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]
background-jobs = "0.1"
failure = "0.1"
futures = "0.1"
tokio = "0.1"

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.

#[derive(Clone, Debug, Deserialize, 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 {
    fn run(self) -> Box<dyn Future<Item = (), Error = Error> + Send> {
        info!("args: {:?}", self);

        Box::new(Ok(()).into_future())
    }
}

Next, define a Processor.

Processors are types that define default attributes for jobs, as well as containing some logic used internally to perform the job. Processors must implement Proccessor and Clone.

#[derive(Clone, Debug)]
pub struct MyProcessor;

impl Processor for MyProcessor {
    // The kind of job this processor should execute
    type Job = MyJob;

    // The name of the processor. It is super important that each processor has a unique name,
    // because otherwise one processor will overwrite another processor when they're being
    // registered.
    fn name() -> &'static str {
        "MyProcessor"
    }

    // The queue that this processor belongs to
    //
    // Workers have the option to subscribe to specific queues, so this is important to
    // determine which worker will call the processor
    //
    // Jobs can optionally override the queue they're spawned on
    fn queue() -> &'static str {
        DEFAULT_QUEUE
    }

    // The number of times background-jobs should try to retry a job before giving up
    //
    // Jobs can optionally override this value
    fn max_retries() -> MaxRetries {
        MaxRetries::Count(1)
    }

    // The logic to determine how often to retry this job if it fails
    //
    // Jobs can optionally override this value
    fn backoff_strategy() -> Backoff {
        Backoff::Exponential(2)
    }
}

Running jobs

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

Starting the job server

use background_jobs::ServerConfig;
use failure::Error;
use server_jobs_example::queue_set;

fn main() -> Result<(), Error> {
    // Run our job server
    tokio::run(ServerConfig::init(
        "127.0.0.1",
        5555,
        1,
        queue_set(),
        "example-db",
    ));

    Ok(())
}

Starting the job worker

use background_jobs::WorkerConfig;
use failure::Error;
use server_jobs_example::{queue_map, MyProcessor};

fn main() -> Result<(), Error> {
    // Create the worker config
    let mut worker = WorkerConfig::new("localhost".to_owned(), 5555, queue_map());

    // Register our processor
    worker.register_processor(MyProcessor);

    // Spin up the workers
    tokio::run(worker.run());

    Ok(())
}

Queuing jobs

use background_jobs::SpawnerConfig;
use futures::{future::lazy, Future};
use server_jobs_example::{MyJob, MyProcessor};

fn main() {
    // Create 50 new jobs, each with two consecutive values of the fibonacci sequence
    let (_, _, jobs) = (1..50).fold((0, 1, Vec::new()), |(x, y, mut acc), _| {
        acc.push(MyJob::new(x, y));

        (y, x + y, acc)
    });

    // Create the spawner
    let spawner = SpawnerConfig::new("localhost", 5555);

    // Queue each job
    tokio::run(lazy(move || {
        for job in jobs {
            tokio::spawn(spawner.queue::<MyProcessor>(job).map_err(|_| ()));
        }

        Ok(())
    }));
}

Not using a ZeroMQ based client/server model

If you want to create your own jobs processor based on this idea, you can depend on the background-jobs-core crate, which provides the LMDB storage, Processor and Job traits, as well as some other useful types for implementing a jobs processor.

Contributing

Feel free to open issues for anything you find an issue with. Please note that any contributed code will be licensed under the GPLv3.

License

Background Jobs is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Background Jobs is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. This file is part of Background Jobs.

You should have received a copy of the GNU General Public License along with Background Jobs. If not, see http://www.gnu.org/licenses/.

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