npm/callback-tracker

Track your callbacks

callback-tracker

Track your callbacks.

This module is designed to help make sure that callback functions are called before exit, and not before you are done with them.

If they are called prematurely, then an error will be thrown.

If they are not called before exit, then the tracking info will be reported on stderr for your debugging convenience.

This module is designed to help debug the cb() never called! error that happens in some cases when a bug in npm prevents it from completing all operations.

USAGE

var cbTracker = require('callback-tracker')

function someMethodOfMine(args, cb) {
  // set up the tracking device
  // cbTracker(cb, tagline)
  // tagline should ideally be unique to this *call*
  // but that is not essential.  What's important is to provide
  // enough details that you'll know wtf it was trying to do.
  cb = cbTracker('some-method:' + args.join(':'), cb)

  cb.track('start')
  fs.readFile('some-file', function (er, data) {
    cb.track('read the file')
    if (er) return cb(er)
    doSomethingWithData(data, function (er, res) {
      cb.track('did stuff with data')
      cb(er, res)
    })
  })
}

If the callback is not called before process.on('exit'), it'll print out a log of how far along it got.

If any cb.track() calls are made after the callback, then it'll throw an error and crash immediately.

The cb.track() function takes the same arguments and formats things like console.log and the like.

API

• trackCb(options, callback) Returns a tracked callback. Tracked callbacks have a cb.track() method, and a cb.key property.
• trackCb.print() Dump currently in-progress trackers.
• trackCb.pretty() Return a prettified string of the trackers in progress.

Options

The second argument to track-callback is an options object which can contain the following fields:

• track If set to false, then don't track stuff. This allows conditionally tracking cb's based on an env var or whatever.
• key A key to use to track this callback. If already in use, then a number will be appended to the end.