ITS#6954 fix consistency checker prematurely deleting cached queries

diff --git a/servers/slapd/overlays/pcache.c b/servers/slapd/overlays/pcache.c
index dca24cea033628466b39be9c015002f73c515d26..fb5f8eebfc6eb4daca364dd8530da084931144ca 100644 (file)
--- a/servers/slapd/overlays/pcache.c
+++ b/servers/slapd/overlays/pcache.c
@@ -84,6 +84,7 @@ typedef struct cached_query_s {
        time_t                                          expiry_time;    /* time till the query is considered invalid */
        time_t                                          refresh_time;   /* time till the query is refreshed */
        time_t                                          bindref_time;   /* time till the bind is refreshed */
+       int                                             bind_refcnt;    /* number of bind operation referencing this query */
        unsigned long                   answerable_cnt; /* how many times it was answerable */
        int                                             refcnt; /* references since last refresh */
        ldap_pvt_thread_mutex_t         answerable_cnt_mutex;
@@ -1554,6 +1555,7 @@ add_query(
        new_cached_query->refresh_time = ttr;
        new_cached_query->bindref_time = 0;
 
+       new_cached_query->bind_refcnt = 0;
        new_cached_query->answerable_cnt = 0;
        new_cached_query->refcnt = 1;
        ldap_pvt_thread_mutex_init(&new_cached_query->answerable_cnt_mutex);
@@ -1614,16 +1616,16 @@ add_query(
        Debug( pcache_debug, "TEMPLATE %p QUERIES++ %d\n",
                        (void *) templ, templ->no_of_queries, 0 );
 
-       Debug( pcache_debug, "Unlock AQ index = %p \n",
-                       (void *) templ, 0, 0 );
-       ldap_pvt_thread_rdwr_wunlock(&templ->t_rwlock);
-
        /* Adding on top of LRU list  */
        if ( rc == 0 ) {
                ldap_pvt_thread_mutex_lock(&qm->lru_mutex);
                add_query_on_top(qm, new_cached_query);
                ldap_pvt_thread_mutex_unlock(&qm->lru_mutex);
        }
+       Debug( pcache_debug, "Unlock AQ index = %p \n",
+                       (void *) templ, 0, 0 );
+       ldap_pvt_thread_rdwr_wunlock(&templ->t_rwlock);
+
        return rc == 0 ? new_cached_query : NULL;
 }
 
@@ -2395,8 +2397,10 @@ over:;
                                switch ( si->caching_reason ) {
                                case PC_POSITIVE:
                                        cache_entries( op, &qc->q_uuid );
-                                       if ( si->pbi )
+                                       if ( si->pbi ) {
+                                               qc->bind_refcnt++;
                                                si->pbi->bi_cq = qc;
+                                       }
                                        break;
 
                                case PC_SIZELIMIT:
@@ -2597,10 +2601,20 @@ pc_bind_save( Operation *op, SlapReply *rs )
                bindcacheinfo *bci = op->o_callback->sc_private;
                slap_overinst *on = bci->on;
                cache_manager *cm = on->on_bi.bi_private;
-
-               Operation op2 = *op;
-               if ( pc_setpw( &op2, &op->orb_cred, cm ) == LDAP_SUCCESS )
-                       bci->qc->bindref_time = op->o_time + bci->qc->qtemp->bindttr;
+               CachedQuery *qc = bci->qc;
+               int delete = 0;
+
+               ldap_pvt_thread_rdwr_wlock( &qc->rwlock );
+               if ( qc->bind_refcnt-- ) {
+                       Operation op2 = *op;
+                       if ( pc_setpw( &op2, &op->orb_cred, cm ) == LDAP_SUCCESS )
+                               bci->qc->bindref_time = op->o_time + bci->qc->qtemp->bindttr;
+               } else {
+                       bci->qc = NULL;
+                       delete = 1;
+               }
+               ldap_pvt_thread_rdwr_wunlock( &qc->rwlock );
+               if ( delete ) free_query(qc);
        }
        return SLAP_CB_CONTINUE;
 }
@@ -2865,6 +2879,7 @@ pcache_op_bind(
        if ( bi.bi_flags & BI_HASHED ) {
                BackendDB *be = op->o_bd;
                op->o_bd = &cm->db;
+               int delete = 0;
 
                Debug( pcache_debug, "pcache_op_bind: CACHED BIND for %s\n",
                        op->o_req_dn.bv_val, 0, 0 );
@@ -2873,6 +2888,12 @@ pcache_op_bind(
                        op->o_conn->c_authz_cookie = cm->db.be_private;
                }
                op->o_bd = be;
+               ldap_pvt_thread_rdwr_wlock( &bi.bi_cq->rwlock );
+               if ( !bi.bi_cq->bind_refcnt-- ) {
+                       delete = 1;
+               }
+               ldap_pvt_thread_rdwr_wunlock( &bi.bi_cq->rwlock );
+               if ( delete ) free_query( bi.bi_cq );
                return rs->sr_err;
        }
 
@@ -3013,15 +3034,17 @@ pcache_op_search(
                        answerable->answerable_cnt, 0, 0 );
                ldap_pvt_thread_mutex_unlock( &answerable->answerable_cnt_mutex );
 
-               ldap_pvt_thread_rdwr_rlock(&answerable->rwlock);
+               ldap_pvt_thread_rdwr_wlock(&answerable->rwlock);
                if ( BER_BVISNULL( &answerable->q_uuid )) {
                        /* No entries cached, just an empty result set */
                        i = rs->sr_err = 0;
                        send_ldap_result( op, rs );
                } else {
                        /* Let Bind know we used a cached query */
-                       if ( pbi )
+                       if ( pbi ) {
+                               answerable->bind_refcnt++;
                                pbi->bi_cq = answerable;
+                       }
 
                        op->o_bd = &cm->db;
                        if ( cm->response_cb == PCACHE_RESPONSE_CB_TAIL ) {
@@ -3044,7 +3067,7 @@ pcache_op_search(
                        }
                        i = cm->db.bd_info->bi_op_search( op, rs );
                }
-               ldap_pvt_thread_rdwr_runlock(&answerable->rwlock);
+               ldap_pvt_thread_rdwr_wunlock(&answerable->rwlock);
                /* locked by qtemp->qcfunc (query_containment) */
                ldap_pvt_thread_rdwr_runlock(&qtemp->t_rwlock);
                op->o_bd = save_bd;
@@ -3515,8 +3538,8 @@ consistency_check(
                                        Debug( pcache_debug, "Unlock CR index = %p\n",
                                                        (void *) templ, 0, 0 );
                                }
-                               ldap_pvt_thread_rdwr_wunlock(&templ->t_rwlock);
                                if ( !rem ) {
+                                       ldap_pvt_thread_rdwr_wunlock(&templ->t_rwlock);
                                        continue;
                                }
                                ldap_pvt_thread_mutex_lock(&qm->lru_mutex);
@@ -3538,7 +3561,15 @@ consistency_check(
                                        "STALE QUERY REMOVED, CACHE ="
                                        "%d entries\n",
                                        cm->cur_entries, 0, 0 );
-                               free_query(query);
+                               ldap_pvt_thread_rdwr_wlock( &query->rwlock );
+                               if ( query->bind_refcnt-- ) {
+                                       rem = 0;
+                               } else {
+                                       rem = 1;
+                               }
+                               ldap_pvt_thread_rdwr_wunlock( &query->rwlock );
+                               if ( rem ) free_query(query);
+                               ldap_pvt_thread_rdwr_wunlock(&templ->t_rwlock);
                        } else if ( !templ->ttr && query->expiry_time > ttl ) {
                                /* We don't need to check for refreshes, and this
                                 * query's expiry is too new, and all subsequent queries