catstreams: Concatenate data from multiple streams fetched concurrently

catstreams provides a Readable stream interface that concatenates the results of N other streams.

Example

$ cat examples/catstreams.js
/*
 * examples/catstreams.js: basic CatStreams example
 */

var mod_restify = require('restify');
var mod_bunyan = require('bunyan');
var HttpStream = require('httpstream');
var CatStreams = require('../lib/catstreams');

var log = new mod_bunyan({
    'name': 'example',
    'level': 'warn',
    'serializers': mod_restify.bunyan.serializers
});

var client = mod_restify.createClient({
    'log': log,
    'url': 'https://us-east.manta.joyent.com'
});

var stream = new CatStreams({
    'log': log,
    'perRequestBuffer': 10 * 1024 * 1024,
    'maxConcurrency': 2
});

stream.cat(function (options) {
	return (new HttpStream({
	    'client': client,
	    'path': '/manta/public/sdks/node-manta.tar.gz',
	    'log': log,
	    'highWaterMark': options['highWaterMark']
	}));
});

stream.cat(function (options) {
	return (new HttpStream({
	    'client': client,
	    'path': '/manta/public/sdks/node-manta.tar.gz',
	    'log': log,
	    'highWaterMark': options['highWaterMark']
	}));
});

stream.cat(null);

var sum = 0;
console.log('fetching ... ');
stream.on('data', function (c) { sum += c.length; });
stream.on('end', function () {
	console.log('fetched %d bytes', sum);
	client.close();
});

$ mls -l /manta/public/sdks/node-manta.tar.gz
-rwxr-xr-x 1 manta       2697998 Jul 22 15:52 node-manta.tar.gz

$ node examples/catstream.js
fetching ...
fetched 5395996 bytes

Contributions

Pull requests should be "make prepush" clean.