aboutsummaryrefslogtreecommitdiffhomepage
path: root/server/lib/jobs/job-scheduler.ts
blob: 2f01387e7258cfc2722efc47ed84f439e289a106 (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
135
136
137
138
139
140
141
import { 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, (err, jobs) => {
      this.enqueueJobs(err, 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, (err, jobs) => {
            if (err) {
              logger.error('Cannot list pending jobs.', { error: err })
            } else {
              jobs.forEach(job => {
                jobsQueue.push(job)
              })
            }

            // Optimization: we could use "drain" from queue object
            return setTimeout(next, JOBS_FETCHING_INTERVAL)
          })
        },

        err => { logger.error('Error in job scheduler queue.', { error: err }) }
      )
    })
  }

  createJob (transaction: Sequelize.Transaction, handlerName: string, handlerInputData: object, callback: (err: Error) => void) {
    const createQuery = {
      state: JOB_STATES.PENDING,
      handlerName,
      handlerInputData
    }
    const options = { transaction }

    db.Job.create(createQuery, options).asCallback(callback)
  }

  private enqueueJobs (err: Error, jobsQueue: AsyncQueue<JobInstance>, jobs: JobInstance[]) {
    if (err) {
      logger.error('Cannot list pending jobs.', { error: err })
    } else {
      jobs.forEach(job => {
        jobsQueue.push(job)
      })
    }
  }

  private processJob (job: JobInstance, callback: (err: Error) => void) {
    const jobHandler = jobHandlers[job.handlerName]

    logger.info('Processing job %d with handler %s.', job.id, job.handlerName)

    job.state = JOB_STATES.PROCESSING
    job.save().asCallback(err => {
      if (err) return this.cannotSaveJobError(err, callback)

      if (jobHandler === undefined) {
        logger.error('Unknown job handler for job %s.', job.handlerName)
        return callback(null)
      }

      return jobHandler.process(job.handlerInputData, (err, result) => {
        if (err) {
          logger.error('Error in job handler %s.', job.handlerName, { error: err })
          return this.onJobError(jobHandler, job, result, callback)
        }

        return this.onJobSuccess(jobHandler, job, result, callback)
      })
    })
  }

  private onJobError (jobHandler: JobHandler<any>, job: JobInstance, jobResult: any, callback: (err: Error) => void) {
    job.state = JOB_STATES.ERROR

    job.save().asCallback(err => {
      if (err) return this.cannotSaveJobError(err, callback)

      return jobHandler.onError(err, job.id, jobResult, callback)
    })
  }

  private onJobSuccess (jobHandler: JobHandler<any>, job: JobInstance, jobResult: any, callback: (err: Error) => void) {
    job.state = JOB_STATES.SUCCESS

    job.save().asCallback(err => {
      if (err) return this.cannotSaveJobError(err, callback)

      return jobHandler.onSuccess(err, job.id, jobResult, callback)
    })
  }

  private cannotSaveJobError (err: Error, callback: (err: Error) => void) {
    logger.error('Cannot save new job state.', { error: err })
    return callback(err)
  }
}

// ---------------------------------------------------------------------------

export {
  JobScheduler
}