InitShardMaster: make it more idempotent

If ISM is retried, it's possible it gets stuck. The specific use
case where this happens is when the first attempt went past the
point where semi-sync gets enabled. If we retry ISM after that,
the part where we create the reparent journal table will hang
because the master will have semi-sync enabled, but no replica
will be pointing to it.

To overcome this, we always disable semi-sync when resetting
replication. All the code that enables replication turns semi
sync on as needed already.

Signed-off-by: Sugu Sougoumarane <ssougou@gmail.com>

go/mysql/flavor_mariadb.go

@@ -87,6 +87,7 @@ func (mariadbFlavor) resetReplicationCommands() []string {
 		"RESET SLAVE ALL", // "ALL" makes it forget master host:port.
 		"RESET MASTER",
 		"SET GLOBAL gtid_slave_pos = ''",
+		"SET GLOBAL rpl_semi_sync_master_enabled = false, GLOBAL rpl_semi_sync_slave_enabled = false", // semi-sync will be enabled if needed when slave is started.
 	}
 }
 

go/mysql/flavor_mysql.go

@@ -69,6 +69,7 @@ func (mysqlFlavor) resetReplicationCommands() []string {
 		"STOP SLAVE",
 		"RESET SLAVE ALL", // "ALL" makes it forget master host:port.
 		"RESET MASTER",    // This will also clear gtid_executed and gtid_purged.
+		"SET GLOBAL rpl_semi_sync_master_enabled = false, GLOBAL rpl_semi_sync_slave_enabled = false", // semi-sync will be enabled if needed when slave is started.
 	}
 }