );
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bdb_cache_entryinfo_lock( *eip );
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islocked = 1;
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flag |= ID_LOCKED;
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goto load1;
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#ifdef BDB_HIER
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} else {
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@ -904,7 +940,7 @@ load1:
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}
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}
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}
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if ( islocked ) {
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if ( flag & ID_LOCKED ) {
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bdb_cache_entryinfo_unlock( *eip );
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}
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if ( ep ) {
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@ -919,14 +955,16 @@ load1:
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int purge = 0;
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if ( load ) {
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ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_count_mutex );
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bdb->bi_cache.c_cursize++;
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if ( bdb->bi_cache.c_cursize > bdb->bi_cache.c_maxsize &&
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!bdb->bi_cache.c_purging ) {
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purge = 1;
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bdb->bi_cache.c_purging = 1;
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if ( !( flag & ID_NOCACHE )) {
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ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_count_mutex );
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bdb->bi_cache.c_cursize++;
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if ( bdb->bi_cache.c_cursize > bdb->bi_cache.c_maxsize &&
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!bdb->bi_cache.c_purging ) {
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purge = 1;
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bdb->bi_cache.c_purging = 1;
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}
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ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_count_mutex );
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}
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ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_count_mutex );
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}
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if ( purge )
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bdb_cache_lru_purge( bdb );
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@ -54,7 +54,7 @@ bdb_dn2entry(
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*e = ei;
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if ( ei && ei->bei_id ) {
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rc2 = bdb_cache_find_id( op, tid, ei->bei_id,
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&ei, 1, locker, lock );
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&ei, ID_LOCKED, locker, lock );
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if ( rc2 ) rc = rc2;
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} else if ( ei ) {
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bdb_cache_entryinfo_unlock( ei );
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@ -65,7 +65,7 @@ bdb_dn2entry(
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bdb_cache_entryinfo_unlock( ei );
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}
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} else {
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rc = bdb_cache_find_id( op, tid, ei->bei_id, &ei, 1,
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rc = bdb_cache_find_id( op, tid, ei->bei_id, &ei, ID_LOCKED,
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locker, lock );
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if ( rc == 0 ) {
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*e = ei;
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@ -73,7 +73,7 @@ bdb_dn2entry(
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/* always return EntryInfo */
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if ( ei->bei_parent ) {
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ei = ei->bei_parent;
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rc2 = bdb_cache_find_id( op, tid, ei->bei_id, &ei, 1,
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rc2 = bdb_cache_find_id( op, tid, ei->bei_id, &ei, ID_LOCKED,
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locker, lock );
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if ( rc2 ) rc = rc2;
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}
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@ -456,6 +456,7 @@ bdb_monitor_idx_add(
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* cache.c
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*/
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#define bdb_cache_entry_db_unlock BDB_SYMBOL(cache_entry_db_unlock)
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#define bdb_cache_return_entry_rw BDB_SYMBOL(cache_return_entry_rw)
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#define bdb_cache_entryinfo_lock(e) \
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ldap_pvt_thread_mutex_lock( &(e)->bei_kids_mutex )
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@ -467,15 +468,8 @@ bdb_monitor_idx_add(
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/* What a mess. Hopefully the current cache scheme will stabilize
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* and we can trim out all of this stuff.
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*/
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#if 0
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void bdb_cache_return_entry_rw( struct bdb_info *bdb, Entry *e,
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int rw, DB_LOCK *lock );
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#else
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#define bdb_cache_return_entry_rw( bdb, e, rw, lock ) \
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bdb_cache_entry_db_unlock( bdb, lock )
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#define bdb_cache_return_entry( bdb, lock ) \
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bdb_cache_entry_db_unlock( bdb, lock )
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#endif
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#define bdb_cache_return_entry_r(bdb, e, l) \
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bdb_cache_return_entry_rw((bdb), (e), 0, (l))
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#define bdb_cache_return_entry_w(bdb, e, l) \
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@ -542,12 +536,15 @@ EntryInfo * bdb_cache_find_info(
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struct bdb_info *bdb,
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ID id
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);
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#define ID_LOCKED 1
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#define ID_NOCACHE 2
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int bdb_cache_find_id(
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Operation *op,
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DB_TXN *tid,
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ID id,
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EntryInfo **eip,
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int islocked,
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int flag,
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BDB_LOCKER locker,
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DB_LOCK *lock
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);
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@ -303,19 +303,20 @@ int
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bdb_search( Operation *op, SlapReply *rs )
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{
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struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
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time_t stoptime;
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ID id, cursor;
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ID lastid = NOID;
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ID candidates[BDB_IDL_UM_SIZE];
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ID scopes[BDB_IDL_DB_SIZE];
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Entry *e = NULL, base, *e_root;
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Entry *matched = NULL;
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EntryInfo *ei;
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AttributeName *attrs;
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struct berval realbase = BER_BVNULL;
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slap_mask_t mask;
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time_t stoptime;
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int manageDSAit;
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int tentries = 0;
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ID lastid = NOID;
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AttributeName *attrs;
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int tentries = 0, nentries = 0;
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int idflag = 0;
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BDB_LOCKER locker = 0;
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DB_LOCK lock;
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@ -640,6 +641,7 @@ dn2entry_retry:
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rs->sr_err = LDAP_OTHER;
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goto done;
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}
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nentries = ps->ps_count;
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goto loop_begin;
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}
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@ -676,11 +678,19 @@ loop_begin:
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goto done;
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}
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/* If we inspect more entries than will
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* fit into the entry cache, stop caching
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* any subsequent entries
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*/
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nentries++;
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if ( nentries > bdb->bi_cache.c_maxsize && !idflag )
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idflag = ID_NOCACHE;
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fetch_entry_retry:
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/* get the entry with reader lock */
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ei = NULL;
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rs->sr_err = bdb_cache_find_id( op, ltid,
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id, &ei, 0, locker, &lock );
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id, &ei, idflag, locker, &lock );
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if (rs->sr_err == LDAP_BUSY) {
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rs->sr_text = "ldap server busy";
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