feat(client): support goroutine-safety of pkg/var log.(LogStream Appe…

…nder).Append Batch

This PR makes `kg/var log.(LogStream Appender).Append Batch` goroutine-safe.

pkg/varlog/config.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"time"
 
+	"github.com/kakao/varlog/internal/storagenode"
 	"github.com/kakao/varlog/pkg/types"
 	"github.com/kakao/varlog/proto/varlogpb"
 )
@@ -97,8 +98,8 @@ func WithTimeout(timeout time.Duration) AdminCallOption {
 
 const (
 	defaultPipelineSize = 2
-	minPipelineSize     = 1
-	maxPipelineSize     = 8
+	minPipelineSize     = storagenode.MinAppendPipelineSize
+	maxPipelineSize     = storagenode.MaxAppendPipelineSize
 )
 
 type logStreamAppenderConfig struct {

pkg/varlog/log_stream_appender.go

@@ -30,6 +30,7 @@ type LogStreamAppender interface {
 	// The only error from the AppendBatch is ErrClosed, which is returned when
 	// the LogStreamAppender is already closed. It returns nil even if the
 	// underlying stream is disconnected and notifies errors via callback.
+	//
 	// It is safe to have multiple goroutines calling AppendBatch
 	// simultaneously, but the order between them is not guaranteed.
 	AppendBatch(dataBatch [][]byte, callback BatchCallback) error
@@ -48,8 +49,9 @@ type LogStreamAppender interface {
 type BatchCallback func([]varlogpb.LogEntryMeta, error)
 
 type cbQueueEntry struct {
-	cb  BatchCallback
-	err error
+	cb   BatchCallback
+	data [][]byte
+	err  error
 }
 
 func newCallbackQueueEntry() *cbQueueEntry {
@@ -71,8 +73,10 @@ type logStreamAppender struct {
 	logStreamAppenderConfig
 	stream     snpb.LogIO_AppendClient
 	cancelFunc context.CancelCauseFunc
+	causeFunc  func() error
 	sema       chan struct{}
-	cbq        chan *cbQueueEntry
+	sq         chan *cbQueueEntry
+	rq         chan *cbQueueEntry
 	wg         sync.WaitGroup
 	closed     struct {
 		xsync.RBMutex
@@ -110,10 +114,15 @@ func (v *logImpl) newLogStreamAppender(ctx context.Context, tpid types.TopicID,
 		logStreamAppenderConfig: cfg,
 		stream:                  stream,
 		sema:                    make(chan struct{}, cfg.pipelineSize),
-		cbq:                     make(chan *cbQueueEntry, cfg.pipelineSize),
+		sq:                      make(chan *cbQueueEntry, cfg.pipelineSize),
+		rq:                      make(chan *cbQueueEntry, cfg.pipelineSize),
 		cancelFunc:              cancelFunc,
+		causeFunc: func() error {
+			return context.Cause(ctx)
+		},
 	}
-	lsa.wg.Add(1)
+	lsa.wg.Add(2)
+	go lsa.sendLoop()
 	go lsa.recvLoop()
 	return lsa, nil
 }
@@ -128,23 +137,14 @@ func (lsa *logStreamAppender) AppendBatch(dataBatch [][]byte, callback BatchCall
 	lsa.sema <- struct{}{}
 
 	qe := newCallbackQueueEntry()
+	qe.data = dataBatch
 	qe.cb = callback
-
-	err := lsa.stream.Send(&snpb.AppendRequest{
-		TopicID:     lsa.tpid,
-		LogStreamID: lsa.lsid,
-		Payload:     dataBatch,
-	})
-	if err != nil {
-		_ = lsa.stream.CloseSend()
-		qe.err = err
-	}
-	lsa.cbq <- qe
+	lsa.sq <- qe
 	return nil
 }
 
 func (lsa *logStreamAppender) Close() {
-	lsa.cancelFunc(nil)
+	lsa.cancelFunc(ErrClosed)
 
 	lsa.closed.Lock()
 	defer lsa.closed.Unlock()
@@ -153,10 +153,39 @@ func (lsa *logStreamAppender) Close() {
 	}
 	lsa.closed.value = true
 
-	close(lsa.cbq)
+	close(lsa.sq)
 	lsa.wg.Wait()
 }
 
+func (lsa *logStreamAppender) sendLoop() {
+	defer func() {
+		close(lsa.rq)
+		lsa.wg.Done()
+	}()
+
+	var sendErr error
+	req := &snpb.AppendRequest{
+		TopicID:     lsa.tpid,
+		LogStreamID: lsa.lsid,
+	}
+	for qe := range lsa.sq {
+		if sendErr == nil {
+			req.Payload = qe.data
+			sendErr = lsa.stream.Send(req)
+			if sendErr != nil {
+				if cause := lsa.causeFunc(); cause != nil {
+					sendErr = cause
+				}
+				_ = lsa.stream.CloseSend()
+			}
+		}
+		if sendErr != nil {
+			qe.err = sendErr
+		}
+		lsa.rq <- qe
+	}
+}
+
 func (lsa *logStreamAppender) recvLoop() {
 	defer lsa.wg.Done()
 
@@ -165,7 +194,7 @@ func (lsa *logStreamAppender) recvLoop() {
 	var cb BatchCallback
 	rsp := &snpb.AppendResponse{}
 
-	for qe := range lsa.cbq {
+	for qe := range lsa.rq {
 		meta = nil
 		err = qe.err
 		if err != nil {
@@ -188,6 +217,11 @@ func (lsa *logStreamAppender) recvLoop() {
 			break
 		}
 	Call:
+		if err != nil {
+			if cause := lsa.causeFunc(); cause != nil {
+				err = cause
+			}
+		}
 		if qe.cb != nil {
 			cb = qe.cb
 		} else {

tests/it/cluster/client_test.go

@@ -12,8 +12,6 @@ import (
 	. "github.com/smartystreets/goconvey/convey"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"google.golang.org/grpc/codes"
-	"google.golang.org/grpc/status"
 
 	"github.com/kakao/varlog/pkg/types"
 	"github.com/kakao/varlog/pkg/util/testutil"
@@ -780,7 +778,7 @@ func TestLogStreamAppender(t *testing.T) {
 				cb := func(metas []varlogpb.LogEntryMeta, err error) {
 					called.Add(1)
 					if err != nil {
-						assert.Equal(t, codes.Canceled, status.Code(err))
+						assert.Equal(t, varlog.ErrClosed, err)
 						return
 					}
 					assert.NoError(t, err)
@@ -833,6 +831,37 @@ func TestLogStreamAppender(t *testing.T) {
 				}, 5*time.Second, 100*time.Millisecond)
 			},
 		},
+		{
+			name: "ConcurrentAppendBatch",
+			testf: func(t *testing.T, tpid types.TopicID, lsid types.LogStreamID, vcli varlog.Log) {
+				lsa, err := vcli.NewLogStreamAppender(tpid, lsid, varlog.WithPipelineSize(pipelineSize))
+				require.NoError(t, err)
+				defer func() {
+					lsa.Close()
+				}()
+
+				var wg sync.WaitGroup
+				wg.Add(calls * 2)
+				expected := 0
+				dataBatch := [][]byte{[]byte("foo")}
+				cb := func(metas []varlogpb.LogEntryMeta, err error) {
+					defer wg.Done()
+					assert.NoError(t, err)
+					assert.Len(t, metas, 1)
+					expected++
+					assert.EqualValues(t, expected, metas[0].LLSN)
+					assert.EqualValues(t, expected, metas[0].GLSN)
+				}
+				for i := 0; i < calls; i++ {
+					go func() {
+						defer wg.Done()
+						err := lsa.AppendBatch(dataBatch, cb)
+						require.NoError(t, err)
+					}()
+				}
+				wg.Wait()
+			},
+		},
 	}
 
 	for _, tc := range tcs {