sink/mysql: rollback txn to recycle db conn, refine timeout param in db conn (#1279)

cdc/sink/mysql.go

@@ -62,6 +62,7 @@ const (
 	defaultBatchReplaceSize    = 20
 	defaultReadTimeout         = "2m"
 	defaultWriteTimeout        = "2m"
+	defaultDialTimeout         = "2m"
 	defaultSafeMode            = true
 )
 
@@ -286,6 +287,7 @@ type sinkParams struct {
 	batchReplaceSize    int
 	readTimeout         string
 	writeTimeout        string
+	dialTimeout         string
 	enableOldValue      bool
 	safeMode            bool
 	timezone            string
@@ -305,6 +307,7 @@ var defaultParams = &sinkParams{
 	batchReplaceSize:    defaultBatchReplaceSize,
 	readTimeout:         defaultReadTimeout,
 	writeTimeout:        defaultWriteTimeout,
+	dialTimeout:         defaultDialTimeout,
 	safeMode:            defaultSafeMode,
 }
 
@@ -343,6 +346,7 @@ func configureSinkURI(
 	}
 	dsnCfg.Params["readTimeout"] = params.readTimeout
 	dsnCfg.Params["writeTimeout"] = params.writeTimeout
+	dsnCfg.Params["timeout"] = params.dialTimeout
 
 	autoRandom, err := checkTiDBVariable(ctx, testDB, "allow_auto_random_explicit_insert", "1")
 	if err != nil {
@@ -467,6 +471,23 @@ func parseSinkURI(ctx context.Context, sinkURI *url.URL, opts map[string]string)
 		params.timezone = fmt.Sprintf(`"%s"`, tz.String())
 	}
 
+	// read, write, and dial timeout for each individual connection, equals to
+	// readTimeout, writeTimeout, timeout in go mysql driver respectively.
+	// ref: https://github.com/go-sql-driver/mysql#connection-pool-and-timeouts
+	// To keep the same style with other sink parameters, we use dash as word separator.
+	s = sinkURI.Query().Get("read-timeout")
+	if s != "" {
+		params.readTimeout = s
+	}
+	s = sinkURI.Query().Get("write-timeout")
+	if s != "" {
+		params.writeTimeout = s
+	}
+	s = sinkURI.Query().Get("timeout")
+	if s != "" {
+		params.dialTimeout = s
+	}
+
 	return params, nil
 }
 
@@ -480,6 +501,10 @@ func getDBConn(ctx context.Context, dsnStr string) (*sql.DB, error) {
 	}
 	err = db.PingContext(ctx)
 	if err != nil {
+		// close db to recycle resources
+		if closeErr := db.Close(); closeErr != nil {
+			log.Warn("close db failed", zap.Error(err))
+		}
 		return nil, errors.Annotate(
 			cerror.WrapError(cerror.ErrMySQLConnectionError, err), "fail to open MySQL connection")
 	}
@@ -528,6 +553,9 @@ func newMySQLSink(
 	if params.timezone != "" {
 		dsn.Params["time_zone"] = params.timezone
 	}
+	dsn.Params["readTimeout"] = params.readTimeout
+	dsn.Params["writeTimeout"] = params.writeTimeout
+	dsn.Params["timeout"] = params.dialTimeout
 	testDB, err := getDBConnImpl(ctx, dsn.FormatDSN())
 	if err != nil {
 		return nil, err
@@ -815,12 +843,18 @@ func (s *mysqlSink) execDMLWithMaxRetries(
 					args := dmls.values[i]
 					log.Debug("exec row", zap.String("sql", query), zap.Any("args", args))
 					if _, err := tx.ExecContext(ctx, query, args...); err != nil {
+						if rbErr := tx.Rollback(); rbErr != nil {
+							log.Warn("failed to rollback txn", zap.Error(err))
+						}
 						return 0, checkTxnErr(cerror.WrapError(cerror.ErrMySQLTxnError, err))
 					}
 				}
 				if len(dmls.markSQL) != 0 {
 					log.Debug("exec row", zap.String("sql", dmls.markSQL))
 					if _, err := tx.ExecContext(ctx, dmls.markSQL); err != nil {
+						if rbErr := tx.Rollback(); rbErr != nil {
+							log.Warn("failed to rollback txn", zap.Error(err))
+						}
 						return 0, checkTxnErr(cerror.WrapError(cerror.ErrMySQLTxnError, err))
 					}
 				}