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replication.go
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replication.go
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// Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
/*
Handle creating replicas and setting up the replication streams.
*/
package mysqlctl
import (
"bytes"
"errors"
"fmt"
"strconv"
"strings"
"text/template"
"time"
log "github.com/golang/glog"
"github.com/youtube/vitess/go/mysql"
"github.com/youtube/vitess/go/netutil"
"github.com/youtube/vitess/go/sqldb"
"github.com/youtube/vitess/go/vt/dbconfigs"
"github.com/youtube/vitess/go/vt/hook"
"github.com/youtube/vitess/go/vt/mysqlctl/replication"
)
const (
// SQLStartSlave is the SQl command issued to start MySQL replication
SQLStartSlave = "START SLAVE"
// SQLStopSlave is the SQl command issued to stop MySQL replication
SQLStopSlave = "STOP SLAVE"
)
func fillStringTemplate(tmpl string, vars interface{}) (string, error) {
myTemplate := template.Must(template.New("").Parse(tmpl))
data := new(bytes.Buffer)
if err := myTemplate.Execute(data, vars); err != nil {
return "", err
}
return data.String(), nil
}
func changeMasterArgs(params *sqldb.ConnParams, masterHost string, masterPort int, masterConnectRetry int) []string {
var args []string
args = append(args, fmt.Sprintf("MASTER_HOST = '%s'", masterHost))
args = append(args, fmt.Sprintf("MASTER_PORT = %d", masterPort))
args = append(args, fmt.Sprintf("MASTER_USER = '%s'", params.Uname))
args = append(args, fmt.Sprintf("MASTER_PASSWORD = '%s'", params.Pass))
args = append(args, fmt.Sprintf("MASTER_CONNECT_RETRY = %d", masterConnectRetry))
if mysql.SslEnabled(params) {
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))
}
return args
}
// parseSlaveStatus parses the common fields of SHOW SLAVE STATUS.
func parseSlaveStatus(fields map[string]string) replication.Status {
status := replication.Status{
MasterHost: fields["Master_Host"],
SlaveIORunning: fields["Slave_IO_Running"] == "Yes",
SlaveSQLRunning: 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)
return status
}
// WaitForSlaveStart waits until the deadline for replication to start.
// This validates the current master is correct and can be connected to.
func WaitForSlaveStart(mysqld MysqlDaemon, slaveStartDeadline int) error {
var rowMap map[string]string
for slaveWait := 0; slaveWait < slaveStartDeadline; slaveWait++ {
status, err := mysqld.SlaveStatus()
if err != nil {
return err
}
if status.SlaveRunning() {
return nil
}
time.Sleep(time.Second)
}
errorKeys := []string{"Last_Error", "Last_IO_Error", "Last_SQL_Error"}
errs := make([]string, 0, len(errorKeys))
for _, key := range errorKeys {
if rowMap[key] != "" {
errs = append(errs, key+": "+rowMap[key])
}
}
if len(errs) != 0 {
return errors.New(strings.Join(errs, ", "))
}
return nil
}
// StartSlave starts a slave on the provided MysqldDaemon
func StartSlave(md MysqlDaemon, hookExtraEnv map[string]string) error {
if err := md.ExecuteSuperQueryList([]string{SQLStartSlave}); err != nil {
return err
}
h := hook.NewSimpleHook("postflight_start_slave")
h.ExtraEnv = hookExtraEnv
return h.ExecuteOptional()
}
// StopSlave stops a slave on the provided MysqldDaemon
func StopSlave(md MysqlDaemon, hookExtraEnv map[string]string) error {
h := hook.NewSimpleHook("preflight_stop_slave")
h.ExtraEnv = hookExtraEnv
if err := h.ExecuteOptional(); err != nil {
return err
}
return md.ExecuteSuperQueryList([]string{SQLStopSlave})
}
// GetMysqlPort returns mysql port
func (mysqld *Mysqld) GetMysqlPort() (int32, error) {
qr, err := mysqld.FetchSuperQuery("SHOW VARIABLES LIKE 'port'")
if err != nil {
return 0, err
}
if len(qr.Rows) != 1 {
return 0, errors.New("no port variable in mysql")
}
utemp, err := strconv.ParseUint(qr.Rows[0][1].String(), 10, 16)
if err != nil {
return 0, err
}
return int32(utemp), nil
}
// IsReadOnly return true if the instance is read only
func (mysqld *Mysqld) IsReadOnly() (bool, error) {
qr, err := mysqld.FetchSuperQuery("SHOW VARIABLES LIKE 'read_only'")
if err != nil {
return true, err
}
if len(qr.Rows) != 1 {
return true, errors.New("no read_only variable in mysql")
}
if qr.Rows[0][1].String() == "ON" {
return true, nil
}
return false, nil
}
// SetReadOnly set/unset the read_only flag
func (mysqld *Mysqld) SetReadOnly(on bool) error {
query := "SET GLOBAL read_only = "
if on {
query += "ON"
} else {
query += "OFF"
}
return mysqld.ExecuteSuperQuery(query)
}
var (
// ErrNotSlave means there is no slave status
ErrNotSlave = errors.New("no slave status")
// ErrNotMaster means there is no master status
ErrNotMaster = errors.New("no master status")
)
// WaitMasterPos lets slaves wait to given replication position
func (mysqld *Mysqld) WaitMasterPos(targetPos replication.Position, waitTimeout time.Duration) error {
flavor, err := mysqld.flavor()
if err != nil {
return fmt.Errorf("WaitMasterPos needs flavor: %v", err)
}
return flavor.WaitMasterPos(mysqld, targetPos, waitTimeout)
}
// SlaveStatus returns the slave replication statuses
func (mysqld *Mysqld) SlaveStatus() (replication.Status, error) {
flavor, err := mysqld.flavor()
if err != nil {
return replication.Status{}, fmt.Errorf("SlaveStatus needs flavor: %v", err)
}
return flavor.SlaveStatus(mysqld)
}
// MasterPosition returns master replication position
func (mysqld *Mysqld) MasterPosition() (rp replication.Position, err error) {
flavor, err := mysqld.flavor()
if err != nil {
return rp, fmt.Errorf("MasterPosition needs flavor: %v", err)
}
return flavor.MasterPosition(mysqld)
}
// SetSlavePositionCommands returns the commands to set the
// replication position at which the slave will resume
// when it is later reparented with SetMasterCommands.
func (mysqld *Mysqld) SetSlavePositionCommands(pos replication.Position) ([]string, error) {
flavor, err := mysqld.flavor()
if err != nil {
return nil, fmt.Errorf("SetSlavePositionCommands needs flavor: %v", err)
}
return flavor.SetSlavePositionCommands(pos)
}
// SetMasterCommands returns the commands to run to make the provided
// host / port the master.
func (mysqld *Mysqld) SetMasterCommands(masterHost string, masterPort int) ([]string, error) {
flavor, err := mysqld.flavor()
if err != nil {
return nil, fmt.Errorf("SetMasterCommands needs flavor: %v", err)
}
params, err := dbconfigs.MysqlParams(mysqld.replParams)
if err != nil {
return nil, err
}
return flavor.SetMasterCommands(¶ms, masterHost, masterPort, int(masterConnectRetry.Seconds()))
}
// ResetReplicationCommands returns the commands to run to reset all
// replication for this host.
func (mysqld *Mysqld) ResetReplicationCommands() ([]string, error) {
flavor, err := mysqld.flavor()
if err != nil {
return nil, fmt.Errorf("ResetReplicationCommands needs flavor: %v", err)
}
return flavor.ResetReplicationCommands(), nil
}
// +------+---------+---------------------+------+-------------+------+----------------------------------------------------------------+------------------+
// | Id | User | Host | db | Command | Time | State | Info |
// +------+---------+---------------------+------+-------------+------+----------------------------------------------------------------+------------------+
// | 9792 | vt_repl | host:port | NULL | Binlog Dump | 54 | Has sent all binlog to slave; waiting for binlog to be updated | NULL |
// | 9797 | vt_dba | localhost | NULL | Query | 0 | NULL | show processlist |
// +------+---------+---------------------+------+-------------+------+----------------------------------------------------------------+------------------+
//
// Array indices for the results of SHOW PROCESSLIST.
const (
colConnectionID = iota
colUsername
colClientAddr
colDbName
colCommand
)
const (
// this is the command used by mysql slaves
binlogDumpCommand = "Binlog Dump"
)
// FindSlaves gets IP addresses for all currently connected slaves.
func FindSlaves(mysqld MysqlDaemon) ([]string, error) {
qr, err := mysqld.FetchSuperQuery("SHOW PROCESSLIST")
if err != nil {
return nil, err
}
addrs := make([]string, 0, 32)
for _, row := range qr.Rows {
// Check for prefix, since it could be "Binlog Dump GTID".
if strings.HasPrefix(row[colCommand].String(), binlogDumpCommand) {
host, _, err := netutil.SplitHostPort(row[colClientAddr].String())
if err != nil {
return nil, fmt.Errorf("FindSlaves: malformed addr %v", err)
}
addrs = append(addrs, host)
}
}
return addrs, nil
}
// WaitBlpPosition will wait for the filtered replication to reach at least
// the provided position.
func WaitBlpPosition(mysqld MysqlDaemon, sql string, replicationPosition string, waitTimeout time.Duration) error {
position, err := replication.DecodePosition(replicationPosition)
if err != nil {
return err
}
timeOut := time.Now().Add(waitTimeout)
for {
if time.Now().After(timeOut) {
break
}
qr, err := mysqld.FetchSuperQuery(sql)
if err != nil {
return err
}
if len(qr.Rows) != 1 {
return fmt.Errorf("QueryBlpCheckpoint(%v) returned unexpected row count: %v", sql, len(qr.Rows))
}
var pos replication.Position
if !qr.Rows[0][0].IsNull() {
pos, err = replication.DecodePosition(qr.Rows[0][0].String())
if err != nil {
return err
}
}
if pos.AtLeast(position) {
return nil
}
log.Infof("Sleeping 1 second waiting for binlog replication(%v) to catch up: %v != %v", sql, pos, position)
time.Sleep(1 * time.Second)
}
return fmt.Errorf("WaitBlpPosition(%v) timed out", sql)
}
// EnableBinlogPlayback prepares the server to play back events from a binlog stream.
// Whatever it does for a given flavor, it must be idempotent.
func (mysqld *Mysqld) EnableBinlogPlayback() error {
flavor, err := mysqld.flavor()
if err != nil {
return fmt.Errorf("EnableBinlogPlayback needs flavor: %v", err)
}
return flavor.EnableBinlogPlayback(mysqld)
}
// DisableBinlogPlayback returns the server to the normal state after streaming.
// Whatever it does for a given flavor, it must be idempotent.
func (mysqld *Mysqld) DisableBinlogPlayback() error {
flavor, err := mysqld.flavor()
if err != nil {
return fmt.Errorf("DisableBinlogPlayback needs flavor: %v", err)
}
return flavor.DisableBinlogPlayback(mysqld)
}
// SetSemiSyncEnabled enables or disables semi-sync replication for
// master and/or slave mode.
func (mysqld *Mysqld) SetSemiSyncEnabled(master, slave bool) error {
log.Infof("Setting semi-sync mode: master=%v, slave=%v", master, slave)
// Convert bool to int.
var m, s int
if master {
m = 1
}
if slave {
s = 1
}
err := mysqld.ExecuteSuperQuery(
fmt.Sprintf(
"SET GLOBAL rpl_semi_sync_master_enabled = %v, GLOBAL rpl_semi_sync_slave_enabled = %v",
m, s))
if err != nil {
return fmt.Errorf("can't set semi-sync mode: %v; make sure plugins are loaded in my.cnf", err)
}
return nil
}
// SemiSyncEnabled returns whether semi-sync is enabled for master or slave.
// If the semi-sync plugin is not loaded, we assume semi-sync is disabled.
func (mysqld *Mysqld) SemiSyncEnabled() (master, slave bool) {
vars, err := mysqld.fetchVariables("rpl_semi_sync_%_enabled")
if err != nil {
return false, false
}
master = (vars["rpl_semi_sync_master_enabled"] == "ON")
slave = (vars["rpl_semi_sync_slave_enabled"] == "ON")
return master, slave
}