135 lines
3.7 KiB
Go
135 lines
3.7 KiB
Go
package binlog
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import (
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"fmt"
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"strconv"
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"strings"
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"github.com/localhots/bocadillo/tools"
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)
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// FormatDescription is a description of binary log format.
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type FormatDescription struct {
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Version uint16
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ServerVersion string
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CreateTimestamp uint32
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EventHeaderLength uint8
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EventTypeHeaderLengths []uint8
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ServerDetails ServerDetails
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}
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// ServerDetails contains server feature details.
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type ServerDetails struct {
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Flavor Flavor
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Version int
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ChecksumAlgorithm ChecksumAlgorithm
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}
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// FormatDescriptionEvent contains server details and binary log format
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// description. It is usually the first event in a log file.
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type FormatDescriptionEvent struct {
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FormatDescription
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}
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// Flavor defines the specific kind of MySQL-like database.
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type Flavor string
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// ChecksumAlgorithm is a checksum algorithm is the one used by the server.
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type ChecksumAlgorithm byte
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const (
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// FlavorMySQL is the MySQL db flavor.
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FlavorMySQL = "MySQL"
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// ChecksumAlgorithmNone means no checksum appened.
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ChecksumAlgorithmNone ChecksumAlgorithm = 0x00
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// ChecksumAlgorithmCRC32 used to append a 4 byte checksum at the end.
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ChecksumAlgorithmCRC32 ChecksumAlgorithm = 0x01
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// ChecksumAlgorithmUndefined is used when checksum algorithm is not known.
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ChecksumAlgorithmUndefined ChecksumAlgorithm = 0xFF
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)
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// Decode decodes given buffer into a format description event.
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// Spec: https://dev.mysql.com/doc/internals/en/format-description-event.html
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func (e *FormatDescriptionEvent) Decode(data []byte) error {
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buf := tools.NewBuffer(data)
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e.Version = buf.ReadUint16()
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e.ServerVersion = trimStringEOF(buf.ReadStringVarLen(50))
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e.CreateTimestamp = buf.ReadUint32()
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e.EventHeaderLength = buf.ReadUint8()
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e.EventTypeHeaderLengths = buf.ReadStringEOF()
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e.ServerDetails = ServerDetails{
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Flavor: FlavorMySQL,
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Version: parseVersionNumber(e.ServerVersion),
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ChecksumAlgorithm: ChecksumAlgorithmUndefined,
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}
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if e.ServerDetails.Version > 50601 {
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e.ServerDetails.ChecksumAlgorithm = ChecksumAlgorithm(data[len(data)-5])
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e.EventTypeHeaderLengths = e.EventTypeHeaderLengths[:len(e.EventTypeHeaderLengths)-5]
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}
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return nil
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}
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// HeaderLen returns length of event header.
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func (fd FormatDescription) HeaderLen() int {
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const defaultHeaderLength = 19
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if fd.EventHeaderLength > 0 {
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return int(fd.EventHeaderLength)
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}
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return defaultHeaderLength
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}
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// PostHeaderLen returns length of a post-header for a given event type.
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func (fd FormatDescription) PostHeaderLen(et EventType) int {
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return int(fd.EventTypeHeaderLengths[et-1])
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}
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// TableIDSize returns table ID size for a given event type.
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func (fd FormatDescription) TableIDSize(et EventType) int {
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if fd.PostHeaderLen(et) == 6 {
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return 4
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}
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return 6
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}
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func (ca ChecksumAlgorithm) String() string {
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switch ca {
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case ChecksumAlgorithmNone:
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return "None"
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case ChecksumAlgorithmCRC32:
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return "CRC32"
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case ChecksumAlgorithmUndefined:
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return "Undefined"
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default:
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return fmt.Sprintf("Unknown(%d)", ca)
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}
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}
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// parseVersionNumber turns string version into a number just like the library
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// mysql_get_server_version function does.
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// Example: 5.7.19-log gets represented as 50719
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// Spec: https://dev.mysql.com/doc/refman/8.0/en/mysql-get-server-version.html
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func parseVersionNumber(v string) int {
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tokens := strings.Split(v, ".")
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major, _ := strconv.Atoi(tokens[0])
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minor, _ := strconv.Atoi(tokens[1])
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var patch int
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for i, c := range tokens[2] {
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if c < '0' || c > '9' {
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patch, _ = strconv.Atoi(tokens[2][:i])
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break
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}
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}
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return major*10000 + minor*100 + patch
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}
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func trimStringEOF(str []byte) string {
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for i, c := range str {
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if c == 0x00 {
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return string(str[:i])
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}
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}
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return string(str)
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}
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