Queues in go is not as prominent as in some other languages, since go excels at handling concurrency. However, the deferrableDecorator queue can still offer some benefit missing from the native mechanism, say go channels. The queued job won't be lost even if the system shutdown. In other words, it means jobs can be retried until success. Plus, it is also possible to queue the execution of a particular job until a lengthy period of time. Useful when you need to implement "send email after 30 days" type of Job handler.
package main
import (
"context"
"fmt"
queue "github.com/DoNewsCode/core-queue"
"time"
)
type ExampleJob string
func (e ExampleJob) Type() string {
return "example"
}
func (e ExampleJob) Data() interface{} {
return e
}
type ExampleListener struct {
ch chan struct{}
}
func (e *ExampleListener) Listen() queue.Job {
return ExampleJob("")
}
func (e *ExampleListener) Process(ctx context.Context, job queue.Job) error {
fmt.Println(job.Data())
e.ch <- struct{}{}
return nil
}
func main() {
queueDispatcher := queue.NewQueue(queue.NewInProcessDriver())
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
var ch = make(chan struct{})
go queueDispatcher.Consume(ctx)
queueDispatcher.Subscribe(&ExampleListener{ch: ch})
queueDispatcher.Dispatch(ctx, queue.Adjust(ExampleJob("foo"), queue.Defer(time.Second)))
queueDispatcher.Dispatch(ctx, queue.Adjust(ExampleJob("bar"), queue.Defer(time.Hour)))
<-ch
}