flavor.go

/*
Copyright 2019 The Vitess Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package mysql

import (
	"errors"
	"fmt"
	"strconv"
	"strings"

	"context"

	"vitess.io/vitess/go/sqltypes"
	"vitess.io/vitess/go/vt/proto/vtrpc"
	"vitess.io/vitess/go/vt/vterrors"
)

var (
	// ErrNotReplica means there is no replication status.
	// Returned by ShowReplicationStatus().
	ErrNotReplica = errors.New("no replication status")

	// ErrNoMasterStatus means no status was returned by ShowMasterStatus().
	ErrNoMasterStatus = errors.New("no master status")
)

const (
	// mariaDBReplicationHackPrefix is the prefix of a version for MariaDB 10.0
	// versions, to work around replication bugs.
	mariaDBReplicationHackPrefix = "5.5.5-"
	// mariaDBVersionString is present in
	mariaDBVersionString = "MariaDB"
	// mysql57VersionPrefix is the prefix for 5.7 mysql version, such as 5.7.31-log
	mysql57VersionPrefix = "5.7."
	// mysql80VersionPrefix is the prefix for 8.0 mysql version, such as 8.0.19
	mysql80VersionPrefix = "8.0."
)

// flavor is the abstract interface for a flavor.
// Flavors are auto-detected upon connection using the server version.
// We have two major implementations (the main difference is the GTID
// handling):
// 1. Oracle MySQL 5.6, 5.7, 8.0, ...
// 2. MariaDB 10.X
type flavor interface {
	// masterGTIDSet returns the current GTIDSet of a server.
	masterGTIDSet(c *Conn) (GTIDSet, error)

	// startReplicationCommand returns the command to start the replication.
	startReplicationCommand() string

	// restartReplicationCommands returns the commands to stop, reset and start the replication.
	restartReplicationCommands() []string

	// startReplicationUntilAfter will restart replication, but only allow it
	// to run until `pos` is reached. After reaching pos, replication will be stopped again
	startReplicationUntilAfter(pos Position) string

	// stopReplicationCommand returns the command to stop the replication.
	stopReplicationCommand() string

	// stopIOThreadCommand returns the command to stop the replica's io thread only.
	stopIOThreadCommand() string

	// sendBinlogDumpCommand sends the packet required to start
	// dumping binlogs from the specified location.
	sendBinlogDumpCommand(c *Conn, serverID uint32, startPos Position) error

	// readBinlogEvent reads the next BinlogEvent from the connection.
	readBinlogEvent(c *Conn) (BinlogEvent, error)

	// resetReplicationCommands returns the commands to completely reset
	// replication on the host.
	resetReplicationCommands(c *Conn) []string

	// setReplicationPositionCommands returns the commands to set the
	// replication position at which the replica will resume.
	setReplicationPositionCommands(pos Position) []string

	// changeMasterArg returns the specific parameter to add to
	// a change master command.
	changeMasterArg() string

	// status returns the result of the appropriate status command,
	// with parsed replication position.
	status(c *Conn) (ReplicationStatus, error)

	// masterStatus returns the result of 'SHOW MASTER STATUS',
	// with parsed executed position.
	masterStatus(c *Conn) (MasterStatus, error)

	// waitUntilPositionCommand returns the SQL command to issue
	// to wait until the given position, until the context
	// expires.  The command returns -1 if it times out. It
	// returns NULL if GTIDs are not enabled.
	waitUntilPositionCommand(ctx context.Context, pos Position) (string, error)

	// enableBinlogPlaybackCommand and disableBinlogPlaybackCommand return an
	// optional command to run to enable or disable binlog
	// playback. This is used internally in Google, as the
	// timestamp cannot be set by regular clients.
	enableBinlogPlaybackCommand() string
	disableBinlogPlaybackCommand() string

	baseShowTablesWithSizes() string
}

// flavors maps flavor names to their implementation.
// Flavors need to register only if they support being specified in the
// connection parameters.
var flavors = make(map[string]func() flavor)

// fillFlavor fills in c.Flavor. If the params specify the flavor,
// that is used. Otherwise, we auto-detect.
//
// This is the same logic as the ConnectorJ java client. We try to recognize
// MariaDB as much as we can, but default to MySQL.
//
// MariaDB note: the server version returned here might look like:
// 5.5.5-10.0.21-MariaDB-...
// If that is the case, we are removing the 5.5.5- prefix.
// Note on such servers, 'select version()' would return 10.0.21-MariaDB-...
// as well (not matching what c.ServerVersion is, but matching after we remove
// the prefix).
func (c *Conn) fillFlavor(params *ConnParams) {
	flavorFunc := flavors[params.Flavor]

	switch {
	case flavorFunc != nil:
		c.flavor = flavorFunc()
	case strings.HasPrefix(c.ServerVersion, mariaDBReplicationHackPrefix):
		c.ServerVersion = c.ServerVersion[len(mariaDBReplicationHackPrefix):]
		c.flavor = mariadbFlavor101{}
	case strings.Contains(c.ServerVersion, mariaDBVersionString):
		mariadbVersion, err := strconv.ParseFloat(c.ServerVersion[:4], 64)
		if err != nil || mariadbVersion < 10.2 {
			c.flavor = mariadbFlavor101{}
		}
		c.flavor = mariadbFlavor102{}
	case strings.HasPrefix(c.ServerVersion, mysql57VersionPrefix):
		c.flavor = mysqlFlavor57{}
	case strings.HasPrefix(c.ServerVersion, mysql80VersionPrefix):
		c.flavor = mysqlFlavor80{}
	default:
		c.flavor = mysqlFlavor56{}
	}
}

//
// The following methods are dependent on the flavor.
// Only valid for client connections (will panic for server connections).
//

// IsMariaDB returns true iff the other side of the client connection
// is identified as MariaDB. Most applications should not care, but
// this is useful in tests.
func (c *Conn) IsMariaDB() bool {
	switch c.flavor.(type) {
	case mariadbFlavor101, mariadbFlavor102:
		return true
	}
	return false
}

// MasterPosition returns the current master replication position.
func (c *Conn) MasterPosition() (Position, error) {
	gtidSet, err := c.flavor.masterGTIDSet(c)
	if err != nil {
		return Position{}, err
	}
	return Position{
		GTIDSet: gtidSet,
	}, nil
}

// MasterFilePosition returns the current master's file based replication position.
func (c *Conn) MasterFilePosition() (Position, error) {
	filePosFlavor := filePosFlavor{}
	gtidSet, err := filePosFlavor.masterGTIDSet(c)
	if err != nil {
		return Position{}, err
	}
	return Position{
		GTIDSet: gtidSet,
	}, nil
}

// StartReplicationCommand returns the command to start the replication.
func (c *Conn) StartReplicationCommand() string {
	return c.flavor.startReplicationCommand()
}

// RestartReplicationCommands returns the commands to stop, reset and start the replication.
func (c *Conn) RestartReplicationCommands() []string {
	return c.flavor.restartReplicationCommands()
}

// StartReplicationUntilAfterCommand returns the command to start the replication.
func (c *Conn) StartReplicationUntilAfterCommand(pos Position) string {
	return c.flavor.startReplicationUntilAfter(pos)
}

// StopReplicationCommand returns the command to stop the replication.
func (c *Conn) StopReplicationCommand() string {
	return c.flavor.stopReplicationCommand()
}

// StopIOThreadCommand returns the command to stop the replica's io thread.
func (c *Conn) StopIOThreadCommand() string {
	return c.flavor.stopIOThreadCommand()
}

// SendBinlogDumpCommand sends the flavor-specific version of
// the COM_BINLOG_DUMP command to start dumping raw binlog
// events over a server connection, starting at a given GTID.
func (c *Conn) SendBinlogDumpCommand(serverID uint32, startPos Position) error {
	return c.flavor.sendBinlogDumpCommand(c, serverID, startPos)
}

// ReadBinlogEvent reads the next BinlogEvent. This must be used
// in conjunction with SendBinlogDumpCommand.
func (c *Conn) ReadBinlogEvent() (BinlogEvent, error) {
	return c.flavor.readBinlogEvent(c)
}

// ResetReplicationCommands returns the commands to completely reset
// replication on the host.
func (c *Conn) ResetReplicationCommands() []string {
	return c.flavor.resetReplicationCommands(c)
}

// SetReplicationPositionCommands returns the commands to set the
// replication position at which the replica will resume
// when it is later reparented with SetMasterCommands.
func (c *Conn) SetReplicationPositionCommands(pos Position) []string {
	return c.flavor.setReplicationPositionCommands(pos)
}

// SetMasterCommand returns the command to use the provided master
// as the new master (without changing any GTID position).
// It is guaranteed to be called with replication stopped.
// It should not start or stop replication.
func (c *Conn) SetMasterCommand(params *ConnParams, masterHost string, masterPort int, masterConnectRetry int) string {
	args := []string{
		fmt.Sprintf("MASTER_HOST = '%s'", masterHost),
		fmt.Sprintf("MASTER_PORT = %d", masterPort),
		fmt.Sprintf("MASTER_USER = '%s'", params.Uname),
		fmt.Sprintf("MASTER_PASSWORD = '%s'", params.Pass),
		fmt.Sprintf("MASTER_CONNECT_RETRY = %d", masterConnectRetry),
	}
	if params.SslEnabled() {
		args = append(args, "MASTER_SSL = 1")
	}
	if params.SslCa != "" {
		args = append(args, fmt.Sprintf("MASTER_SSL_CA = '%s'", params.SslCa))
	}
	if params.SslCaPath != "" {
		args = append(args, fmt.Sprintf("MASTER_SSL_CAPATH = '%s'", params.SslCaPath))
	}
	if params.SslCert != "" {
		args = append(args, fmt.Sprintf("MASTER_SSL_CERT = '%s'", params.SslCert))
	}
	if params.SslKey != "" {
		args = append(args, fmt.Sprintf("MASTER_SSL_KEY = '%s'", params.SslKey))
	}
	args = append(args, c.flavor.changeMasterArg())
	return "CHANGE MASTER TO\n  " + strings.Join(args, ",\n  ")
}

// resultToMap is a helper function used by ShowReplicationStatus.
func resultToMap(qr *sqltypes.Result) (map[string]string, error) {
	if len(qr.Rows) == 0 {
		// The query succeeded, but there is no data.
		return nil, nil
	}
	if len(qr.Rows) > 1 {
		return nil, vterrors.Errorf(vtrpc.Code_INTERNAL, "query returned %d rows, expected 1", len(qr.Rows))
	}
	if len(qr.Fields) != len(qr.Rows[0]) {
		return nil, vterrors.Errorf(vtrpc.Code_INTERNAL, "query returned %d column names, expected %d", len(qr.Fields), len(qr.Rows[0]))
	}

	result := make(map[string]string, len(qr.Fields))
	for i, field := range qr.Fields {
		result[field.Name] = qr.Rows[0][i].ToString()
	}
	return result, nil
}

// parseReplicationStatus parses the common (non-flavor-specific) fields of ReplicationStatus
func parseReplicationStatus(fields map[string]string) ReplicationStatus {
	status := ReplicationStatus{
		MasterHost: fields["Master_Host"],
		// These fields are returned from the underlying DB and cannot be renamed
		IOThreadRunning:  fields["Slave_IO_Running"] == "Yes" || fields["Slave_IO_Running"] == "Connecting",
		SQLThreadRunning: fields["Slave_SQL_Running"] == "Yes",
	}
	parseInt, _ := strconv.ParseInt(fields["Master_Port"], 10, 0)
	status.MasterPort = int(parseInt)
	parseInt, _ = strconv.ParseInt(fields["Connect_Retry"], 10, 0)
	status.MasterConnectRetry = int(parseInt)
	parseUint, _ := strconv.ParseUint(fields["Seconds_Behind_Master"], 10, 0)
	status.SecondsBehindMaster = uint(parseUint)
	parseUint, _ = strconv.ParseUint(fields["Master_Server_Id"], 10, 0)
	status.MasterServerID = uint(parseUint)

	execMasterLogPosStr := fields["Exec_Master_Log_Pos"]
	file := fields["Relay_Master_Log_File"]
	if file != "" && execMasterLogPosStr != "" {
		filePos, err := strconv.Atoi(execMasterLogPosStr)
		if err == nil {
			status.FilePosition.GTIDSet = filePosGTID{
				file: file,
				pos:  filePos,
			}
		}
	}

	readMasterLogPosStr := fields["Read_Master_Log_Pos"]
	file = fields["Master_Log_File"]
	if file != "" && readMasterLogPosStr != "" {
		fileRelayPos, err := strconv.Atoi(readMasterLogPosStr)
		if err == nil {
			status.FileRelayLogPosition.GTIDSet = filePosGTID{
				file: file,
				pos:  fileRelayPos,
			}
		}
	}
	return status
}

// ShowReplicationStatus executes the right command to fetch replication status,
// and returns a parsed Position with other fields.
func (c *Conn) ShowReplicationStatus() (ReplicationStatus, error) {
	return c.flavor.status(c)
}

// parseMasterStatus parses the common fields of SHOW MASTER STATUS.
func parseMasterStatus(fields map[string]string) MasterStatus {
	status := MasterStatus{}

	fileExecPosStr := fields["Position"]
	file := fields["File"]
	if file != "" && fileExecPosStr != "" {
		filePos, err := strconv.Atoi(fileExecPosStr)
		if err == nil {
			status.FilePosition.GTIDSet = filePosGTID{
				file: file,
				pos:  filePos,
			}
		}
	}

	return status
}

// ShowMasterStatus executes the right SHOW MASTER STATUS command,
// and returns a parsed executed Position, as well as file based Position.
func (c *Conn) ShowMasterStatus() (MasterStatus, error) {
	return c.flavor.masterStatus(c)
}

// WaitUntilPositionCommand returns the SQL command to issue
// to wait until the given position, until the context
// expires.  The command returns -1 if it times out. It
// returns NULL if GTIDs are not enabled.
func (c *Conn) WaitUntilPositionCommand(ctx context.Context, pos Position) (string, error) {
	return c.flavor.waitUntilPositionCommand(ctx, pos)
}

// WaitUntilFilePositionCommand returns the SQL command to issue
// to wait until the given position, until the context
// expires for the file position flavor.  The command returns -1 if it times out. It
// returns NULL if GTIDs are not enabled.
func (c *Conn) WaitUntilFilePositionCommand(ctx context.Context, pos Position) (string, error) {
	filePosFlavor := filePosFlavor{}
	return filePosFlavor.waitUntilPositionCommand(ctx, pos)
}

// EnableBinlogPlaybackCommand returns a command to run to enable
// binlog playback.
func (c *Conn) EnableBinlogPlaybackCommand() string {
	return c.flavor.enableBinlogPlaybackCommand()
}

// DisableBinlogPlaybackCommand returns a command to run to disable
// binlog playback.
func (c *Conn) DisableBinlogPlaybackCommand() string {
	return c.flavor.disableBinlogPlaybackCommand()
}

// BaseShowTables returns a query that shows tables and their sizes
func (c *Conn) BaseShowTables() string {
	return c.flavor.baseShowTablesWithSizes()
}