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

PouchDB replication job (control)

Install

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

Usage

Intended to be used with pouchdb-job-scheduler

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

const startJob = replication { /* PouchDb replication options */}, source, target
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

Replication defaults

def = {

  live: false

  retry: false

  since: 0

}

Job generator

pouchDbReplicationJob = (options, source, target, ctx) ->

Hoist stop and replication (for Promise below)

  stop = replication = null

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

  PouchDB = ctx.PouchDB or PouchDB

Preload databases

  source = new PouchDB source if isString source

  target = new PouchDB target if isString target

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

  resolve = reject = null

  job = new Promise (_resolve, _reject) ->

    [resolve, reject] = [_resolve, _reject]

    replication = ctx.PouchDB.replicate source, target, assign options

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

    stop = (err) ->

      replication.cancel()

      job.finished = true

      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 replication events

    replication.on 'error', stop

    replication.on 'denied', stop

Live replications fire complete only when cancelled

    replication.on 'complete', complete

Applies only to retry replications

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

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

    replication.then(complete).catch(stop)

Extend the promise and return

  uid = uid + 1

  Object.assign job, {
    uid, options, stop, source, target, replication

    continue: ->

      return if job.finished

      return job unless job.done

      job.done = false

      job.continue = new Promise (_resolve, _reject) -> [resolve, reject] = [_resolve, _reject]

  }

Exports (Curried)

module.exports = curryN 4, pouchDbReplicationJob

Tests

test = require 'tape-async'

PouchDB = require 'pouchdb-memory'

pouchDbReplicationJob = module.exports

mkSource = (n = 3) ->

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

  await db.put { _id: "doc-#{ i }" } for i in [1..n]

  db

mkTarget = -> "target-#{ Math.random().toString().slice 2 }"

test 'job completion', (t) ->

One-Shot

  source = await mkSource()

  target = mkTarget()

  startJob = pouchDbReplicationJob {}, source, target

  res = await job = startJob { PouchDB }

  t.equals res.info, job.info

  target = job.target

  t.deepEqual (await source.allDocs()), (await target.allDocs()), 'docs match'

  job.stop()

  t.equals res.info, job.info

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

Live

  target = mkTarget()

  startJob = pouchDbReplicationJob { live: true, retry: true }, source, target

  res = await job = startJob { PouchDB }

  t.equals res.info, job.info

  target = job.target

  t.deepEqual (await source.allDocs()), (await target.allDocs()), 'docs match'

  job.stop()

  t.equals res.info, job.info

  t.equals res.info.status, 'cancelled'

Failure

test 'job fail', (t) ->

  target = mkTarget()

  startJob = pouchDbReplicationJob { live: true, retry: true }, 'http://foo-not-found', target

  try
    await job = startJob { PouchDB }

    t.fail()

  catch err

    t.equals err.status, 500

Version 1.1.2

License MIT