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replication.go
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replication.go
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/*
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.
*/
/*
Handle creating replicas and setting up the replication streams.
*/
package mysqlctl
import (
"errors"
"fmt"
"net"
"strconv"
"strings"
"time"
"vitess.io/vitess/go/vt/vtgate/evalengine"
"context"
"vitess.io/vitess/go/mysql"
"vitess.io/vitess/go/netutil"
"vitess.io/vitess/go/vt/hook"
"vitess.io/vitess/go/vt/log"
)
// WaitForReplicationStart waits until the deadline for replication to start.
// This validates the current primary is correct and can be connected to.
func WaitForReplicationStart(mysqld MysqlDaemon, replicaStartDeadline int) error {
var rowMap map[string]string
for replicaWait := 0; replicaWait < replicaStartDeadline; replicaWait++ {
status, err := mysqld.ReplicationStatus()
if err != nil {
return err
}
if status.Running() {
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
}
// StartReplication starts replication.
func (mysqld *Mysqld) StartReplication(hookExtraEnv map[string]string) error {
ctx := context.TODO()
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
if err := mysqld.executeSuperQueryListConn(ctx, conn, []string{conn.StartReplicationCommand()}); err != nil {
return err
}
h := hook.NewSimpleHook("postflight_start_slave")
h.ExtraEnv = hookExtraEnv
return h.ExecuteOptional()
}
// StartReplicationUntilAfter starts replication until replication has come to `targetPos`, then it stops replication
func (mysqld *Mysqld) StartReplicationUntilAfter(ctx context.Context, targetPos mysql.Position) error {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
queries := []string{conn.StartReplicationUntilAfterCommand(targetPos)}
return mysqld.executeSuperQueryListConn(ctx, conn, queries)
}
// StartSQLThreadUntilAfter starts replication's SQL thread(s) until replication has come to `targetPos`, then it stops it
func (mysqld *Mysqld) StartSQLThreadUntilAfter(ctx context.Context, targetPos mysql.Position) error {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
queries := []string{conn.StartSQLThreadUntilAfterCommand(targetPos)}
return mysqld.executeSuperQueryListConn(ctx, conn, queries)
}
// StopReplication stops replication.
func (mysqld *Mysqld) StopReplication(hookExtraEnv map[string]string) error {
h := hook.NewSimpleHook("preflight_stop_slave")
h.ExtraEnv = hookExtraEnv
if err := h.ExecuteOptional(); err != nil {
return err
}
ctx := context.TODO()
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
return mysqld.executeSuperQueryListConn(ctx, conn, []string{conn.StopReplicationCommand()})
}
// StopIOThread stops a replica's IO thread only.
func (mysqld *Mysqld) StopIOThread(ctx context.Context) error {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
return mysqld.executeSuperQueryListConn(ctx, conn, []string{conn.StopIOThreadCommand()})
}
// StopSQLThread stops a replica's SQL thread(s) only.
func (mysqld *Mysqld) StopSQLThread(ctx context.Context) error {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
return mysqld.executeSuperQueryListConn(ctx, conn, []string{conn.StopSQLThreadCommand()})
}
// RestartReplication stops, resets and starts replication.
func (mysqld *Mysqld) RestartReplication(hookExtraEnv map[string]string) error {
h := hook.NewSimpleHook("preflight_stop_slave")
h.ExtraEnv = hookExtraEnv
if err := h.ExecuteOptional(); err != nil {
return err
}
ctx := context.TODO()
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
if err := mysqld.executeSuperQueryListConn(ctx, conn, conn.RestartReplicationCommands()); err != nil {
return err
}
h = hook.NewSimpleHook("postflight_start_slave")
h.ExtraEnv = hookExtraEnv
return h.ExecuteOptional()
}
// GetMysqlPort returns mysql port
func (mysqld *Mysqld) GetMysqlPort() (int32, error) {
qr, err := mysqld.FetchSuperQuery(context.TODO(), "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 := evalengine.ToUint64(qr.Rows[0][1])
if err != nil {
return 0, err
}
return int32(utemp), nil
}
// GetServerID returns mysql server id
func (mysqld *Mysqld) GetServerID(ctx context.Context) (uint32, error) {
qr, err := mysqld.FetchSuperQuery(ctx, "select @@global.server_id")
if err != nil {
return 0, err
}
if len(qr.Rows) != 1 {
return 0, errors.New("no server_id in mysql")
}
utemp, err := evalengine.ToUint64(qr.Rows[0][0])
if err != nil {
return 0, err
}
return uint32(utemp), nil
}
// GetServerUUID returns mysql server uuid
func (mysqld *Mysqld) GetServerUUID(ctx context.Context) (string, error) {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return "", err
}
defer conn.Recycle()
return conn.GetServerUUID()
}
// IsReadOnly return true if the instance is read only
func (mysqld *Mysqld) IsReadOnly() (bool, error) {
qr, err := mysqld.FetchSuperQuery(context.TODO(), "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].ToString() == "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(context.TODO(), query)
}
// SetSuperReadOnly set/unset the super_read_only flag
func (mysqld *Mysqld) SetSuperReadOnly(on bool) error {
query := "SET GLOBAL super_read_only = "
if on {
query += "ON"
} else {
query += "OFF"
}
return mysqld.ExecuteSuperQuery(context.TODO(), query)
}
// WaitSourcePos lets replicas wait to given replication position
func (mysqld *Mysqld) WaitSourcePos(ctx context.Context, targetPos mysql.Position) error {
// Get a connection.
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
// First check if filePos flavored Position was passed in. If so, we can't defer to the flavor in the connection,
// unless that flavor is also filePos.
waitCommandName := "WaitUntilPositionCommand"
var query string
if targetPos.MatchesFlavor(mysql.FilePosFlavorID) {
// If we are the primary, WaitUntilFilePositionCommand will fail.
// But position is most likely reached. So, check the position
// first.
mpos, err := conn.PrimaryFilePosition()
if err != nil {
return fmt.Errorf("WaitSourcePos: PrimaryFilePosition failed: %v", err)
}
if mpos.AtLeast(targetPos) {
return nil
}
// Find the query to run, run it.
query, err = conn.WaitUntilFilePositionCommand(ctx, targetPos)
if err != nil {
return err
}
waitCommandName = "WaitUntilFilePositionCommand"
} else {
// If we are the primary, WaitUntilPositionCommand will fail.
// But position is most likely reached. So, check the position
// first.
mpos, err := conn.PrimaryPosition()
if err != nil {
return fmt.Errorf("WaitSourcePos: PrimaryPosition failed: %v", err)
}
if mpos.AtLeast(targetPos) {
return nil
}
// Find the query to run, run it.
query, err = conn.WaitUntilPositionCommand(ctx, targetPos)
if err != nil {
return err
}
}
qr, err := mysqld.FetchSuperQuery(ctx, query)
if err != nil {
return fmt.Errorf("%v(%v) failed: %v", waitCommandName, query, err)
}
if len(qr.Rows) != 1 || len(qr.Rows[0]) != 1 {
return fmt.Errorf("unexpected result format from %v(%v): %#v", waitCommandName, query, qr)
}
result := qr.Rows[0][0]
if result.IsNull() {
return fmt.Errorf("%v(%v) failed: replication is probably stopped", waitCommandName, query)
}
if result.ToString() == "-1" {
return fmt.Errorf("timed out waiting for position %v", targetPos)
}
return nil
}
// ReplicationStatus returns the server replication status
func (mysqld *Mysqld) ReplicationStatus() (mysql.ReplicationStatus, error) {
conn, err := getPoolReconnect(context.TODO(), mysqld.dbaPool)
if err != nil {
return mysql.ReplicationStatus{}, err
}
defer conn.Recycle()
return conn.ShowReplicationStatus()
}
// PrimaryStatus returns the primary replication statuses
func (mysqld *Mysqld) PrimaryStatus(ctx context.Context) (mysql.PrimaryStatus, error) {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return mysql.PrimaryStatus{}, err
}
defer conn.Recycle()
return conn.ShowPrimaryStatus()
}
// GetGTIDPurged returns the gtid purged statuses
func (mysqld *Mysqld) GetGTIDPurged(ctx context.Context) (mysql.Position, error) {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return mysql.Position{}, err
}
defer conn.Recycle()
return conn.GetGTIDPurged()
}
// PrimaryPosition returns the primary replication position.
func (mysqld *Mysqld) PrimaryPosition() (mysql.Position, error) {
conn, err := getPoolReconnect(context.TODO(), mysqld.dbaPool)
if err != nil {
return mysql.Position{}, err
}
defer conn.Recycle()
return conn.PrimaryPosition()
}
// SetReplicationPosition sets the replication position at which the replica will resume
// when its replication is started.
func (mysqld *Mysqld) SetReplicationPosition(ctx context.Context, pos mysql.Position) error {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
cmds := conn.SetReplicationPositionCommands(pos)
log.Infof("Executing commands to set replication position: %v", cmds)
return mysqld.executeSuperQueryListConn(ctx, conn, cmds)
}
// SetReplicationSource makes the provided host / port the primary. It optionally
// stops replication before, and starts it after.
func (mysqld *Mysqld) SetReplicationSource(ctx context.Context, host string, port int, replicationStopBefore bool, replicationStartAfter bool) error {
params, err := mysqld.dbcfgs.ReplConnector().MysqlParams()
if err != nil {
return err
}
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
cmds := []string{}
if replicationStopBefore {
cmds = append(cmds, conn.StopReplicationCommand())
}
// If flag value is same as default, check deprecated flag value
if *replicationConnectRetry == 10*time.Second && *masterConnectRetry != *replicationConnectRetry {
*replicationConnectRetry = *masterConnectRetry
}
smc := conn.SetReplicationSourceCommand(params, host, port, int(replicationConnectRetry.Seconds()))
cmds = append(cmds, smc)
if replicationStartAfter {
cmds = append(cmds, conn.StartReplicationCommand())
}
return mysqld.executeSuperQueryListConn(ctx, conn, cmds)
}
// ResetReplication resets all replication for this host.
func (mysqld *Mysqld) ResetReplication(ctx context.Context) error {
conn, connErr := getPoolReconnect(ctx, mysqld.dbaPool)
if connErr != nil {
return connErr
}
defer conn.Recycle()
cmds := conn.ResetReplicationCommands()
return mysqld.executeSuperQueryListConn(ctx, conn, cmds)
}
// ResetReplicationParameters resets the replica replication parameters for this host.
func (mysqld *Mysqld) ResetReplicationParameters(ctx context.Context) error {
conn, connErr := getPoolReconnect(ctx, mysqld.dbaPool)
if connErr != nil {
return connErr
}
defer conn.Recycle()
cmds := conn.ResetReplicationParametersCommands()
return mysqld.executeSuperQueryListConn(ctx, conn, cmds)
}
// +------+---------+---------------------+------+-------------+------+----------------------------------------------------------------+------------------+
// | 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 //nolint
colUsername //nolint
colClientAddr
colDbName //nolint
colCommand
)
const (
// this is the command used by mysql replicas
binlogDumpCommand = "Binlog Dump"
)
// FindReplicas gets IP addresses for all currently connected replicas.
func FindReplicas(mysqld MysqlDaemon) ([]string, error) {
qr, err := mysqld.FetchSuperQuery(context.TODO(), "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].ToString(), binlogDumpCommand) {
host := row[colClientAddr].ToString()
if host == "localhost" {
// If we have a local binlog streamer, it will
// show up as being connected
// from 'localhost' through the local
// socket. Ignore it.
continue
}
host, _, err = netutil.SplitHostPort(host)
if err != nil {
return nil, fmt.Errorf("FindReplicas: malformed addr %v", err)
}
var ips []string
ips, err = net.LookupHost(host)
if err != nil {
return nil, fmt.Errorf("FindReplicas: LookupHost failed %v", err)
}
addrs = append(addrs, ips...)
}
}
return addrs, nil
}
// 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 {
// Get a connection.
conn, err := getPoolReconnect(context.TODO(), mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
// See if we have a command to run, and run it.
cmd := conn.EnableBinlogPlaybackCommand()
if cmd == "" {
return nil
}
if err := mysqld.ExecuteSuperQuery(context.TODO(), cmd); err != nil {
log.Errorf("EnableBinlogPlayback: cannot run query '%v': %v", cmd, err)
return fmt.Errorf("EnableBinlogPlayback: cannot run query '%v': %v", cmd, err)
}
log.Info("EnableBinlogPlayback: successfully ran %v", cmd)
return nil
}
// 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 {
// Get a connection.
conn, err := getPoolReconnect(context.TODO(), mysqld.dbaPool)
if err != nil {
return err
}
defer conn.Recycle()
// See if we have a command to run, and run it.
cmd := conn.DisableBinlogPlaybackCommand()
if cmd == "" {
return nil
}
if err := mysqld.ExecuteSuperQuery(context.TODO(), cmd); err != nil {
log.Errorf("DisableBinlogPlayback: cannot run query '%v': %v", cmd, err)
return fmt.Errorf("DisableBinlogPlayback: cannot run query '%v': %v", cmd, err)
}
log.Info("DisableBinlogPlayback: successfully ran '%v'", cmd)
return nil
}
// GetBinlogInformation gets the binlog format, whether binlog is enabled and if updates on replica logging is enabled.
func (mysqld *Mysqld) GetBinlogInformation(ctx context.Context) (string, bool, bool, string, error) {
qr, err := mysqld.FetchSuperQuery(ctx, "select @@global.binlog_format, @@global.log_bin, @@global.log_slave_updates, @@global.binlog_row_image")
if err != nil {
return "", false, false, "", err
}
if len(qr.Rows) != 1 {
return "", false, false, "", errors.New("unable to read global variables binlog_format, log_bin, log_slave_updates, gtid_mode, binlog_rowge")
}
res := qr.Named().Row()
binlogFormat, err := res.ToString("@@global.binlog_format")
if err != nil {
return "", false, false, "", err
}
logBin, err := res.ToInt64("@@global.log_bin")
if err != nil {
return "", false, false, "", err
}
logReplicaUpdates, err := res.ToInt64("@@global.log_slave_updates")
if err != nil {
return "", false, false, "", err
}
binlogRowImage, err := res.ToString("@@global.binlog_row_image")
if err != nil {
return "", false, false, "", err
}
return binlogFormat, logBin == 1, logReplicaUpdates == 1, binlogRowImage, nil
}
// GetGTIDMode gets the GTID mode for the server
func (mysqld *Mysqld) GetGTIDMode(ctx context.Context) (string, error) {
conn, err := getPoolReconnect(ctx, mysqld.dbaPool)
if err != nil {
return "", err
}
defer conn.Recycle()
return conn.GetGTIDMode()
}
// SetSemiSyncEnabled enables or disables semi-sync replication for
// primary and/or replica mode.
func (mysqld *Mysqld) SetSemiSyncEnabled(primary, replica bool) error {
log.Infof("Setting semi-sync mode: primary=%v, replica=%v", primary, replica)
// Convert bool to int.
var p, s int
if primary {
p = 1
}
if replica {
s = 1
}
err := mysqld.ExecuteSuperQuery(context.TODO(), fmt.Sprintf(
"SET GLOBAL rpl_semi_sync_master_enabled = %v, GLOBAL rpl_semi_sync_slave_enabled = %v",
p, 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 primary or replica.
// If the semi-sync plugin is not loaded, we assume semi-sync is disabled.
func (mysqld *Mysqld) SemiSyncEnabled() (primary, replica bool) {
vars, err := mysqld.fetchVariables(context.TODO(), "rpl_semi_sync_%_enabled")
if err != nil {
return false, false
}
primary = (vars["rpl_semi_sync_master_enabled"] == "ON")
replica = (vars["rpl_semi_sync_slave_enabled"] == "ON")
return primary, replica
}
// SemiSyncStatus returns the current status of semi-sync for primary and replica.
func (mysqld *Mysqld) SemiSyncStatus() (primary, replica bool) {
vars, err := mysqld.fetchStatuses(context.TODO(), "Rpl_semi_sync_%_status")
if err != nil {
return false, false
}
primary = vars["Rpl_semi_sync_master_status"] == "ON"
replica = vars["Rpl_semi_sync_slave_status"] == "ON"
return primary, replica
}
// SemiSyncClients returns the number of semi-sync clients for the primary.
func (mysqld *Mysqld) SemiSyncClients() uint32 {
qr, err := mysqld.FetchSuperQuery(context.TODO(), "SHOW STATUS LIKE 'Rpl_semi_sync_master_clients'")
if err != nil {
return 0
}
if len(qr.Rows) != 1 {
return 0
}
countStr := qr.Rows[0][1].ToString()
count, _ := strconv.ParseUint(countStr, 10, 0)
return uint32(count)
}
// SemiSyncSettings returns the settings of semi-sync which includes the timeout and the number of replicas to wait for.
func (mysqld *Mysqld) SemiSyncSettings() (timeout uint64, numReplicas uint32) {
vars, err := mysqld.fetchVariables(context.TODO(), "rpl_semi_sync_%")
if err != nil {
return 0, 0
}
timeout, _ = strconv.ParseUint(vars["rpl_semi_sync_master_timeout"], 10, 0)
numReplicasUint, _ := strconv.ParseUint(vars["rpl_semi_sync_master_wait_for_slave_count"], 10, 0)
return timeout, uint32(numReplicasUint)
}
// SemiSyncReplicationStatus returns whether semi-sync is currently used by replication.
func (mysqld *Mysqld) SemiSyncReplicationStatus() (bool, error) {
qr, err := mysqld.FetchSuperQuery(context.TODO(), "SHOW STATUS LIKE 'rpl_semi_sync_slave_status'")
if err != nil {
return false, err
}
if len(qr.Rows) != 1 {
return false, errors.New("no rpl_semi_sync_slave_status variable in mysql")
}
if qr.Rows[0][1].ToString() == "ON" {
return true, nil
}
return false, nil
}