Patrick Welche <prlw1@cam.ac.uk>

[netbsd-mini2440.git] / external / bsd / openldap / dist / servers / slapd / back-bdb / cache.c

/* cache.c - routines to maintain an in-core cache of entries */
/* $OpenLDAP: pkg/ldap/servers/slapd/back-bdb/cache.c,v 1.120.2.15 2008/05/01 21:39:35 quanah Exp $ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
 *
 * Copyright 2000-2008 The OpenLDAP Foundation.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted only as authorized by the OpenLDAP
 * Public License.
 *
 * A copy of this license is available in the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 */

#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"

#include "ldap_rq.h"

#ifdef BDB_HIER
#define bdb_cache_lru_purge     hdb_cache_lru_purge
#endif
static void bdb_cache_lru_purge( struct bdb_info *bdb );

static int      bdb_cache_delete_internal(Cache *cache, EntryInfo *e, int decr);
#ifdef LDAP_DEBUG
#define SLAPD_UNUSED
#ifdef SLAPD_UNUSED
static void     bdb_lru_print(Cache *cache);
#endif
#endif

/* For concurrency experiments only! */
#if 0
#define ldap_pvt_thread_rdwr_wlock(a)   0
#define ldap_pvt_thread_rdwr_wunlock(a) 0
#define ldap_pvt_thread_rdwr_rlock(a)   0
#define ldap_pvt_thread_rdwr_runlock(a) 0
#endif

#if 0
#define ldap_pvt_thread_mutex_trylock(a) 0
#endif

static EntryInfo *
bdb_cache_entryinfo_new( Cache *cache )
{
        EntryInfo *ei = NULL;

        if ( cache->c_eifree ) {
                ldap_pvt_thread_mutex_lock( &cache->c_eifree_mutex );
                if ( cache->c_eifree ) {
                        ei = cache->c_eifree;
                        cache->c_eifree = ei->bei_lrunext;
                        ei->bei_finders = 0;
                }
                ldap_pvt_thread_mutex_unlock( &cache->c_eifree_mutex );
        }
        if ( !ei ) {
                ei = ch_calloc(1, sizeof(EntryInfo));
                ldap_pvt_thread_mutex_init( &ei->bei_kids_mutex );
        }

        ei->bei_state = CACHE_ENTRY_REFERENCED;

        return ei;
}

static void
bdb_cache_entryinfo_free( Cache *cache, EntryInfo *ei )
{
        free( ei->bei_nrdn.bv_val );
        ei->bei_nrdn.bv_val = NULL;
#ifdef BDB_HIER
        free( ei->bei_rdn.bv_val );
        ei->bei_rdn.bv_val = NULL;
        ei->bei_modrdns = 0;
        ei->bei_ckids = 0;
        ei->bei_dkids = 0;
#endif
        ei->bei_parent = NULL;
        ei->bei_kids = NULL;
        ei->bei_lruprev = NULL;

        ldap_pvt_thread_mutex_lock( &cache->c_eifree_mutex );
        ei->bei_lrunext = cache->c_eifree;
        cache->c_eifree = ei;
        ldap_pvt_thread_mutex_unlock( &cache->c_eifree_mutex );
}

#define LRU_DEL( c, e ) do { \
        if ( e == (c)->c_lruhead ) (c)->c_lruhead = e->bei_lruprev; \
        if ( e == (c)->c_lrutail ) (c)->c_lrutail = e->bei_lruprev; \
        e->bei_lrunext->bei_lruprev = e->bei_lruprev; \
        e->bei_lruprev->bei_lrunext = e->bei_lrunext; \
        e->bei_lruprev = NULL; \
} while ( 0 )

/* Note - we now use a Second-Chance / Clock algorithm instead of
 * Least-Recently-Used. This tremendously improves concurrency
 * because we no longer need to manipulate the lists every time an
 * entry is touched. We only need to lock the lists when adding
 * or deleting an entry. It's now a circular doubly-linked list.
 * We always append to the tail, but the head traverses the circle
 * during a purge operation.
 */
static void
bdb_cache_lru_link( struct bdb_info *bdb, EntryInfo *ei )
{

        /* Already linked, ignore */
        if ( ei->bei_lruprev )
                return;

        /* Insert into circular LRU list */
        ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_lru_mutex );

        ei->bei_lruprev = bdb->bi_cache.c_lrutail;
        if ( bdb->bi_cache.c_lrutail ) {
                ei->bei_lrunext = bdb->bi_cache.c_lrutail->bei_lrunext;
                bdb->bi_cache.c_lrutail->bei_lrunext = ei;
                if ( ei->bei_lrunext )
                        ei->bei_lrunext->bei_lruprev = ei;
        } else {
                ei->bei_lrunext = ei->bei_lruprev = ei;
                bdb->bi_cache.c_lruhead = ei;
        }
        bdb->bi_cache.c_lrutail = ei;
        ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_lru_mutex );
}

#ifdef NO_THREADS
#define NO_DB_LOCK
#endif

/* #define NO_DB_LOCK 1 */
/* Note: The BerkeleyDB locks are much slower than regular
 * mutexes or rdwr locks. But the BDB implementation has the
 * advantage of using a fixed size lock table, instead of
 * allocating a lock object per entry in the DB. That's a
 * key benefit for scaling. It also frees us from worrying
 * about undetectable deadlocks between BDB activity and our
 * own cache activity. It's still worth exploring faster
 * alternatives though.
 */

/* Atomically release and reacquire a lock */
int
bdb_cache_entry_db_relock(
        struct bdb_info *bdb,
        BDB_LOCKER locker,
        EntryInfo *ei,
        int rw,
        int tryOnly,
        DB_LOCK *lock )
{
#ifdef NO_DB_LOCK
        return 0;
#else
        int     rc;
        DBT     lockobj;
        DB_LOCKREQ list[2];

        if ( !lock ) return 0;

        lockobj.data = &ei->bei_id;
        lockobj.size = sizeof(ei->bei_id) + 1;

        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 = bdb->bi_dbenv->lock_vec(bdb->bi_dbenv, BDB_LOCKID(locker), tryOnly ? DB_LOCK_NOWAIT : 0,
                list, 2, NULL );

        if (rc && !tryOnly) {
                Debug( LDAP_DEBUG_TRACE,
                        "bdb_cache_entry_db_relock: entry %ld, rw %d, rc %d\n",
                        ei->bei_id, rw, rc );
        } else {
                *lock = list[1].lock;
        }
        return rc;
#endif
}

static int
bdb_cache_entry_db_lock( struct bdb_info *bdb, BDB_LOCKER locker, EntryInfo *ei,
        int rw, int tryOnly, DB_LOCK *lock )
{
#ifdef NO_DB_LOCK
        return 0;
#else
        int       rc;
        DBT       lockobj;
        int       db_rw;

        if ( !lock ) return 0;

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

        lockobj.data = &ei->bei_id;
        lockobj.size = sizeof(ei->bei_id) + 1;

        rc = LOCK_GET(bdb->bi_dbenv, BDB_LOCKID(locker), tryOnly ? DB_LOCK_NOWAIT : 0,
                                        &lockobj, db_rw, lock);
        if (rc && !tryOnly) {
                Debug( LDAP_DEBUG_TRACE,
                        "bdb_cache_entry_db_lock: entry %ld, rw %d, rc %d\n",
                        ei->bei_id, rw, rc );
        }
        return rc;
#endif /* NO_DB_LOCK */
}

int
bdb_cache_entry_db_unlock ( struct bdb_info *bdb, DB_LOCK *lock )
{
#ifdef NO_DB_LOCK
        return 0;
#else
        int rc;

        if ( !lock || lock->mode == DB_LOCK_NG ) return 0;

        rc = LOCK_PUT ( bdb->bi_dbenv, lock );
        return rc;
#endif
}

void
bdb_cache_return_entry_rw( struct bdb_info *bdb, Entry *e,
        int rw, DB_LOCK *lock )
{
        EntryInfo *ei;
        int free = 0;

        ei = e->e_private;
        if ( ei &&
                ( ei->bei_state & CACHE_ENTRY_NOT_CACHED ) &&
                ( bdb_cache_entryinfo_trylock( ei ) == 0 )) {
                if ( ei->bei_state & CACHE_ENTRY_NOT_CACHED ) {
                        /* Releasing the entry can only be done when
                         * we know that nobody else is using it, i.e we
                         * should have an entry_db writelock.  But the
                         * flag is only set by the thread that loads the
                         * entry, and only if no other threads has found
                         * it while it was working.  All other threads
                         * clear the flag, which mean that we should be
                         * the only thread using the entry if the flag
                         * is set here.
                         */
                        ei->bei_e = NULL;
                        ei->bei_state ^= CACHE_ENTRY_NOT_CACHED;
                        free = 1;
                }
                bdb_cache_entryinfo_unlock( ei );
        }
        bdb_cache_entry_db_unlock( bdb, lock );
        if ( free ) {
                e->e_private = NULL;
                bdb_entry_return( e );
        }
}

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

/* Do a length-ordered 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 = e1->bei_nrdn.bv_len - e2->bei_nrdn.bv_len;
        if (rc == 0) {
                rc = strncmp( e1->bei_nrdn.bv_val, e2->bei_nrdn.bv_val,
                        e1->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;
}

static int
bdb_id_dup_err( void *v1, void *v2 )
{
        EntryInfo *e2 = v2;
        e2->bei_lrunext = v1;
        return -1;
}

/* Create an entryinfo in the cache. Caller must release the locks later.
 */
static int
bdb_entryinfo_add_internal(
        struct bdb_info *bdb,
        EntryInfo *ei,
        EntryInfo **res )
{
        EntryInfo *ei2 = NULL;

        *res = NULL;

        ei2 = bdb_cache_entryinfo_new( &bdb->bi_cache );

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

        ei2->bei_id = ei->bei_id;
        ei2->bei_parent = ei->bei_parent;
#ifdef BDB_HIER
        ei2->bei_rdn = ei->bei_rdn;
#endif
#ifdef SLAP_ZONE_ALLOC
        ei2->bei_bdb = bdb;
#endif

        /* Add to cache ID tree */
        if (avl_insert( &bdb->bi_cache.c_idtree, ei2, bdb_id_cmp,
                bdb_id_dup_err )) {
                EntryInfo *eix = ei2->bei_lrunext;
                bdb_cache_entryinfo_free( &bdb->bi_cache, ei2 );
                ei2 = eix;
#ifdef BDB_HIER
                /* It got freed above because its value was
                 * assigned to ei2.
                 */
                ei->bei_rdn.bv_val = NULL;
#endif
        } else {
                int rc;

                bdb->bi_cache.c_eiused++;
                ber_dupbv( &ei2->bei_nrdn, &ei->bei_nrdn );

                /* This is a new leaf node. But if parent had no kids, then it was
                 * a leaf and we would be decrementing that. So, only increment if
                 * the parent already has kids.
                 */
                if ( ei->bei_parent->bei_kids || !ei->bei_parent->bei_id )
                        bdb->bi_cache.c_leaves++;
                rc = avl_insert( &ei->bei_parent->bei_kids, ei2, bdb_rdn_cmp,
                        avl_dup_error );
                if ( rc ) {
                        /* This should never happen; entry cache is corrupt */
                        bdb->bi_dbenv->log_flush( bdb->bi_dbenv, NULL );
                        assert( !rc );
                }
#ifdef BDB_HIER
                ei->bei_parent->bei_ckids++;
#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_ndn(
        Operation       *op,
        BDB_LOCKER              locker,
        struct berval   *ndn,
        EntryInfo       **res )
{
        struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
        EntryInfo       ei, *eip, *ei2;
        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( op->o_bd, ndn );
                eip = *res;
        } else {
                /* we're searching a full DN from the root */
                ptr = ndn->bv_val + ndn->bv_len - op->o_bd->be_nsuffix[0].bv_len;
                ei.bei_nrdn.bv_val = ptr;
                ei.bei_nrdn.bv_len = op->o_bd->be_nsuffix[0].bv_len;
                /* Skip to next rdn if suffix is empty */
                if ( ei.bei_nrdn.bv_len == 0 ) {
                        for (ptr = ei.bei_nrdn.bv_val - 2; ptr > ndn->bv_val
                                && !DN_SEPARATOR(*ptr); ptr--) /* empty */;
                        if ( ptr >= ndn->bv_val ) {
                                if (DN_SEPARATOR(*ptr)) ptr++;
                                ei.bei_nrdn.bv_len = ei.bei_nrdn.bv_val - ptr;
                                ei.bei_nrdn.bv_val = ptr;
                        }
                }
                eip = &bdb->bi_cache.c_dntree;
        }
        
        for ( bdb_cache_entryinfo_lock( eip ); eip; ) {
                eip->bei_state |= CACHE_ENTRY_REFERENCED;
                ei.bei_parent = eip;
                ei2 = (EntryInfo *)avl_find( eip->bei_kids, &ei, bdb_rdn_cmp );
                if ( !ei2 ) {
                        DB_LOCK lock;
                        int len = ei.bei_nrdn.bv_len;
                                
                        if ( BER_BVISEMPTY( ndn )) {
                                *res = eip;
                                return LDAP_SUCCESS;
                        }

                        ei.bei_nrdn.bv_len = ndn->bv_len -
                                (ei.bei_nrdn.bv_val - ndn->bv_val);
                        bdb_cache_entryinfo_unlock( eip );

                        BDB_LOG_PRINTF( bdb->bi_dbenv, NULL, "slapd Reading %s",
                                ei.bei_nrdn.bv_val );

                        lock.mode = DB_LOCK_NG;
                        rc = bdb_dn2id( op, &ei.bei_nrdn, &ei, locker, &lock );
                        if (rc) {
                                bdb_cache_entryinfo_lock( eip );
                                bdb_cache_entry_db_unlock( bdb, &lock );
                                *res = eip;
                                return rc;
                        }

                        BDB_LOG_PRINTF( bdb->bi_dbenv, NULL, "slapd Read got %s(%d)",
                                ei.bei_nrdn.bv_val, ei.bei_id );

                        /* DN exists but needs to be added to cache */
                        ei.bei_nrdn.bv_len = len;
                        rc = bdb_entryinfo_add_internal( bdb, &ei, &ei2 );
                        /* add_internal left eip and c_rwlock locked */
                        ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
                        bdb_cache_entry_db_unlock( bdb, &lock );
                        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--) /* empty */;
                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;
}

#ifdef BDB_HIER
/* Walk up the tree from a child node, looking for an ID that's already
 * been linked into the cache.
 */
int
hdb_cache_find_parent(
        Operation *op,
        BDB_LOCKER      locker,
        ID id,
        EntryInfo **res )
{
        struct bdb_info *bdb = (struct bdb_info *) op->o_bd->be_private;
        EntryInfo ei, eip, *ei2 = NULL, *ein = NULL, *eir = NULL;
        int rc;

        ei.bei_id = id;
        ei.bei_kids = NULL;
        ei.bei_ckids = 0;

        for (;;) {
                rc = hdb_dn2id_parent( op, locker, &ei, &eip.bei_id );
                if ( rc ) break;

                /* Save the previous node, if any */
                ei2 = ein;

                /* Create a new node for the current ID */
                ein = bdb_cache_entryinfo_new( &bdb->bi_cache );
                ein->bei_id = ei.bei_id;
                ein->bei_kids = ei.bei_kids;
                ein->bei_nrdn = ei.bei_nrdn;
                ein->bei_rdn = ei.bei_rdn;
                ein->bei_ckids = ei.bei_ckids;
#ifdef SLAP_ZONE_ALLOC
                ein->bei_bdb = bdb;
#endif
                ei.bei_ckids = 0;
                
                /* This node is not fully connected yet */
                ein->bei_state |= CACHE_ENTRY_NOT_LINKED;

                /* Insert this node into the ID tree */
                ldap_pvt_thread_rdwr_wlock( &bdb->bi_cache.c_rwlock );
                if ( avl_insert( &bdb->bi_cache.c_idtree, (caddr_t)ein,
                        bdb_id_cmp, bdb_id_dup_err ) ) {
                        EntryInfo *eix = ein->bei_lrunext;

                        /* Someone else created this node just before us.
                         * Free our new copy and use the existing one.
                         */
                        bdb_cache_entryinfo_free( &bdb->bi_cache, ein );
                        ein = eix;
                        
                        /* Link in any kids we've already processed */
                        if ( ei2 ) {
                                bdb_cache_entryinfo_lock( ein );
                                avl_insert( &ein->bei_kids, (caddr_t)ei2,
                                        bdb_rdn_cmp, avl_dup_error );
                                ein->bei_ckids++;
                                bdb_cache_entryinfo_unlock( ein );
                        }
                }

                /* If this is the first time, save this node
                 * to be returned later.
                 */
                if ( eir == NULL ) eir = ein;

                /* If there was a previous node, link it to this one */
                if ( ei2 ) ei2->bei_parent = ein;

                /* Look for this node's parent */
                if ( eip.bei_id ) {
                        ei2 = (EntryInfo *) avl_find( bdb->bi_cache.c_idtree,
                                        (caddr_t) &eip, bdb_id_cmp );
                } else {
                        ei2 = &bdb->bi_cache.c_dntree;
                }
                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 );

                /* Got the parent, link in and we're done. */
                if ( ei2 ) {
                        bdb_cache_entryinfo_lock( eir );
                        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++;

                        /* Reset all the state info */
                        for (ein = eir; ein != ei2; ein=ein->bei_parent)
                                ein->bei_state &= ~CACHE_ENTRY_NOT_LINKED;

                        bdb_cache_entryinfo_unlock( ei2 );

                        *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

/* This is best-effort only. If all entries in the cache are
 * busy, they will all be kept. This is unlikely to happen
 * unless the cache is very much smaller than the working set.
 */
static void
bdb_cache_lru_purge( struct bdb_info *bdb )
{
        DB_LOCK         lock, *lockp;
        EntryInfo *elru, *elnext = NULL;
        int count, islocked, eimax;

        /* Wait for the mutex; we're the only one trying to purge. */
        ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_lru_mutex );

        if ( bdb->bi_cache.c_cursize <= bdb->bi_cache.c_maxsize ) {
                ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_lru_mutex );
                bdb->bi_cache.c_purging = 0;
                return;
        }

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

        count = 0;

        /* maximum number of EntryInfo leaves to cache. In slapcat
         * we always free all leaf nodes.
         */
        if ( slapMode & SLAP_TOOL_READONLY )
                eimax = 0;
        else
                eimax = bdb->bi_cache.c_eimax;

        /* Look for an unused entry to remove */
        for ( elru = bdb->bi_cache.c_lruhead; elru; elru = elnext ) {
                elnext = elru->bei_lrunext;

                if ( bdb_cache_entryinfo_trylock( elru ))
                        goto bottom;

                /* This flag implements the clock replacement behavior */
                if ( elru->bei_state & ( CACHE_ENTRY_REFERENCED )) {
                        elru->bei_state &= ~CACHE_ENTRY_REFERENCED;
                        bdb_cache_entryinfo_unlock( elru );
                        goto bottom;
                }

                /* 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 | CACHE_ENTRY_LOADING )) ||
                        elru->bei_finders > 0 ) {
                        bdb_cache_entryinfo_unlock( elru );
                        goto bottom;
                }

                /* entryinfo is locked */
                islocked = 1;

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

                        /* 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++;
                        }
                        bdb_cache_entry_db_unlock( bdb, lockp );

                        /* 
                         * If it is a leaf node, and we're over the limit, free it.
                         */
                        if ( elru->bei_kids ) {
                                /* Drop from list, we ignore it... */
                                LRU_DEL( &bdb->bi_cache, elru );
                        } else if ( bdb->bi_cache.c_leaves > eimax ) {
                                /* Too many leaf nodes, free this one */
                                bdb_cache_delete_internal( &bdb->bi_cache, elru, 0 );
                                bdb_cache_delete_cleanup( &bdb->bi_cache, elru );
                                islocked = 0;
                        }       /* Leave on list until we need to free it */
                }

                if ( islocked )
                        bdb_cache_entryinfo_unlock( elru );

                if ( count >= bdb->bi_cache.c_minfree ) {
                        ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_count_mutex );
                        bdb->bi_cache.c_cursize -= count;
                        ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_count_mutex );
                        break;
                }
bottom:
                if ( elnext == bdb->bi_cache.c_lruhead )
                        break;
        }

        bdb->bi_cache.c_lruhead = elnext;
        ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_lru_mutex );
        bdb->bi_cache.c_purging = 0;
}

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 flag ID_LOCKED if
 * the supplied *eip was already locked.
 */

int
bdb_cache_find_id(
        Operation *op,
        DB_TXN  *tid,
        ID                              id,
        EntryInfo       **eip,
        int             flag,
        BDB_LOCKER      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 ( bdb_cache_entryinfo_trylock( *eip )) {
                                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;
                        }
                        flag |= ID_LOCKED;
                }
                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, locker,
                                &ep->e_nname, eip );
                        if ( *eip ) flag |= ID_LOCKED;
                        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, locker, id, eip );
                if ( rc == 0 ) flag |= ID_LOCKED;
#endif
        }

        /* Ok, we found the info, do we have the entry? */
        if ( rc == 0 ) {
                if ( !( flag & ID_LOCKED )) {
                        bdb_cache_entryinfo_lock( *eip );
                        flag |= ID_LOCKED;
                }

                if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
                        rc = DB_NOTFOUND;
                } else {
                        (*eip)->bei_finders++;
                        (*eip)->bei_state |= CACHE_ENTRY_REFERENCED;
                        /* 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 ( !load ) {
                                /* Clear the uncached state if we are not
                                 * loading it, i.e it is already cached or
                                 * another thread is currently loading it.
                                 */
                                (*eip)->bei_state &= ~CACHE_ENTRY_NOT_CACHED;
                                flag &= ~ID_NOCACHE;
                        }

                        if ( flag & ID_LOCKED ) {
                                bdb_cache_entryinfo_unlock( *eip );
                                flag ^= ID_LOCKED;
                        }
                        rc = bdb_cache_entry_db_lock( bdb, locker, *eip, load, 0, lock );
                        if ( (*eip)->bei_state & CACHE_ENTRY_DELETED ) {
                                rc = DB_NOTFOUND;
                                bdb_cache_entry_db_unlock( bdb, lock );
                        } else if ( rc == 0 ) {
                                if ( load ) {
                                        if ( !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_lru_link( bdb, *eip );
                                                if (( flag & ID_NOCACHE ) &&
                                                        ( bdb_cache_entryinfo_trylock( *eip ) == 0 )) {
                                                        /* Set the cached state only if no other thread
                                                         * found the info while we were loading the entry.
                                                         */
                                                        if ( (*eip)->bei_finders == 1 )
                                                                (*eip)->bei_state |= CACHE_ENTRY_NOT_CACHED;
                                                        bdb_cache_entryinfo_unlock( *eip );
                                                }
                                        }
                                        if ( rc == 0 ) {
                                                /* If we succeeded, downgrade back to a readlock. */
                                                rc = bdb_cache_entry_db_relock( bdb, locker,
                                                        *eip, 0, 0, lock );
                                        } else {
                                                /* Otherwise, release the lock. */
                                                bdb_cache_entry_db_unlock( bdb, lock );
                                        }
                                } else if ( !(*eip)->bei_e ) {
                                        /* Some other thread is trying to load the entry,
                                         * wait for it to finish.
                                         */
                                        bdb_cache_entry_db_unlock( bdb, lock );
                                        bdb_cache_entryinfo_lock( *eip );
                                        flag |= ID_LOCKED;
                                        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,
                                                        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,
                                                        locker, *eip, 0, 0, lock );
                                        }
#endif
                                }
                        }
                        bdb_cache_entryinfo_lock( *eip );
                        (*eip)->bei_finders--;
                        if ( load )
                                (*eip)->bei_state ^= CACHE_ENTRY_LOADING;
                        bdb_cache_entryinfo_unlock( *eip );
                }
        }
        if ( flag & ID_LOCKED ) {
                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 ) {
                int purge = 0;

                if ( load ) {
                        if ( !( flag & ID_NOCACHE )) {
                                ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_count_mutex );
                                bdb->bi_cache.c_cursize++;
                                if ( bdb->bi_cache.c_cursize > bdb->bi_cache.c_maxsize &&
                                        !bdb->bi_cache.c_purging ) {
                                        purge = 1;
                                        bdb->bi_cache.c_purging = 1;
                                }
                                ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_count_mutex );
                        }
                }
                if ( purge )
                        bdb_cache_lru_purge( bdb );
        }

#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,
        BDB_LOCKER locker,
        DB_LOCK *lock )
{
        EntryInfo *new, ei;
        int rc, purge = 0;
#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, locker, &ei, 0, 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 );
        /* bdb_csn_commit can cause this when adding the database root entry */
        if ( new->bei_e ) {
                new->bei_e->e_private = NULL;
#ifdef SLAP_ZONE_ALLOC
                bdb_entry_return( bdb, new->bei_e, new->bei_zseq );
#else
                bdb_entry_return( new->bei_e );
#endif
        }
        new->bei_e = e;
        e->e_private = new;
        new->bei_state |= CACHE_ENTRY_NO_KIDS | CACHE_ENTRY_NO_GRANDKIDS;
        eip->bei_state &= ~CACHE_ENTRY_NO_KIDS;
        if (eip->bei_parent) {
                eip->bei_parent->bei_state &= ~CACHE_ENTRY_NO_GRANDKIDS;
        }
        bdb_cache_entryinfo_unlock( eip );

        ldap_pvt_thread_rdwr_wunlock( &bdb->bi_cache.c_rwlock );
        ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_count_mutex );
        ++bdb->bi_cache.c_cursize;
        if ( bdb->bi_cache.c_cursize > bdb->bi_cache.c_maxsize &&
                !bdb->bi_cache.c_purging ) {
                purge = 1;
                bdb->bi_cache.c_purging = 1;
        }
        ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_count_mutex );

        bdb_cache_lru_link( bdb, new );

        if ( purge )
                bdb_cache_lru_purge( bdb );

        return rc;
}

int
bdb_cache_modify(
        struct bdb_info *bdb,
        Entry *e,
        Attribute *newAttrs,
        BDB_LOCKER locker,
        DB_LOCK *lock )
{
        EntryInfo *ei = BEI(e);
        int rc;
        /* Get write lock on data */
        rc = bdb_cache_entry_db_relock( bdb, 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 ( ! rc ) {
                if ( (void *)e->e_attrs != (void *)(e+1) ) {
                        attrs_free( e->e_attrs ); 
                }
                e->e_attrs = newAttrs;
        }
        return rc;
}

/*
 * Change the rdn in the entryinfo. Also move to a new parent if needed.
 */
int
bdb_cache_modrdn(
        struct bdb_info *bdb,
        Entry *e,
        struct berval *nrdn,
        Entry *new,
        EntryInfo *ein,
        BDB_LOCKER locker,
        DB_LOCK *lock )
{
        EntryInfo *ei = BEI(e), *pei;
        int rc;
#ifdef BDB_HIER
        struct berval rdn;
#endif

        /* Get write lock on data */
        rc =  bdb_cache_entry_db_relock( bdb, locker, ei, 1, 0, lock );
        if ( rc ) return rc;

        /* 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;
        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);
        }
        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 );

#ifdef BDB_HIER
        free( ei->bei_rdn.bv_val );

        rdn = e->e_name;
        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 new parent, decrement kid counts */
        if ( ein ) {
                pei->bei_ckids--;
                if ( pei->bei_dkids ) {
                        pei->bei_dkids--;
                        if ( pei->bei_dkids < 2 )
                                pei->bei_state |= CACHE_ENTRY_NO_KIDS | CACHE_ENTRY_NO_GRANDKIDS;
                }
        }
#endif

        if (!ein) {
                ein = ei->bei_parent;
        } else {
                ei->bei_parent = ein;
                bdb_cache_entryinfo_unlock( pei );
                bdb_cache_entryinfo_lock( ein );

                /* new parent now has kids */
                if ( ein->bei_state & CACHE_ENTRY_NO_KIDS )
                        ein->bei_state ^= CACHE_ENTRY_NO_KIDS;
                /* grandparent has grandkids */
                if ( ein->bei_parent )
                        ein->bei_parent->bei_state &= ~CACHE_ENTRY_NO_GRANDKIDS;
#ifdef BDB_HIER
                /* parent might now have grandkids */
                if ( ein->bei_state & CACHE_ENTRY_NO_GRANDKIDS &&
                        !(ei->bei_state & CACHE_ENTRY_NO_KIDS))
                        ein->bei_state ^= CACHE_ENTRY_NO_GRANDKIDS;

                ein->bei_ckids++;
                if ( ein->bei_dkids ) ein->bei_dkids++;
#endif
        }

#ifdef BDB_HIER
        /* Record the generation number of this change */
        ldap_pvt_thread_mutex_lock( &bdb->bi_modrdns_mutex );
        bdb->bi_modrdns++;
        ei->bei_modrdns = bdb->bi_modrdns;
        ldap_pvt_thread_mutex_unlock( &bdb->bi_modrdns_mutex );
#endif

        avl_insert( &ein->bei_kids, ei, bdb_rdn_cmp, avl_dup_error );
        bdb_cache_entryinfo_unlock( ein );
        return rc;
}
/*
 * cache_delete - 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(
        struct bdb_info *bdb,
    Entry               *e,
    BDB_LOCKER  locker,
    DB_LOCK     *lock )
{
        EntryInfo *ei = BEI(e);
        int     rc;

        assert( e->e_private != NULL );

        /* Lock the entry's info */
        bdb_cache_entryinfo_lock( ei );

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

        bdb_cache_entryinfo_unlock( ei );

        /* Get write lock on the data */
        rc = bdb_cache_entry_db_relock( bdb, locker, ei, 1, 0, lock );
        if ( rc ) {
                /* couldn't lock, undo and give up */
                ei->bei_state ^= CACHE_ENTRY_DELETED;
                return rc;
        }

        Debug( LDAP_DEBUG_TRACE, "====> bdb_cache_delete( %ld )\n",
                e->e_id, 0, 0 );

        /* set lru mutex */
        ldap_pvt_thread_mutex_lock( &bdb->bi_cache.c_lru_mutex );

        rc = bdb_cache_delete_internal( &bdb->bi_cache, e->e_private, 1 );

        /* free lru mutex */
        ldap_pvt_thread_mutex_unlock( &bdb->bi_cache.c_lru_mutex );

        return( rc );
}

void
bdb_cache_delete_cleanup(
        Cache *cache,
        EntryInfo *ei )
{
        /* Enter with ei locked */

        if ( ei->bei_e ) {
                ei->bei_e->e_private = NULL;
#ifdef SLAP_ZONE_ALLOC
                bdb_entry_return( ei->bei_bdb, ei->bei_e, ei->bei_zseq );
#else
                bdb_entry_return( ei->bei_e );
#endif
                ei->bei_e = NULL;
        }

        bdb_cache_entryinfo_free( cache, ei );
        bdb_cache_entryinfo_unlock( ei );
}

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

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

#ifdef BDB_HIER
        e->bei_parent->bei_ckids--;
        if ( decr && e->bei_parent->bei_dkids ) e->bei_parent->bei_dkids--;
#endif
        /* dn tree */
        if ( avl_delete( &e->bei_parent->bei_kids, (caddr_t) e, bdb_rdn_cmp )
                == NULL )
        {
                rc = -1;
        }
        if ( e->bei_parent->bei_kids )
                decr_leaf = 1;

        bdb_cache_entryinfo_unlock( e->bei_parent );

        ldap_pvt_thread_rdwr_wlock( &cache->c_rwlock );
        /* id tree */
        if ( avl_delete( &cache->c_idtree, (caddr_t) e, bdb_id_cmp )) {
                cache->c_eiused--;
                if ( decr_leaf )
                        cache->c_leaves--;
        } else {
                rc = -1;
        }
        ldap_pvt_thread_rdwr_wunlock( &cache->c_rwlock );

        if ( rc == 0 ){
                /* lru */
                LRU_DEL( cache, e );

                if ( e->bei_e ) {
                        ldap_pvt_thread_mutex_lock( &cache->c_count_mutex );
                        cache->c_cursize--;
                        ldap_pvt_thread_mutex_unlock( &cache->c_count_mutex );
                }
        }

        return( rc );
}

static void
bdb_entryinfo_release( void *data )
{
        EntryInfo *ei = (EntryInfo *)data;
        if ( ei->bei_kids ) {
                avl_free( ei->bei_kids, NULL );
        }
        if ( ei->bei_e ) {
                ei->bei_e->e_private = NULL;
#ifdef SLAP_ZONE_ALLOC
                bdb_entry_return( ei->bei_bdb, ei->bei_e, ei->bei_zseq );
#else
                bdb_entry_return( ei->bei_e );
#endif
        }
        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->c_lru_mutex );

        Debug( LDAP_DEBUG_TRACE, "====> bdb_cache_release_all\n", 0, 0, 0 );

        avl_free( cache->c_dntree.bei_kids, NULL );
        avl_free( cache->c_idtree, bdb_entryinfo_release );
        for (;cache->c_eifree;cache->c_eifree = cache->c_lruhead) {
                cache->c_lruhead = cache->c_eifree->bei_lrunext;
                bdb_cache_entryinfo_destroy(cache->c_eifree);
        }
        cache->c_cursize = 0;
        cache->c_eiused = 0;
        cache->c_leaves = 0;
        cache->c_idtree = NULL;
        cache->c_lruhead = NULL;
        cache->c_lrutail = NULL;
        cache->c_dntree.bei_kids = NULL;

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

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

        fprintf( stderr, "LRU circle head: %p\n", (void *) cache->c_lruhead );
        fprintf( stderr, "LRU circle (tail forward):\n" );
        for ( e = cache->c_lrutail; ; ) {
                fprintf( stderr, "\t%p, %p id %ld rdn \"%s\"\n",
                        (void *) e, (void *) e->bei_e, e->bei_id, e->bei_nrdn.bv_val );
                e = e->bei_lrunext;
                if ( e == cache->c_lrutail )
                        break;
        }
        fprintf( stderr, "LRU circle (tail backward):\n" );
        for ( e = cache->c_lrutail; ; ) {
                fprintf( stderr, "\t%p, %p id %ld rdn \"%s\"\n",
                        (void *) e, (void *) e->bei_e, e->bei_id, e->bei_nrdn.bv_val );
                e = e->bei_lruprev;
                if ( e == cache->c_lrutail )
                        break;
        }
}
#endif
#endif

#ifdef BDB_REUSE_LOCKERS
static void
bdb_locker_id_free( void *key, void *data )
{
        DB_ENV *env = key;
        u_int32_t lockid;
        int rc;

#if DB_VERSION_FULL >= 0x04060012
        BDB_LOCKER lptr = data;
        lockid = lptr->id;
#else
        lockid = (long)data;
#endif
        rc = XLOCK_ID_FREE( env, lockid );
        if ( rc == EINVAL ) {
                DB_LOCKREQ lr;
                Debug( LDAP_DEBUG_ANY,
                        "bdb_locker_id_free: %lu err %s(%d)\n",
                        (unsigned long) lockid, db_strerror(rc), rc );
                /* release all locks held by this locker. */
                lr.op = DB_LOCK_PUT_ALL;
                lr.obj = NULL;
                env->lock_vec( env, lockid, 0, &lr, 1, NULL );
                XLOCK_ID_FREE( env, lockid );
        }
}

/* free up any keys used by the main thread */
void
bdb_locker_flush( DB_ENV *env )
{
        void *data;
        void *ctx = ldap_pvt_thread_pool_context();

        if ( !ldap_pvt_thread_pool_getkey( ctx, env, &data, NULL ) ) {
                ldap_pvt_thread_pool_setkey( ctx, env, NULL, 0, NULL, NULL );
                bdb_locker_id_free( env, data );
        }
}

int
bdb_locker_id( Operation *op, DB_ENV *env, BDB_LOCKER *locker )
{
        int i, rc;
        u_int32_t 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;
                }
#if DB_VERSION_FULL >= 0x04060012
                { BDB_LOCKER lptr;
                __lock_getlocker( env->lk_handle, lockid, 0, &lptr );
                data = lptr;
                }
#else
                data = (void *)((long)lockid);
#endif
                if ( ( rc = ldap_pvt_thread_pool_setkey( ctx, env,
                        data, bdb_locker_id_free, NULL, NULL ) ) ) {
                        XLOCK_ID_FREE( env, lockid );
                        Debug( LDAP_DEBUG_ANY, "bdb_locker_id: err %s(%d)\n",
                                db_strerror(rc), rc, 0 );

                        return rc;
                }
        } else {
                lockid = (long)data;
        }
#if DB_VERSION_FULL >= 0x04060012
        *locker = data;
#else
        *locker = lockid;
#endif
        return 0;
}
#endif /* BDB_REUSE_LOCKERS */