gracefully handle server down while initiating a search (ITS#4518)

diff --git a/servers/slapd/back-meta/search.c b/servers/slapd/back-meta/search.c
index 34ac69dc73899023ee59d0c5519608fa5e513b53..ef2a12991206b5539417d8c271f8d3a20f38537b 100644 (file)
--- a/servers/slapd/back-meta/search.c
+++ b/servers/slapd/back-meta/search.c
@@ -35,6 +35,12 @@
 #include "ldap_log.h"
 #include "../../../libraries/libldap/ldap-int.h"
 
+/* IGNORE means that target does not (no longer) participate
+ * in the search;
+ * NOTREADY means the search on that target has not been initialized yet
+ */
+#define        META_MSGID_IGNORE       (-1)
+
 static int
 meta_send_entry(
        Operation       *op,
@@ -54,21 +60,24 @@ meta_back_search_start(
        Operation               *op,
        SlapReply               *rs,
        dncookie                *dc,
-       metasingleconn_t        *msc,
+       metaconn_t              **mcp,
        int                     candidate,
-       SlapReply               *candidates
-)
+       SlapReply               *candidates )
 {
-       metainfo_t      *mi = ( metainfo_t * )op->o_bd->be_private;
-       struct berval   realbase = op->o_req_dn;
-       int             realscope = op->ors_scope;
-       ber_len_t       suffixlen = 0;
-       struct berval   mbase = BER_BVNULL; 
-       struct berval   mfilter = BER_BVNULL;
-       char            **mapped_attrs = NULL;
-       int             rc;
+       metainfo_t              *mi = ( metainfo_t * )op->o_bd->be_private;
+       metatarget_t            *mt = &mi->mi_targets[ candidate ];
+       metaconn_t              *mc = *mcp;
+       metasingleconn_t        *msc = &mc->mc_conns[ candidate ];
+       struct berval           realbase = op->o_req_dn;
+       int                     realscope = op->ors_scope;
+       ber_len_t               suffixlen = 0;
+       struct berval           mbase = BER_BVNULL; 
+       struct berval           mfilter = BER_BVNULL;
+       char                    **mapped_attrs = NULL;
+       int                     rc;
        meta_search_candidate_t retcode;
-       struct timeval  tv, *tvp = NULL;
+       struct timeval          tv, *tvp = NULL;
+       int                     nretries = 1;
 
        /* should we check return values? */
        if ( op->ors_deref != -1 ) {
@@ -78,15 +87,16 @@ meta_back_search_start(
 
        if ( op->ors_tlimit != SLAP_NO_LIMIT ) {
                tv.tv_sec = op->ors_tlimit > 0 ? op->ors_tlimit : 1;
+               tv.tv_usec = 0;
                tvp = &tv;
        }
 
-       dc->target = &mi->mi_targets[ candidate ];
+       dc->target = mt;
 
        /*
         * modifies the base according to the scope, if required
         */
-       suffixlen = mi->mi_targets[ candidate ].mt_nsuffix.bv_len;
+       suffixlen = mt->mt_nsuffix.bv_len;
        if ( suffixlen > op->o_req_ndn.bv_len ) {
                switch ( op->ors_scope ) {
                case LDAP_SCOPE_SUBTREE:
@@ -98,11 +108,9 @@ meta_back_search_start(
                         * the requested searchBase already passed
                         * thru the candidate analyzer...
                         */
-                       if ( dnIsSuffix( &mi->mi_targets[ candidate ].mt_nsuffix,
-                                       &op->o_req_ndn ) )
-                       {
-                               realbase = mi->mi_targets[ candidate ].mt_nsuffix;
-                               if ( mi->mi_targets[ candidate ].mt_scope == LDAP_SCOPE_SUBORDINATE ) {
+                       if ( dnIsSuffix( &mt->mt_nsuffix, &op->o_req_ndn ) ) {
+                               realbase = mt->mt_nsuffix;
+                               if ( mt->mt_scope == LDAP_SCOPE_SUBORDINATE ) {
                                        realscope = LDAP_SCOPE_SUBORDINATE;
                                }
 
@@ -117,19 +125,19 @@ meta_back_search_start(
                case LDAP_SCOPE_SUBORDINATE:
                case LDAP_SCOPE_ONELEVEL:
                {
-                       struct berval   rdn = mi->mi_targets[ candidate ].mt_nsuffix;
+                       struct berval   rdn = mt->mt_nsuffix;
                        rdn.bv_len -= op->o_req_ndn.bv_len + STRLENOF( "," );
                        if ( dnIsOneLevelRDN( &rdn )
-                                       && dnIsSuffix( &mi->mi_targets[ candidate ].mt_nsuffix, &op->o_req_ndn ) )
+                                       && dnIsSuffix( &mt->mt_nsuffix, &op->o_req_ndn ) )
                        {
                                /*
                                 * if there is exactly one level,
                                 * make the target suffix the new
                                 * base, and make scope "base"
                                 */
-                               realbase = mi->mi_targets[ candidate ].mt_nsuffix;
+                               realbase = mt->mt_nsuffix;
                                if ( op->ors_scope == LDAP_SCOPE_SUBORDINATE ) {
-                                       if ( mi->mi_targets[ candidate ].mt_scope == LDAP_SCOPE_SUBORDINATE ) {
+                                       if ( mt->mt_scope == LDAP_SCOPE_SUBORDINATE ) {
                                                realscope = LDAP_SCOPE_SUBORDINATE;
                                        } else {
                                                realscope = LDAP_SCOPE_SUBTREE;
@@ -192,7 +200,7 @@ meta_back_search_start(
        /*
         * Maps required attributes
         */
-       rc = ldap_back_map_attrs( &mi->mi_targets[ candidate ].mt_rwmap.rwm_at,
+       rc = ldap_back_map_attrs( &mt->mt_rwmap.rwm_at,
                        op->ors_attrs, BACKLDAP_MAP, &mapped_attrs );
        if ( rc != LDAP_SUCCESS ) {
                /*
@@ -205,16 +213,31 @@ meta_back_search_start(
        /*
         * Starts the search
         */
+retry:;
        rc = ldap_search_ext( msc->msc_ld,
                        mbase.bv_val, realscope, mfilter.bv_val,
                        mapped_attrs, op->ors_attrsonly,
                        op->o_ctrls, NULL, tvp, op->ors_slimit,
                        &candidates[ candidate ].sr_msgid ); 
-       if ( rc == LDAP_SUCCESS ) {
+       switch ( rc ) {
+       case LDAP_SUCCESS:
                retcode = META_SEARCH_CANDIDATE;
+               break;
+       
+       case LDAP_SERVER_DOWN:
+               if ( nretries && meta_back_retry( op, rs, mcp, candidate, LDAP_BACK_DONTSEND ) ) {
+                       nretries = 0;
+                       goto retry;
+               }
 
-       } else {
-               candidates[ candidate ].sr_msgid = -1;
+               if ( *mcp == NULL ) {
+                       retcode = META_SEARCH_ERR;
+                       break;
+               }
+               /* fall thru */
+
+       default:
+               candidates[ candidate ].sr_msgid = META_MSGID_IGNORE;
                retcode = META_SEARCH_NOT_CANDIDATE;
        }
 
@@ -268,9 +291,7 @@ meta_back_search( Operation *op, SlapReply *rs )
         * Inits searches
         */
        for ( i = 0; i < mi->mi_ntargets; i++ ) {
-               metasingleconn_t        *msc = &mc->mc_conns[ i ];
-
-               candidates[ i ].sr_msgid = -1;
+               candidates[ i ].sr_msgid = META_MSGID_IGNORE;
                candidates[ i ].sr_matched = NULL;
                candidates[ i ].sr_text = NULL;
                candidates[ i ].sr_ref = NULL;
@@ -282,7 +303,7 @@ meta_back_search( Operation *op, SlapReply *rs )
                        continue;
                }
 
-               switch ( meta_back_search_start( op, rs, &dc, msc, i, candidates ) )
+               switch ( meta_back_search_start( op, rs, &dc, &mc, i, candidates ) )
                {
                case META_SEARCH_NOT_CANDIDATE:
                        break;
@@ -371,7 +392,7 @@ meta_back_search( Operation *op, SlapReply *rs )
                for ( i = 0; i < mi->mi_ntargets; i++ ) {
                        metasingleconn_t        *msc = &mc->mc_conns[ i ];
 
-                       if ( candidates[ i ].sr_msgid == -1 ) {
+                       if ( candidates[ i ].sr_msgid == META_MSGID_IGNORE ) {
                                continue;
                        }
 
@@ -417,7 +438,7 @@ really_bad:;
                                        candidates[ i ].sr_type = REP_RESULT;
 
                                        if ( meta_back_retry( op, rs, &mc, i, LDAP_BACK_DONTSEND ) ) {
-                                               switch ( meta_back_search_start( op, rs, &dc, msc, i, candidates ) )
+                                               switch ( meta_back_search_start( op, rs, &dc, &mc, i, candidates ) )
                                                {
                                                case META_SEARCH_CANDIDATE:
                                                        goto get_result;
@@ -431,18 +452,20 @@ really_bad:;
                                                }
                                        }
 
-                                       savepriv = op->o_private;
-                                       op->o_private = (void *)i;
-                                       send_ldap_result( op, rs );
-                                       op->o_private = savepriv;
-                                       goto finish;
+                                       if ( META_BACK_ONERR_STOP( mi ) ) {
+                                               savepriv = op->o_private;
+                                               op->o_private = (void *)i;
+                                               send_ldap_result( op, rs );
+                                               op->o_private = savepriv;
+                                               goto finish;
+                                       }
                                }
 
                                /*
                                 * When no candidates are left,
                                 * the outer cycle finishes
                                 */
-                               candidates[ i ].sr_msgid = -1;
+                               candidates[ i ].sr_msgid = META_MSGID_IGNORE;
                                --ncandidates;
                                rs->sr_err = candidates[ i ].sr_err = LDAP_OTHER;
                                rs->sr_text = "remote server unavailable";
@@ -733,7 +756,7 @@ really_bad:;
                                 * When no candidates are left,
                                 * the outer cycle finishes
                                 */
-                               candidates[ i ].sr_msgid = -1;
+                               candidates[ i ].sr_msgid = META_MSGID_IGNORE;
                                --ncandidates;
 
                        } else {
@@ -747,11 +770,12 @@ really_bad:;
                        for ( i = 0; i < mi->mi_ntargets; i++ ) {
                                metasingleconn_t        *msc = &mc->mc_conns[ i ];
 
-                               if ( candidates[ i ].sr_msgid != -1 ) {
+                               if ( candidates[ i ].sr_msgid != META_MSGID_IGNORE )
+                               {
                                        ldap_abandon_ext( msc->msc_ld,
                                                candidates[ i ].sr_msgid,
                                                NULL, NULL );
-                                       candidates[ i ].sr_msgid = -1;
+                                       candidates[ i ].sr_msgid = META_MSGID_IGNORE;
                                }
                        }
 
@@ -764,7 +788,10 @@ really_bad:;
                /* if no entry was found during this loop,
                 * set a minimal timeout */
                if ( gotit == 0 ) {
-                       LDAP_BACK_TV_SET( &tv );
+                       /* make the entire wait last
+                        * LDAP_BACK_RESULT_UTIMEOUT at worst */
+                       tv.tv_sec = 0;
+                       tv.tv_usec = LDAP_BACK_RESULT_UTIMEOUT/initial_candidates;
                         ldap_pvt_thread_yield();
                }
        }