Bug#26589008 SYNC_BINLOG=0 SHOULD IGNORE BINLOG_GROUP_COMMIT_SYNC_DELAY

Problem: When sync_binlog=0, sync stage in binlog group commit is
         never reached. But still each binlog group is waiting for
         BINLOG_GROUP_COMMIT_SYNC_DELAY seconds before entering into
         sync stage.

Fix: Now the code is changed in such a way that the waiting logic considers
     sync_binlog=0 case and skips delay logic in such case.

Author: Venkatesh Duggirala

mysql-test/suite/binlog/r/binlog_group_commit_sync_delay.result

@@ -8,6 +8,10 @@ SET GLOBAL sync_binlog=1000;
 SET @clock_in = SYSDATE();
 SET @elapsed = TIMESTAMPDIFF(MICROSECOND, @clock_in, SYSDATE());
 include/assert.inc ["Assert that the above statements should not take more than 1000 seconds"]
+SET GLOBAL sync_binlog=0;
+SET @clock_in = SYSDATE();
+SET @elapsed = TIMESTAMPDIFF(MICROSECOND, @clock_in, SYSDATE());
+include/assert.inc ["Assert that the above statements should not take more than 1000 seconds"]
 SET GLOBAL binlog_group_commit_sync_delay=0;
 SET GLOBAL sync_binlog=1;
 DROP TABLE t1;

mysql-test/suite/binlog/t/binlog_group_commit_sync_delay.test

@@ -29,23 +29,37 @@ SET @elapsed = TIMESTAMPDIFF(MICROSECOND, @clock_in, SYSDATE());
 # But with fix, it should not take more than few seconds (that depends
 # on Pb2 machine speed and also depends on various build options too.
 #
+# Do above experiment with two iterations
+#  1) When sync_binlog > 1 (i.e., with 1000)
+#  2) When sync_binlog = 0
+#
 --let $group_count=1000
---eval SET GLOBAL sync_binlog=$group_count
---let $i=0
-
-SET @clock_in = SYSDATE();
---disable_query_log
-while ($i <= $group_count)
+--let $iter=1
+while ($iter <= 2)
 {
-  --eval INSERT INTO t1 VALUES ($i)
-  --inc $i
+  if ($iter == 1)
+  {
+    --eval SET GLOBAL sync_binlog=$group_count
+  }
+  if ($iter == 2)
+  {
+    --eval SET GLOBAL sync_binlog=0
+  }
+  --let $i=0
+  SET @clock_in = SYSDATE();
+  --disable_query_log
+  while ($i <= $group_count)
+  {
+    --eval INSERT INTO t1 VALUES ($i)
+    --inc $i
+  }
+  --enable_query_log
+  SET @elapsed = TIMESTAMPDIFF(MICROSECOND, @clock_in, SYSDATE());
+  --let $assert_text="Assert that the above statements should not take more than 1000 seconds"
+  --let $assert_cond= [SELECT @elapsed < 1000 * @@GLOBAL.binlog_group_commit_sync_delay]
+  --source include/assert.inc
+  --inc $iter
 }
---enable_query_log
-SET @elapsed = TIMESTAMPDIFF(MICROSECOND, @clock_in, SYSDATE());
---let $assert_text="Assert that the above statements should not take more than 1000 seconds"
---let $assert_cond= [SELECT @elapsed < 1000 * @@GLOBAL.binlog_group_commit_sync_delay]
---source include/assert.inc
-
 # End of Bug#21420180 test
 
 # Cleanup

sql/binlog.cc

@@ -9157,6 +9157,7 @@ int MYSQL_BIN_LOG::ordered_commit(THD *thd, bool all, bool skip_commit)
   int flush_error= 0, sync_error= 0;
   my_off_t total_bytes= 0;
   bool do_rotate= false;
+  unsigned int current_sync_period;
 
   /*
     These values are used while flushing a transaction, so clear
@@ -9304,7 +9305,8 @@ int MYSQL_BIN_LOG::ordered_commit(THD *thd, bool all, bool skip_commit)
     in this ongoing SYNC stage. The "+1" used below in the
     if condition is to count the ongoing sync stage.
   */
-  if (!flush_error && (sync_counter + 1 >= get_sync_period()))
+  current_sync_period= get_sync_period();
+  if (!flush_error && current_sync_period && (sync_counter + 1 >= current_sync_period))
     stage_manager.wait_count_or_timeout(opt_binlog_group_commit_sync_no_delay_count,
                                         opt_binlog_group_commit_sync_delay,
                                         Stage_manager::SYNC_STAGE);