dm-relay: optimize cpu usage when enabling relay (#3469)

dm/dm/worker/relay_test.go

@@ -47,6 +47,10 @@ type DummyRelay struct {
 	reloadErr     error
 }
 
+func (d *DummyRelay) IsActive(uuid, filename string) (bool, int64) {
+	return false, 0
+}
+
 func (d *DummyRelay) NewReader(logger log.Logger, cfg *relay.BinlogReaderConfig) *relay.BinlogReader {
 	return nil
 }

dm/pkg/binlog/position.go

@@ -37,6 +37,8 @@ const (
 	posUUIDSuffixSeparator = "|"
 	// MinUUIDSuffix is same as relay.MinUUIDSuffix.
 	MinUUIDSuffix = 1
+	// FileHeaderLen is the length of binlog file header.
+	FileHeaderLen = 4
 )
 
 // MinPosition is the min binlog position.

dm/pkg/utils/util.go

@@ -263,3 +263,12 @@ func proxyFields() []zap.Field {
 	}
 	return fields
 }
+
+func NewStoppedTimer() *time.Timer {
+	// stopped timer should be Reset with correct duration, so use 0 here
+	t := time.NewTimer(0)
+	if !t.Stop() {
+		<-t.C
+	}
+	return t
+}

dm/relay/binlog_writer.go

@@ -17,6 +17,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"path/filepath"
 	"sync"
 
 	"github.com/pingcap/errors"
@@ -33,6 +34,8 @@ type BinlogWriter struct {
 
 	offset   atomic.Int64
 	file     *os.File
+	relayDir string
+	uuid     string
 	filename string
 
 	logger log.Logger
@@ -55,14 +58,16 @@ func (s *BinlogWriterStatus) String() string {
 }
 
 // NewBinlogWriter creates a BinlogWriter instance.
-func NewBinlogWriter(logger log.Logger) *BinlogWriter {
+func NewBinlogWriter(logger log.Logger, relayDir string) *BinlogWriter {
 	return &BinlogWriter{
-		logger: logger,
+		logger:   logger,
+		relayDir: relayDir,
 	}
 }
 
-func (w *BinlogWriter) Open(filename string) error {
-	f, err := os.OpenFile(filename, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0o644)
+func (w *BinlogWriter) Open(uuid, filename string) error {
+	fullName := filepath.Join(w.relayDir, uuid, filename)
+	f, err := os.OpenFile(fullName, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0o644)
 	if err != nil {
 		return terror.ErrBinlogWriterOpenFile.Delegate(err)
 	}
@@ -80,6 +85,7 @@ func (w *BinlogWriter) Open(filename string) error {
 
 	w.offset.Store(fs.Size())
 	w.file = f
+	w.uuid = uuid
 	w.filename = filename
 
 	return nil
@@ -100,6 +106,7 @@ func (w *BinlogWriter) Close() error {
 
 	w.file = nil
 	w.offset.Store(0)
+	w.uuid = ""
 	w.filename = ""
 
 	return err
@@ -132,3 +139,9 @@ func (w *BinlogWriter) Status() *BinlogWriterStatus {
 func (w *BinlogWriter) Offset() int64 {
 	return w.offset.Load()
 }
+
+func (w *BinlogWriter) isActive(uuid, filename string) (bool, int64) {
+	w.mu.RLock()
+	defer w.mu.RUnlock()
+	return uuid == w.uuid && filename == w.filename, w.offset.Load()
+}

dm/relay/binlog_writer_test.go

@@ -30,16 +30,20 @@ type testBinlogWriterSuite struct{}
 
 func (t *testBinlogWriterSuite) TestWrite(c *C) {
 	dir := c.MkDir()
-	filename := filepath.Join(dir, "test-mysql-bin.000001")
+	uuid := "3ccc475b-2343-11e7-be21-6c0b84d59f30.000001"
+	binlogDir := filepath.Join(dir, uuid)
+	c.Assert(os.Mkdir(binlogDir, 0o755), IsNil)
+
+	filename := "test-mysql-bin.000001"
 	var (
 		allData bytes.Buffer
 		data1   = []byte("test-data")
 	)
 
 	{
-		w := NewBinlogWriter(log.L())
+		w := NewBinlogWriter(log.L(), dir)
 		c.Assert(w, NotNil)
-		c.Assert(w.Open(filename), IsNil)
+		c.Assert(w.Open(uuid, filename), IsNil)
 		fwStatus := w.Status()
 		c.Assert(fwStatus.Filename, Equals, filename)
 		c.Assert(fwStatus.Offset, Equals, int64(allData.Len()))
@@ -50,19 +54,19 @@ func (t *testBinlogWriterSuite) TestWrite(c *C) {
 
 	{
 		// not opened
-		w := NewBinlogWriter(log.L())
+		w := NewBinlogWriter(log.L(), dir)
 		err := w.Write(data1)
 		c.Assert(err, ErrorMatches, "*not opened")
 
 		// open non exist dir
-		err = w.Open(filepath.Join(dir, "not-exist", "bin.000001"))
+		err = w.Open("not-exist-uuid", "bin.000001")
 		c.Assert(err, ErrorMatches, "*no such file or directory")
 	}
 
 	{
 		// normal call flow
-		w := NewBinlogWriter(log.L())
-		err := w.Open(filename)
+		w := NewBinlogWriter(log.L(), dir)
+		err := w.Open(uuid, filename)
 		c.Assert(err, IsNil)
 		c.Assert(w.file, NotNil)
 		c.Assert(w.filename, Equals, filename)
@@ -93,7 +97,8 @@ func (t *testBinlogWriterSuite) TestWrite(c *C) {
 		c.Assert(w.Close(), IsNil) // noop
 
 		// try to read the data back
-		dataInFile, err := os.ReadFile(filename)
+		fullName := filepath.Join(binlogDir, filename)
+		dataInFile, err := os.ReadFile(fullName)
 		c.Assert(err, IsNil)
 		c.Assert(dataInFile, DeepEquals, allData.Bytes())
 	}

dm/relay/file.go

@@ -14,14 +14,10 @@
 package relay
 
 import (
-	"context"
 	"os"
-	"path"
 	"path/filepath"
 	"sort"
-	"time"
 
-	"github.com/BurntSushi/toml"
 	"go.uber.org/zap"
 
 	"github.com/pingcap/ticdc/dm/pkg/binlog"
@@ -42,12 +38,6 @@ const (
 	FileCmpBigger
 )
 
-// SwitchPath represents next binlog file path which should be switched.
-type SwitchPath struct {
-	nextUUID       string
-	nextBinlogName string
-}
-
 // EventNotifier notifies whether there is new binlog event written to the file.
 type EventNotifier interface {
 	// Notified returns a channel used to check whether there is new binlog event written to the file
@@ -206,122 +196,3 @@ func fileSizeUpdated(path string, latestSize int64) (int, error) {
 		return -1, nil
 	}
 }
-
-type relayLogFileChecker struct {
-	notifier                                      EventNotifier
-	relayDir, currentUUID                         string
-	latestRelayLogDir, latestFilePath, latestFile string
-	beginOffset, endOffset                        int64
-}
-
-// relayLogUpdatedOrNewCreated checks whether current relay log file is updated or new relay log is created.
-func (r *relayLogFileChecker) relayLogUpdatedOrNewCreated(ctx context.Context, updatePathCh chan string, switchCh chan SwitchPath, errCh chan error) {
-	// binlog file may have rotated if we read nothing last time(either it's the first read or after notified)
-	lastReadCnt := r.endOffset - r.beginOffset
-	if lastReadCnt == 0 {
-		meta := &LocalMeta{}
-		_, err := toml.DecodeFile(filepath.Join(r.latestRelayLogDir, utils.MetaFilename), meta)
-		if err != nil {
-			errCh <- terror.Annotate(err, "decode relay meta toml file failed")
-			return
-		}
-		// current watched file size have no change means that no new writes have been made
-		// our relay meta file will be updated immediately after receive the rotate event,
-		// although we cannot ensure that the binlog filename in the meta is the next file after latestFile
-		// but if we return a different filename with latestFile, the outer logic (parseDirAsPossible)
-		// will find the right one
-		if meta.BinLogName != r.latestFile {
-			// we need check file size again, as the file may have been changed during our metafile check
-			cmp, err2 := fileSizeUpdated(r.latestFilePath, r.endOffset)
-			if err2 != nil {
-				errCh <- terror.Annotatef(err2, "latestFilePath=%s endOffset=%d", r.latestFilePath, r.endOffset)
-				return
-			}
-			switch {
-			case cmp < 0:
-				errCh <- terror.ErrRelayLogFileSizeSmaller.Generate(r.latestFilePath)
-			case cmp > 0:
-				updatePathCh <- r.latestFilePath
-			default:
-				nextFilePath := filepath.Join(r.latestRelayLogDir, meta.BinLogName)
-				log.L().Info("newer relay log file is already generated",
-					zap.String("now file path", r.latestFilePath),
-					zap.String("new file path", nextFilePath))
-				updatePathCh <- nextFilePath
-			}
-			return
-		}
-
-		// maybe UUID index file changed
-		switchPath, err := r.getSwitchPath()
-		if err != nil {
-			errCh <- err
-			return
-		}
-		if switchPath != nil {
-			// we need check file size again, as the file may have been changed during path check
-			cmp, err := fileSizeUpdated(r.latestFilePath, r.endOffset)
-			if err != nil {
-				errCh <- terror.Annotatef(err, "latestFilePath=%s endOffset=%d", r.latestFilePath, r.endOffset)
-				return
-			}
-			switch {
-			case cmp < 0:
-				errCh <- terror.ErrRelayLogFileSizeSmaller.Generate(r.latestFilePath)
-			case cmp > 0:
-				updatePathCh <- r.latestFilePath
-			default:
-				log.L().Info("newer relay uuid path is already generated",
-					zap.String("current path", r.latestRelayLogDir),
-					zap.Any("new path", switchPath))
-				switchCh <- *switchPath
-			}
-			return
-		}
-	}
-
-	timer := time.NewTimer(watcherInterval)
-	defer timer.Stop()
-	select {
-	case <-ctx.Done():
-		errCh <- terror.Annotate(ctx.Err(), "context meet error")
-	case <-r.notifier.Notified():
-		// the notified event may not be the current relay file
-		// in that case we may read 0 bytes and check again
-		updatePathCh <- r.latestFilePath
-	case <-timer.C:
-		// for a task start after source shutdown or there's no new write, it'll not be notified,
-		// and if it's reading from dir 000001 and there's need to switch dir to 000002,
-		// after the task read files in dir 000001, the read size > 0, so it goes to the select directly,
-		// since there is no notify, it blocks, that'll leave dir 000002 un-synced.
-		// so we stop waiting after watcherInterval to give it a chance to check again
-		updatePathCh <- r.latestFilePath
-	}
-}
-
-func (r *relayLogFileChecker) getSwitchPath() (*SwitchPath, error) {
-	// reload uuid
-	uuids, err := utils.ParseUUIDIndex(path.Join(r.relayDir, utils.UUIDIndexFilename))
-	if err != nil {
-		return nil, err
-	}
-	nextUUID, _, err := getNextUUID(r.currentUUID, uuids)
-	if err != nil {
-		return nil, err
-	}
-	if len(nextUUID) == 0 {
-		return nil, nil
-	}
-
-	// try to get the first binlog file in next subdirectory
-	nextBinlogName, err := getFirstBinlogName(r.relayDir, nextUUID)
-	if err != nil {
-		// because creating subdirectory and writing relay log file are not atomic
-		if terror.ErrBinlogFilesNotFound.Equal(err) {
-			return nil, nil
-		}
-		return nil, err
-	}
-
-	return &SwitchPath{nextUUID, nextBinlogName}, nil
-}