openldap/servers/slapd/back-bdb/cache.c

/* cache.c - routines to maintain an in-core cache of entries */
/* $OpenLDAP$ */
/*
 * Copyright 1998-2003 The OpenLDAP Foundation, All Rights Reserved.
 * COPYING RESTRICTIONS APPLY, see COPYRIGHT file
 */

#include "portable.h"

#include <stdio.h>

#include <ac/errno.h>
#include <ac/string.h>
#include <ac/socket.h>

#include "slap.h"

#include "back-bdb.h"

static int	bdb_cache_delete_entry_internal(Cache *cache, EntryInfo *e);
#ifdef LDAP_DEBUG
static void	bdb_lru_print(Cache *cache);
#endif

static EntryInfo *
bdb_cache_entryinfo_new( )
{
	EntryInfo *ei;

	ei = ch_calloc(1, sizeof(struct bdb_entry_info));
	ldap_pvt_thread_mutex_init( &ei->bei_kids_mutex );

	return ei;
}

/* Atomically release and reacquire a lock */
int
bdb_cache_entry_db_relock(
	DB_ENV *env,
	u_int32_t locker,
	EntryInfo *ei,
	int rw,
	int tryOnly,
	DB_LOCK *lock )
{
#ifdef NO_THREADS
	return 0;
#else
	int	rc;
	DBT	lockobj;
	DB_LOCKREQ list[2];

	lockobj.data = ei;
	lockobj.size = sizeof(ei->bei_parent) + sizeof(ei->bei_id);

	list[0].op = DB_LOCK_PUT;
	list[0].lock = *lock;
	list[1].op = DB_LOCK_GET;
	list[1].lock = *lock;
	list[1].mode = rw ? DB_LOCK_WRITE : DB_LOCK_READ;
	list[1].obj = &lockobj;
	rc = env->lock_vec(env, locker, tryOnly ? DB_LOCK_NOWAIT : 0,
		list, 2, NULL );

	if (rc) {
#ifdef NEW_LOGGING
		LDAP_LOG( CACHE, DETAIL1, 
			"bdb_cache_entry_db_relock: entry %d, rw %d, rc %d\n",
			ei->bei_id, rw, rc );
#else
		Debug( LDAP_DEBUG_TRACE,
			"bdb_cache_entry_db_relock: entry %d, rw %d, rc %d\n",
			ei->bei_id, rw, rc );
#endif
	} else {
		*lock = list[1].lock;
	}
	return rc;
#endif
}
int
bdb_cache_entry_db_lock
( DB_ENV *env, u_int32_t locker, EntryInfo *ei, int rw, int tryOnly, DB_LOCK *lock )
{
#ifdef NO_THREADS
	return 0;
#else
	int       rc;
	DBT       lockobj;
	int       db_rw;

	if (rw)
		db_rw = DB_LOCK_WRITE;
	else
		db_rw = DB_LOCK_READ;

	lockobj.data = ei;
	lockobj.size = sizeof(ei->bei_parent) + sizeof(ei->bei_id);

	rc = LOCK_GET(env, locker, tryOnly ? DB_LOCK_NOWAIT : 0,
					&lockobj, db_rw, lock);
	if (rc) {
#ifdef NEW_LOGGING
		LDAP_LOG( CACHE, DETAIL1, 
			"bdb_cache_entry_db_lock: entry %d, rw %d, rc %d\n",
			ei->bei_id, rw, rc );
#else
		Debug( LDAP_DEBUG_TRACE,
			"bdb_cache_entry_db_lock: entry %d, rw %d, rc %d\n",
			ei->bei_id, rw, rc );
#endif
	}
	return rc;
#endif /* NO_THREADS */
}

int
bdb_cache_entry_db_unlock
( DB_ENV *env, DB_LOCK *lock )
{
#ifdef NO_THREADS
	return 0;
#else
	int rc;

	rc = LOCK_PUT ( env, lock );
	return rc;
#endif
}

static int
bdb_cache_entryinfo_destroy( EntryInfo *e )
{
	ldap_pvt_thread_mutex_destroy( &e->bei_kids_mutex );
	free( e->bei_nrdn.bv_val );
	free( e );
	return 0;
}

#define LRU_DELETE( cache, ei ) do { \
	if ( (ei)->bei_lruprev != NULL ) { \
		(ei)->bei_lruprev->bei_lrunext = (ei)->bei_lrunext; \
	} else { \
		(cache)->c_lruhead = (ei)->bei_lrunext; \
	} \
	if ( (ei)->bei_lrunext != NULL ) { \
		(ei)->bei_lrunext->bei_lruprev = (ei)->bei_lruprev; \
	} else { \
		(cache)->c_lrutail = (ei)->bei_lruprev; \
	} \
} while(0)

#define LRU_ADD( cache, ei ) do { \
	(ei)->bei_lrunext = (cache)->c_lruhead; \
	if ( (ei)->bei_lrunext != NULL ) { \
		(ei)->bei_lrunext->bei_lruprev = (ei); \
	} \
	(cache)->c_lruhead = (ei); \
	(ei)->bei_lruprev = NULL; \
	if ( (cache)->c_lrutail == NULL ) { \
		(cache)->c_lrutail = (ei); \
	} \
} while(0)

/* Do a lexical sort on normalized RDNs */
static int
bdb_rdn_cmp( const void *v_e1, const void *v_e2 )
{
	const EntryInfo *e1 = v_e1, *e2 = v_e2;
	int rc = strncmp( e1->bei_nrdn.bv_val, e2->bei_nrdn.bv_val, e1->bei_nrdn.bv_len );
	if (rc == 0) rc = e1->bei_nrdn.bv_len - e2->bei_nrdn.bv_len;
	return rc;
}

static int
bdb_id_cmp( const void *v_e1, const void *v_e2 )
{
	const EntryInfo *e1 = v_e1, *e2 = v_e2;
	return e1->bei_id - e2->bei_id;
}

/* Create an entryinfo in the cache. Caller must release the locks later.
 */
int
bdb_entryinfo_add_internal(
	struct bdb_info *bdb,
	EntryInfo *eip,
	ID id,
	struct berval *nrdn,
	EntryInfo **res,
	u_int32_t locker
)
{
	Cache *cache = &bdb->bi_cache;
	DB_ENV *env = bdb->bi_dbenv;
	EntryInfo *ei2 = NULL;
	int incr = 1;
	int addkid = 1;
	int rc;
	DB_LOCK lock;

	*res = NULL;

	ldap_pvt_thread_rdwr_wlock( &bdb->bi_cache.c_rwlock );
	bdb_cache_entryinfo_lock( eip );

	/* if parent was previously considered a leaf node,
	 * it was on the LRU list. Now it's going to have
	 * kids, take it off the LRU list.
	 */
	ldap_pvt_thread_mutex_lock( &cache->lru_mutex );
	if ( eip->bei_id && !eip->bei_kids ) {
		LRU_DELETE( cache, eip );
		incr = 0;
	}

	cache->c_cursize += incr;

	/* See if we're above the cache size limit */
	if ( cache->c_cursize > cache->c_maxsize ) {
		EntryInfo *elru, *elprev;
		int i = 0;

		/* Look for an unused entry to remove */
		for (elru = cache->c_lrutail; elru; elru = elprev, i++ ) {
			elprev = elru->bei_lruprev;

			/* Too many probes, not enough idle, give up */
			if (i > 10) break;

			/* If we can successfully writelock it, then
			 * the object is idle.
			 */
			if ( bdb_cache_entry_db_lock( env, locker, elru, 1, 1,
				&lock ) == 0 ) {
				/* Need to lock parent to delete child */
				if ( ldap_pvt_thread_mutex_trylock(
					&elru->bei_parent->bei_kids_mutex )) {
					bdb_cache_entry_db_unlock( env, &lock );
					continue;
				}
				bdb_cache_delete_entry_internal( cache, elru );
				bdb_cache_entryinfo_unlock( elru->bei_parent );
				elru->bei_e->e_private = NULL;
				bdb_entry_return( elru->bei_e );
				bdb_cache_entry_db_unlock( env, &lock );
				if (ei2) {
					bdb_cache_entryinfo_destroy( elru );
				} else {
					/* re-use this one */
					ch_free(elru->bei_nrdn.bv_val);
					elru->bei_nrdn.bv_val = NULL;
					elru->bei_e = NULL;
					elru->bei_kids = NULL;
					elru->bei_lrunext = NULL;
					elru->bei_lruprev = NULL;
					elru->bei_state = 0;
					ei2 = elru;
				}
				if (cache->c_cursize < cache->c_maxsize)
					break;
			}
		}
	}
	if (!ei2) {
		ei2 = bdb_cache_entryinfo_new();
	}
	ei2->bei_id = id;
	ei2->bei_parent = eip;

	/* Add to cache ID tree */
	if (avl_insert( &cache->c_idtree, ei2, bdb_id_cmp, avl_dup_error )) {
		EntryInfo *ei;
		ei = avl_find( cache->c_idtree, ei2, bdb_id_cmp );
		bdb_cache_entryinfo_destroy( ei2 );
		ei2 = ei;
		addkid = 0;
		cache->c_cursize -= incr;
	} else {
		LRU_ADD( cache, ei2 );
		ber_dupbv( &ei2->bei_nrdn, nrdn );
	}

	if ( addkid ) {
		avl_insert( &eip->bei_kids, ei2, bdb_rdn_cmp, avl_dup_error );
	}

	ldap_pvt_thread_mutex_unlock( &cache->lru_mutex );

#if 0 /* caller must do these frees */
	ldap_pvt_thread_rdwr_wunlock( &cache->c_rwlock );
	bdb_cache_entryinfo_unlock( eip );
#endif

	*res = ei2;
	return 0;
}

/* Find the EntryInfo for the requested DN. If the DN cannot be found, return
 * the info for its closest ancestor. *res should be NULL to process a
 * complete DN starting from the tree root. Otherwise *res must be the
 * immediate parent of the requested DN, and only the RDN will be searched.
 * The EntryInfo is locked upon return and must be unlocked by the caller.
 */
int
bdb_cache_find_entry_ndn2id(
	Backend		*be,
	DB_TXN		*txn,
	struct berval	*ndn,
	EntryInfo	**res,
	u_int32_t	locker,
	void		*ctx
)
{
	struct bdb_info *bdb = (struct bdb_info *) be->be_private;
	EntryInfo	ei, *eip, *ei2;
	ID			id;
	int rc = 0;
	char *ptr;

	/* this function is always called with normalized DN */
	if ( *res ) {
		/* we're doing a onelevel search for an RDN */
		ei.bei_nrdn.bv_val = ndn->bv_val;
		ei.bei_nrdn.bv_len = dn_rdnlen( be, ndn );
		eip = *res;
	} else {
		/* we're searching a full DN from the root */
		ptr = ndn->bv_val + ndn->bv_len - be->be_nsuffix[0].bv_len;
		ei.bei_nrdn.bv_val = ptr;
		ei.bei_nrdn.bv_len = be->be_nsuffix[0].bv_len;
		eip = &bdb->bi_cache.c_dntree;
	}
	
	for ( bdb_cache_entryinfo_lock( eip ); eip; ) {
		ei2 = (EntryInfo *)avl_find( eip->bei_kids, &ei, bdb_rdn_cmp );
		if ( !ei2 ) {
			int len = ei.bei_nrdn.bv_len;
				
			ei.bei_nrdn.bv_len = ndn->bv_len - (ei.bei_nrdn.bv_val - ndn->bv_val);
			bdb_cache_entryinfo_unlock( eip );

			rc = bdb_dn2id( be, txn, &ei.bei_nrdn, &id, ctx );
			if (rc) {
				bdb_cache_entryinfo_lock( eip );
				*res = eip;
				return rc;
			}

			/* DN exists but needs to be added to cache */
			ei.bei_nrdn.bv_len = len;
			rc = bdb_entryinfo_add_internal( bdb,
				eip, id, &ei.bei_nrdn, &ei2, locker );
			/* add_internal left eip and c_rwlock locked */
			ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
			if ( rc ) {
				*res = eip;
				return rc;
			}
		} else if ( ei2->bei_state & CACHE_ENTRY_DELETED ) {
			/* In the midst of deleting? Give it a chance to
			 * complete.
			 */
			bdb_cache_entryinfo_unlock( eip );
			ldap_pvt_thread_yield();
			bdb_cache_entryinfo_lock( eip );
			*res = eip;
			return DB_NOTFOUND;
		}
		bdb_cache_entryinfo_unlock( eip );
		bdb_cache_entryinfo_lock( ei2 );

		eip = ei2;

		/* Advance to next lower RDN */
		for (ptr = ei.bei_nrdn.bv_val - 2; ptr > ndn->bv_val
			&& !DN_SEPARATOR(*ptr); ptr--);
		if ( ptr >= ndn->bv_val ) {
			if (DN_SEPARATOR(*ptr)) ptr++;
			ei.bei_nrdn.bv_len = ei.bei_nrdn.bv_val - ptr - 1;
			ei.bei_nrdn.bv_val = ptr;
		}
		if ( ptr < ndn->bv_val ) {
			*res = eip;
			break;
		}
	}

	return rc;
}

/*
 * cache_find_entry_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_entry_id(
	Backend *be,
	DB_TXN	*tid,
	ID				id,
	EntryInfo	**eip,
	int		islocked,
	u_int32_t	locker,
	DB_LOCK		*lock,
	void		*ctx
)
{
	struct bdb_info *bdb = (struct bdb_info *) be->be_private;
	Entry	*ep = NULL;
	int	rc = 0;
	EntryInfo ei;

	ei.bei_id = id;

	/* If we weren't given any info, see if we have it already cached */
	if ( !*eip ) {
		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 ) {
			bdb_cache_entryinfo_lock( *eip );
			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 ) {
		rc = bdb_id2entry( be, tid, id, &ep );
		if ( rc == 0 ) {
			rc = bdb_cache_find_entry_ndn2id( be, tid,
				&ep->e_nname, eip, locker, ctx );
			if ( *eip )
				islocked = 1;
			if ( rc ) {
				bdb_entry_return( ep );
				ep = NULL;
			}
		}
	}

	/* Ok, we found the info, do we have the entry? */
	if ( *eip && rc == 0 ) {
		if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
			rc = DB_NOTFOUND;
		} else if (!(*eip)->bei_e ) {
			if (!ep) {
				rc = bdb_id2entry( be, tid, id, &ep );
			}
			if ( rc == 0 ) {
				bdb_cache_entry_db_lock( bdb->bi_dbenv, locker,
					*eip, 1, 0, lock );
				(*eip)->bei_e = ep;
				ep->e_private = *eip;
				bdb_cache_entry_db_relock( bdb->bi_dbenv, locker,
					*eip, 0, 0, lock );
			}
		} else {
			bdb_cache_entry_db_lock( bdb->bi_dbenv, locker,
					*eip, 0, 0, lock );
		}
	}
	if ( rc == 0 && (*eip)->bei_kids == NULL ) {
		/* set lru mutex */
		ldap_pvt_thread_mutex_lock( &bdb->bi_cache.lru_mutex );
		LRU_DELETE( &bdb->bi_cache, *eip );
		LRU_ADD( &bdb->bi_cache, *eip );
		ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.lru_mutex );
	}

	if ( islocked ) {
		bdb_cache_entryinfo_unlock( *eip );
	}
	return rc;
}

/* Update the cache after a successful database Add. */
int
bdb_cache_add(
	struct bdb_info *bdb,
	EntryInfo *ei,
	Entry *e,
	struct berval *nrdn,
	u_int32_t locker
)
{
	EntryInfo *new;
	int rc;

	rc = bdb_entryinfo_add_internal( bdb, ei, e->e_id, nrdn, &new, locker );
	new->bei_e = e;
	e->e_private = new;
	new->bei_state = CACHE_ENTRY_NO_KIDS;
	ei->bei_state &= ~CACHE_ENTRY_NO_KIDS;
	bdb_cache_entryinfo_unlock( ei );
	ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
	return rc;
}

int
bdb_cache_modify(
	Entry *e,
	Attribute *newAttrs,
	DB_ENV *env,
	u_int32_t locker,
	DB_LOCK *lock
)
{
	EntryInfo *ei = BEI(e);
	
	/* Get write lock on data */
	bdb_cache_entry_db_relock( env, locker, ei, 1, 0, lock );

	/* If we've done repeated mods on a cached entry, then e_attrs
	 * is no longer contiguous with the entry, and must be freed.
	 */
	if ( (void *)e->e_attrs != (void *)(e+1) ) {
		attrs_free( e->e_attrs );
	}
	e->e_attrs = newAttrs;

	return 0;
}

/*
 * Change the rdn in the entryinfo. Also move to a new parent if needed.
 */
int
bdb_cache_modrdn(
	Entry *e,
	struct berval *nrdn,
	Entry *new,
	EntryInfo *ein,
	DB_ENV *env,
	u_int32_t locker,
	DB_LOCK *lock
)
{
	EntryInfo *ei = BEI(e), *pei;
	int rc = 0;

	/* Get write lock on data */
	bdb_cache_entry_db_relock( env, locker, ei, 1, 0, lock );

	/* If we've done repeated mods on a cached entry, then e_attrs
	 * is no longer contiguous with the entry, and must be freed.
	 */
	if ( (void *)e->e_attrs != (void *)(e+1) ) {
		attrs_free( e->e_attrs );
	}
	e->e_attrs = new->e_attrs;
#ifdef BDB_HIER
	ch_free(e->e_name.bv_val);
#else
	if( e->e_nname.bv_val < e->e_bv.bv_val || e->e_nname.bv_val >
		e->e_bv.bv_val + e->e_bv.bv_len ) {
		ch_free(e->e_name.bv_val);
		ch_free(e->e_nname.bv_val);
	}
#endif
	e->e_name = new->e_name;
	e->e_nname = new->e_nname;

	/* Lock the parent's kids AVL tree */
	pei = ei->bei_parent;
	bdb_cache_entryinfo_lock( pei );
	avl_delete( &pei->bei_kids, (caddr_t) ei, bdb_rdn_cmp );
	free( ei->bei_nrdn.bv_val );
	ber_dupbv( &ei->bei_nrdn, nrdn );
	if (!ein) {
		ein = ei->bei_parent;
	} else {
		ei->bei_parent = ein;
		bdb_cache_entryinfo_unlock( pei );
		bdb_cache_entryinfo_lock( ein );
	}
	avl_insert( &ein->bei_kids, ei, bdb_rdn_cmp, avl_dup_error );
	bdb_cache_entryinfo_unlock( ein );
	return rc;
}
/*
 * cache_delete_entry - delete the entry e from the cache. 
 *
 * returns:	0	e was deleted ok
 *		1	e was not in the cache
 *		-1	something bad happened
 */
int
bdb_cache_delete_entry(
    Cache	*cache,
    Entry		*e,
    DB_ENV	*env,
    u_int32_t	locker,
    DB_LOCK	*lock
)
{
	EntryInfo *ei = BEI(e);
	int	rc;

	assert( e->e_private );

	/* Set this early, warn off any queriers */
	ei->bei_state |= CACHE_ENTRY_DELETED;

	/* Get write lock on the data */
	bdb_cache_entry_db_relock( env, locker, ei, 1, 0, lock );

	/* set cache write lock */
	ldap_pvt_thread_rdwr_wlock( &cache->c_rwlock );

	/* Lock the parent's kids tree */
	bdb_cache_entryinfo_lock( ei->bei_parent );

#ifdef NEW_LOGGING
	LDAP_LOG( CACHE, ENTRY, 
		"bdb_cache_delete_entry: delete %ld.\n", e->e_id, 0, 0 );
#else
	Debug( LDAP_DEBUG_TRACE, "====> bdb_cache_delete_entry( %ld )\n",
		e->e_id, 0, 0 );
#endif

	/* set lru mutex */
	ldap_pvt_thread_mutex_lock( &cache->lru_mutex );
	rc = bdb_cache_delete_entry_internal( cache, e->e_private );
	/* free lru mutex */
	ldap_pvt_thread_mutex_unlock( &cache->lru_mutex );

	/* free cache write lock */
	ldap_pvt_thread_rdwr_wunlock( &cache->c_rwlock );
	bdb_cache_entryinfo_unlock( ei->bei_parent );
	bdb_cache_entryinfo_destroy( ei );
	e->e_private = NULL;
	return( rc );
}

static int
bdb_cache_delete_entry_internal(
    Cache	*cache,
    EntryInfo		*e
)
{
	int rc = 0;	/* return code */

	/* dn tree */
	if ( avl_delete( &e->bei_parent->bei_kids, (caddr_t) e, bdb_rdn_cmp ) == NULL )
	{
		rc = -1;
	}

	/* If parent has no more kids, put in on LRU list */
	if ( e->bei_parent->bei_kids == NULL ) {
		LRU_ADD( cache, e->bei_parent );
		cache->c_cursize++;
	}

	/* id tree */
	if ( avl_delete( &cache->c_idtree, (caddr_t) e, bdb_id_cmp ) == NULL )
	{
		rc = -1;
	}

	if (rc != 0) {
		return rc;
	}

	/* lru */
	LRU_DELETE( cache, e );
	cache->c_cursize--;

	/*
	 * flag entry to be freed later by a call to cache_return_entry()
	 */
	e->bei_state |= CACHE_ENTRY_DELETED;

	return( 0 );
}

static void
bdb_entryinfo_release( void *data )
{
	EntryInfo *ei = (EntryInfo *)data;
	avl_free( ei->bei_kids, NULL );
	if ( ei->bei_e ) {
		ei->bei_e->e_private = NULL;
		bdb_entry_return( ei->bei_e );
	}
	bdb_cache_entryinfo_destroy( ei );
}

void
bdb_cache_release_all( Cache *cache )
{
	/* set cache write lock */
	ldap_pvt_thread_rdwr_wlock( &cache->c_rwlock );
	/* set lru mutex */
	ldap_pvt_thread_mutex_lock( &cache->lru_mutex );

#ifdef NEW_LOGGING
	LDAP_LOG( CACHE, ENTRY, "bdb_cache_release_all: enter\n", 0, 0, 0 );
#else
	Debug( LDAP_DEBUG_TRACE, "====> bdb_cache_release_all\n", 0, 0, 0 );
#endif

	avl_free( cache->c_dntree.bei_kids, NULL );
	avl_free( cache->c_idtree, bdb_entryinfo_release );
	cache->c_lruhead = NULL;
	cache->c_lrutail = NULL;

	/* free lru mutex */
	ldap_pvt_thread_mutex_unlock( &cache->lru_mutex );
	/* free cache write lock */
	ldap_pvt_thread_rdwr_wunlock( &cache->c_rwlock );
}

#ifdef LDAP_DEBUG
static void
bdb_lru_print( Cache *cache )
{
	EntryInfo	*e;

	fprintf( stderr, "LRU queue (head to tail):\n" );
	for ( e = cache->c_lruhead; e != NULL; e = e->bei_lrunext ) {
		fprintf( stderr, "\trdn \"%20s\" id %ld\n",
			e->bei_nrdn.bv_val, e->bei_id );
	}
	fprintf( stderr, "LRU queue (tail to head):\n" );
	for ( e = cache->c_lrutail; e != NULL; e = e->bei_lruprev ) {
		fprintf( stderr, "\trdn \"%20s\" id %ld\n",
			e->bei_nrdn.bv_val, e->bei_id );
	}
}
#endif

#ifdef BDB_REUSE_LOCKERS
void
bdb_locker_id_free( void *key, void *data )
{
	DB_ENV *env = key;
	int lockid = (int) data;

	XLOCK_ID_FREE( env, lockid );
}

int
bdb_locker_id( Operation *op, DB_ENV *env, int *locker )
{
	int i, rc, lockid;
	void *data;
	void *ctx;

	if ( !env || !locker ) return -1;

	/* If no op was provided, try to find the ctx anyway... */
	if ( op ) {
		ctx = op->o_threadctx;
	} else {
		ctx = ldap_pvt_thread_pool_context();
	}

	/* Shouldn't happen unless we're single-threaded */
	if ( !ctx ) {
		*locker = 0;
		return 0;
	}

	if ( ldap_pvt_thread_pool_getkey( ctx, env, &data, NULL ) ) {
		for ( i=0, rc=1; rc != 0 && i<4; i++ ) {
			rc = XLOCK_ID( env, &lockid );
			if (rc) ldap_pvt_thread_yield();
		}
		if ( rc != 0) {
			return rc;
		}
		data = (void *)lockid;
		if ( ( rc = ldap_pvt_thread_pool_setkey( ctx, env,
			data, bdb_locker_id_free ) ) ) {
			XLOCK_ID_FREE( env, lockid );
#ifdef NEW_LOGGING
			LDAP_LOG( BACK_BDB, ERR, "bdb_locker_id: err %s(%d)\n",
				db_strerror(rc), rc, 0 );
#else
			Debug( LDAP_DEBUG_ANY, "bdb_locker_id: err %s(%d)\n",
				db_strerror(rc), rc, 0 );
#endif

			return rc;
		}
	} else {
		lockid = (int)data;
	}
	*locker = lockid;
	return 0;
}
#endif