Crate background_jobs[−][src]

Expand description

Background Jobs

This crate provides tooling required to run some processes asynchronously from a usually synchronous application. The standard example of this is Web Services, where certain things need to be processed, but processing them while a user is waiting for their browser to respond might not be the best experience.

Usage

Add Background Jobs to your project

[dependencies]
actix = "0.8"
background-jobs = "0.6.0"
anyhow = "1.0"
futures = "0.1"
serde = { version = "1.0", features = ["derive"] }

To get started with Background Jobs, first you should define a job.

Jobs are a combination of the data required to perform an operation, and the logic of that operation. They implment the Job, serde::Serialize, and serde::DeserializeOwned.

use anyhow::Error;
use background_jobs::Job;
use futures::future::{ok, Ready};

#[derive(Clone, Debug, serde::Deserialize, serde::Serialize)]
pub struct MyJob {
    some_usize: usize,
    other_usize: usize,
}

impl MyJob {
    pub fn new(some_usize: usize, other_usize: usize) -> Self {
        MyJob {
            some_usize,
            other_usize,
        }
    }
}

impl Job for MyJob {
    type State = ();
    type Future = Ready<Result<(), Error>>;

    const NAME: &'static str = "MyJob";

    fn run(self, _: Self::State) -> Self::Future {
        println!("args: {:?}", self);

        ok(())
    }
}

The run method for a job takes an additional argument, which is the state the job expects to use. The state for all jobs defined in an application must be the same. By default, the state is an empty tuple, but it’s likely you’ll want to pass in some Actix address, or something else.

Let’s re-define the job to care about some application state.

use anyhow::Error;
use background_jobs::Job;
use futures::future::{ok, Ready};

#[derive(Clone, Debug)]
pub struct MyState {
    pub app_name: String,
}

impl MyState {
    pub fn new(app_name: &str) -> Self {
        MyState {
            app_name: app_name.to_owned(),
        }
    }
}

impl Job for MyJob {
    type State = MyState;
    type Future = Ready<Result<(), Error>>;

    const NAME: &'static str = "MyJob";

    fn run(self, state: Self::State) -> Self::Future {
        info!("{}: args, {:?}", state.app_name, self);

        ok(())
    }
}

Running jobs

By default, this crate ships with the background-jobs-actix feature enabled. This uses the background-jobs-actix crate to spin up a Server and Workers, and provides a mechanism for spawning new jobs.

background-jobs-actix on it’s own doesn’t have a mechanism for storing worker state. This can be implemented manually by implementing the Storage trait from background-jobs-core, or the provided in-memory store can be used.

With that out of the way, back to the examples:

Main

use anyhow::Error;
use background_jobs::{ServerConfig, memory_storage::Storage, WorkerConfig};

#[actix_rt::main]
async fn main() -> Result<(), Error> {
    // Set up our Storage
    let storage = Storage::new();

    // Configure and start our workers
    let queue_handle = WorkerConfig::new(move || MyState::new("My App"))
        .register::<MyJob>()
        .set_processor_count(DEFAULT_QUEUE, 16)
        .start(storage);

    // Queue our jobs
    queue_handle.queue(MyJob::new(1, 2))?;
    queue_handle.queue(MyJob::new(3, 4))?;
    queue_handle.queue(MyJob::new(5, 6))?;

    // Block on Actix
    actix_rt::signal::ctrl_c().await?;
    Ok(())
}