@nhz.io/pouch-db-sync-job

PouchDB sync job (control)

Install

npm i -S @nhz.io/pouch-db-sync-job

Usage

Intended to be used with [pouchdb-job-scheduler]

const PouchDB = require 'pouchdb'
const sync = require('@nhz.io/pouch-db-sync-job')

const startJob = sync { /* PouchDb sync options */}, databaseA, databaseB
const job = startJob { PouchDB }

...

const res = await job

...

Literate Source

Imports

curryN = require 'curry-n'

Helpers

assign = (sources...) -> Object.assign {}, sources...

isString = (maybeString) -> typeof maybeString is 'string'

getter = (obj, name, fn) -> Object.defineProperty obj, name, {
  configurable: true, enumerable: true, get: fn
}

Definitions

Global Job UID

uid = 0

Sync defaults

def = {

  live: false

  retry: false

  since: 0

}

Job generator

pouchDbSyncJob = (options, databaseA, databaseB, ctx) ->

Hoist stop and sync (for Promise below)

  stop = sync = null

Get pouch from context or global (context comes from queue manager, if any)

  PouchDB = ctx.PouchDB or PouchDB

Preload databases

  databaseA = new PouchDB databaseA if isString databaseA

  databaseB = new PouchDB databaseB if isString databaseB

Assign defaults

  options = assign def, options

Create and start the job

Job is actually a promise extended with extra properties.

Promise states meaning:

• Promise resolved → sync has finished (Connection might still be open)
• Promise rejected
  • err is empty → sync was cancelled
  • otherwise, err contains the reason and will be set to job.error

  job = new Promise (resolve, reject) ->

    sync = ctx.PouchDB.sync databaseA, databaseB, assign options

Job stopper (err is optional - no err means manual stop)

    stop = (err) ->

      sync.cancel()

      return if job.done

      job.done = true

      job.error = err or false

      reject job.error

      return job

Job completer

    complete = (info) ->

      job.info = info if info

      return if job.done

      job.done = true

      job.error = false

Create result by stripping promise from the job and aliasing job.info

      resolve getter (assign job), 'info', () -> job.info

PouchDB sync events

    sync.on 'error', stop

    sync.on 'denied', stop

Live syncs fire complete only when cancelled

    sync.on 'complete', complete

Applies only to retry syncs

    sync.on 'active', -> job.started = true

    sync.on 'paused', (err) -> if err then stop err else complete()

    sync.then(complete).catch(stop)

Extend the promise and return

  uid = uid + 1

  Object.assign job, {
    uid, options, stop, sync, databases: [ databaseA, databaseB ]
  }

Exports (Curried)

module.exports = curryN 4, pouchDbSyncJob

Tests

test = require 'tape-async'

PouchDB = require 'pouchdb-memory'

pouchDbSyncJob = module.exports

mkdb = (s = 1, e = 3) ->

  db = new PouchDB "db-#{ Math.random().toString().slice 2 }"

  await db.put { _id: "doc-#{ i }" } for i in [s..e]

  db

Job completion

test 'job completion', (t) ->

One-Shot

  dbA = await mkdb 1, 3

  dbB = await mkdb 4, 6

  startJob = pouchDbSyncJob {}, dbA, dbB

  job = startJob { PouchDB }

  res = await job

  t.equals res.info, job.info

  t.deepEqual (await dbA.allDocs()), (await dbB.allDocs()), 'docs match'

  job.stop()

  t.equals res.info, job.info

  t.equals res.info.push.status, 'complete'
  t.equals res.info.pull.status, 'complete'

Live

  dbA = await mkdb 1, 3

  dbB = await mkdb 4, 6

  startJob = pouchDbSyncJob { live: true, retry: true }, dbA, dbB

  res = await job = startJob { PouchDB }

  t.equals res.info, job.info

  t.deepEqual (await dbA.allDocs()), (await dbB.allDocs()), 'docs match'

  t.equals job.started, true

  t.false job.sync.canceled

  job.stop()

  t.true job.sync.canceled

Job failure

test 'job failure', (t) ->

  db = await mkdb 1, 3

  startJob = pouchDbSyncJob { live: true, retry: false }, 'http://foo-not-found', db

  try
    await job = startJob { PouchDB }

    t.fail()

  catch err

    t.equals err.status, 500

Version 1.0.0

License MIT