server/lib/jobs/job-scheduler.ts

   1 import { AsyncQueue, forever, queue } from 'async'
   2 import * as Sequelize from 'sequelize'
   3 import { JobCategory } from '../../../shared'
   4 import { logger } from '../../helpers'
   5 import { database as db, JOB_STATES, JOBS_FETCH_LIMIT_PER_CYCLE, JOBS_FETCHING_INTERVAL } from '../../initializers'
   6 import { JobInstance } from '../../models'
   7
   8 export interface JobHandler<P, T> {
   9   process (data: object, jobId: number): Promise<T>
  10   onError (err: Error, jobId: number)
  11   onSuccess (jobId: number, jobResult: T, jobScheduler: JobScheduler<P, T>)
  12 }
  13 type JobQueueCallback = (err: Error) => void
  14
  15 class JobScheduler<P, T> {
  16
  17   constructor (
  18     private jobCategory: JobCategory,
  19     private jobHandlers: { [ id: string ]: JobHandler<P, T> }
  20   ) {}
  21
  22   async activate () {
  23     const limit = JOBS_FETCH_LIMIT_PER_CYCLE[this.jobCategory]
  24
  25     logger.info('Jobs scheduler %s activated.', this.jobCategory)
  26
  27     const jobsQueue = queue<JobInstance, JobQueueCallback>(this.processJob.bind(this))
  28
  29     // Finish processing jobs from a previous start
  30     const state = JOB_STATES.PROCESSING
  31     try {
  32       const jobs = await db.Job.listWithLimitByCategory(limit, state, this.jobCategory)
  33
  34       this.enqueueJobs(jobsQueue, jobs)
  35     } catch (err) {
  36       logger.error('Cannot list pending jobs.', err)
  37     }
  38
  39     forever(
  40       async next => {
  41         if (jobsQueue.length() !== 0) {
  42           // Finish processing the queue first
  43           return setTimeout(next, JOBS_FETCHING_INTERVAL)
  44         }
  45
  46         const state = JOB_STATES.PENDING
  47         try {
  48           const jobs = await db.Job.listWithLimitByCategory(limit, state, this.jobCategory)
  49
  50           this.enqueueJobs(jobsQueue, jobs)
  51         } catch (err) {
  52           logger.error('Cannot list pending jobs.', err)
  53         }
  54
  55         // Optimization: we could use "drain" from queue object
  56         return setTimeout(next, JOBS_FETCHING_INTERVAL)
  57       },
  58
  59       err => logger.error('Error in job scheduler queue.', err)
  60     )
  61   }
  62
  63   createJob (transaction: Sequelize.Transaction, handlerName: string, handlerInputData: P) {
  64     const createQuery = {
  65       state: JOB_STATES.PENDING,
  66       category: this.jobCategory,
  67       handlerName,
  68       handlerInputData
  69     }
  70
  71     const options = { transaction }
  72
  73     return db.Job.create(createQuery, options)
  74   }
  75
  76   private enqueueJobs (jobsQueue: AsyncQueue<JobInstance>, jobs: JobInstance[]) {
  77     jobs.forEach(job => jobsQueue.push(job))
  78   }
  79
  80   private async processJob (job: JobInstance, callback: (err: Error) => void) {
  81     const jobHandler = this.jobHandlers[job.handlerName]
  82     if (jobHandler === undefined) {
  83       logger.error('Unknown job handler for job %s.', job.handlerName)
  84       return callback(null)
  85     }
  86
  87     logger.info('Processing job %d with handler %s.', job.id, job.handlerName)
  88
  89     job.state = JOB_STATES.PROCESSING
  90     await job.save()
  91
  92     try {
  93       const result: T = await jobHandler.process(job.handlerInputData, job.id)
  94       await this.onJobSuccess(jobHandler, job, result)
  95     } catch (err) {
  96       logger.error('Error in job handler %s.', job.handlerName, err)
  97
  98       try {
  99         await this.onJobError(jobHandler, job, err)
 100       } catch (innerErr) {
 101         this.cannotSaveJobError(innerErr)
 102         return callback(innerErr)
 103       }
 104     }
 105
 106     callback(null)
 107   }
 108
 109   private async onJobError (jobHandler: JobHandler<P, T>, job: JobInstance, err: Error) {
 110     job.state = JOB_STATES.ERROR
 111
 112     try {
 113       await job.save()
 114       await jobHandler.onError(err, job.id)
 115     } catch (err) {
 116       this.cannotSaveJobError(err)
 117     }
 118   }
 119
 120   private async onJobSuccess (jobHandler: JobHandler<P, T>, job: JobInstance, jobResult: T) {
 121     job.state = JOB_STATES.SUCCESS
 122
 123     try {
 124       await job.save()
 125       jobHandler.onSuccess(job.id, jobResult, this)
 126     } catch (err) {
 127       this.cannotSaveJobError(err)
 128     }
 129   }
 130
 131   private cannotSaveJobError (err: Error) {
 132     logger.error('Cannot save new job state.', err)
 133   }
 134 }
 135
 136 // ---------------------------------------------------------------------------
 137
 138 export {
 139   JobScheduler
 140 }