store/tikv: remove util/codec dependency (#22681)

store/tikv/pd_codec.go

@@ -18,7 +18,7 @@ import (
 
 	"github.com/pingcap/errors"
 	"github.com/pingcap/kvproto/pkg/metapb"
-	"github.com/pingcap/tidb/util/codec"
+	"github.com/pingcap/tidb/store/tikv/util/codec"
 	pd "github.com/tikv/pd/client"
 )
 

store/tikv/ticlient_test.go

@@ -26,7 +26,7 @@ import (
 	"github.com/pingcap/tidb/kv"
 	"github.com/pingcap/tidb/store/mockstore/unistore"
 	"github.com/pingcap/tidb/store/tikv/config"
-	"github.com/pingcap/tidb/util/codec"
+	"github.com/pingcap/tidb/store/tikv/util/codec"
 	pd "github.com/tikv/pd/client"
 )
 

store/tikv/util/codec/bytes.go

@@ -0,0 +1,170 @@
+// Copyright 2021 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package codec
+
+import (
+	"runtime"
+	"unsafe"
+
+	"github.com/pingcap/errors"
+)
+
+const (
+	encGroupSize = 8
+	encMarker    = byte(0xFF)
+	encPad       = byte(0x0)
+)
+
+var (
+	pads = make([]byte, encGroupSize)
+)
+
+// EncodeBytes guarantees the encoded value is in ascending order for comparison,
+// encoding with the following rule:
+//  [group1][marker1]...[groupN][markerN]
+//  group is 8 bytes slice which is padding with 0.
+//  marker is `0xFF - padding 0 count`
+// For example:
+//   [] -> [0, 0, 0, 0, 0, 0, 0, 0, 247]
+//   [1, 2, 3] -> [1, 2, 3, 0, 0, 0, 0, 0, 250]
+//   [1, 2, 3, 0] -> [1, 2, 3, 0, 0, 0, 0, 0, 251]
+//   [1, 2, 3, 4, 5, 6, 7, 8] -> [1, 2, 3, 4, 5, 6, 7, 8, 255, 0, 0, 0, 0, 0, 0, 0, 0, 247]
+// Refer: https://github.com/facebook/mysql-5.6/wiki/MyRocks-record-format#memcomparable-format
+func EncodeBytes(b []byte, data []byte) []byte {
+	// Allocate more space to avoid unnecessary slice growing.
+	// Assume that the byte slice size is about `(len(data) / encGroupSize + 1) * (encGroupSize + 1)` bytes,
+	// that is `(len(data) / 8 + 1) * 9` in our implement.
+	dLen := len(data)
+	reallocSize := (dLen/encGroupSize + 1) * (encGroupSize + 1)
+	result := reallocBytes(b, reallocSize)
+	for idx := 0; idx <= dLen; idx += encGroupSize {
+		remain := dLen - idx
+		padCount := 0
+		if remain >= encGroupSize {
+			result = append(result, data[idx:idx+encGroupSize]...)
+		} else {
+			padCount = encGroupSize - remain
+			result = append(result, data[idx:]...)
+			result = append(result, pads[:padCount]...)
+		}
+
+		marker := encMarker - byte(padCount)
+		result = append(result, marker)
+	}
+
+	return result
+}
+
+func decodeBytes(b []byte, buf []byte, reverse bool) ([]byte, []byte, error) {
+	if buf == nil {
+		buf = make([]byte, 0, len(b))
+	}
+	buf = buf[:0]
+	for {
+		if len(b) < encGroupSize+1 {
+			return nil, nil, errors.New("insufficient bytes to decode value")
+		}
+
+		groupBytes := b[:encGroupSize+1]
+
+		group := groupBytes[:encGroupSize]
+		marker := groupBytes[encGroupSize]
+
+		var padCount byte
+		if reverse {
+			padCount = marker
+		} else {
+			padCount = encMarker - marker
+		}
+		if padCount > encGroupSize {
+			return nil, nil, errors.Errorf("invalid marker byte, group bytes %q", groupBytes)
+		}
+
+		realGroupSize := encGroupSize - padCount
+		buf = append(buf, group[:realGroupSize]...)
+		b = b[encGroupSize+1:]
+
+		if padCount != 0 {
+			var padByte = encPad
+			if reverse {
+				padByte = encMarker
+			}
+			// Check validity of padding bytes.
+			for _, v := range group[realGroupSize:] {
+				if v != padByte {
+					return nil, nil, errors.Errorf("invalid padding byte, group bytes %q", groupBytes)
+				}
+			}
+			break
+		}
+	}
+	if reverse {
+		reverseBytes(buf)
+	}
+	return b, buf, nil
+}
+
+// DecodeBytes decodes bytes which is encoded by EncodeBytes before,
+// returns the leftover bytes and decoded value if no error.
+// `buf` is used to buffer data to avoid the cost of makeslice in decodeBytes when DecodeBytes is called by Decoder.DecodeOne.
+func DecodeBytes(b []byte, buf []byte) ([]byte, []byte, error) {
+	return decodeBytes(b, buf, false)
+}
+
+// See https://golang.org/src/crypto/cipher/xor.go
+const wordSize = int(unsafe.Sizeof(uintptr(0)))
+const supportsUnaligned = runtime.GOARCH == "386" || runtime.GOARCH == "amd64"
+
+func fastReverseBytes(b []byte) {
+	n := len(b)
+	w := n / wordSize
+	if w > 0 {
+		bw := *(*[]uintptr)(unsafe.Pointer(&b))
+		for i := 0; i < w; i++ {
+			bw[i] = ^bw[i]
+		}
+	}
+
+	for i := w * wordSize; i < n; i++ {
+		b[i] = ^b[i]
+	}
+}
+
+func safeReverseBytes(b []byte) {
+	for i := range b {
+		b[i] = ^b[i]
+	}
+}
+
+func reverseBytes(b []byte) {
+	if supportsUnaligned {
+		fastReverseBytes(b)
+		return
+	}
+
+	safeReverseBytes(b)
+}
+
+// reallocBytes is like realloc.
+func reallocBytes(b []byte, n int) []byte {
+	newSize := len(b) + n
+	if cap(b) < newSize {
+		bs := make([]byte, len(b), newSize)
+		copy(bs, b)
+		return bs
+	}
+
+	// slice b has capability to store n bytes
+	return b
+}