@lokalise/background-jobs-common

Common background jobs library

This library provides a basic abstraction over BullMQ-powered background jobs. There are two types available:

• AbstractBackgroundJobProcessor: a base class for running jobs, it provides a instrumentation and logger integration plus basic API for enqueuing jobs.

Getting Started

Install all dependencies:

npm install

Run all tests:

npm run test

Usage

See test implementations in ./test/processors folder. Extend AbstractBackgroundJobProcessor and implement required methods.

Common jobs

For that type of jobs, you will need to extend AbstractBackgroundJobProcessor and implement a processInternal method. It will be called when a job is dequeued. Processing logic is automatically wrapped into NewRelic and basic logger calls, so you only need to add your domain logic.

Both queue and worker is automatically started when you instantiate the processor. There is a default configuration which you can override by passing queueConfig.queueOptions and workerOptions params to the constructor.

Use dispose() to correctly stop processing any new messages and wait for the current ones to finish.

Spies

Testing asynchronous code is hard. For that purpose we have implemented built-in spy functionality for jobs. Example usage:

const scheduledJobIds = await processor.scheduleBulk([
	{
		id: randomUUID(),
		value: 'first',
		metadata: { correlationId: generateMonotonicUuid() },
	},
	{
		id: randomUUID(),
		value: 'second',
		metadata: { correlationId: randomUUID() },
	},
])

const firstJob = await processor.spy.waitForJobWithId(scheduledJobIds[0], 'completed')
const secondJob = await await processor.spy.waitForJob(
	(data) => data.value === 'second',
	'completed',
)

expect(firstJob.data.value).toBe('first')
expect(secondJob.data.value).toBe('second')

Here, processor.spy.waitForJobWithId() returns an instance of a job with a given id, and with the expected status, and processor.spy.waitForJob() performs lookup by a custom predicate, accordingly.

Note that spies do not rely on being invoked before the job was processed, to account for the unpredictability of asynchronous operations. Even if you call await processor.spy.waitForJobWithId(scheduledJobIds[0], 'completed') after the job was already processed, spy will be able to resolve the processing result for you.

Spies are disabled in production. In order to enable them, you need to set the isTest option of BackgroundJobProcessorConfig of your processor to true.