bk commit into 5.0 tree (evgen:1.1918) BUG#11934

[eugene]

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ChangeSet
  1.1918 05/08/03 02:01:27 evgen@stripped +3 -0
  Fix bug #11934 Two sequential FLUSH TABLES WITH READ LOCK hangs client
  
  Bug was introduced by cset 1.1659.14.1. Before it server was silently
  ignoring that lock can't be acquired because it already acquired.
  
  This patch makes make_global_read_lock_block_commit() return without error
  if lock already acquired.

  sql/lock.cc
    1.75 05/08/03 01:40:17 evgen@stripped +1 -1
    Fix bug #11934 Two sequential FLUSH TABLES WITH READ LOCK hangs client.
    Make make_global_read_lock_block_commit() return without error if lock already
acquired.

  mysql-test/r/flush_table.result
    1.6 05/08/02 23:35:46 evgen@stripped +3 -0
    Test case for bug#11934 FLUSH TABLES WITH READ LOCK hangs client.

  mysql-test/t/flush_table.test
    1.9 05/08/02 23:34:13 evgen@stripped +7 -0
    Test case for bug#11934 FLUSH TABLES WITH READ LOCK hangs client.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	evgen
# Host:	moonbone.local
# Root:	/work/mysql-5.0-bug-11934

--- 1.74/sql/lock.cc	2005-07-28 22:39:14 +04:00
+++ 1.75/sql/lock.cc	2005-08-03 01:40:17 +04:00
@@ -990,7 +990,7 @@
     make_global_read_lock_block_commit(), do nothing.
   */
   if (thd->global_read_lock != GOT_GLOBAL_READ_LOCK)
-    DBUG_RETURN(1);
+    DBUG_RETURN(0);
   pthread_mutex_lock(&LOCK_global_read_lock);
   /* increment this BEFORE waiting on cond (otherwise race cond) */
   global_read_lock_blocks_commit++;

--- 1.5/mysql-test/r/flush_table.result	2004-10-07 11:50:09 +04:00
+++ 1.6/mysql-test/r/flush_table.result	2005-08-02 23:35:46 +04:00
@@ -101,3 +101,6 @@
 Record-02
 handler t1 close;
 drop table t1;
+FLUSH TABLES WITH READ LOCK ;
+FLUSH TABLES WITH READ LOCK ;
+UNLOCK TABLES;

--- 1.8/mysql-test/t/flush_table.test	2005-07-28 04:21:41 +04:00
+++ 1.9/mysql-test/t/flush_table.test	2005-08-02 23:34:13 +04:00
@@ -73,4 +73,11 @@
 handler t1 close;
 drop table t1;
 
+#
+# Bug #11934 Two sequential FLUSH TABLES WITH READ LOCK hangs client
+#
+FLUSH TABLES WITH READ LOCK ;
+FLUSH TABLES WITH READ LOCK ;
+UNLOCK TABLES;
+
 # End of 4.1 tests