/
base_conn.go
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/
base_conn.go
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// Copyright 2014 The go-mysql Authors. All rights reserved.
// Use of this source code is governed by a MIT License
// that can be found in the LICENSES/go-mysql-LICENSE file.
// Copyright 2018 The kingbus Authors
//
// 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.
package mysql
import (
"bufio"
"bytes"
"fmt"
"io"
"net"
"github.com/flike/kingbus/log"
)
const (
//MaxPayloadLen is the max size of one packet in mysql
MaxPayloadLen int = 1<<24 - 1
//OKHeaderByte is is the flag for OK packet header
OKHeaderByte = 1
)
//BaseConn is the base class to handle MySQL protocol.
type BaseConn struct {
net.Conn
br *bufio.Reader
bw *bufio.Writer
Sequence uint8
}
//NewBaseConn implements create a BaseConn
func NewBaseConn(conn net.Conn) *BaseConn {
c := new(BaseConn)
c.br = bufio.NewReaderSize(conn, 1<<20)
c.bw = bufio.NewWriterSize(conn, 1<<20)
c.Conn = conn
return c
}
//ReadPacket implements read data from connection into buffer
func (c *BaseConn) ReadPacket() ([]byte, error) {
var buf bytes.Buffer
err := c.ReadPacketTo(&buf)
if err != nil {
return nil, err
}
return buf.Bytes(), nil
}
//ReadPacketTo implements read data from connection into writer
func (c *BaseConn) ReadPacketTo(w io.Writer) error {
header := []byte{0, 0, 0, 0}
if _, err := io.ReadFull(c.br, header); err != nil {
return err
}
length := int(uint32(header[0]) | uint32(header[1])<<8 | uint32(header[2])<<16)
if length < 1 {
return fmt.Errorf("invalid payload length %d", length)
}
sequence := uint8(header[3])
if sequence != c.Sequence {
return fmt.Errorf("invalid sequence %d != %d", sequence, c.Sequence)
}
c.Sequence++
if n, err := io.CopyN(w, c.br, int64(length)); err != nil {
return err
} else if n != int64(length) {
return fmt.Errorf("read length not expect")
} else {
if length < MaxPayloadLen {
return nil
}
if err := c.ReadPacketTo(w); err != nil {
return err
}
}
return nil
}
//WritePacket implements encode data into a mysql packet,
//then write the packet by connection
func (c *BaseConn) WritePacket(data []byte) error {
length := len(data) - 4
for length >= MaxPayloadLen {
data[0] = 0xff
data[1] = 0xff
data[2] = 0xff
data[3] = c.Sequence
if n, err := c.Write(data[:4+MaxPayloadLen]); err != nil {
return err
} else if n != (4 + MaxPayloadLen) {
return fmt.Errorf("write length not expect")
} else {
c.Sequence++
length -= MaxPayloadLen
data = data[MaxPayloadLen:]
}
}
data[0] = byte(length)
data[1] = byte(length >> 8)
data[2] = byte(length >> 16)
data[3] = c.Sequence
if n, err := c.Write(data); err != nil {
return err
} else if n != len(data) {
return fmt.Errorf("write length not expect")
} else {
c.Sequence++
return nil
}
}
//WriteEvent implements encode data into a binlog event,then write by the connection.
//the syncer will divide the size large than 16MB packet
//WriteEvent don't need dividing packet
func (c *BaseConn) WriteEvent(data []byte, first bool) error {
var packetLen int
header := make([]byte, 4)
if first {
packetLen = len(data) + OKHeaderByte
} else {
packetLen = len(data)
}
if MaxPayloadLen < packetLen {
log.Log.Errorf("data is large than 0xffffff,packetLen:%d", packetLen)
return ErrLargePacket
}
header[0] = byte(packetLen)
header[1] = byte(packetLen >> 8)
header[2] = byte(packetLen >> 16)
header[3] = c.Sequence
_, err := c.bw.Write(header)
if err != nil {
return err
}
//todo need add semi sync flag?
//ok_header
if first {
err = c.bw.WriteByte(0)
if err != nil {
return err
}
}
if 0 < len(data) {
_, err = c.bw.Write(data)
if err != nil {
return err
}
}
err = c.bw.Flush()
if err != nil {
return err
}
c.Sequence++
return nil
}
//ResetSequence implements reset the sequence of BaseConn
func (c *BaseConn) ResetSequence() {
c.Sequence = 0
}
//Close the BaseConn
func (c *BaseConn) Close() error {
c.Sequence = 0
if c.Conn != nil {
return c.Conn.Close()
}
return nil
}