lock

README

mysql-lock

a simple distributed lock based on mysql

• 中文 README

Usage

go get github.com/vearne/mysql-lock

Notice

• Distributed locks based on mysql are not rigorous.

  For example, at t1, A holds the lock, and B waits for the lock. At t2, the network between A and MySQL is abnormal. MySQL actively releases the lock imposed by A (rolling back the transaction that A has not committed), and B adds the lock. At this time, A will think that it owns the lock; B will also think that it holds the lock. The distributed lock actually fails.

• Table _lock_store will be created by mysql-lock.

  So MySQL user need CREATE permission. Or you can use doc/schema.sql to create the table _lock_store yourself.

example

package main

import (
	mlock "github.com/vearne/mysql-lock"
	"log"
	"time"
)

func main() {
	debug := false
	dsn := "tc_user:20C462C9C614@tcp(127.0.0.1:3306)/xxx?charset=utf8&loc=Asia%2FShanghai&parseTime=true"
	locker := mlock.NewMySQLLock(dsn, debug)
	// init() can be executed multiple times
	locker.Init([]string{"lock1", "lock2"})

	beginTime := time.Now()
	// max wait for 5 secs
	err := locker.Acquire("lock1", 5*time.Second)
	if err != nil {
		log.Println("can't acquire lock", err)
		log.Println(time.Since(beginTime))
		return
	}

	log.Println("got lock1")
	log.Println(time.Since(beginTime))
	time.Sleep(8 * time.Second)
	locker.Release("lock1")
	log.Println("release lock1")
}

Documentation

Index

• func InitMySQL(dsn string, debug bool) *gorm.DB
• type LockStore
  • func (LockStore) TableName() string
• type MySQLLock
  • func NewMySQLLock(dsn string, debug bool) *MySQLLock
  • func (l *MySQLLock) Acquire(lockName string, wait time.Duration) error
  • func (l *MySQLLock) Init(lockNameList []string)
  • func (l *MySQLLock) Release(lockName string) error

Functions

func InitMySQL

func InitMySQL(dsn string, debug bool) *gorm.DB

Types

type LockStore

type LockStore struct {
	Name      string    `gorm:"column:name;size:100;index:uni_name,unique" json:"name"`
	CreatedAt time.Time `gorm:"column:created_at" json:"createdAt"`
	// other
	ID int `gorm:"column:id" json:"id"`
}

func (LockStore) TableName

func (LockStore) TableName() string

type MySQLLock

type MySQLLock struct {
	sync.Mutex
	MySQLClient *gorm.DB
	TXMap       map[string]*gorm.DB
}

func NewMySQLLock

func NewMySQLLock(dsn string, debug bool) *MySQLLock

func (*MySQLLock) Acquire

func (l *MySQLLock) Acquire(lockName string, wait time.Duration) error

Lock :If the lock cannot be obtained, it will keep blocking

func (*MySQLLock) Init

func (l *MySQLLock) Init(lockNameList []string)

Init :Create tables Create row record

func (*MySQLLock) Release

func (l *MySQLLock) Release(lockName string) error