refs codership/mysql-wsrep#201

- Eliminates code duplication in query cache patch
- Reduces the number of iterations in mysql-wsrep#201.test
  to shorten the execution time
- Adds a new test case that exercises more scenarios

mysql-test/suite/galera/r/galera_query_cache_sync_wait.result

+CREATE TABLE t1 (id INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+SET GLOBAL wsrep_provider_options = "repl.causal_read_timeout=PT1S";
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+SET SESSION wsrep_sync_wait = 7;
+SELECT MAX(id) FROM t1;
+MAX(id)
+1
+INSERT INTO t1 VALUES (2);
+SELECT MAX(id) FROM t1;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+FLUSH QUERY CACHE;
+SET SESSION wsrep_sync_wait = 7;
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+INSERT INTO t1 VALUES (3);
+SELECT MAX(id) FROM t1;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+INSERT INTO t1 VALUES (4);
+SET SESSION wsrep_sync_wait = 7;
+SELECT MAX(id) FROM t1;
+MAX(id)
+4
+SET SESSION wsrep_sync_wait = 7;
+FLUSH STATUS;
+SELECT MAX(id) FROM t1;
+MAX(id)
+4
+SELECT VARIABLE_VALUE = 1 FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME = 'Qcache_hits';
+VARIABLE_VALUE = 1
+1
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+INSERT INTO t1 VALUES (5);
+SET SESSION wsrep_sync_wait = 7;
+SELECT MAX(id) FROM t1 ;
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+MAX(id)
+5
+SELECT VARIABLE_VALUE = 1 FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME = 'Qcache_hits';
+VARIABLE_VALUE = 1
+1

mysql-test/suite/galera/t/galera_query_cache_sync_wait-master.opt

+--query_cache_type=1

mysql-test/suite/galera/t/galera_query_cache_sync_wait.test

+--source include/galera_cluster.inc
+--source include/have_innodb.inc
+--source include/have_debug_sync.inc
+--source include/have_query_cache.inc
+
+CREATE TABLE t1 (id INT PRIMARY KEY AUTO_INCREMENT) ENGINE=InnoDB;
+INSERT INTO t1 VALUES (1);
+
+--connection node_2
+--let $wsrep_provider_options_orig = `SELECT @@wsrep_provider_options`
+SET GLOBAL wsrep_provider_options = "repl.causal_read_timeout=PT1S";
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+SET SESSION wsrep_sync_wait = 7;
+SELECT MAX(id) FROM t1; # first lookup miss
+
+#
+# Query cache hit, wait timeout
+#
+
+--connection node_1
+INSERT INTO t1 VALUES (2);
+
+--connection node_2
+--error ER_LOCK_WAIT_TIMEOUT
+SELECT MAX(id) FROM t1;
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+
+FLUSH QUERY CACHE;
+SET SESSION wsrep_sync_wait = 7;
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+
+#
+# Query cache miss, wait timeout
+#
+
+--connection node_1
+INSERT INTO t1 VALUES (3);
+
+--connection node_2
+--error ER_LOCK_WAIT_TIMEOUT
+SELECT MAX(id) FROM t1;
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+
+#
+# Query cache miss
+#
+
+--connection node_1
+INSERT INTO t1 VALUES (4);
+
+--connection node_2
+SET SESSION wsrep_sync_wait = 7;
+SELECT MAX(id) FROM t1;
+SET SESSION wsrep_sync_wait = 7;
+
+#
+# Query cache hit
+#
+
+FLUSH STATUS;
+SELECT MAX(id) FROM t1;
+SELECT VARIABLE_VALUE = 1 FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME = 'Qcache_hits';
+SET GLOBAL DEBUG = "d,sync.wsrep_apply_cb";
+
+#
+# Query cache invalidated
+#
+
+--connection node_1
+INSERT INTO t1 VALUES (5);
+
+--connection node_2
+SET SESSION wsrep_sync_wait = 7;
+--send SELECT MAX(id) FROM t1 
+
+--connect node_2a, 127.0.0.1, root, , test, $NODE_MYPORT_2
+--connection node_2a
+SET GLOBAL DEBUG = "";
+SET DEBUG_SYNC = "now SIGNAL signal.wsrep_apply_cb";
+
+--connection node_2
+--reap
+SELECT VARIABLE_VALUE = 1 FROM INFORMATION_SCHEMA.SESSION_STATUS WHERE VARIABLE_NAME = 'Qcache_hits';
+
+
+--disable_query_log
+--eval SET GLOBAL wsrep_provider_options = "$wsrep_provider_options_orig"
+DROP TABLE t1;

mysql-test/suite/galera/t/mysql-wsrep#201.test

@@ -12,7 +12,7 @@ SET SESSION wsrep_sync_wait = 7;
 
 --disable_query_log
 
---let $count = 10000
+--let $count = 500
 while ($count)
 {
   --connection node_1

sql/sql_cache.cc

@@ -1804,7 +1804,6 @@ Query_cache::send_result_to_client(THD *thd, char *org_sql, uint query_length)
       goto err;
     }
   }
-
   /*
     Try to obtain an exclusive lock on the query cache. If the cache is
     disabled or if a full cache flush is in progress, the attempt to
@@ -1904,6 +1903,13 @@ def_week_frmt: %lu, in_trans: %d, autocommit: %d",
                           (int)flags.autocommit));
   memcpy((uchar *)(sql + (tot_length - QUERY_CACHE_FLAGS_SIZE)),
 	 (uchar*) &flags, QUERY_CACHE_FLAGS_SIZE);
+
+#ifdef WITH_WSREP
+  bool once_more;
+  once_more= true;
+lookup:
+#endif /* WITH_WSREP */
+
   query_block = (Query_cache_block *)  my_hash_search(&queries, (uchar*) sql,
                                                       tot_length);
   /* Quick abort on unlocked data */
@@ -1917,21 +1923,15 @@ def_week_frmt: %lu, in_trans: %d, autocommit: %d",
   DBUG_PRINT("qcache", ("Query in query hash 0x%lx", (ulong)query_block));
 
 #ifdef WITH_WSREP
-  if (WSREP_CLIENT(thd) && wsrep_must_sync_wait(thd)) {
+  if (once_more && WSREP_CLIENT(thd) && wsrep_must_sync_wait(thd))
+  {
     unlock();
     if (wsrep_sync_wait(thd))
       goto err;
     if (try_lock(TRUE))
       goto err;
-    query_block = (Query_cache_block *) my_hash_search(&queries,
-                                                       (uchar*) sql,
-                                                       tot_length);
-    if (query_block == 0 ||
-        query_block->query()->result() == 0 ||
-        query_block->query()->result()->type != Query_cache_block::RESULT)
-    {
-      goto err_unlock;
-    }
+    once_more= false;
+    goto lookup;
   }
 #endif /* WITH_WSREP */