ITS#7904 more tweaks

Must save/restore mcd cursor if we're doing a scope-based search.

diff --git a/servers/slapd/back-mdb/search.c b/servers/slapd/back-mdb/search.c
index c63db9c1640f89373f318f1f201471e582cda9d6..2114c10ad0ca6f5f9f7a1521fd8390de8cd6304f 100644 (file)
--- a/servers/slapd/back-mdb/search.c
+++ b/servers/slapd/back-mdb/search.c
@@ -318,19 +318,73 @@ static void *search_stack( Operation *op );
 
 typedef struct ww_ctx {
        MDB_txn *txn;
+       MDB_cursor *mcd;        /* if set, save cursor context */
+       ID key;
+       MDB_val data;
        int flag;
 } ww_ctx;
 
+/* ITS#7904 if we get blocked while writing results to client,
+ * release the current reader txn and reacquire it after we
+ * unblock.
+ * Slight problem - if we're doing a scope-based walk (mdb_dn2id_walk)
+ * to return results, we need to remember the state of the mcd cursor.
+ * If the node that cursor was pointing to gets deleted while we're
+ * blocked, we may be unable to restore the cursor position. In that
+ * case return an LDAP_BUSY error - let the client know this search
+ * couldn't succeed, but might succeed on a retry.
+ */
 static void
 mdb_writewait( Operation *op, slap_callback *sc )
 {
        ww_ctx *ww = sc->sc_private;
        if ( !ww->flag ) {
+               if ( ww->mcd ) {
+                       MDB_val key, data;
+                       mdb_cursor_get( ww->mcd, &key, &data, MDB_GET_CURRENT );
+                       memcpy( &ww->key, key.mv_data, sizeof(ID) );
+                       ww->data.mv_size = data.mv_size;
+                       ww->data.mv_data = op->o_tmpalloc( data.mv_size, op->o_tmpmemctx );
+                       memcpy(ww->data.mv_data, data.mv_data, data.mv_size);
+               }
                mdb_txn_reset( ww->txn );
                ww->flag = 1;
        }
 }
 
+static int
+mdb_waitfixup( Operation *op, ww_ctx *ww, MDB_cursor *mci, MDB_cursor *mcd )
+{
+       int rc = 0;
+       ww->flag = 0;
+       mdb_txn_renew( ww->txn );
+       mdb_cursor_renew( ww->txn, mci );
+       mdb_cursor_renew( ww->txn, mcd );
+       if ( ww->mcd ) {
+               MDB_val key, data;
+               key.mv_size = sizeof(ID);
+               key.mv_data = &ww->key;
+               data = ww->data;
+               rc = mdb_cursor_get( mcd, &key, &data, MDB_GET_BOTH );
+               if ( rc == MDB_NOTFOUND ) {
+                       data = ww->data;
+                       rc = mdb_cursor_get( mcd, &key, &data, MDB_GET_BOTH_RANGE );
+                       /* the loop will skip this node using NEXT_DUP but we want it
+                        * sent, so go back one space first
+                        */
+                       if ( rc == MDB_SUCCESS )
+                               mdb_cursor_get( mcd, &key, &data, MDB_PREV_DUP );
+                       else
+                               rc = LDAP_BUSY;
+               } else if ( rc ) {
+                       rc = LDAP_OTHER;
+               }
+               op->o_tmpfree( ww->data.mv_data, op->o_tmpmemctx );
+               ww->data.mv_data = NULL;
+       }
+       return rc;
+}
+
 int
 mdb_search( Operation *op, SlapReply *rs )
 {
@@ -678,6 +732,7 @@ dn2entry_retry:
                        iscopes[0] = 0;
                }
 
+               wwctx.mcd = mcd;
                isc.id = base->e_id;
                isc.numrdns = 0;
                rc = mdb_dn2id_walk( op, &isc );
@@ -688,6 +743,7 @@ dn2entry_retry:
                cscope = 0;
        } else {
                id = mdb_idl_first( candidates, &cursor );
+               wwctx.mcd = NULL;
        }
 
        wwctx.flag = 0;
@@ -962,12 +1018,6 @@ notfound:
                        rs->sr_flags = 0;
 
                        send_search_reference( op, rs );
-                       if ( wwctx.flag ) {
-                               wwctx.flag = 0;
-                               mdb_txn_renew( ltid );
-                               mdb_cursor_renew( ltid, mci );
-                               mdb_cursor_renew( ltid, mcd );
-                       }
 
                        mdb_entry_return( op, e );
                        rs->sr_entry = NULL;
@@ -977,6 +1027,14 @@ notfound:
                        ber_bvarray_free( erefs );
                        rs->sr_ref = NULL;
 
+                       if ( wwctx.flag ) {
+                               rs->sr_err = mdb_waitfixup( op, &wwctx, mci, mcd );
+                               if ( rs->sr_err ) {
+                                       send_ldap_result( op, rs );
+                                       goto done;
+                               }
+                       }
+
                        goto loop_continue;
                }
 
@@ -1005,12 +1063,6 @@ notfound:
                                rs->sr_flags = 0;
                                rs->sr_err = LDAP_SUCCESS;
                                rs->sr_err = send_search_entry( op, rs );
-                               if ( wwctx.flag ) {
-                                       wwctx.flag = 0;
-                                       mdb_txn_renew( ltid );
-                                       mdb_cursor_renew( ltid, mci );
-                                       mdb_cursor_renew( ltid, mcd );
-                               }
                                rs->sr_attrs = NULL;
                                rs->sr_entry = NULL;
                                if (e != base)
@@ -1037,6 +1089,13 @@ notfound:
                                        }
                                        goto done;
                                }
+                               if ( wwctx.flag ) {
+                                       rs->sr_err = mdb_waitfixup( op, &wwctx, mci, mcd );
+                                       if ( rs->sr_err ) {
+                                               send_ldap_result( op, rs );
+                                               goto done;
+                                       }
+                               }
                        }
 
                } else {