fix(storagenode): ignore context error while checking to interleave of Append RPC errors

internal/storagenode/logstream/append.go

@@ -2,6 +2,7 @@ package logstream
 
 import (
 	"context"
+	"errors"
 	"sync"
 	"time"
 
@@ -56,23 +57,44 @@ func (at *AppendTask) WaitForCompletion(ctx context.Context) (res []snpb.AppendR
 		return nil, at.err
 	}
 
+	// Append batch requests can succeed partially. In case of partial failure,
+	// failed log entries must be sequential. That is, suffixes of the batch
+	// can be failed to append, whose length can be from zero to the full size.
+	hasNonContextErr := false
 	res = make([]snpb.AppendResult, at.dataBatchLen)
 	for i := range at.apc.awgs {
 		cerr := at.apc.awgs[i].wait(ctx)
 		if cerr != nil {
+			if !hasNonContextErr {
+				hasNonContextErr = !errors.Is(cerr, context.Canceled) && !errors.Is(cerr, context.DeadlineExceeded)
+			}
+
 			res[i].Error = cerr.Error()
 			if err == nil {
 				err = cerr
 			}
 			continue
 		}
-		if err != nil {
+
+		// It has not failed yet.
+		if err == nil {
+			res[i].Meta.TopicID = at.lse.tpid
+			res[i].Meta.LogStreamID = at.lse.lsid
+			res[i].Meta.GLSN = at.apc.awgs[i].glsn
+			res[i].Meta.LLSN = at.apc.awgs[i].llsn
+			at.apc.awgs[i].release()
+			continue
+		}
+
+		// It panics when the batch's success and failure are interleaved.
+		// However, context errors caused by clients can be ignored since
+		// the batch can succeed in the storage node, although clients
+		// canceled it.
+		// Once the codebase stabilizes, it is planned to be removed.
+		if hasNonContextErr {
 			at.lse.logger.Panic("Results of batch requests of Append RPC must not be interleaved with success and failure", zap.Error(err))
 		}
-		res[i].Meta.TopicID = at.lse.tpid
-		res[i].Meta.LogStreamID = at.lse.lsid
-		res[i].Meta.GLSN = at.apc.awgs[i].glsn
-		res[i].Meta.LLSN = at.apc.awgs[i].llsn
+		res[i].Error = err.Error()
 		at.apc.awgs[i].release()
 	}
 	if res[0].Meta.GLSN.Invalid() {

internal/storagenode/logstream/append_waitgroup.go

@@ -147,6 +147,9 @@ func (awg *appendWaitGroup) wait(ctx context.Context) error {
 	if awg == nil {
 		return nil
 	}
+	if err := ctx.Err(); err != nil {
+		return err
+	}
 	err := awg.wwg.wait(ctx)
 	if err != nil {
 		return err