Add VTGate drain flag

go/flags/endtoend/vtgate.txt

@@ -141,6 +141,7 @@ Flags:
  --mysql_ldap_auth_config_string string JSON representation of LDAP server config.
  --mysql_ldap_auth_method string client-side authentication method to use. Supported values: mysql_clear_password, dialog. (default "mysql_clear_password")
  --mysql_server_bind_address string Binds on this address when listening to MySQL binary protocol. Useful to restrict listening to 'localhost' only for instance.
+ --mysql_server_drain_onterm If set, the server waits for --onterm_timeout for connected clients to drain
  --mysql_server_flush_delay duration Delay after which buffered response will be flushed to the client. (default 100ms)
  --mysql_server_port int If set, also listen for MySQL binary protocol connections on this port. (default -1)
  --mysql_server_query_timeout duration mysql query timeout

go/vt/servenv/run.go

@@ -59,7 +59,6 @@ func Run(bindAddress string, port int) {
  signal.Notify(ExitChan, syscall.SIGTERM, syscall.SIGINT)
  // Wait for signal
  <-ExitChan
- l.Close()
 
  startTime := time.Now()
  log.Infof("Entering lameduck mode for at least %v", timeouts.LameduckPeriod)
@@ -71,6 +70,7 @@ func Run(bindAddress string, port int) {
  log.Infof("Sleeping an extra %v after OnTermSync to finish lameduck period", remain)
  time.Sleep(remain)
  }
+ l.Close()
 
  log.Info("Shutting down gracefully")
  fireOnCloseHooks(timeouts.OnCloseTimeout)

go/vt/vtgate/plugin_mysql_server.go

@@ -75,6 +75,7 @@ var (
 
  mysqlDefaultWorkloadName = "OLTP"
  mysqlDefaultWorkload int32
+ mysqlDrainOnTerm bool
 
  mysqlServerFlushDelay = 100 * time.Millisecond
 )
@@ -102,6 +103,7 @@ func registerPluginFlags(fs *pflag.FlagSet) {
  fs.DurationVar(&mysqlKeepAlivePeriod, "mysql-server-keepalive-period", mysqlKeepAlivePeriod, "TCP period between keep-alives")
  fs.DurationVar(&mysqlServerFlushDelay, "mysql_server_flush_delay", mysqlServerFlushDelay, "Delay after which buffered response will be flushed to the client.")
  fs.StringVar(&mysqlDefaultWorkloadName, "mysql_default_workload", mysqlDefaultWorkloadName, "Default session workload (OLTP, OLAP, DBA)")
+ fs.BoolVar(&mysqlDrainOnTerm, "mysql_server_drain_onterm", mysqlDrainOnTerm, "If set, the server waits for --onterm_timeout for connected clients to drain")
 }
 
 // vtgateHandler implements the Listener interface.
@@ -633,6 +635,26 @@ func (srv *mysqlServer) shutdownMysqlProtocolAndDrain() {
  signal.Stop(srv.sigChan)
  }
 
+ if mysqlDrainOnTerm {
+ // We wait for connected clients to drain, instead of just
+ // active (in transaction) clients
+ if srv.vtgateHandle == nil {
+ // server never started properly?
+ return
+ }
+
+ log.Infof("Starting drain loop, waiting for all clients to disconnect")
+ reported := time.Now()
+ for srv.vtgateHandle.numConnections() > 0 {
+ if time.Since(reported) > 5*time.Second {
+ log.Infof("Still waiting for client connections to drain (%d connected)...", srv.vtgateHandle.numConnections())
+ reported = time.Now()
+ }
+ time.Sleep(1000 * time.Millisecond)
+ }
+ return
+ }
+
  if busy := srv.vtgateHandle.busyConnections.Load(); busy > 0 {
  log.Infof("Waiting for all client connections to be idle (%d active)...", busy)
  start := time.Now()