gh-ost/go/binlog/gomysql_reader.go
2017-10-02 08:42:38 +03:00

170 lines
5.3 KiB
Go

/*
Copyright 2016 GitHub Inc.
See https://github.com/github/gh-ost/blob/master/LICENSE
*/
package binlog
import (
"fmt"
"sync"
"github.com/github/gh-ost/go/base"
"github.com/github/gh-ost/go/mysql"
"github.com/github/gh-ost/go/sql"
"github.com/outbrain/golib/log"
gomysql "github.com/siddontang/go-mysql/mysql"
"github.com/siddontang/go-mysql/replication"
"golang.org/x/net/context"
)
type GoMySQLReader struct {
connectionConfig *mysql.ConnectionConfig
binlogSyncer *replication.BinlogSyncer
binlogStreamer *replication.BinlogStreamer
currentCoordinates mysql.BinlogCoordinates
currentCoordinatesMutex *sync.Mutex
LastAppliedRowsEventHint mysql.BinlogCoordinates
MigrationContext *base.MigrationContext
}
func NewGoMySQLReader(connectionConfig *mysql.ConnectionConfig) (binlogReader *GoMySQLReader, err error) {
binlogReader = &GoMySQLReader{
connectionConfig: connectionConfig,
currentCoordinates: mysql.BinlogCoordinates{},
currentCoordinatesMutex: &sync.Mutex{},
binlogSyncer: nil,
binlogStreamer: nil,
MigrationContext: base.GetMigrationContext(),
}
serverId := uint32(binlogReader.MigrationContext.ReplicaServerId)
binlogSyncerConfig := &replication.BinlogSyncerConfig{
ServerID: serverId,
Flavor: "mysql",
Host: connectionConfig.Key.Hostname,
Port: uint16(connectionConfig.Key.Port),
User: connectionConfig.User,
Password: connectionConfig.Password,
}
binlogReader.binlogSyncer = replication.NewBinlogSyncer(*binlogSyncerConfig)
return binlogReader, err
}
// ConnectBinlogStreamer
func (this *GoMySQLReader) ConnectBinlogStreamer(coordinates mysql.BinlogCoordinates) (err error) {
if coordinates.IsEmpty() {
return log.Errorf("Emptry coordinates at ConnectBinlogStreamer()")
}
this.currentCoordinates = coordinates
log.Infof("Connecting binlog streamer at %+v", this.currentCoordinates)
// Start sync with sepcified binlog file and position
this.binlogStreamer, err = this.binlogSyncer.StartSync(gomysql.Position{this.currentCoordinates.LogFile, uint32(this.currentCoordinates.LogPos)})
return err
}
func (this *GoMySQLReader) GetCurrentBinlogCoordinates() *mysql.BinlogCoordinates {
this.currentCoordinatesMutex.Lock()
defer this.currentCoordinatesMutex.Unlock()
returnCoordinates := this.currentCoordinates
return &returnCoordinates
}
// StreamEvents
func (this *GoMySQLReader) handleRowsEvent(ev *replication.BinlogEvent, rowsEvent *replication.RowsEvent, entriesChannel chan<- *BinlogEntry) error {
if this.currentCoordinates.SmallerThanOrEquals(&this.LastAppliedRowsEventHint) {
log.Debugf("Skipping handled query at %+v", this.currentCoordinates)
return nil
}
dml := ToEventDML(ev.Header.EventType.String())
if dml == NotDML {
return fmt.Errorf("Unknown DML type: %s", ev.Header.EventType.String())
}
for i, row := range rowsEvent.Rows {
if dml == UpdateDML && i%2 == 1 {
// An update has two rows (WHERE+SET)
// We do both at the same time
continue
}
binlogEntry := NewBinlogEntryAt(this.currentCoordinates)
binlogEntry.DmlEvent = NewBinlogDMLEvent(
string(rowsEvent.Table.Schema),
string(rowsEvent.Table.Table),
dml,
)
switch dml {
case InsertDML:
{
binlogEntry.DmlEvent.NewColumnValues = sql.ToColumnValues(row)
}
case UpdateDML:
{
binlogEntry.DmlEvent.WhereColumnValues = sql.ToColumnValues(row)
binlogEntry.DmlEvent.NewColumnValues = sql.ToColumnValues(rowsEvent.Rows[i+1])
}
case DeleteDML:
{
binlogEntry.DmlEvent.WhereColumnValues = sql.ToColumnValues(row)
}
}
// The channel will do the throttling. Whoever is reding from the channel
// decides whether action is taken sycnhronously (meaning we wait before
// next iteration) or asynchronously (we keep pushing more events)
// In reality, reads will be synchronous
entriesChannel <- binlogEntry
}
this.LastAppliedRowsEventHint = this.currentCoordinates
return nil
}
// StreamEvents
func (this *GoMySQLReader) StreamEvents(canStopStreaming func() bool, entriesChannel chan<- *BinlogEntry) error {
if canStopStreaming() {
return nil
}
for {
if canStopStreaming() {
break
}
ev, err := this.binlogStreamer.GetEvent(context.Background())
if err != nil {
return err
}
func() {
this.currentCoordinatesMutex.Lock()
defer this.currentCoordinatesMutex.Unlock()
this.currentCoordinates.LogPos = int64(ev.Header.LogPos)
}()
if rotateEvent, ok := ev.Event.(*replication.RotateEvent); ok {
func() {
this.currentCoordinatesMutex.Lock()
defer this.currentCoordinatesMutex.Unlock()
this.currentCoordinates.LogFile = string(rotateEvent.NextLogName)
}()
log.Infof("rotate to next log name: %s", rotateEvent.NextLogName)
} else if rowsEvent, ok := ev.Event.(*replication.RowsEvent); ok {
if err := this.handleRowsEvent(ev, rowsEvent, entriesChannel); err != nil {
return err
}
}
}
log.Debugf("done streaming events")
return nil
}
func (this *GoMySQLReader) Close() error {
// Historically there was a:
// this.binlogSyncer.Close()
// here. A new go-mysql version closes the binlog syncer connection independently.
// I will go against the sacred rules of comments and just leave this here.
// This is the year 2017. Let's see what year these comments get deleted.
return nil
}