stream-throttle

A rate limiter for Node.js streams.

API usage

This module exports two classes, Throttle and ThrottleGroup.

Throttle creates a single throttled stream, based on stream.Transform. It accepts an opts parameter with the following keys:

• opts.rate is the throttling rate, in bytes per second.
• opts.chunksize (optional) is the maximum chunk size into which larger writes are decomposed; the default is opts.rate/10.

The opts object may also contain options to be passed to the stream.Transform constructor.

For example, the following code throttles stdin to stdout at 10 bytes per second:

process.stdin.pipe(new Throttle({rate: 10})).pipe(process.stdout)

ThrottleGroup allows the creation of a group of streams whose aggregate bandwidth is throttled. The constructor accepts the same opts argument as for Throttle. Call throttle on a ThrottleGroup object to create a new throttled stream belonging to the group.

For example, the following code creates two HTTP connections to www.google.com:80, and throttles their aggregate (downstream) bandwidth to 10 KB/s:

var addr = { host: 'www.google.com', port: 80 };
var tg = new ThrottleGroup({rate: 10240});

var conn1 = net.createConnection(addr),
    conn2 = net.createConnection(addr);

var thr1 = conn1.pipe(tg.throttle()),
    thr2 = conn2.pipe(tg.throttle());

// Reads from thr1 and thr2 are throttled to 10 KB/s in aggregate

Command line usage

This package installs a throttleproxy binary which implements a command-line utility for throttling connections. Run throttleproxy -h for instructions.

Contributing

Feel free to open an issue or send a pull request.

License

BSD-style. See the LICENSE file.

Author

Copyright © 2013 Tiago Quelhas. Contact me at <tiagoq@gmail.com>.