From e1ec4de43f3fd812acee1f7c197cd73c929f7675 Mon Sep 17 00:00:00 2001
From: unknown <petr/cps@mysql.com/owlet.>
Date: Thu, 3 Aug 2006 17:23:37 +0400
Subject: [PATCH] Fix Bug #20139 Infinite loop after "FLUSH" and "LOCK tabX,
 general_log" Due to incorrect handling of FLUSH TABLES, log tables were
 marked for flush, but not reopened. Later we started to wait for the log
 table to be closed (disabled) after the flush. And as nobody disabled logs in
 concurrent treads, the command lasted forever. After internal consultations
 it was decided to skip logs during FLUSH TABLES. The reasoning is that
 logging is done in the "log device", whatever it is which is always active
 and controlled by FLUSH LOGS. So, to flush logs one should use FLUSH LOGS,
 and not FLUSH TABLES.

mysql-test/r/log_tables.result:
  update result file
mysql-test/t/log_tables.test:
  add a test for the bug
sql/sql_base.cc:
  Skip log tables during FLUSH TABLES
---
 mysql-test/r/log_tables.result |  5 +++++
 mysql-test/t/log_tables.test   | 10 ++++++++++
 sql/sql_base.cc                | 18 +++++++++++-------
 3 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/mysql-test/r/log_tables.result b/mysql-test/r/log_tables.result
index c61dd2247ee..c817c2752a0 100644
--- a/mysql-test/r/log_tables.result
+++ b/mysql-test/r/log_tables.result
@@ -72,3 +72,8 @@ sleep(2)
 select * from mysql.slow_log;
 start_time	user_host	query_time	lock_time	rows_sent	rows_examined	db	last_insert_id	insert_id	server_id	sql_text
 TIMESTAMP	USER_HOST	QUERY_TIME	00:00:00	1	0	test	0	0	1	select sleep(2)
+flush tables with read lock;
+unlock tables;
+use mysql;
+lock tables general_log read local, help_category read local;
+unlock tables;
diff --git a/mysql-test/t/log_tables.test b/mysql-test/t/log_tables.test
index 5b79e5e4625..236ef87e948 100644
--- a/mysql-test/t/log_tables.test
+++ b/mysql-test/t/log_tables.test
@@ -171,6 +171,16 @@ select sleep(2);
 --replace_column 1 TIMESTAMP 2 USER_HOST 3 QUERY_TIME
 select * from mysql.slow_log;
 
+#
+# Bug #20139 Infinite loop after "FLUSH" and "LOCK tabX, general_log"
+#
+
+flush tables with read lock;
+unlock tables;
+use mysql;
+lock tables general_log read local, help_category read local;
+unlock tables;
+
 # kill all connections
 disconnect con1;
 disconnect con2;
diff --git a/sql/sql_base.cc b/sql/sql_base.cc
index db11a3442c2..53ece79562a 100644
--- a/sql/sql_base.cc
+++ b/sql/sql_base.cc
@@ -1997,17 +1997,17 @@ TABLE *open_table(THD *thd, TABLE_LIST *table_list, MEM_ROOT *mem_root,
        table= (TABLE*) hash_next(&open_cache, (byte*) key, key_length,
                                  &state))
   {
-    if (table->s->version != refresh_version)
+    /*
+      Here we flush tables marked for flush. However we never flush log
+      tables here. They are flushed only on FLUSH LOGS.
+    */
+    if (table->s->version != refresh_version && !table->s->log_table)
     {
       DBUG_PRINT("note",
                  ("Found table '%s.%s' with different refresh version",
                   table_list->db, table_list->table_name));
 
-      /*
-        Don't close tables if we are working with a log table or were
-        asked not to close the table explicitly
-      */
-      if (flags & MYSQL_LOCK_IGNORE_FLUSH || table->s->log_table)
+      if (flags & MYSQL_LOCK_IGNORE_FLUSH)
       {
         /* Force close at once after usage */
         thd->version= table->s->version;
@@ -2346,7 +2346,11 @@ void close_old_data_files(THD *thd, TABLE *table, bool abort_locks,
 
   for (; table ; table=table->next)
   {
-    if (table->s->version != refresh_version)
+    /*
+      Reopen marked for flush. But close log tables. They are flushed only
+      explicitly on FLUSH LOGS
+    */
+    if (table->s->version != refresh_version && !table->s->log_table)
     {
       found=1;
       if (table->db_stat)