144 lines
3.3 KiB
Go
144 lines
3.3 KiB
Go
package driver
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import (
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"context"
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"fmt"
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"os"
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"github.com/localhots/bocadillo/buffer"
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"github.com/localhots/bocadillo/mysql/driver/internal/mysql"
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)
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// Conn is a slave connection used to issue a binlog dump command.
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type Conn struct {
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conn *mysql.ExtendedConn
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conf Config
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}
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// Config contains slave connection configuration. It is passed to master upon
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// registration.
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type Config struct {
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ServerID uint32
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File string
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Offset uint32
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Hostname string
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}
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const (
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// Commands
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comRegisterSlave byte = 21
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comBinlogDump byte = 18
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// Bytes
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resultOK byte = 0x00
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resultEOF byte = 0xFE
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resultERR byte = 0xFF
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)
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// Connect esablishes a new slave connection.
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func Connect(dsn string, conf Config) (*Conn, error) {
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if conf.Hostname == "" {
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name, err := os.Hostname()
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if err != nil {
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return nil, err
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}
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conf.Hostname = name
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}
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conf.Hostname = "localhost"
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if conf.Offset == 0 {
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conf.Offset = 4
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}
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conn, err := (mysql.MySQLDriver{}).Open(dsn)
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if err != nil {
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return nil, err
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}
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extconn, err := mysql.ExtendConn(conn)
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if err != nil {
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return nil, err
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}
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return &Conn{conn: extconn, conf: conf}, nil
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}
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// ReadPacket reads next packet from the server and processes the first status
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// byte.
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func (c *Conn) ReadPacket(ctx context.Context) ([]byte, error) {
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data, err := c.conn.ReadPacket(ctx)
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if err != nil {
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return nil, err
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}
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switch data[0] {
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case resultOK:
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return data[1:], nil
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case resultERR:
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return nil, c.conn.HandleErrorPacket(data)
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case resultEOF:
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return nil, nil
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default:
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return nil, fmt.Errorf("unexpected header: %x", data[0])
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}
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}
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// RegisterSlave issues a REGISTER_SLAVE command to master.
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// Spec: https://dev.mysql.com/doc/internals/en/com-register-slave.html
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func (c *Conn) RegisterSlave() error {
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c.conn.ResetSequence()
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buf := buffer.NewCommandBuffer(1 + 4 + 1 + len(c.conf.Hostname) + 1 + 1 + 2 + 4 + 4)
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buf.WriteByte(comRegisterSlave)
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buf.WriteUint32(c.conf.ServerID)
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buf.WriteStringLenEnc(c.conf.Hostname)
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// The rest of the payload would be zeroes, consider following code for
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// reference:
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//
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// buf.WriteStringLenEnc(username)
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// buf.WriteStringLenEnc(password)
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// buf.WriteUint16(port)
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// buf.WriteUint32(replicationRank)
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// buf.WriteUint32(masterID)
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return c.runCmd(buf.Bytes())
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}
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// StartBinlogDump issues a BINLOG_DUMP command to master.
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// Spec: https://dev.mysql.com/doc/internals/en/com-binlog-dump.html
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// TODO: https://dev.mysql.com/doc/internals/en/com-binlog-dump-gtid.html
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func (c *Conn) StartBinlogDump() error {
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c.conn.ResetSequence()
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buf := buffer.NewCommandBuffer(1 + 4 + 2 + 4 + len(c.conf.File))
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buf.WriteByte(comBinlogDump)
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buf.WriteUint32(uint32(c.conf.Offset))
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buf.Skip(2) // Flags
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buf.WriteUint32(c.conf.ServerID)
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buf.WriteStringEOF(c.conf.File)
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return c.runCmd(buf.Bytes())
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}
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// DisableChecksum disables CRC32 checksums for this connection.
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func (c *Conn) DisableChecksum() error {
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return c.SetVar("@master_binlog_checksum", "NONE")
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}
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// SetVar assigns a new value to the given variable.
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func (c *Conn) SetVar(name, val string) error {
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return c.conn.Exec(fmt.Sprintf("SET %s=%q", name, val))
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}
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// Close the connection.
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func (c *Conn) Close() error {
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return c.conn.Close()
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}
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func (c *Conn) runCmd(data []byte) error {
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err := c.conn.WritePacket(data)
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if err != nil {
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return err
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}
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return c.conn.ReadResultOK()
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}
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