etcdutl: fix TotalKey counting in snapshot status

- Expose IsTombstone function from mvcc package
- Use IsTombstone to check deletion state on revision keys
- Add more tests

Fixes etcd-io#19253

Signed-off-by: Xiang Ji <johnsmith.jix@gmail.com>

etcdutl/snapshot/v3_snapshot.go

@@ -176,7 +176,13 @@ func (s *v3Manager) Status(dbPath string) (ds Status, err error) {
 					if err != nil {
 						return fmt.Errorf("cannot unmarshal value, key: %q value: %q err: %w", k, v, err)
 					}
-					seenKeys[string(kv.Key)] = struct{}{}
+					key := string(kv.Key)
+					// refer to https://etcd.io/docs/v3.5/learning/data_model/
+					if !mvcc.IsTombstone(k) {
+						seenKeys[key] = struct{}{}
+					} else {
+						delete(seenKeys, key)
+					}
 				}
 				return nil
 			}); err != nil {

etcdutl/snapshot/v3_snapshot_test.go

@@ -138,7 +138,84 @@ func TestSnapshotStatusDuplicateKeys(t *testing.T) {
 	status, err := NewV3(zap.NewNop()).Status(dbpath)
 	require.NoError(t, err)
 	// unique keys: key1, key2
-	assert.Equal(t, 2, status.TotalKey)
+	assert.Equalf(t, 2, status.TotalKey, "mismatch on duplicate inserts, expected 2 unique keys (key1/key2)")
+}
+
+// TestSnapshotStatusMixedRevisions tests if key count respects latest revision state
+func TestSnapshotStatusMixedRevisions(t *testing.T) {
+	dbpath := createDB(t, func(srv *etcdserver.EtcdServer) {
+		// key1: create -> put -> delete
+		key := []byte("key1")
+		for i := 0; i < 3; i++ {
+			if i < 2 {
+				_, err := srv.Put(context.TODO(), &etcdserverpb.PutRequest{Key: key, Value: []byte(strconv.Itoa(i))})
+				require.NoError(t, err)
+			} else {
+				_, err := srv.DeleteRange(context.TODO(), &etcdserverpb.DeleteRangeRequest{Key: key})
+				require.NoError(t, err)
+			}
+		}
+	})
+
+	status, err := NewV3(zap.NewNop()).Status(dbpath)
+	require.NoError(t, err)
+	assert.Equalf(t, 0, status.TotalKey, "final state should be tombstone")
+}
+
+// TestSnapshotStatusIgnoredTombstones tests if deleted keys are excluded from TotalKey count
+func TestSnapshotStatusIgnoredTombstones(t *testing.T) {
+	dbpath := createDB(t, func(srv *etcdserver.EtcdServer) {
+		// key1: create -> delete -> re-create -> delete
+		key := []byte("key1")
+		for i := 0; i < 2; i++ {
+			_, err := srv.Put(context.TODO(), &etcdserverpb.PutRequest{Key: key, Value: make([]byte, 1)})
+			require.NoError(t, err)
+			_, err = srv.DeleteRange(context.TODO(), &etcdserverpb.DeleteRangeRequest{Key: key})
+			require.NoError(t, err)
+		}
+	})
+
+	status, err := NewV3(zap.NewNop()).Status(dbpath)
+	require.NoError(t, err)
+	assert.Equalf(t, 0, status.TotalKey, "expected 0 active keys after multi delete cycle")
+}
+
+// TestSnapshotStatusRestoredKeys tests if recreated keys after deletion are counted
+func TestSnapshotStatusRestoredKeys(t *testing.T) {
+	dbpath := createDB(t, func(srv *etcdserver.EtcdServer) {
+		// key1: create -> delete -> re-create -> delete -> re-create
+		key := []byte("key1")
+		for i := 0; i < 5; i++ {
+			if i%2 == 0 {
+				_, err := srv.Put(context.TODO(), &etcdserverpb.PutRequest{Key: key, Value: make([]byte, 1)})
+				require.NoError(t, err)
+			} else {
+				_, err := srv.DeleteRange(context.TODO(), &etcdserverpb.DeleteRangeRequest{Key: key})
+				require.NoError(t, err)
+			}
+		}
+	})
+
+	status, err := NewV3(zap.NewNop()).Status(dbpath)
+	require.NoError(t, err)
+	assert.Equalf(t, 1, status.TotalKey, "recreated key should count as active")
+}
+
+// TestSnapshotStatusMixedDeletions tests if only active keys survive after mixed operations
+func TestSnapshotStatusMixedDeletions(t *testing.T) {
+	dbpath := createDB(t, func(srv *etcdserver.EtcdServer) {
+		// Put("key1") -> Put("key2")-> Delete("key1")
+		_, err := srv.Put(context.TODO(), &etcdserverpb.PutRequest{Key: []byte("key1"), Value: make([]byte, 1)})
+		require.NoError(t, err)
+		_, err = srv.Put(context.TODO(), &etcdserverpb.PutRequest{Key: []byte("key2"), Value: make([]byte, 1)})
+		require.NoError(t, err)
+		_, err = srv.DeleteRange(context.TODO(), &etcdserverpb.DeleteRangeRequest{Key: []byte("key1")})
+		require.NoError(t, err)
+	})
+
+	status, err := NewV3(zap.NewNop()).Status(dbpath)
+	require.NoError(t, err)
+	assert.Equalf(t, 1, status.TotalKey, "only remaining valid key should be key2")
 }
 
 // insertKeys insert `numKeys` number of keys of `valueSize` size into a running etcd server.

server/storage/mvcc/revision.go

@@ -120,3 +120,7 @@ func BytesToBucketKey(bytes []byte) BucketKey {
 func isTombstone(b []byte) bool {
 	return len(b) == markedRevBytesLen && b[markBytePosition] == markTombstone
 }
+
+func IsTombstone(b []byte) bool {
+	return isTombstone(b)
+}