ghost/job-manager/lib/JobManager.js
const path = require('path');
const util = require('util');
const setTimeoutPromise = util.promisify(setTimeout);
const fastq = require('fastq');
const later = require('@breejs/later');
const Bree = require('bree');
const pWaitFor = require('p-wait-for');
const {UnhandledJobError, IncorrectUsageError} = require('@tryghost/errors');
const logging = require('@tryghost/logging');
const isCronExpression = require('./is-cron-expression');
const assembleBreeJob = require('./assemble-bree-job');
const JobsRepository = require('./JobsRepository');
const worker = async (task, callback) => {
try {
let result = await task();
await callback(null, result);
} catch (error) {
await callback(error);
}
};
const ALL_STATUSES = {
started: 'started',
finished: 'finished',
failed: 'failed',
queued: 'queued'
};
class JobManager {
#domainEvents;
#completionPromises = new Map();
/**
* @param {Object} options
* @param {Function} [options.errorHandler] - custom job error handler
* @param {Function} [options.workerMessageHandler] - custom message handler coming from workers
* @param {Object} [options.JobModel] - a model which can persist job data in the storage
* @param {Object} [options.domainEvents] - domain events emitter
*/
constructor({errorHandler, workerMessageHandler, JobModel, domainEvents}) {
this.queue = fastq(this, worker, 3);
this._jobMessageHandler = this._jobMessageHandler.bind(this);
this._jobErrorHandler = this._jobErrorHandler.bind(this);
this.#domainEvents = domainEvents;
const combinedMessageHandler = workerMessageHandler
? ({name, message}) => {
workerMessageHandler({name, message});
this._jobMessageHandler({name, message});
}
: this._jobMessageHandler;
const combinedErrorHandler = errorHandler
? (error, workerMeta) => {
errorHandler(error, workerMeta);
this._jobErrorHandler(error, workerMeta);
}
: this._jobErrorHandler;
this.bree = new Bree({
root: false, // set this to `false` to prevent requiring a root directory of jobs
hasSeconds: true, // precision is needed to avoid task overlaps after immediate execution
outputWorkerMetadata: true,
logger: logging,
errorHandler: combinedErrorHandler,
workerMessageHandler: combinedMessageHandler
});
this.bree.on('worker created', (name) => {
this._jobMessageHandler({name, message: ALL_STATUSES.started});
});
if (JobModel) {
this._jobsRepository = new JobsRepository({JobModel});
}
}
inlineJobHandler(jobName) {
return async (error, result) => {
if (error) {
await this._jobErrorHandler(error, {
name: jobName
});
} else {
await this._jobMessageHandler({
name: jobName,
message: 'done'
});
}
// Can potentially standardize the result here
return result;
};
}
async _jobMessageHandler({name, message}) {
if (name) {
if (message === ALL_STATUSES.started) {
if (this._jobsRepository) {
const job = await this._jobsRepository.read(name);
if (job) {
await this._jobsRepository.update(job.id, {
status: ALL_STATUSES.started,
started_at: new Date()
});
}
}
} else if (message === 'done') {
if (this._jobsRepository) {
const job = await this._jobsRepository.read(name);
if (job) {
await this._jobsRepository.update(job.id, {
status: ALL_STATUSES.finished,
finished_at: new Date()
});
}
}
// Check completion listeners
if (this.#completionPromises.has(name)) {
for (const listeners of this.#completionPromises.get(name)) {
listeners.resolve();
}
// Clear the listeners
this.#completionPromises.delete(name);
}
if (this.queue.length() <= 1) {
if (this.#completionPromises.has('all')) {
for (const listeners of this.#completionPromises.get('all')) {
listeners.resolve();
}
// Clear the listeners
this.#completionPromises.delete('all');
}
}
} else {
if (typeof message === 'object' && this.#domainEvents) {
// Is this an event?
if (message.event) {
this.#domainEvents.dispatchRaw(message.event.type, message.event.data);
}
}
}
}
}
async _jobErrorHandler(error, jobMeta) {
if (this._jobsRepository && jobMeta.name) {
const job = await this._jobsRepository.read(jobMeta.name);
if (job) {
await this._jobsRepository.update(job.id, {
status: ALL_STATUSES.failed
});
}
}
// Check completion listeners and call them with error
if (this.#completionPromises.has(jobMeta.name)) {
for (const listeners of this.#completionPromises.get(jobMeta.name)) {
listeners.reject(error);
}
// Clear the listeners
this.#completionPromises.delete(jobMeta.name);
}
if (this.queue.length() <= 1) {
if (this.#completionPromises.has('all')) {
for (const listeners of this.#completionPromises.get('all')) {
listeners.reject(error);
}
// Clear the listeners
this.#completionPromises.delete('all');
}
}
}
/**
* By default schedules an "offloaded" job. If `offloaded: true` parameter is set,
* puts an "inline" immediate job into the queue.
*
* @param {Object} GhostJob - job options
* @prop {Function | String} GhostJob.job - function or path to a module defining a job
* @prop {String} [GhostJob.name] - unique job name, if not provided takes function name or job script filename
* @prop {String | Date} [GhostJob.at] - Date, cron or human readable schedule format. Manage will do immediate execution if not specified. Not supported for "inline" jobs
* @prop {Object} [GhostJob.data] - data to be passed into the job
* @prop {Boolean} [GhostJob.offloaded] - creates an "offloaded" job running in a worker thread by default. If set to "false" runs an "inline" job on the same event loop
*/
addJob({name, at, job, data, offloaded = true}) {
if (offloaded) {
logging.info('Adding offloaded job to the queue');
let schedule;
if (!name) {
if (typeof job === 'string') {
name = path.parse(job).name;
} else {
throw new IncorrectUsageError({
message: 'Name parameter should be present if job is a function'
});
}
}
if (at && !(at instanceof Date)) {
if (isCronExpression(at)) {
schedule = later.parse.cron(at, true);
} else {
schedule = later.parse.text(at);
}
if ((schedule.error && schedule.error !== -1) || schedule.schedules.length === 0) {
throw new IncorrectUsageError({
message: 'Invalid schedule format'
});
}
logging.info(`Scheduling job ${name} at ${at}. Next run on: ${later.schedule(schedule).next()}`);
} else if (at !== undefined) {
logging.info(`Scheduling job ${name} at ${at}`);
} else {
logging.info(`Scheduling job ${name} to run immediately`);
}
const breeJob = assembleBreeJob(at, job, data, name);
this.bree.add(breeJob);
return this.bree.start(name);
} else {
logging.info(`Adding one-off job to queue with current length = ${this.queue.length()} called '${name || 'anonymous'}'`);
this.queue.push(async () => {
try {
// NOTE: setting the status here otherwise it is impossible to
// distinguish between states when the job fails immediately
await this._jobMessageHandler({
name: name,
message: ALL_STATUSES.started
});
if (typeof job === 'function') {
await job(data);
} else {
await require(job)(data);
}
} catch (err) {
// NOTE: each job should be written in a safe way and handle all errors internally
// if the error is caught here jobs implementation should be changed
logging.error(new UnhandledJobError({
context: (typeof job === 'function') ? 'function' : job,
err
}));
throw err;
}
}, this.inlineJobHandler(name));
}
}
/**
* Adds a job that could ever be executed once. In case the job fails
* can be "added" again, effectively restarting the failed job.
*
* @param {Object} GhostJob - job options
* @prop {Function | String} GhostJob.job - function or path to a module defining a job
* @prop {String} GhostJob.name - unique job name, if not provided takes function name or job script filename
* @prop {String | Date} [GhostJob.at] - Date, cron or human readable schedule format. Manage will do immediate execution if not specified. Not supported for "inline" jobs
* @prop {Object} [GhostJob.data] - data to be passed into the job
* @prop {Boolean} [GhostJob.offloaded] - creates an "offloaded" job running in a worker thread by default. If set to "false" runs an "inline" job on the same event loop
*/
async addOneOffJob({name, job, data, offloaded = true}) {
if (!name) {
throw new IncorrectUsageError({
message: `The name parameter is required for a one off job.`
});
}
const persistedJob = await this._jobsRepository.read(name);
if (persistedJob && (persistedJob.get('status') !== ALL_STATUSES.failed)) {
throw new IncorrectUsageError({
message: `A "${name}" one off job has already been executed.`
});
}
if (persistedJob && (persistedJob.get('status') === ALL_STATUSES.failed)) {
await this._jobsRepository.update(persistedJob.id, {
status: ALL_STATUSES.queued
});
} else {
await this._jobsRepository.add({
name,
status: ALL_STATUSES.queued
});
}
// NOTE: there's a assumption the job with the same name failed while
// running under different instance of job manager (bree).
// For example, it failed and the process was restarted.
// If we want to be able to restart within the same instance,
// we'd need to handle job restart/removal in Bree first
this.addJob({name, job, data, offloaded});
}
/**
* Checks if the one-off job has ever been executed successfully.
* @param {String} name one-off job name
*/
async hasExecutedSuccessfully(name) {
if (this._jobsRepository) {
const persistedJob = await this._jobsRepository.read(name);
if (!persistedJob) {
return false;
} else {
return (persistedJob.get('status') !== ALL_STATUSES.failed);
}
} else {
return false;
}
}
/**
* Awaits completion of the offloaded one-off job.
* CAUTION: it might take a long time to resolve!
* @param {String} name one-off job name
* @returns resolves with a Job model at current state
*/
async awaitOneOffCompletion(name) {
const persistedJob = await this._jobsRepository.read({
name
});
if (!persistedJob || ![ALL_STATUSES.finished, ALL_STATUSES.failed].includes(persistedJob.get('status'))) {
// NOTE: can implement exponential backoff here if that's ever needed
await setTimeoutPromise(500);
return this.awaitOneOffCompletion(name);
}
return persistedJob;
}
/***
* Create this promise before you add the job you want to listen for. Then await the returned promise.
* Resolves if the job has been executed successfully.
* Throws an error if the job has failed execution.
*/
async awaitCompletion(name) {
const promise = new Promise((resolve, reject) => {
this.#completionPromises.set(name, [
...(this.#completionPromises.get(name) ?? []),
{resolve, reject}
]);
});
return promise;
}
/**
* Wait for all inline jobs to be completed.
*/
async allSettled() {
const name = 'all';
return new Promise((resolve, reject) => {
if (this.queue.idle()) {
resolve();
return;
}
this.#completionPromises.set(name, [
...(this.#completionPromises.get(name) ?? []),
{resolve, reject}
]);
});
}
/**
* Removes an "offloaded" job from scheduled jobs queue.
* It's NOT yet possible to remove "inline" jobs (will be possible when scheduling is added https://github.com/breejs/bree/issues/68).
* The method will throw an Error if job with provided name does not exist.
*
* NOTE: current implementation does not guarante running job termination
* for details see https://github.com/breejs/bree/pull/64
*
* @param {String} name - job name
*/
async removeJob(name) {
await this.bree.remove(name);
}
/**
* @param {import('p-wait-for').Options} [options]
*/
async shutdown(options) {
await this.bree.stop();
if (this.queue.idle()) {
return;
}
logging.warn('Waiting for busy job queue');
await pWaitFor(() => this.queue.idle() === true, options);
logging.warn('Job queue finished');
}
}
module.exports = JobManager;