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jobQueue.js
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jobQueue.js
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const EventEmitter = require('events');
const Bull = require('bull');
// This is a wrapper API for Bull that allows creating jobs in a way that you can see when they are done
const JobQueue = function (config) {
if (config === void 0) config = {};
this.config = config;
this.queueName = config.queueName || 'worker queue';
this.queue = new Bull(this.queueName, {
redis: config.redisOptions
});
this.queue.on('global:completed', (jobId, result) => {
this.callbackEmitter.emit('completed:' + jobId, result);
});
this.queue.on('global:failed', (jobId, err) => {
this.callbackEmitter.emit('failed:' + jobId, err);
});
this.callbackEmitter = new EventEmitter();
};
// method that creates job and returns a promise that will be resolved or rejected with results of the job
JobQueue.prototype.doJob = function (name, data) {
return new Promise((resolve, reject) => {
this.queue.add(name, data).then(job => {
const completed = (result) => {
// event data is always passed as the result of JSON.stringify
// We need to attempt to JSON.parse it
// NOTE: even if the result of the job is a String it's still given to JSON.stringify,
// which wraps the string in quotes, but JSON.parse must still be called to unwrap
// the quotes surrounding the original String
try {
result = JSON.parse(result);
} catch (err) {
if (process.env.DEBUG === 'bullrack') {
console.error(err);
console.log('\ncould not `JSON.parse` job result ' + job.id + '\n');
console.log(result);
}
}
resolve(result);
// remove failed listener for this job since it will never be called
this.callbackEmitter.off('failed:' + job.id, failed);
};
const failed = (err) => {
// It seems that Bull passes the error as a string
if (typeof err === 'string') err = new Error(err);
reject(err);
// remove completed listener for this job since it will never be called
this.callbackEmitter.off('completed:' + job.id, completed);
};
this.callbackEmitter.once('completed:' + job.id, completed);
this.callbackEmitter.once('failed:' + job.id, failed);
}).catch(err => {
reject(err);
});
});
};
module.exports = JobQueue;