lint

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

internal/unionstore/art/art.go

@@ -48,10 +48,12 @@ func New() *ART {
 }
 
 func (t *ART) Get(key []byte) ([]byte, error) {
+	// 1. search the leaf node.
 	_, leaf := t.search(key)
 	if leaf == nil || leaf.vAddr.IsNull() {
 		return nil, tikverr.ErrNotExist
 	}
+	// 2. get the value from the vlog.
 	return t.allocator.vlogAllocator.GetValue(leaf.vAddr), nil
 }
 
@@ -79,7 +81,9 @@ func (t *ART) Set(key artKey, value []byte, ops ...kv.FlagsOp) error {
 	if len(t.stages) == 0 {
 		t.dirty = true
 	}
+	// 1. create or search the exist leaf in the tree.
 	addr, leaf := t.recursiveInsert(key)
+	// 2. set the value and flags.
 	t.setValue(addr, leaf, value, ops)
 	if uint64(t.Size()) > t.bufferSizeLimit {
 		return &tikverr.ErrTxnTooLarge{Size: t.Size()}

internal/unionstore/art/art_arena.go

@@ -12,7 +12,6 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-//nolint:unused
 package art
 
 import (

internal/unionstore/art/art_node.go

@@ -16,12 +16,13 @@ package art
 
 import (
 	"bytes"
-	"github.com/tikv/client-go/v2/internal/unionstore/arena"
-	"github.com/tikv/client-go/v2/kv"
 	"math"
 	"math/bits"
 	"sort"
 	"unsafe"
+
+	"github.com/tikv/client-go/v2/internal/unionstore/arena"
+	"github.com/tikv/client-go/v2/kv"
 )
 
 type nodeKind uint16
@@ -55,22 +56,6 @@ const (
 
 var nullArtNode = artNode{kind: typeInvalid, addr: arena.NullAddr}
 
-var (
-	// nullNode48 is used to initialize the node48
-	nullNode48 = node48{}
-	// nullNode256 is used to initialize the node256
-	nullNode256 = node256{}
-)
-
-func init() {
-	for i := 0; i < node48cap; i++ {
-		nullNode48.children[i] = artNode{kind: typeInvalid, addr: arena.NullAddr}
-	}
-	for i := 0; i < node256cap; i++ {
-		nullNode256.children[i] = artNode{kind: typeInvalid, addr: arena.NullAddr}
-	}
-}
-
 type artKey []byte
 
 type artNode struct {
@@ -161,7 +146,9 @@ func (an *artNode) node(a *artAllocator) *nodeBase {
 	}
 }
 
-// at returns the nth child of the node.
+// at returns the nth child of the node, used for test.
+//
+//nolint:unused
 func (an *artNode) at(a *artAllocator, idx int) artNode {
 	switch an.kind {
 	case typeNode4:
@@ -183,7 +170,6 @@ func (n48 *node48) init() {
 	n48.nodeBase.init()
 	// initialize node48
 	n48.present[0], n48.present[1], n48.present[2], n48.present[3] = 0, 0, 0, 0
-	copy(n48.children[:], nullNode48.children[:])
 }
 
 // nextPresentIdx returns the next present index starting from the given index.
@@ -222,7 +208,7 @@ func (n256 *node256) init() {
 	// initialize nodeBase
 	n256.nodeBase.init()
 	// initialize node256
-	copy(n256.children[:], nullNode256.children[:])
+	n256.present[0], n256.present[1], n256.present[2], n256.present[3] = 0, 0, 0, 0
 }
 
 func (n256 *node256) nextPresentIdx(start int) int {
@@ -302,6 +288,8 @@ const (
 )
 
 // markDelete marks the artLeaf as deleted
+//
+//nolint:unused
 func (l *artLeaf) markDelete() {
 	l.flags = deleteFlag
 }
@@ -470,7 +458,10 @@ func (an *artNode) findChild48(a *artAllocator, c byte) (int, artNode) {
 
 func (an *artNode) findChild256(a *artAllocator, c byte) (int, artNode) {
 	n256 := an.node256(a)
-	return int(c), n256.children[c]
+	if n256.present[c>>n48s]&(1<<(c%n48m)) != 0 {
+		return int(c), n256.children[c]
+	}
+	return -2, nullArtNode
 }
 
 func (an *artNode) swapChild(a *artAllocator, c byte, child artNode) {

internal/unionstore/art/art_node_test.go

@@ -21,9 +21,7 @@ func TestAllocNode(t *testing.T) {
 			require.Equal(t, [4]uint64{0, 0, 0, 0}, n.present)
 		case *node256:
 			base = &n.nodeBase
-			for i := 0; i < node256cap; i++ {
-				require.Equal(t, n.children[i], nullArtNode)
-			}
+			require.Equal(t, [4]uint64{0, 0, 0, 0}, n.present)
 		default:
 			require.Fail(t, "unknown node type")
 		}