multistream's Introduction

multistream

A stream that emits multiple other streams one after another (streams3)

Simple, robust streams3 version of combined-stream. Allows you to combine multiple streams into a single stream. When the first stream ends, the next one starts, and so on, until all streams are consumed.

This module is used by WebTorrent, specifically create-torrent.

install

npm install multistream

usage

Use multistream like this:

var MultiStream = require('multistream')
var fs = require('fs')

var streams = [
  fs.createReadStream(__dirname + '/numbers/1.txt'),
  fs.createReadStream(__dirname + '/numbers/2.txt'),
  fs.createReadStream(__dirname + '/numbers/3.txt')
]

new MultiStream(streams).pipe(process.stdout) // => 123

You can also create an object-mode stream with MultiStream.obj(streams).

To lazily create the streams, wrap them in a function:

var streams = [
  fs.createReadStream(__dirname + '/numbers/1.txt'),
  function () { // will be executed when the stream is active
    return fs.createReadStream(__dirname + '/numbers/2.txt')
  },
  function () { // same
    return fs.createReadStream(__dirname + '/numbers/3.txt')
  }
]

new MultiStream(streams).pipe(process.stdout) // => 123

Alternatively, streams may be created by an asynchronous "factory" function:

var count = 0
function factory (cb) {
  if (count > 3) return cb(null, null)
  count++
  setTimeout(function () {
    cb(null, fs.createReadStream(__dirname + '/numbers/' + count + '.txt'))
  }, 100)
}

new MultiStream(factory).pipe(process.stdout) // => 123