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import { AsyncQueue, forever, queue } from 'async'
import * as Sequelize from 'sequelize'
import { database as db } from '../../initializers/database'
import {
JOBS_FETCHING_INTERVAL,
JOBS_FETCH_LIMIT_PER_CYCLE,
JOB_STATES
} from '../../initializers'
import { logger } from '../../helpers'
import { JobInstance } from '../../models'
import { JobHandler, jobHandlers } from './handlers'
type JobQueueCallback = (err: Error) => void
class JobScheduler {
private static instance: JobScheduler
private constructor () { }
static get Instance () {
return this.instance || (this.instance = new this())
}
activate () {
const limit = JOBS_FETCH_LIMIT_PER_CYCLE
logger.info('Jobs scheduler activated.')
const jobsQueue = queue<JobInstance, JobQueueCallback>(this.processJob.bind(this))
// Finish processing jobs from a previous start
const state = JOB_STATES.PROCESSING
db.Job.listWithLimit(limit, state)
.then(jobs => {
this.enqueueJobs(jobsQueue, jobs)
forever(
next => {
if (jobsQueue.length() !== 0) {
// Finish processing the queue first
return setTimeout(next, JOBS_FETCHING_INTERVAL)
}
const state = JOB_STATES.PENDING
db.Job.listWithLimit(limit, state)
.then(jobs => {
this.enqueueJobs(jobsQueue, jobs)
// Optimization: we could use "drain" from queue object
return setTimeout(next, JOBS_FETCHING_INTERVAL)
})
.catch(err => logger.error('Cannot list pending jobs.', err))
},
err => logger.error('Error in job scheduler queue.', err)
)
})
.catch(err => logger.error('Cannot list pending jobs.', err))
}
createJob (transaction: Sequelize.Transaction, handlerName: string, handlerInputData: object) {
const createQuery = {
state: JOB_STATES.PENDING,
handlerName,
handlerInputData
}
const options = { transaction }
return db.Job.create(createQuery, options)
}
private enqueueJobs (jobsQueue: AsyncQueue<JobInstance>, jobs: JobInstance[]) {
jobs.forEach(job => jobsQueue.push(job))
}
private processJob (job: JobInstance, callback: (err: Error) => void) {
const jobHandler = jobHandlers[job.handlerName]
if (jobHandler === undefined) {
logger.error('Unknown job handler for job %s.', job.handlerName)
return callback(null)
}
logger.info('Processing job %d with handler %s.', job.id, job.handlerName)
job.state = JOB_STATES.PROCESSING
return job.save()
.then(() => {
return jobHandler.process(job.handlerInputData, job.id)
})
.then(
result => {
return this.onJobSuccess(jobHandler, job, result)
},
err => {
logger.error('Error in job handler %s.', job.handlerName, err)
return this.onJobError(jobHandler, job, err)
}
)
.then(() => callback(null))
.catch(err => {
this.cannotSaveJobError(err)
return callback(err)
})
}
private onJobError (jobHandler: JobHandler<any>, job: JobInstance, err: Error) {
job.state = JOB_STATES.ERROR
return job.save()
.then(() => jobHandler.onError(err, job.id))
.catch(err => this.cannotSaveJobError(err))
}
private onJobSuccess (jobHandler: JobHandler<any>, job: JobInstance, jobResult: any) {
job.state = JOB_STATES.SUCCESS
return job.save()
.then(() => jobHandler.onSuccess(job.id, jobResult))
.catch(err => this.cannotSaveJobError(err))
}
private cannotSaveJobError (err: Error) {
logger.error('Cannot save new job state.', err)
}
}
// ---------------------------------------------------------------------------
export {
JobScheduler
}
|
