gocron-gorm-lock

A gocron locker implementation using gorm

install

go get github.com/go-co-op/gocron-gorm-lock

usage

Here is an example usage that would be deployed in multiple instances

package main

import (
    "fmt"

    "github.com/go-co-op/gocron"
    gormlock "github.com/go-co-op/gocron-gorm-lock"
    "gorm.io/gorm"
    "time"
)

func main() {
    var db * gorm.DB // gorm db connection
    var worker string // name of this instance to be used to know which instance run the job
    db.AutoMigrate(&CronJobLock{}) // We need the table to store the job execution
    locker, err := gormlock.NewGormLocker(db, worker)
    if err != nil {
        // handle the error
    }

    s := gocron.NewScheduler(time.UTC)
    s.WithDistributedLocker(locker)

    _, err = s.Every("1s").Name("unique_name").Do(func() {
        // task to do
        fmt.Println("call 1s")
    })
    if err != nil {
        // handle the error
    }

    s.StartBlocking()
}

Prerequisites

• The table cron_job_locks needs to exist in the database. This can be achieved, as an example, using gorm automigrate functionality db.Automigrate(&CronJobLock{})
• In order to uniquely identify the job, the locker uses the unique combination of the job name + timestamp (by default with precision to seconds).

FAQ

• Q: The locker uses the unique combination of the job name + timestamp with seconds precision, how can I change that?
  • A: It's possible to change the timestamp precision used to uniquely identify the job, here is an example to set an hour precision:

    locker, err := gormlock.NewGormLocker(db, "local", gormlock.WithDefaultJobIdentifier(60 * time.Minute))

• Q: But what about if we want to write our own implementation:
  • A: It's possible to set how to create the job identifier:

    locker, err := gormlock.NewGormLocker(db, "local",
      gormlock.WithJobIdentifier(
          func(ctx context.Context, key string) string {
              return ...
          },
      ),
    )