memdb: fix memdb snapshot get/iter is not actually snapshot (#1393) (#…

…1434)

ref #1394

Signed-off-by: you06 <[email protected]>

.github/workflows/test.yml

@@ -52,5 +52,5 @@ jobs:
       - name: Lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.51.2
+          version: v1.55.2
 

.golangci.yml

@@ -4,7 +4,7 @@ linters:
   disable-all: true
   enable:
     - bodyclose
-    - depguard
+    #- depguard
     - exportloopref
     - gofmt
     - goimports

internal/unionstore/memdb.go

@@ -838,6 +838,7 @@ func (n *memdbNode) setBlack() {
 
 func (n *memdbNode) getKey() []byte {
 	var ret []byte
+	//nolint: staticcheck
 	hdr := (*reflect.SliceHeader)(unsafe.Pointer(&ret))
 	hdr.Data = uintptr(unsafe.Pointer(&n.flags)) + kv.FlagBytes
 	hdr.Len = int(n.klen)

internal/unionstore/memdb_arena.go

@@ -353,7 +353,7 @@ func (l *memdbVlog) getSnapshotValue(addr memdbArenaAddr, snap *MemDBCheckpoint)
 	if result.isNull() {
 		return nil, false
 	}
-	return l.getValue(addr), true
+	return l.getValue(result), true
 }
 
 func (l *memdbVlog) selectValueHistory(addr memdbArenaAddr, predicate func(memdbArenaAddr) bool) memdbArenaAddr {

internal/unionstore/memdb_test.go

@@ -860,3 +860,38 @@ func TestUnsetTemporaryFlag(t *testing.T) {
 	require.Nil(err)
 	require.False(flags.HasNeedConstraintCheckInPrewrite())
 }
+
+func TestSnapshotGetIter(t *testing.T) {
+	assert := assert.New(t)
+	buffer := newMemDB()
+	var getters []Getter
+	var iters []Iterator
+	for i := 0; i < 100; i++ {
+		assert.Nil(buffer.Set([]byte{byte(0)}, []byte{byte(i)}))
+		// getter
+		getter := buffer.SnapshotGetter()
+		val, err := getter.Get([]byte{byte(0)})
+		assert.Nil(err)
+		assert.Equal(val, []byte{byte(min(i, 50))})
+		getters = append(getters, getter)
+		// iter
+		iter := buffer.SnapshotIter(nil, nil)
+		assert.Nil(err)
+		assert.Equal(iter.Key(), []byte{byte(0)})
+		assert.Equal(iter.Value(), []byte{byte(min(i, 50))})
+		iter.Close()
+		iters = append(iters, buffer.SnapshotIter(nil, nil))
+		if i == 50 {
+			_ = buffer.Staging()
+		}
+	}
+	for _, getter := range getters {
+		val, err := getter.Get([]byte{byte(0)})
+		assert.Nil(err)
+		assert.Equal(val, []byte{byte(50)})
+	}
+	for _, iter := range iters {
+		assert.Equal(iter.Key(), []byte{byte(0)})
+		assert.Equal(iter.Value(), []byte{byte(50)})
+	}
+}

util/misc.go

@@ -168,7 +168,9 @@ func String(b []byte) (s string) {
 	if len(b) == 0 {
 		return ""
 	}
+	//nolint: staticcheck
 	pbytes := (*reflect.SliceHeader)(unsafe.Pointer(&b))
+	//nolint: staticcheck
 	pstring := (*reflect.StringHeader)(unsafe.Pointer(&s))
 	pstring.Data = pbytes.Data
 	pstring.Len = pbytes.Len