cache.c

ldap服务器源码

		bdb->bi_cache.c_eiused++;
		if ( ei2 && ( ei2->bei_kids || !ei2->bei_id ))
				bdb->bi_cache.c_leaves++;
		ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );

		if ( addlru ) {
			ldap_pvt_thread_mutex_lock( &bdb->bi_cache.lru_head_mutex );
			bdb_cache_lru_add( bdb, ein );
		}
		addlru = 1;

		/* Got the parent, link in and we're done. */
		if ( ei2 ) {
			bdb_cache_entryinfo_lock( ei2 );
			ein->bei_parent = ei2;
			avl_insert( &ei2->bei_kids, (caddr_t)ein, bdb_rdn_cmp,
				avl_dup_error);
			ei2->bei_ckids++;
			bdb_cache_entryinfo_unlock( ei2 );
			bdb_cache_entryinfo_lock( eir );

			/* Reset all the state info */
			for (ein = eir; ein != ei2; ein=ein->bei_parent)
				ein->bei_state &= ~CACHE_ENTRY_NOT_LINKED;
			*res = eir;
			break;
		}
		ei.bei_kids = NULL;
		ei.bei_id = eip.bei_id;
		ei.bei_ckids = 1;
		avl_insert( &ei.bei_kids, (caddr_t)ein, bdb_rdn_cmp,
			avl_dup_error );
	}
	return rc;
}

/* Used by hdb_dn2idl when loading the EntryInfo for all the children
 * of a given node
 */
int hdb_cache_load(
	struct bdb_info *bdb,
	EntryInfo *ei,
	EntryInfo **res )
{
	EntryInfo *ei2;
	int rc;

	/* See if we already have this one */
	bdb_cache_entryinfo_lock( ei->bei_parent );
	ei2 = (EntryInfo *)avl_find( ei->bei_parent->bei_kids, ei, bdb_rdn_cmp );
	bdb_cache_entryinfo_unlock( ei->bei_parent );

	if ( !ei2 ) {
		/* Not found, add it */
		struct berval bv;

		/* bei_rdn was not malloc'd before, do it now */
		ber_dupbv( &bv, &ei->bei_rdn );
		ei->bei_rdn = bv;

		rc = bdb_entryinfo_add_internal( bdb, ei, res );
		bdb_cache_entryinfo_unlock( ei->bei_parent );
		ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
	} else {
		/* Found, return it */
		*res = ei2;
		return 0;
	}
	return rc;
}
#endif

/* caller must have lru_head_mutex locked. mutex
 * will be unlocked on return.
 */
static void
bdb_cache_lru_add(
	struct bdb_info *bdb,
	EntryInfo *ei )
{
	DB_LOCK		lock, *lockp;
	EntryInfo *elru, *elprev;
	int count = 0;

	LRU_ADD( &bdb->bi_cache, ei );
	ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.lru_head_mutex );

	/* See if we're above the cache size limit */
	if ( bdb->bi_cache.c_cursize <= bdb->bi_cache.c_maxsize )
		return;

	if ( bdb->bi_cache.c_locker ) {
		lockp = &lock;
	} else {
		lockp = NULL;
	}

	/* Don't bother if we can't get the lock */
	if ( ldap_pvt_thread_mutex_trylock( &bdb->bi_cache.lru_tail_mutex ) )
		return;

	/* Look for an unused entry to remove */
	for (elru = bdb->bi_cache.c_lrutail; elru; elru = elprev ) {
		elprev = elru->bei_lruprev;

		/* If we can successfully writelock it, then
		 * the object is idle.
		 */
		if ( bdb_cache_entry_db_lock( bdb->bi_dbenv,
				bdb->bi_cache.c_locker, elru, 1, 1, lockp ) == 0 ) {


			/* If this node is in the process of linking into the cache,
			 * or this node is being deleted, skip it.
			 */
			if ( elru->bei_state &
				( CACHE_ENTRY_NOT_LINKED | CACHE_ENTRY_DELETED )) {
				bdb_cache_entry_db_unlock( bdb->bi_dbenv, lockp );
				continue;
			}
			/* Free entry for this node if it's present */
			if ( elru->bei_e ) {
				elru->bei_e->e_private = NULL;
#ifdef SLAP_ZONE_ALLOC
				bdb_entry_return( bdb, elru->bei_e, elru->bei_zseq );
#else
				bdb_entry_return( elru->bei_e );
#endif
				elru->bei_e = NULL;
				count++;
			}
			/* ITS#4010 if we're in slapcat, and this node is a leaf
			 * node, free it.
			 *
			 * FIXME: we need to do this for slapd as well, (which is
			 * why we compute bi_cache.c_leaves now) but at the moment
			 * we can't because it causes unresolvable deadlocks. 
			 */
			if ( slapMode & SLAP_TOOL_READONLY ) {
				if ( !elru->bei_kids ) {
					/* This does LRU_DELETE for us */
					bdb_cache_delete_internal( &bdb->bi_cache, elru, 0 );
					bdb_cache_delete_cleanup( &bdb->bi_cache, elru );
				}
				/* Leave node on LRU list for a future pass */
			} else {
				LRU_DELETE( &bdb->bi_cache, elru );
			}
			bdb_cache_entry_db_unlock( bdb->bi_dbenv, lockp );

			if ( count >= bdb->bi_cache.c_minfree ) {
				ldap_pvt_thread_rdwr_wlock( &bdb->bi_cache.c_rwlock );
				bdb->bi_cache.c_cursize -= count;
				ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
				break;
			}
		}
	}

	ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.lru_tail_mutex );
}

EntryInfo *
bdb_cache_find_info(
	struct bdb_info *bdb,
	ID id )
{
	EntryInfo	ei = { 0 },
			*ei2;

	ei.bei_id = id;

	ldap_pvt_thread_rdwr_rlock( &bdb->bi_cache.c_rwlock );
	ei2 = (EntryInfo *) avl_find( bdb->bi_cache.c_idtree,
					(caddr_t) &ei, bdb_id_cmp );
	ldap_pvt_thread_rdwr_runlock( &bdb->bi_cache.c_rwlock );
	return ei2;
}

/*
 * cache_find_id - find an entry in the cache, given id.
 * The entry is locked for Read upon return. Call with islocked TRUE if
 * the supplied *eip was already locked.
 */

int
bdb_cache_find_id(
	Operation *op,
	DB_TXN	*tid,
	ID				id,
	EntryInfo	**eip,
	int		islocked,
	u_int32_t	locker,
	DB_LOCK		*lock )
{
	struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
	Entry	*ep = NULL;
	int	rc = 0, load = 0;
	EntryInfo ei = { 0 };

	ei.bei_id = id;

#ifdef SLAP_ZONE_ALLOC
	slap_zh_rlock(bdb->bi_cache.c_zctx);
#endif
	/* If we weren't given any info, see if we have it already cached */
	if ( !*eip ) {
again:	ldap_pvt_thread_rdwr_rlock( &bdb->bi_cache.c_rwlock );
		*eip = (EntryInfo *) avl_find( bdb->bi_cache.c_idtree,
			(caddr_t) &ei, bdb_id_cmp );
		if ( *eip ) {
			/* If the lock attempt fails, the info is in use */
			if ( ldap_pvt_thread_mutex_trylock(
					&(*eip)->bei_kids_mutex )) {
				ldap_pvt_thread_rdwr_runlock( &bdb->bi_cache.c_rwlock );
				/* If this node is being deleted, treat
				 * as if the delete has already finished
				 */
				if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
					return DB_NOTFOUND;
				}
				/* otherwise, wait for the info to free up */
				ldap_pvt_thread_yield();
				goto again;
			}
			/* If this info isn't hooked up to its parent yet,
			 * unlock and wait for it to be fully initialized
			 */
			if ( (*eip)->bei_state & CACHE_ENTRY_NOT_LINKED ) {
				bdb_cache_entryinfo_unlock( *eip );
				ldap_pvt_thread_rdwr_runlock( &bdb->bi_cache.c_rwlock );
				ldap_pvt_thread_yield();
				goto again;
			}
			islocked = 1;
		}
		ldap_pvt_thread_rdwr_runlock( &bdb->bi_cache.c_rwlock );
	}

	/* See if the ID exists in the database; add it to the cache if so */
	if ( !*eip ) {
#ifndef BDB_HIER
		rc = bdb_id2entry( op->o_bd, tid, locker, id, &ep );
		if ( rc == 0 ) {
			rc = bdb_cache_find_ndn( op, tid,
				&ep->e_nname, eip );
			if ( *eip ) islocked = 1;
			if ( rc ) {
				ep->e_private = NULL;
#ifdef SLAP_ZONE_ALLOC
				bdb_entry_return( bdb, ep, (*eip)->bei_zseq );
#else
				bdb_entry_return( ep );
#endif
				ep = NULL;
			}
		}
#else
		rc = hdb_cache_find_parent(op, tid, locker, id, eip );
		if ( rc == 0 ) islocked = 1;
#endif
	}

	/* Ok, we found the info, do we have the entry? */
	if ( rc == 0 ) {
		if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
			rc = DB_NOTFOUND;
		} else {
			/* Make sure only one thread tries to load the entry */
load1:
#ifdef SLAP_ZONE_ALLOC
			if ((*eip)->bei_e && !slap_zn_validate(
					bdb->bi_cache.c_zctx, (*eip)->bei_e, (*eip)->bei_zseq)) {
				(*eip)->bei_e = NULL;
				(*eip)->bei_zseq = 0;
			}
#endif
			if ( !(*eip)->bei_e && !((*eip)->bei_state & CACHE_ENTRY_LOADING)) {
				load = 1;
				(*eip)->bei_state |= CACHE_ENTRY_LOADING;
			}
			if ( islocked ) {
				bdb_cache_entryinfo_unlock( *eip );
				islocked = 0;
			}
			rc = bdb_cache_entry_db_lock( bdb->bi_dbenv, locker, *eip, 0, 0, lock );
			if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
				rc = DB_NOTFOUND;
				bdb_cache_entry_db_unlock( bdb->bi_dbenv, lock );
			} else if ( rc == 0 ) {
				if ( load ) {
					/* Give up original read lock, obtain write lock
					 */
				    if ( rc == 0 ) {
						rc = bdb_cache_entry_db_relock( bdb->bi_dbenv, locker,
							*eip, 1, 0, lock );
					}
					if ( rc == 0 && !ep) {
						rc = bdb_id2entry( op->o_bd, tid, locker, id, &ep );
					}
					if ( rc == 0 ) {
						ep->e_private = *eip;
#ifdef BDB_HIER
						bdb_fix_dn( ep, 0 );
#endif
						(*eip)->bei_e = ep;
#ifdef SLAP_ZONE_ALLOC
						(*eip)->bei_zseq = *((ber_len_t *)ep - 2);
#endif
						ep = NULL;
					}
					bdb_cache_entryinfo_lock( *eip );
					(*eip)->bei_state ^= CACHE_ENTRY_LOADING;
					bdb_cache_entryinfo_unlock( *eip );
					if ( rc == 0 ) {
						/* If we succeeded, downgrade back to a readlock. */
						rc = bdb_cache_entry_db_relock( bdb->bi_dbenv, locker,
							*eip, 0, 0, lock );
					} else {
						/* Otherwise, release the lock. */
						bdb_cache_entry_db_unlock( bdb->bi_dbenv, lock );
					}
				} else if ( !(*eip)->bei_e ) {
					/* Some other thread is trying to load the entry,
					 * give it a chance to finish.
					 */
					bdb_cache_entry_db_unlock( bdb->bi_dbenv, lock );
					ldap_pvt_thread_yield();
					bdb_cache_entryinfo_lock( *eip );
					islocked = 1;
					goto load1;
#ifdef BDB_HIER
				} else {
					/* Check for subtree renames
					 */
					rc = bdb_fix_dn( (*eip)->bei_e, 1 );
					if ( rc ) {
						bdb_cache_entry_db_relock( bdb->bi_dbenv,
							locker, *eip, 1, 0, lock );
						/* check again in case other modifier did it already */
						if ( bdb_fix_dn( (*eip)->bei_e, 1 ) )
							rc = bdb_fix_dn( (*eip)->bei_e, 2 );
						bdb_cache_entry_db_relock( bdb->bi_dbenv,
							locker, *eip, 0, 0, lock );
					}
#endif
				}

			}
		}
	}
	if ( islocked ) {
		bdb_cache_entryinfo_unlock( *eip );
	}
	if ( ep ) {
		ep->e_private = NULL;
#ifdef SLAP_ZONE_ALLOC
		bdb_entry_return( bdb, ep, (*eip)->bei_zseq );
#else
		bdb_entry_return( ep );
#endif
	}
	if ( rc == 0 ) {

		if ( load ) {
			ldap_pvt_thread_rdwr_wlock( &bdb->bi_cache.c_rwlock );
			bdb->bi_cache.c_cursize++;
			ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
		}

		ldap_pvt_thread_mutex_lock( &bdb->bi_cache.lru_head_mutex );

		/* If the LRU list has only one entry and this is it, it
		 * doesn't need to be added again.
		 */
		if ( bdb->bi_cache.c_lruhead == bdb->bi_cache.c_lrutail &&
			bdb->bi_cache.c_lruhead == *eip ) {
			ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.lru_head_mutex );
		} else {
			/* if entry is on LRU list, remove from old spot */
			if ( (*eip)->bei_lrunext || (*eip)->bei_lruprev ) {
				ldap_pvt_thread_mutex_lock( &bdb->bi_cache.lru_tail_mutex );
				LRU_DELETE( &bdb->bi_cache, *eip );
				ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.lru_tail_mutex );
			}
			/* lru_head_mutex is unlocked for us */
			bdb_cache_lru_add( bdb, *eip );
		}
	}

#ifdef SLAP_ZONE_ALLOC
	if (rc == 0 && (*eip)->bei_e) {
		slap_zn_rlock(bdb->bi_cache.c_zctx, (*eip)->bei_e);
	}
	slap_zh_runlock(bdb->bi_cache.c_zctx);
#endif
	return rc;
}

int
bdb_cache_children(
	Operation *op,
	DB_TXN *txn,
	Entry *e )
{
	int rc;

	if ( BEI(e)->bei_kids ) {
		return 0;
	}
	if ( BEI(e)->bei_state & CACHE_ENTRY_NO_KIDS ) {
		return DB_NOTFOUND;
	}
	rc = bdb_dn2id_children( op, txn, e );
	if ( rc == DB_NOTFOUND ) {
		BEI(e)->bei_state |= CACHE_ENTRY_NO_KIDS | CACHE_ENTRY_NO_GRANDKIDS;
	}
	return rc;
}

/* Update the cache after a successful database Add. */
int
bdb_cache_add(
	struct bdb_info *bdb,
	EntryInfo *eip,
	Entry *e,
	struct berval *nrdn,
	u_int32_t locker )
{
	EntryInfo *new, ei;
	DB_LOCK lock;
	int rc;
#ifdef BDB_HIER
	struct berval rdn = e->e_name;
#endif

	ei.bei_id = e->e_id;
	ei.bei_parent = eip;
	ei.bei_nrdn = *nrdn;
	ei.bei_lockpad = 0;

	/* Lock this entry so that bdb_add can run to completion.
	 * It can only fail if BDB has run out of lock resources.
	 */
	rc = bdb_cache_entry_db_lock( bdb->bi_dbenv, locker, &ei, 1, 0, &lock );
	if ( rc ) {
		bdb_cache_entryinfo_unlock( eip );
		return rc;
	}

#ifdef BDB_HIER
	if ( nrdn->bv_len != e->e_nname.bv_len ) {
		char *ptr = ber_bvchr( &rdn, ',' );
		assert( ptr != NULL );
		rdn.bv_len = ptr - rdn.bv_val;
	}
	ber_dupbv( &ei.bei_rdn, &rdn );
	if ( eip->bei_dkids ) eip->bei_dkids++;
#endif

	rc = bdb_entryinfo_add_internal( bdb, &ei, &new );