evented-async

Event-based extensions for the Node.js async library

Installation

npm install evented-async

timer()

Instruments an async function so it emits timing values when the async callback is called.

Example

function task(taskDone) {
  setTimeout(taskDone, 1000);
}
 
emitter = new events.EventEmitter;
emitter.on('timeToRunTask', function(time) {
  console.log("Time to run task: " + time + "ms");
});
 
timedTask = eventedAsync.timer(emitter, 'timeToRunTask', task);
timedTask(function(){
  console.log("Timed task complete.")
});

profile()

Syntactic sugar for the timer function. profile will apply arguments to an async function and emit timing events, eliminating the need to pass a wrapper function to timer.

Example

function slowAdd(arg1, arg2, done) {
  setTimeout(function() {
    done(arg1 + arg2);
  }, 1000);
}
 
emitter = new events.EventEmitter
emitter.on('timeToSlowAdd', function(time, result) {
  console.log("Time to calculate 5 + 6 = " + result + ": " + time + "ms");
});
 
eventedAsync.profile(emitter, 'timeToSlowAdd', slowAdd, 5, 6);

Queue class

An event-driven wrapper for async.queue. There are two major differences in semantics:

• The push and unshift methods take a standard comma-separated list of arguments, rather than an object that maps argument names to argument values. These methods do not accept callbacks, nor do they support adding multiple tasks at once.
• The queue emits events for the 'saturated', 'empty', and 'drain' callbacks.

Example

q = new eventedAsync.Queue(function(message, done){
  setTimeout(function(){
    console.log("New message: " + message);
    done();
  }, 1000);
});
 
q.on('drain', function(){
  console.log("All queued messages have been written.");
});
 
q.push("Hello...");
q.push("World!");