filer: test IsSameData leaves input chunk order unchanged

Guards the clone-then-sort fix: a regression back to in-place sorting would reorder caller-owned chunk slices and reintroduce the remote-sync IF_ENTRY_EQUAL mismatch.

weed/filer/stream.go

@@ -85,14 +85,16 @@ func isSameChunks(a, b []*filer_pb.FileChunk) bool {
 	if len(a) != len(b) {
 		return false
 	}
-	slices.SortFunc(a, func(i, j *filer_pb.FileChunk) int {
+	sortedA := slices.Clone(a)
+	sortedB := slices.Clone(b)
+	slices.SortFunc(sortedA, func(i, j *filer_pb.FileChunk) int {
 		return strings.Compare(i.ETag, j.ETag)
 	})
-	slices.SortFunc(b, func(i, j *filer_pb.FileChunk) int {
+	slices.SortFunc(sortedB, func(i, j *filer_pb.FileChunk) int {
 		return strings.Compare(i.ETag, j.ETag)
 	})
-	for i := 0; i < len(a); i++ {
-		if a[i].ETag != b[i].ETag {
+	for i := 0; i < len(sortedA); i++ {
+		if sortedA[i].ETag != sortedB[i].ETag {
 			return false
 		}
 	}

weed/filer/stream_test.go

@@ -0,0 +1,28 @@
+package filer
+
+import (
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
+	"github.com/stretchr/testify/assert"
+)
+
+// IsSameData must not reorder the caller's chunk slices: filer.remote.sync
+// stamps the filer entry an event described under an IF_ENTRY_EQUAL guard,
+// and an in-place sort leaves the event entry ordered differently from the
+// stored one, so the stamp never matches.
+func TestIsSameDataLeavesChunkOrderAlone(t *testing.T) {
+	chunkA := &filer_pb.FileChunk{FileId: "1,aaa", ETag: "zzzz", Size: 4}
+	chunkB := &filer_pb.FileChunk{FileId: "2,bbb", ETag: "aaaa", Size: 2}
+	a := &filer_pb.Entry{Chunks: []*filer_pb.FileChunk{chunkA, chunkB}}
+	b := &filer_pb.Entry{Chunks: []*filer_pb.FileChunk{
+		{FileId: "3,ccc", ETag: "zzzz", Size: 4},
+		{FileId: "4,ddd", ETag: "aaaa", Size: 2},
+	}}
+
+	assert.True(t, IsSameData(a, b))
+	assert.Equal(t, "1,aaa", a.Chunks[0].FileId)
+	assert.Equal(t, "2,bbb", a.Chunks[1].FileId)
+	assert.Equal(t, "3,ccc", b.Chunks[0].FileId)
+	assert.Equal(t, "4,ddd", b.Chunks[1].FileId)
+}