refactor: Remove unnecessary code from proto/varlogpb/log_entry.go

- replaced InvalidLogEntry with an empty LogEntry across the codebase
- removed proto/varlogpb/log_entry.go as it contained unused code
- updated related files to reflect these changes

internal/storagenode/client/log_client.go

@@ -18,7 +18,7 @@ type SubscribeResult struct {
 }
 
 var InvalidSubscribeResult = SubscribeResult{
-	LogEntry: varlogpb.InvalidLogEntry(),
+	LogEntry: varlogpb.LogEntry{},
 	Error:    errors.New("invalid subscribe result"),
 }
 

pkg/varlog/subscribe.go

@@ -518,7 +518,7 @@ func (p *dispatcher) dispatch(_ context.Context) {
 		sentErr = sentErr || res.Error != nil
 	}
 	if !sentErr {
-		p.onNextFunc(varlogpb.InvalidLogEntry(), io.EOF)
+		p.onNextFunc(varlogpb.LogEntry{}, io.EOF)
 	}
 }
 
@@ -532,7 +532,7 @@ type invalidSubscriber struct {
 }
 
 func (s invalidSubscriber) Next() (varlogpb.LogEntry, error) {
-	return varlogpb.InvalidLogEntry(), s.err
+	return varlogpb.LogEntry{}, s.err
 }
 
 func (s invalidSubscriber) Close() error {

pkg/varlogtest/admin.go

@@ -82,6 +82,7 @@ func (c *testAdmin) ListStorageNodes(ctx context.Context, opts ...varlog.AdminCa
 
 	return ret, nil
 }
+
 func (c *testAdmin) GetStorageNodes(ctx context.Context, opts ...varlog.AdminCallOption) (map[types.StorageNodeID]admpb.StorageNodeMetadata, error) {
 	snms, err := c.ListStorageNodes(ctx)
 	if err != nil {
@@ -182,8 +183,7 @@ func (c *testAdmin) AddTopic(ctx context.Context, opts ...varlog.AdminCallOption
 	c.vt.topics[topicID] = topicDesc
 	c.vt.trimGLSNs[topicID] = types.InvalidGLSN
 
-	invalidLogEntry := varlogpb.InvalidLogEntry()
-	c.vt.globalLogEntries[topicID] = []*varlogpb.LogEntry{&invalidLogEntry}
+	c.vt.globalLogEntries[topicID] = []*varlogpb.LogEntry{{}}
 
 	return proto.Clone(&topicDesc).(*varlogpb.TopicDescriptor), nil
 }
@@ -294,8 +294,7 @@ func (c *testAdmin) AddLogStream(_ context.Context, topicID types.TopicID, logSt
 
 	c.vt.logStreams[logStreamID] = lsd
 
-	invalidLogEntry := varlogpb.InvalidLogEntry()
-	c.vt.localLogEntries[logStreamID] = []*varlogpb.LogEntry{&invalidLogEntry}
+	c.vt.localLogEntries[logStreamID] = []*varlogpb.LogEntry{{}}
 
 	topicDesc.LogStreams = append(topicDesc.LogStreams, logStreamID)
 	c.vt.topics[topicID] = topicDesc

pkg/varlogtest/log.go

@@ -215,7 +215,7 @@ func (c *testLog) Subscribe(ctx context.Context, topicID types.TopicID, begin ty
 		for _, logEntry := range copiedLogEntries {
 			onNextFunc(logEntry, nil)
 		}
-		onNextFunc(varlogpb.InvalidLogEntry(), io.EOF)
+		onNextFunc(varlogpb.LogEntry{}, io.EOF)
 	}()
 
 	return func() {
@@ -319,7 +319,6 @@ func (c *testLog) PeekLogStream(ctx context.Context, tpid types.TopicID, lsid ty
 		GLSN: tail.GLSN,
 	}
 	return first, last, nil
-
 }
 
 func (c *testLog) AppendableLogStreams(tpid types.TopicID) map[types.LogStreamID]struct{} {
@@ -463,7 +462,7 @@ func newErrSubscriber(err error) *errSubscriber {
 }
 
 func (s errSubscriber) Next() (varlogpb.LogEntry, error) {
-	return varlogpb.InvalidLogEntry(), s.err
+	return varlogpb.LogEntry{}, s.err
 }
 
 func (s errSubscriber) Close() error {
@@ -496,7 +495,7 @@ func (s *subscriberImpl) Next() (varlogpb.LogEntry, error) {
 	logEntry, err := s.next()
 	if err != nil {
 		s.setErr(err)
-		return varlogpb.InvalidLogEntry(), err
+		return varlogpb.LogEntry{}, err
 	}
 	if s.cursor == s.end {
 		s.setErr(io.EOF)