gh-ost/go/mysql/binlog.go

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2016-04-06 11:05:21 +00:00
/*
Copyright 2015 Shlomi Noach, courtesy Booking.com
See https://github.com/github/gh-osc/blob/master/LICENSE
*/
package mysql
import (
"errors"
"fmt"
"regexp"
"strconv"
"strings"
)
var detachPattern *regexp.Regexp
func init() {
detachPattern, _ = regexp.Compile(`//([^/:]+):([\d]+)`) // e.g. `//binlog.01234:567890`
}
type BinlogType int
const (
BinaryLog BinlogType = iota
RelayLog
)
// BinlogCoordinates described binary log coordinates in the form of log file & log position.
type BinlogCoordinates struct {
LogFile string
LogPos int64
Type BinlogType
}
// ParseInstanceKey will parse an InstanceKey from a string representation such as 127.0.0.1:3306
func ParseBinlogCoordinates(logFileLogPos string) (*BinlogCoordinates, error) {
tokens := strings.SplitN(logFileLogPos, ":", 2)
if len(tokens) != 2 {
return nil, fmt.Errorf("ParseBinlogCoordinates: Cannot parse BinlogCoordinates from %s. Expected format is file:pos", logFileLogPos)
}
if logPos, err := strconv.ParseInt(tokens[1], 10, 0); err != nil {
return nil, fmt.Errorf("ParseBinlogCoordinates: invalid pos: %s", tokens[1])
} else {
return &BinlogCoordinates{LogFile: tokens[0], LogPos: logPos}, nil
}
}
// DisplayString returns a user-friendly string representation of these coordinates
func (this *BinlogCoordinates) DisplayString() string {
return fmt.Sprintf("%s:%d", this.LogFile, this.LogPos)
}
// String returns a user-friendly string representation of these coordinates
func (this BinlogCoordinates) String() string {
return this.DisplayString()
}
// Equals tests equality of this corrdinate and another one.
func (this *BinlogCoordinates) Equals(other *BinlogCoordinates) bool {
if other == nil {
return false
}
return this.LogFile == other.LogFile && this.LogPos == other.LogPos && this.Type == other.Type
}
// IsEmpty returns true if the log file is empty, unnamed
func (this *BinlogCoordinates) IsEmpty() bool {
return this.LogFile == ""
}
// SmallerThan returns true if this coordinate is strictly smaller than the other.
func (this *BinlogCoordinates) SmallerThan(other *BinlogCoordinates) bool {
if this.LogFile < other.LogFile {
return true
}
if this.LogFile == other.LogFile && this.LogPos < other.LogPos {
return true
}
return false
}
// SmallerThanOrEquals returns true if this coordinate is the same or equal to the other one.
// We do NOT compare the type so we can not use this.Equals()
func (this *BinlogCoordinates) SmallerThanOrEquals(other *BinlogCoordinates) bool {
if this.SmallerThan(other) {
return true
}
return this.LogFile == other.LogFile && this.LogPos == other.LogPos // No Type comparison
}
// FileSmallerThan returns true if this coordinate's file is strictly smaller than the other's.
func (this *BinlogCoordinates) FileSmallerThan(other *BinlogCoordinates) bool {
return this.LogFile < other.LogFile
}
// FileNumberDistance returns the numeric distance between this corrdinate's file number and the other's.
// Effectively it means "how many roatets/FLUSHes would make these coordinates's file reach the other's"
func (this *BinlogCoordinates) FileNumberDistance(other *BinlogCoordinates) int {
thisNumber, _ := this.FileNumber()
otherNumber, _ := other.FileNumber()
return otherNumber - thisNumber
}
// FileNumber returns the numeric value of the file, and the length in characters representing the number in the filename.
// Example: FileNumber() of mysqld.log.000789 is (789, 6)
func (this *BinlogCoordinates) FileNumber() (int, int) {
tokens := strings.Split(this.LogFile, ".")
numPart := tokens[len(tokens)-1]
numLen := len(numPart)
fileNum, err := strconv.Atoi(numPart)
if err != nil {
return 0, 0
}
return fileNum, numLen
}
// PreviousFileCoordinatesBy guesses the filename of the previous binlog/relaylog, by given offset (number of files back)
func (this *BinlogCoordinates) PreviousFileCoordinatesBy(offset int) (BinlogCoordinates, error) {
result := BinlogCoordinates{LogPos: 0, Type: this.Type}
fileNum, numLen := this.FileNumber()
if fileNum == 0 {
return result, errors.New("Log file number is zero, cannot detect previous file")
}
newNumStr := fmt.Sprintf("%d", (fileNum - offset))
newNumStr = strings.Repeat("0", numLen-len(newNumStr)) + newNumStr
tokens := strings.Split(this.LogFile, ".")
tokens[len(tokens)-1] = newNumStr
result.LogFile = strings.Join(tokens, ".")
return result, nil
}
// PreviousFileCoordinates guesses the filename of the previous binlog/relaylog
func (this *BinlogCoordinates) PreviousFileCoordinates() (BinlogCoordinates, error) {
return this.PreviousFileCoordinatesBy(1)
}
// PreviousFileCoordinates guesses the filename of the previous binlog/relaylog
func (this *BinlogCoordinates) NextFileCoordinates() (BinlogCoordinates, error) {
result := BinlogCoordinates{LogPos: 0, Type: this.Type}
fileNum, numLen := this.FileNumber()
newNumStr := fmt.Sprintf("%d", (fileNum + 1))
newNumStr = strings.Repeat("0", numLen-len(newNumStr)) + newNumStr
tokens := strings.Split(this.LogFile, ".")
tokens[len(tokens)-1] = newNumStr
result.LogFile = strings.Join(tokens, ".")
return result, nil
}
// FileSmallerThan returns true if this coordinate's file is strictly smaller than the other's.
func (this *BinlogCoordinates) DetachedCoordinates() (isDetached bool, detachedLogFile string, detachedLogPos string) {
detachedCoordinatesSubmatch := detachPattern.FindStringSubmatch(this.LogFile)
if len(detachedCoordinatesSubmatch) == 0 {
return false, "", ""
}
return true, detachedCoordinatesSubmatch[1], detachedCoordinatesSubmatch[2]
}