atomic-queue

atomic-queue

a crash friendly queue that persists queue state and can restart. uses a worker pool and has configurable concurrency

API

for example usage see test.js

var queue = require('atomic-queue')(worker, opts)

initialize a new queue with a worker function and optional options

worker must be a function that has this API:

function work (data, done) {
  // do work, then call done with (err) if there was an error
}

data in the worker function will be a changesdown change event that looks like this:

{
 change: 1, // the local change number from the queue
 value: {
   type: 'get', // will be either get, put, del or batch
   key: 'foo', // the key you put
   value: 'bar' // the value you put
 }
}

note that if you use .batch to insert stuff into the queue you will receive the data as type: 'batch' so your worker code will need to be able to handle that if you choose to use batches (for e.g. atomicity reasons)

queue.put, queue.get, queue.del, queue.batch

these four methods are for modifying data in the queue. most of the time you will most likely be using put to add jobs to the queue.

these methods are forwarded from a levelup instance. if you need the full instance you can access it at queue.change.db

queue.on

you can listen to the following events:

error

when a catastrophic error has occurred

start

when a job starts working

end

when a job finishes working

update-start

when the queue starts flushing its state to disk

update-end

when the queue finishes flushing its state to disk