leveldb: use s[i:j:k] syntax.

R=bradfitz, dsymonds, adg
CC=golang-dev
https://codereview.appspot.com/15020050

leveldb/memdb/memdb.go

@@ -86,7 +86,8 @@ func (m *MemDB) load(kvOffset int) (b []byte) {
 		return nil
 	}
 	bLen, n := binary.Uvarint(m.kvData[kvOffset:])
-	return m.kvData[kvOffset+n : kvOffset+n+int(bLen)]
+	i, j := kvOffset+n, kvOffset+n+int(bLen)
+	return m.kvData[i:j:j]
 }
 
 // save saves a []byte to m.kvData.

leveldb/memdb/memdb_test.go

@@ -167,6 +167,9 @@ func Test1000Entries(t *testing.T) {
 		j := r.Intn(N)
 		k := []byte(strconv.Itoa(j))
 		v, err := m0.Get(k, nil)
+		if len(v) != cap(v) {
+			t.Fatalf("get: j=%d, got len(v)=%d, cap(v)=%d", j, len(v), cap(v))
+		}
 		var c uint8
 		if len(v) != 0 {
 			c = v[0]
@@ -210,6 +213,12 @@ func Test1000Entries(t *testing.T) {
 		if got := string(x.Key()); got != want {
 			t.Fatalf("iter: got %q, want %q", got, want)
 		}
+		if k := x.Key(); len(k) != cap(k) {
+			t.Fatalf("iter: len(k)=%d, cap(k)=%d", len(k), cap(k))
+		}
+		if v := x.Value(); len(v) != cap(v) {
+			t.Fatalf("iter: len(v)=%d, cap(v)=%d", len(v), cap(v))
+		}
 	}
 	if err := x.Close(); err != nil {
 		t.Fatalf("close: %v", err)

leveldb/table/reader.go

@@ -132,7 +132,7 @@ func (i *blockIter) Key() []byte {
 	if i.soi {
 		return nil
 	}
-	return i.key
+	return i.key[:len(i.key):len(i.key)]
 }
 
 // Value implements Iterator.Value, as documented in the leveldb/db package.
@@ -140,7 +140,7 @@ func (i *blockIter) Value() []byte {
 	if i.soi {
 		return nil
 	}
-	return i.val
+	return i.val[:len(i.val):len(i.val)]
 }
 
 // Close implements Iterator.Close, as documented in the leveldb/db package.

leveldb/table/table_test.go

@@ -54,6 +54,8 @@ func check(f db.File) error {
 		// Check using Get.
 		if v1, err := r.Get([]byte(k), nil); string(v1) != string(v) || err != nil {
 			return fmt.Errorf("Get %q: got (%q, %v), want (%q, %v)", k, v1, err, v, error(nil))
+		} else if len(v1) != cap(v1) {
+			return fmt.Errorf("Get %q: len(v1)=%d, cap(v1)=%d", k, len(v1), cap(v1))
 		}
 
 		// Check using Find.
@@ -61,9 +63,15 @@ func check(f db.File) error {
 		if !i.Next() || string(i.Key()) != k {
 			return fmt.Errorf("Find %q: key was not in the table", k)
 		}
+		if k1 := i.Key(); len(k1) != cap(k1) {
+			return fmt.Errorf("Find %q: len(k1)=%d, cap(k1)=%d", k, len(k1), cap(k1))
+		}
 		if string(i.Value()) != v {
 			return fmt.Errorf("Find %q: got value %q, want %q", k, i.Value(), v)
 		}
+		if v1 := i.Value(); len(v1) != cap(v1) {
+			return fmt.Errorf("Find %q: len(v1)=%d, cap(v1)=%d", k, len(v1), cap(v1))
+		}
 		if err := i.Close(); err != nil {
 			return err
 		}