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'use strict'
const forever = require('async/forever')
const queue = require('async/queue')
const constants = require('../../initializers/constants')
const db = require('../../initializers/database')
const logger = require('../../helpers/logger')
const jobHandlers = require('./handlers')
const jobScheduler = {
activate,
createJob
}
function activate () {
logger.info('Jobs scheduler activated.')
const jobsQueue = queue(processJob)
forever(
function (next) {
if (jobsQueue.length() !== 0) {
// Finish processing the queue first
return setTimeout(next, constants.JOBS_FETCHING_INTERVAL)
}
db.Job.listWithLimit(constants.JOBS_FETCH_LIMIT_PER_CYCLE, function (err, jobs) {
if (err) {
logger.error('Cannot list pending jobs.', { error: err })
} else {
jobs.forEach(function (job) {
jobsQueue.push(job)
})
}
// Optimization: we could use "drain" from queue object
return setTimeout(next, constants.JOBS_FETCHING_INTERVAL)
})
}
)
}
// ---------------------------------------------------------------------------
module.exports = jobScheduler
// ---------------------------------------------------------------------------
function createJob (transaction, handlerName, handlerInputData, callback) {
const createQuery = {
state: constants.JOB_STATES.PENDING,
handlerName,
handlerInputData
}
const options = { transaction }
db.Job.create(createQuery, options).asCallback(callback)
}
function processJob (job, callback) {
const jobHandler = jobHandlers[job.handlerName]
logger.info('Processing job %d with handler %s.', job.id, job.handlerName)
job.state = constants.JOB_STATES.PROCESSING
job.save().asCallback(function (err) {
if (err) return cannotSaveJobError(err, callback)
if (jobHandler === undefined) {
logger.error('Unknown job handler for job %s.', jobHandler.handlerName)
return callback()
}
return jobHandler.process(job.handlerInputData, function (err, result) {
if (err) {
logger.error('Error in job handler %s.', job.handlerName, { error: err })
return onJobError(jobHandler, job, callback)
}
return onJobSuccess(jobHandler, job, callback)
})
})
}
function onJobError (jobHandler, job, callback) {
job.state = constants.JOB_STATES.ERROR
job.save().asCallback(function (err) {
if (err) return cannotSaveJobError(err, callback)
return jobHandler.onError(err, job.id, callback)
})
}
function onJobSuccess (jobHandler, job, callback) {
job.state = constants.JOB_STATES.SUCCESS
job.save().asCallback(function (err) {
if (err) return cannotSaveJobError(err, callback)
return jobHandler.onSuccess(err, job.id, callback)
})
}
function cannotSaveJobError (err, callback) {
logger.error('Cannot save new job state.', { error: err })
return callback(err)
}
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