tree-stream

tree-stream

tree-stream is a small node module that pipes streams together and destroys all of them if one of them closes.

npm install tree-stream

This package is forked from pump and aims to be a superset of pump. When the pipe() topology is a linked list they're functionally equivalent.

What problem does it solve?

When using standard source.pipe(dest) source will not be destroyed if dest emits close or an error. You are also not able to provide a callback to tell when then pipe has finished.

tree-stream does these two things for you

Usage

var streamTree = require('tree-stream')
var fs = require('fs')

var source = fs.createReadStream('/dev/random')
var dest = fs.createWriteStream('/dev/null')

var stream = streamTree.readable(source)
stream = stream.pipe(dest)
stream.finish(function(err) {
  console.log('pipe finished', err)
})

setTimeout(function() {
  dest.destroy() // when dest is closed tree-stream will destroy source
}, 1000)

You can process an input stream and also hash it:

var streamTree = require('tree-stream')
var fs = require('fs')
var hasha = require('hasha')

var readable = streamTree.readable(fs.createReadStream('/tmp/foo.txt'))
readable = readable.split(2)
hasha.fromStream(readable[0].finish()).then((hash) => console.log(`Hash: ${hash}`))
readable[1].finish().on('data', function(data){ console.log(`Data: ${data}`) })

// Outputs:
// Data: unicorn
// Hash: e233b19aabc7d5e53826fb734d1222f1f0444c3a3fc67ff4af370a66e7cadd2cb24009f1bc86f0bed12ca5fcb226145ad10fc5f650f6ef0959f8aadc5a594b27

You can get pretty wild:

var streamTree = require('./tree-stream')
var fs = require('fs')
var hasha = require('hasha')

var writable = streamTree.writable(fs.createWriteStream('/tmp/foo.txt'))
var readable
[writable, readable] = writable.joinReadable(1)
hasha.fromStream(readable[0].finish()).then((hash) => console.log(`Hash: ${hash}`))

writable = writable.joinWritable([fs.createWriteStream('/tmp/bar.txt')])
var stream = writable.finish()
stream.write('unicorn', function() { stream.end() })

// /tmp/foo.txt and /tmp/bar.text now contain "unicorn"
// Outputs:
// Hash: e233b19aabc7d5e53826fb734d1222f1f0444c3a3fc67ff4af370a66e7cadd2cb24009f1bc86f0bed12ca5fcb226145ad10fc5f650f6ef0959f8aadc5a594b27

License

MIT

Related

Derived from pump, part of the mississippi stream utility collection.