relay: add async/batch relay writer

dm/relay/binlog_writer.go

@@ -14,30 +14,41 @@
 package relay
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
 	"sync"
 
-	"github.com/pingcap/errors"
 	"github.com/pingcap/tiflow/dm/pkg/log"
 	"github.com/pingcap/tiflow/dm/pkg/terror"
 	"go.uber.org/atomic"
 	"go.uber.org/zap"
 )
 
+const (
+	bufferSize = 1 * 1024 * 1024 // 1MB
+	chanSize   = 1024
+)
+
+var nilErr error
+
 // BinlogWriter is a binlog event writer which writes binlog events to a file.
+// Open/Write/Close cannot be called concurrently.
 type BinlogWriter struct {
-	mu sync.RWMutex
-
 	offset   atomic.Int64
 	file     *os.File
 	relayDir string
-	uuid     string
-	filename string
+	uuid     atomic.String
+	filename atomic.String
+	err      atomic.Error
 
 	logger log.Logger
+
+	input   chan []byte
+	flushWg sync.WaitGroup
+	wg      sync.WaitGroup
 }
 
 // BinlogWriterStatus represents the status of a BinlogWriter.
@@ -64,6 +75,53 @@ func NewBinlogWriter(logger log.Logger, relayDir string) *BinlogWriter {
 	}
 }
 
+// run starts the binlog writer.
+func (w *BinlogWriter) run() {
+	var (
+		buf       = &bytes.Buffer{}
+		errOccurs bool
+	)
+
+	// writeToFile writes buffer to file
+	writeToFile := func() {
+		if buf.Len() == 0 {
+			return
+		}
+
+		if w.file == nil {
+			w.err.CompareAndSwap(nilErr, terror.ErrRelayWriterNotOpened.Generate())
+			errOccurs = true
+			return
+		}
+		n, err := w.file.Write(buf.Bytes())
+		if err != nil {
+			w.err.CompareAndSwap(nilErr, terror.ErrBinlogWriterWriteDataLen.Delegate(err, n))
+			errOccurs = true
+			return
+		}
+		buf.Reset()
+	}
+
+	for bs := range w.input {
+		if errOccurs {
+			continue
+		}
+		if bs != nil {
+			buf.Write(bs)
+		}
+		// we use bs = nil to mean flush
+		if bs == nil || buf.Len() > bufferSize || len(w.input) == 0 {
+			writeToFile()
+		}
+		if bs == nil {
+			w.flushWg.Done()
+		}
+	}
+	if !errOccurs {
+		writeToFile()
+	}
+}
+
 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, 0o600)
@@ -79,58 +137,66 @@ func (w *BinlogWriter) Open(uuid, filename string) error {
 		return terror.ErrBinlogWriterGetFileStat.Delegate(err, f.Name())
 	}
 
-	w.mu.Lock()
-	defer w.mu.Unlock()
-
 	w.offset.Store(fs.Size())
 	w.file = f
-	w.uuid = uuid
-	w.filename = filename
+	w.uuid.Store(uuid)
+	w.filename.Store(filename)
+	w.err.Store(nilErr)
+
+	w.input = make(chan []byte, chanSize)
+	w.wg.Add(1)
+	go func() {
+		defer w.wg.Done()
+		w.run()
+	}()
 
 	return nil
 }
 
 func (w *BinlogWriter) Close() error {
-	w.mu.Lock()
-	defer w.mu.Unlock()
+	if w.input != nil {
+		close(w.input)
+	}
+	w.wg.Wait()
 
-	var err error
 	if w.file != nil {
-		err2 := w.file.Sync() // try sync manually before close.
-		if err2 != nil {
-			w.logger.Error("fail to flush buffered data", zap.String("component", "file writer"), zap.Error(err2))
+		if err := w.file.Sync(); err != nil {
+			w.logger.Error("fail to flush buffered data", zap.String("component", "file writer"), zap.Error(err))
+		}
+		if err := w.file.Close(); err != nil {
+			w.err.CompareAndSwap(nilErr, err)
 		}
-		err = w.file.Close()
 	}
 
 	w.file = nil
 	w.offset.Store(0)
-	w.uuid = ""
-	w.filename = ""
-
-	return err
+	w.uuid.Store("")
+	w.filename.Store("")
+	w.input = nil
+	return w.err.Swap(nilErr)
 }
 
 func (w *BinlogWriter) Write(rawData []byte) error {
-	w.mu.RLock()
-	defer w.mu.RUnlock()
-
 	if w.file == nil {
-		return terror.ErrRelayWriterNotOpened.Delegate(errors.New("file not opened"))
+		return terror.ErrRelayWriterNotOpened.Generate()
 	}
+	w.input <- rawData
+	w.offset.Add(int64(len(rawData)))
+	return w.err.Load()
+}
 
-	n, err := w.file.Write(rawData)
-	w.offset.Add(int64(n))
-
-	return terror.ErrBinlogWriterWriteDataLen.Delegate(err, len(rawData))
+func (w *BinlogWriter) Flush() error {
+	w.flushWg.Add(1)
+	if err := w.Write(nil); err != nil {
+		return err
+	}
+	w.flushWg.Wait()
+	return w.err.Load()
 }
 
 func (w *BinlogWriter) Status() *BinlogWriterStatus {
-	w.mu.RLock()
-	defer w.mu.RUnlock()
-
 	return &BinlogWriterStatus{
-		Filename: w.filename,
+		Filename: w.filename.Load(),
 		Offset:   w.offset.Load(),
 	}
 }
@@ -140,7 +206,5 @@ func (w *BinlogWriter) Offset() int64 {
 }
 
 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()
+	return uuid == w.uuid.Load() && filename == w.filename.Load(), w.offset.Load()
 }

dm/relay/binlog_writer_test.go

@@ -17,21 +17,27 @@ import (
 	"bytes"
 	"os"
 	"path/filepath"
-	"strings"
+	"testing"
 
-	. "github.com/pingcap/check"
 	"github.com/pingcap/tiflow/dm/pkg/log"
+	"github.com/pingcap/tiflow/dm/pkg/terror"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
 )
 
-var _ = Suite(&testBinlogWriterSuite{})
+type testBinlogWriterSuite struct {
+	suite.Suite
+}
 
-type testBinlogWriterSuite struct{}
+func TestBinlogWriterSuite(t *testing.T) {
+	suite.Run(t, new(testBinlogWriterSuite))
+}
 
-func (t *testBinlogWriterSuite) TestWrite(c *C) {
-	dir := c.MkDir()
+func (t *testBinlogWriterSuite) TestWrite() {
+	dir := t.T().TempDir()
 	uuid := "3ccc475b-2343-11e7-be21-6c0b84d59f30.000001"
 	binlogDir := filepath.Join(dir, uuid)
-	c.Assert(os.Mkdir(binlogDir, 0o755), IsNil)
+	require.NoError(t.T(), os.Mkdir(binlogDir, 0o755))
 
 	filename := "test-mysql-bin.000001"
 	var (
@@ -41,64 +47,87 @@ func (t *testBinlogWriterSuite) TestWrite(c *C) {
 
 	{
 		w := NewBinlogWriter(log.L(), dir)
-		c.Assert(w, NotNil)
-		c.Assert(w.Open(uuid, filename), IsNil)
+		require.NotNil(t.T(), w)
+		require.NoError(t.T(), w.Open(uuid, filename))
 		fwStatus := w.Status()
-		c.Assert(fwStatus.Filename, Equals, filename)
-		c.Assert(fwStatus.Offset, Equals, int64(allData.Len()))
+		require.Equal(t.T(), filename, fwStatus.Filename)
+		require.Equal(t.T(), int64(allData.Len()), fwStatus.Offset)
 		fwStatusStr := fwStatus.String()
-		c.Assert(strings.Contains(fwStatusStr, "filename"), IsTrue)
-		c.Assert(w.Close(), IsNil)
+		require.Contains(t.T(), fwStatusStr, filename)
+		require.NoError(t.T(), w.Close())
 	}
 
 	{
 		// not opened
 		w := NewBinlogWriter(log.L(), dir)
 		err := w.Write(data1)
-		c.Assert(err, ErrorMatches, "*not opened")
+		require.Contains(t.T(), err.Error(), "no underlying writer opened")
 
 		// open non exist dir
 		err = w.Open("not-exist-uuid", "bin.000001")
-		c.Assert(err, ErrorMatches, "*no such file or directory")
+		require.Contains(t.T(), err.Error(), "no such file or directory")
 	}
 
 	{
 		// normal call flow
 		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)
-		c.Assert(w.offset.Load(), Equals, int64(0))
+		require.NoError(t.T(), err)
+		require.NotNil(t.T(), w.file)
+		require.Equal(t.T(), filename, w.filename.Load())
+		require.Equal(t.T(), int64(0), w.offset.Load())
 
 		err = w.Write(data1)
-		c.Assert(err, IsNil)
+		require.NoError(t.T(), err)
+		err = w.Flush()
+		require.NoError(t.T(), err)
 		allData.Write(data1)
 
 		fwStatus := w.Status()
-		c.Assert(fwStatus.Filename, Equals, filename)
-		c.Assert(fwStatus.Offset, Equals, int64(len(data1)))
+		require.Equal(t.T(), fwStatus.Filename, w.filename.Load())
+		require.Equal(t.T(), int64(len(data1)), fwStatus.Offset)
 
 		// write data again
 		data2 := []byte("another-data")
 		err = w.Write(data2)
-		c.Assert(err, IsNil)
+		require.NoError(t.T(), err)
 		allData.Write(data2)
 
-		c.Assert(w.offset.Load(), Equals, int64(allData.Len()))
+		require.LessOrEqual(t.T(), int64(allData.Len()), w.offset.Load())
 
 		err = w.Close()
-		c.Assert(err, IsNil)
-		c.Assert(w.file, IsNil)
-		c.Assert(w.filename, Equals, "")
-		c.Assert(w.offset.Load(), Equals, int64(0))
-
-		c.Assert(w.Close(), IsNil) // noop
+		require.NoError(t.T(), err)
+		require.Nil(t.T(), w.file)
+		require.Equal(t.T(), "", w.filename.Load())
+		require.Equal(t.T(), int64(0), w.offset.Load())
 
 		// try to read the data back
 		fullName := filepath.Join(binlogDir, filename)
 		dataInFile, err := os.ReadFile(fullName)
-		c.Assert(err, IsNil)
-		c.Assert(dataInFile, DeepEquals, allData.Bytes())
+		require.NoError(t.T(), err)
+		require.Equal(t.T(), allData.Bytes(), dataInFile)
+	}
+
+	{
+		// cover for error
+		w := NewBinlogWriter(log.L(), dir)
+		err := w.Open(uuid, filename)
+		require.NoError(t.T(), err)
+		require.NotNil(t.T(), w.file)
+
+		err = w.Write(data1)
+		require.NoError(t.T(), err)
+		err = w.Flush()
+		require.NoError(t.T(), err)
+
+		require.NoError(t.T(), w.file.Close())
+		// write data again
+		data2 := []byte("another-data")
+		// we cannot determine the error is caused by `Write` or `Flush`
+		// nolint:errcheck
+		w.Write(data2)
+		// nolint:errcheck
+		w.Flush()
+		require.True(t.T(), terror.ErrBinlogWriterWriteDataLen.Equal(w.Close()))
 	}
 }

dm/relay/local_reader_test.go

@@ -76,7 +76,8 @@ func newBinlogReaderForTest(logger log.Logger, cfg *BinlogReaderConfig, notify b
 func (t *testReaderSuite) setActiveRelayLog(r Process, uuid, filename string, offset int64) {
 	relay := r.(*Relay)
 	writer := relay.writer.(*FileWriter)
-	writer.out.uuid, writer.out.filename = uuid, filename
+	writer.out.uuid.Store(uuid)
+	writer.out.filename.Store(filename)
 	writer.out.offset.Store(offset)
 }
 
@@ -1234,6 +1235,10 @@ func (m *mockFileWriterForActiveTest) Close() error {
 	panic("should be used")
 }
 
+func (m *mockFileWriterForActiveTest) Flush() error {
+	panic("should be used")
+}
+
 func (m *mockFileWriterForActiveTest) WriteEvent(ev *replication.BinlogEvent) (WResult, error) {
 	panic("should be used")
 }

dm/relay/relay.go

@@ -569,6 +569,8 @@ func (r *Relay) handleEvents(
 	}
 
 	firstEvent := true
+	relayPosGauge := relayLogPosGauge.WithLabelValues("relay")
+	relayFileGauge := relayLogFileGauge.WithLabelValues("relay")
 	for {
 		// 1. read events from upstream server
 		readTimer := time.Now()
@@ -704,11 +706,11 @@ func (r *Relay) handleEvents(
 		}
 
 		relayLogWriteSizeHistogram.Observe(float64(e.Header.EventSize))
-		relayLogPosGauge.WithLabelValues("relay").Set(float64(lastPos.Pos))
+		relayPosGauge.Set(float64(lastPos.Pos))
 		if index, err2 := utils.GetFilenameIndex(lastPos.Name); err2 != nil {
 			r.logger.Error("parse binlog file name", zap.String("file name", lastPos.Name), log.ShortError(err2))
 		} else {
-			relayLogFileGauge.WithLabelValues("relay").Set(float64(index))
+			relayFileGauge.Set(float64(index))
 		}
 
 		if needSavePos {