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packetio.go
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packetio.go
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// Copyright 2015 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Copyright 2013 The Go-MySQL-Driver Authors. All rights reserved.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.
// The MIT License (MIT)
//
// Copyright (c) 2014 wandoulabs
// Copyright (c) 2014 siddontang
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
package server
import (
"bufio"
"bytes"
"compress/zlib"
"io"
"time"
"github.com/klauspost/compress/zstd"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/parser/mysql"
"github.com/pingcap/tidb/parser/terror"
server_metrics "github.com/pingcap/tidb/server/metrics"
"github.com/pingcap/tidb/sessionctx/variable"
)
const defaultWriterSize = 16 * 1024
// packetIO is a helper to read and write data in packet format.
// MySQL Packets: https://dev.mysql.com/doc/internals/en/mysql-packet.html
type packetIO struct {
bufReadConn *bufferedReadConn
bufWriter *bufio.Writer
sequence uint8
readTimeout time.Duration
// maxAllowedPacket is the maximum size of one packet in readPacket.
maxAllowedPacket uint64
// accumulatedLength count the length of totally received 'payload' in readPacket.
accumulatedLength uint64
compressionAlgorithm int
compressedSequence uint8
zstdLevel zstd.EncoderLevel
compressedWriter *compressedWriter
}
func newPacketIO(bufReadConn *bufferedReadConn) *packetIO {
p := &packetIO{sequence: 0, compressionAlgorithm: mysql.CompressionNone, compressedSequence: 0, zstdLevel: 3}
p.setBufferedReadConn(bufReadConn)
p.setMaxAllowedPacket(variable.DefMaxAllowedPacket)
return p
}
func (p *packetIO) SetCompressionAlgorithm(ca int) {
p.compressionAlgorithm = ca
p.compressedWriter = newCompressedWriter(p.bufReadConn, ca)
p.compressedWriter.zstdLevel = p.zstdLevel
p.bufWriter.Flush()
}
func (p *packetIO) setBufferedReadConn(bufReadConn *bufferedReadConn) {
p.bufReadConn = bufReadConn
p.bufWriter = bufio.NewWriterSize(bufReadConn, defaultWriterSize)
}
func (p *packetIO) setReadTimeout(timeout time.Duration) {
p.readTimeout = timeout
}
func (p *packetIO) readOnePacket() ([]byte, error) {
var header [4]byte
r := io.NopCloser(p.bufReadConn)
if p.readTimeout > 0 {
if err := p.bufReadConn.SetReadDeadline(time.Now().Add(p.readTimeout)); err != nil {
return nil, err
}
}
if p.compressionAlgorithm != mysql.CompressionNone {
var compressedHeader [7]byte
if _, err := io.ReadFull(p.bufReadConn, compressedHeader[:]); err != nil {
return nil, errors.Trace(err)
}
compressedSequence := compressedHeader[3]
if compressedSequence != p.compressedSequence {
return nil, errInvalidSequence.GenWithStack(
"invalid compressed sequence %d != %d", compressedSequence, p.compressedSequence)
}
p.compressedSequence++
p.compressedWriter.compressedSequence = p.compressedSequence
uncompressedLength := int(uint32(compressedHeader[4]) | uint32(compressedHeader[5])<<8 | uint32(compressedHeader[6])<<16)
if uncompressedLength > 0 {
switch p.compressionAlgorithm {
case mysql.CompressionZlib:
var err error
r, err = zlib.NewReader(p.bufReadConn)
if err != nil {
return nil, errors.Trace(err)
}
case mysql.CompressionZstd:
zstdReader, err := zstd.NewReader(p.bufReadConn, zstd.WithDecoderConcurrency(1))
if err != nil {
return nil, errors.Trace(err)
}
r = zstdReader.IOReadCloser()
default:
return nil, errors.New("Unknown compression algorithm")
}
}
}
if _, err := io.ReadFull(r, header[:]); err != nil {
return nil, errors.Trace(err)
}
sequence := header[3]
if sequence != p.sequence {
return nil, errInvalidSequence.GenWithStack("invalid sequence %d != %d", sequence, p.sequence)
}
p.sequence++
length := int(uint32(header[0]) | uint32(header[1])<<8 | uint32(header[2])<<16)
// Accumulated payload length exceeds the limit.
if p.accumulatedLength += uint64(length); p.accumulatedLength > p.maxAllowedPacket {
terror.Log(errNetPacketTooLarge)
return nil, errNetPacketTooLarge
}
data := make([]byte, length)
if p.readTimeout > 0 {
if err := p.bufReadConn.SetReadDeadline(time.Now().Add(p.readTimeout)); err != nil {
return nil, err
}
}
if _, err := io.ReadFull(r, data); err != nil {
return nil, errors.Trace(err)
}
err := r.Close()
if err != nil {
return nil, errors.Trace(err)
}
return data, nil
}
func (p *packetIO) setMaxAllowedPacket(maxAllowedPacket uint64) {
p.maxAllowedPacket = maxAllowedPacket
}
func (p *packetIO) readPacket() ([]byte, error) {
p.accumulatedLength = 0
if p.readTimeout == 0 {
if err := p.bufReadConn.SetReadDeadline(time.Time{}); err != nil {
return nil, errors.Trace(err)
}
}
data, err := p.readOnePacket()
if err != nil {
return nil, errors.Trace(err)
}
if len(data) < mysql.MaxPayloadLen {
server_metrics.ReadPacketBytes.Add(float64(len(data)))
return data, nil
}
// handle multi-packet
for {
buf, err := p.readOnePacket()
if err != nil {
return nil, errors.Trace(err)
}
data = append(data, buf...)
if len(buf) < mysql.MaxPayloadLen {
break
}
}
server_metrics.ReadPacketBytes.Add(float64(len(data)))
return data, nil
}
// writePacket writes data that already have header
func (p *packetIO) writePacket(data []byte) error {
length := len(data) - 4
server_metrics.WritePacketBytes.Add(float64(len(data)))
maxPayloadLen := mysql.MaxPayloadLen
if p.compressionAlgorithm != mysql.CompressionNone {
maxPayloadLen -= 4
}
for length >= maxPayloadLen {
data[3] = p.sequence
data[0] = 0xff
data[1] = 0xff
data[2] = 0xff
if p.compressionAlgorithm != mysql.CompressionNone {
if n, err := p.compressedWriter.Write(data[:4+maxPayloadLen]); err != nil {
return errors.Trace(mysql.ErrBadConn)
} else if n != (4 + maxPayloadLen) {
return errors.Trace(mysql.ErrBadConn)
}
} else {
if n, err := p.bufWriter.Write(data[:4+maxPayloadLen]); err != nil {
return errors.Trace(mysql.ErrBadConn)
} else if n != (4 + maxPayloadLen) {
return errors.Trace(mysql.ErrBadConn)
}
}
p.sequence++
length -= maxPayloadLen
data = data[maxPayloadLen:]
}
data[3] = p.sequence
data[0] = byte(length)
data[1] = byte(length >> 8)
data[2] = byte(length >> 16)
if p.compressionAlgorithm != mysql.CompressionNone {
if n, err := p.compressedWriter.Write(data); err != nil {
terror.Log(errors.Trace(err))
return errors.Trace(mysql.ErrBadConn)
} else if n != len(data) {
return errors.Trace(mysql.ErrBadConn)
} else {
p.sequence++
return nil
}
} else {
if n, err := p.bufWriter.Write(data); err != nil {
terror.Log(errors.Trace(err))
return errors.Trace(mysql.ErrBadConn)
} else if n != len(data) {
return errors.Trace(mysql.ErrBadConn)
} else {
p.sequence++
return nil
}
}
}
func (p *packetIO) flush() error {
var err error
if p.compressionAlgorithm != mysql.CompressionNone {
err = p.compressedWriter.Flush()
} else {
err = p.bufWriter.Flush()
}
if err != nil {
return errors.Trace(err)
}
return err
}
func newCompressedWriter(w io.Writer, ca int) *compressedWriter {
return &compressedWriter{
w,
new(bytes.Buffer),
ca,
0,
3,
}
}
type compressedWriter struct {
w io.Writer
buf *bytes.Buffer
compressionAlgorithm int
compressedSequence uint8
zstdLevel zstd.EncoderLevel
}
func (cw *compressedWriter) Write(data []byte) (n int, err error) {
// MySQL starts with `net_buffer_length` (default 16384) and larger packets after that.
// The length itself must fit in the 3 byte field in the header.
// Can't be bigger then the max value for `net_buffer_length` (1048576)
maxCompressedSize := 1048576 // 1 MiB
for {
remainingLen := maxCompressedSize - cw.buf.Len()
if len(data) <= remainingLen {
written, err := cw.buf.Write(data)
if err != nil {
return 0, err
}
return n + written, nil
}
written, err := cw.buf.Write(data[:remainingLen])
if err != nil {
return 0, err
}
n += written
data = data[remainingLen:]
err = cw.Flush()
if err != nil {
return 0, err
}
}
}
func (cw *compressedWriter) Flush() error {
var payload, compressedPacket bytes.Buffer
var w io.WriteCloser
var err error
// https://dev.mysql.com/doc/dev/mysql-server/latest/page_protocol_basic_compression_packet.html
// suggests a MIN_COMPRESS_LENGTH of 50.
minCompressLength := 50
data := cw.buf.Bytes()
cw.buf.Reset()
switch cw.compressionAlgorithm {
case mysql.CompressionZlib:
w, err = zlib.NewWriterLevel(&payload, zlib.HuffmanOnly)
case mysql.CompressionZstd:
w, err = zstd.NewWriter(&payload, zstd.WithEncoderLevel(cw.zstdLevel))
default:
return errors.New("Unknown compression algorithm")
}
if err != nil {
return errors.Trace(err)
}
uncompressedLength := 0
compressedHeader := make([]byte, 7)
if len(data) > minCompressLength {
uncompressedLength = len(data)
_, err := w.Write(data)
if err != nil {
return errors.Trace(err)
}
err = w.Close()
if err != nil {
return errors.Trace(err)
}
}
var compressedLength int
if len(data) > minCompressLength {
compressedLength = len(payload.Bytes())
} else {
compressedLength = len(data)
}
compressedHeader[0] = byte(compressedLength)
compressedHeader[1] = byte(compressedLength >> 8)
compressedHeader[2] = byte(compressedLength >> 16)
compressedHeader[3] = cw.compressedSequence
compressedHeader[4] = byte(uncompressedLength)
compressedHeader[5] = byte(uncompressedLength >> 8)
compressedHeader[6] = byte(uncompressedLength >> 16)
_, err = compressedPacket.Write(compressedHeader)
if err != nil {
return errors.Trace(err)
}
cw.compressedSequence++
if len(data) > minCompressLength {
_, err = compressedPacket.Write(payload.Bytes())
} else {
_, err = compressedPacket.Write(data)
}
if err != nil {
return errors.Trace(err)
}
w.Close()
_, err = cw.w.Write(compressedPacket.Bytes())
if err != nil {
return errors.Trace(err)
}
return nil
}