pressure-stream

pressure-stream
====================

call an async function for each data event into through stream. manage concurrency as back pressure.

``js
var pressure = require('pressure-stream');
var split = require('split2');
var request = require('request');


var concurrency = 100 // never ever do more than 100 requests at a time.

process.stdin.pipe(split())
.pipe(pressure(function(data,cb){
request(data,function(err,res,body){
cb(err,body)
});
},concurrency)).pipe(process.stdout);


``

API
===

pressure(fn,opts)
-----------------
- fn is the data handler it is always called with 2 arguments
- fn(data,cb)
- when you are done with the the handler call cb(err,data)
- if err is passed back with cb "error" will be emitted on the stream
- data passed back on this stream will be emited as data

options
-------
- concurrency
- the maximum number of concurrent data handlers the stream will execute.
- defaults to 10