aboutsummaryrefslogtreecommitdiffhomepage
path: root/server/lib/jobs/job-scheduler.ts
blob: 134d270c08c2889cdb6121b638f1771cd0010fdf (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
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)
      })
      .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
}