Partial for for lp bug 796647 - handle DELETED records in ha_rnd_next of backing table

mysql-test/suite/oqgraph/regression_796647c.result

+DROP TABLE IF EXISTS graph_base;
+DROP TABLE IF EXISTS graph;
+CREATE TABLE graph_base (
+from_id INT UNSIGNED NOT NULL,
+to_id INT UNSIGNED NOT NULL,
+PRIMARY KEY (from_id,to_id),
+INDEX (to_id)
+) ENGINE=MyISAM;
+CREATE TABLE graph (
+latch   VARCHAR(32) NULL,
+origid  BIGINT    UNSIGNED NULL,
+destid  BIGINT    UNSIGNED NULL,
+weight  DOUBLE    NULL,
+seq     BIGINT    UNSIGNED NULL,
+linkid  BIGINT    UNSIGNED NULL,
+KEY (latch, origid, destid) USING HASH,
+KEY (latch, destid, origid) USING HASH
+) ENGINE=OQGRAPH DATA_TABLE='graph_base' ORIGID='from_id', DESTID='to_id';
+INSERT INTO graph_base(from_id, to_id) VALUES (1,2), (2,1);
+SELECT count(*) FROM graph;
+count(*)
+2
+SELECT count(*) FROM graph_base;
+count(*)
+2
+INSERT INTO graph_base(from_id, to_id) VALUES (12,10);
+SELECT count(*) FROM graph;
+count(*)
+3
+SELECT count(*) FROM graph_base;
+count(*)
+3
+INSERT INTO graph_base(from_id, to_id) VALUES (14,13);
+SELECT count(*) FROM graph;
+count(*)
+4
+SELECT count(*) FROM graph_base;
+count(*)
+4
+DELETE FROM graph_base where from_id=10 and to_id=11;
+INSERT INTO graph_base(from_id, to_id) VALUES (10,15);
+INSERT INTO graph_base(from_id, to_id) VALUES (15,13);
+INSERT INTO graph_base(from_id, to_id) VALUES (10,11);
+SELECT count(*) FROM graph;
+count(*)
+7
+SELECT count(*) FROM graph_base;
+count(*)
+7
+INSERT INTO graph_base(from_id, to_id) VALUES (21,22);
+INSERT INTO graph_base (from_id,to_id) VALUES (4,6);
+SELECT count(*) FROM graph;
+count(*)
+9
+SELECT count(*) FROM graph_base;
+count(*)
+9
+SELECT * FROM graph  where latch='0';
+latch	origid	destid	weight	seq	linkid
+0	NULL	NULL	NULL	NULL	1
+0	NULL	NULL	NULL	NULL	2
+0	NULL	NULL	NULL	NULL	12
+0	NULL	NULL	NULL	NULL	10
+0	NULL	NULL	NULL	NULL	14
+0	NULL	NULL	NULL	NULL	13
+0	NULL	NULL	NULL	NULL	15
+0	NULL	NULL	NULL	NULL	11
+0	NULL	NULL	NULL	NULL	21
+0	NULL	NULL	NULL	NULL	22
+0	NULL	NULL	NULL	NULL	4
+0	NULL	NULL	NULL	NULL	6
+SELECT * FROM graph_base;
+from_id	to_id
+1	2
+2	1
+4	6
+10	11
+10	15
+12	10
+14	13
+15	13
+21	22
+# And delete all references to node 2
+DELETE FROM graph_base WHERE from_id=2;
+DELETE FROM graph_base WHERE to_id=2;
+SELECT count(*) FROM graph;
+count(*)
+7
+SELECT count(*) FROM graph_base;
+count(*)
+7
+SELECT * FROM graph  where latch='0';
+latch	origid	destid	weight	seq	linkid
+0	NULL	NULL	NULL	NULL	12
+0	NULL	NULL	NULL	NULL	10
+0	NULL	NULL	NULL	NULL	14
+0	NULL	NULL	NULL	NULL	13
+0	NULL	NULL	NULL	NULL	15
+0	NULL	NULL	NULL	NULL	11
+0	NULL	NULL	NULL	NULL	21
+0	NULL	NULL	NULL	NULL	22
+0	NULL	NULL	NULL	NULL	4
+0	NULL	NULL	NULL	NULL	6
+SELECT * FROM graph_base;
+from_id	to_id
+4	6
+10	11
+10	15
+12	10
+14	13
+15	13
+21	22
+DELETE FROM graph_base;
+SELECT count(*) FROM graph;
+count(*)
+0
+SELECT count(*) FROM graph_base;
+count(*)
+0
+SELECT * FROM graph  where latch='0';
+latch	origid	destid	weight	seq	linkid
+SELECT * FROM graph_base;
+from_id	to_id
+FLUSH TABLES;
+TRUNCATE TABLE graph_base;
+DROP TABLE graph_base;
+DROP TABLE graph;

mysql-test/suite/oqgraph/regression_796647c.test

@@ -53,20 +53,25 @@ INSERT INTO graph_base (from_id,to_id) VALUES (4,6);
 #-- we get a segfault
 SELECT count(*) FROM graph;
 SELECT count(*) FROM graph_base;
+SELECT * FROM graph  where latch='0';
+SELECT * FROM graph_base;
 
---echo # And delete all references to node 5
-DELETE FROM graph_base WHERE from_id=5;
-DELETE FROM graph_base WHERE from_id=3 AND to_id=5;
+--echo # And delete all references to node 2
+DELETE FROM graph_base WHERE from_id=2;
+DELETE FROM graph_base WHERE to_id=2;
 
-#-- The following queries would currently return incorrect results
-#-- 6 rows instead of 21
-#-- Maybe manifestation of https://bugs.launchpad.net/oqgraph/+bug/796647
---echo # This is currently bogus:
 SELECT count(*) FROM graph;
 SELECT count(*) FROM graph_base;
+SELECT * FROM graph  where latch='0';
+SELECT * FROM graph_base;
 
 DELETE FROM graph_base;
 
+SELECT count(*) FROM graph;
+SELECT count(*) FROM graph_base;
+SELECT * FROM graph  where latch='0';
+SELECT * FROM graph_base;
+
 #-- The following line would hang mysqld currently, see bug https://bugs.launchpad.net/oqgraph/+bug/1195735
 #-- SELECT * FROM graph;
 

storage/oqgraph/graphcore.cc

@@ -1111,8 +1111,18 @@ int edges_cursor::fetch_row(const row &row_info, row &result,
   {
     result= row_info;
     result.orig_indicator= result.dest_indicator= result.weight_indicator= 1;
-    result.orig= get(boost::vertex_index, share->g, source( *edge, share->g ) );
-    result.dest= get(boost::vertex_index, share->g, target( *edge, share->g ) );
+
+    oqgraph3::vertex_id orig = get(boost::vertex_index, share->g, source( *edge, share->g ) );
+    oqgraph3::vertex_id dest = get(boost::vertex_index, share->g, target( *edge, share->g ) );
+
+    // bug 796647c - may be symptomatic of a bigger problem with representation
+    // but origid and destid can be -1 indicating no such record, NULL? but oqgraph3::vertex_id
+    // seems to resolve to VertexID (unsigned) in row
+    // in any case we should check for errors (-1) in origid... because all edges have at least one vertex by definition
+    assert( ! ((size_t)orig == (size_t)-1 && (size_t)dest == (size_t)-1)); // indicates we havent handle a HA_ERR_RECORD_DELETED somewhere
+
+    result.orig= orig;
+    result.dest= dest;
     result.weight= get(boost::edge_weight, share->g, *edge);
     return oqgraph::OK;
   }

storage/oqgraph/ha_oqgraph.cc

@@ -1050,7 +1050,7 @@ int ha_oqgraph::fill_record(byte *record, const open_query::row &row)
 
 int ha_oqgraph::rnd_init(bool scan)
 {
-  edges->file->info(HA_STATUS_VARIABLE); // Fix for bug 1195735 - ensure we operate with up to date count!
+  edges->file->info(HA_STATUS_VARIABLE); // Fix for bug 1195735, hang after truncate table - ensure we operate with up to date count
   edges->prepare_for_position();
   return error_code(graph->random(scan));
 }
@@ -1060,14 +1060,7 @@ int ha_oqgraph::rnd_next(byte *buf)
   int res;
   open_query::row row = {};
 
-  // Problem: bug 1195735 - mysqld hang if we delete * from the underlying table, we get an infinite loop through here
-  // fetch_row() --> fetch_row() --> num_edges() --> _table->file->stats->records
-  // _table is actually a handle on the backing table we just deleted everything from.  so the statistics are out of date.
-  // so we really need to force a refresh on the backing store statistics, when starting a new query
-  // So we probably need to fix this bug in rnd_init
-  // Note, close() never called in between; this would otherwise clean things up
-
-  if (!(res= graph->fetch_row(row))) // FIXME - this called after DELETE FROM graph_base; hangs...
+  if (!(res= graph->fetch_row(row)))
     res= fill_record(buf, row);
   table->status= res ? STATUS_NOT_FOUND: 0;
   return error_code(res);

storage/oqgraph/oqgraph_thunk.cc

@@ -509,10 +509,14 @@ int oqgraph3::cursor::seek_to(
   }
   else
   {
-    if (int rc= table.file->ha_rnd_init(true))
+    int rc;
+    if ((rc= table.file->ha_rnd_init(true)))
       return clear_position(rc);
-    if (int rc= table.file->ha_rnd_next(table.record[0]))
-    {
+
+    // We need to skip over any deleted records we encounter. Bug 796647
+    while ( ((rc= table.file->ha_rnd_next(table.record[0]))) != 0) {
+      if (rc == HA_ERR_RECORD_DELETED)
+        continue;
       table.file->ha_rnd_end();
       return clear_position(rc);
     }