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asynq/README.md
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# Asynq
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Asynq is a simple Go library for queueing tasks and processing them in the background with workers.
It is backed by Redis and it is designed to have a low barrier to entry. It should be integrated in your web stack easily.
**Important Note**: Current major version is zero (v0.x.x) to accomodate rapid development and fast iteration while getting early feedback from users. The public API could change without a major version update before v1.0.0 release.
![Task Queue Diagram](/docs/assets/task-queue.png)
## Quickstart
First, make sure you are running a Redis server locally.
```sh
$ redis-server
```
To create and schedule tasks, use `Client` and provide a task and when to enqueue the task. Scheduled tasks will be stored in Redis and will be enqueued at the specified time.
```go
func main() {
r := &asynq.RedisClientOpt{
Addr: "127.0.0.1:6379",
}
client := asynq.NewClient(r)
// Create a task with task type and payload
t1 := asynq.NewTask("email:signup", map[string]interface{}{"user_id": 42})
t2 := asynq.NewTask("email:reminder", map[string]interface{}{"user_id": 42})
// Enqueue immediately
err := client.Enqueue(t1)
// Enqueue 24 hrs later
err = client.EnqueueIn(24*time.Hour, t2)
// Enqueue at specified time.
target := time.Date(2020, time.March, 6, 10, 0, 0, 0, time.UTC)
err = client.EnqueueAt(target, t2)
// Pass vararg options to specify processing behavior for the given task.
//
// MaxRetry specifies the max number of retry if the task fails (Default is 25).
// Queue specifies which queue to enqueue this task to (Default is "default" queue).
// Timeout specifies the the task timeout (Default is no timeout).
err = client.Enqueue(t1, asynq.MaxRetry(10), asynq.Queue("critical"), asynq.Timeout(time.Minute))
}
```
To start the background workers, use `Background` and provide your `Handler` to process the tasks.
`Handler` is an interface with one method `ProcessTask` with the following signature.
```go
// ProcessTask should return nil if the processing of a task is successful.
//
// If ProcessTask return a non-nil error or panics, the task will be retried after delay.
type Handler interface {
ProcessTask(context.Context, *asynq.Task) error
}
```
You can optionally use `ServeMux` to create a handler, just as you would with `"net/http"` Handler.
```go
func main() {
r := &asynq.RedisClientOpt{
Addr: "127.0.0.1:6379",
}
bg := asynq.NewBackground(r, &asynq.Config{
// Specify how many concurrent workers to use
Concurrency: 10,
// Optionally specify multiple queues with different priority.
Queues: map[string]int{
"critical": 6,
"default": 3,
"low": 1,
},
// See the godoc for other configuration options
})
// mux maps a type to a handler
mux := asynq.NewServeMux()
mux.HandleFunc("email:signup", signupEmailHandler)
mux.HandleFunc("email:reminder", reminderEmailHandler)
// ...register other handlers...
bg.Run(mux)
}
// function with the same signature as the ProcessTask method for the Handler interface.
func signupEmailHandler(ctx context.Context, t *asynq.Task) error {
id, err := t.Payload.GetInt("user_id")
if err != nil {
return err
}
fmt.Printf("Send welcome email to user %d\n", id)
// ...your email sending logic...
return nil
}
```
For a more detailed walk-through of the library, see our [Getting Started Guide](https://github.com/hibiken/asynq/wiki/Getting-Started).
To Learn more about `asynq` features and APIs, see our [Wiki](https://github.com/hibiken/asynq/wiki) and [godoc](https://godoc.org/github.com/hibiken/asynq).
## Command Line Tool
Asynq ships with a command line tool to inspect the state of queues and tasks.
Here's an example of running the `stats` command.
![Gif](/docs/assets/demo.gif)
For details on how to use the tool, refer to the tool's [README](/tools/asynqmon/README.md).
## Installation
To install `asynq` library, run the following command:
```sh
go get -u github.com/hibiken/asynq
```
To install the CLI tool, run the following command:
```sh
go get -u github.com/hibiken/asynq/tools/asynqmon
```
## Requirements
| Dependency | Version |
| -------------------------- | ------- |
| [Redis](https://redis.io/) | v2.8+ |
| [Go](https://golang.org/) | v1.12+ |
## Contributing
We are open to, and grateful for, any contributions (Github issues/pull-requests, feedback on Gitter channel, etc) made by the community.
Please see the [Contribution Guide](/CONTRIBUTING.md) before contributing.
## Acknowledgements
- [Sidekiq](https://github.com/mperham/sidekiq) : Many of the design ideas are taken from sidekiq and its Web UI
- [RQ](https://github.com/rq/rq) : Client APIs are inspired by rq library.
- [Cobra](https://github.com/spf13/cobra) : Asynqmon CLI is built with cobra
## License
Asynq is released under the MIT license. See [LICENSE](https://github.com/hibiken/asynq/blob/master/LICENSE).