stream-throttle

What is stream-throttle?

The stream-throttle npm package is used to throttle the rate of data flowing through a stream. This can be useful in various scenarios such as limiting the bandwidth usage, controlling the rate of data processing, or simulating network conditions.

What are stream-throttle's main functionalities?

Throttle Read Stream

This feature allows you to throttle the read stream to a specified rate. In this example, the data from 'input.txt' is read at a rate of 1 KB per second and written to 'output.txt'.

const fs = require('fs');
const { Throttle } = require('stream-throttle');

const readStream = fs.createReadStream('input.txt');
const throttle = new Throttle({ rate: 1024 }); // 1 KB per second
const writeStream = fs.createWriteStream('output.txt');

readStream.pipe(throttle).pipe(writeStream);

Throttle Write Stream

This feature allows you to throttle the write stream to a specified rate. In this example, the data from 'input.txt' is read and written to 'output.txt' at a rate of 2 KB per second.

const fs = require('fs');
const { Throttle } = require('stream-throttle');

const readStream = fs.createReadStream('input.txt');
const throttle = new Throttle({ rate: 2048 }); // 2 KB per second
const writeStream = fs.createWriteStream('output.txt');

readStream.pipe(writeStream).pipe(throttle);

Throttle Duplex Stream

This feature allows you to throttle a duplex stream, which is both readable and writable. In this example, the duplex stream is throttled to a rate of 512 bytes per second.

const { Throttle } = require('stream-throttle');
const { Duplex } = require('stream');

const duplexStream = new Duplex({
  read(size) {
    this.push('data');
  },
  write(chunk, encoding, callback) {
    console.log(chunk.toString());
    callback();
  }
});

const throttle = new Throttle({ rate: 512 }); // 512 bytes per second

duplexStream.pipe(throttle).pipe(duplexStream);

Other packages similar to stream-throttle

limiter

The 'limiter' package provides a generic rate limiting solution that can be used to throttle various types of operations, including streams. It is more flexible in terms of the types of operations it can throttle but requires more manual setup compared to stream-throttle.

bottleneck

The 'bottleneck' package is a powerful rate limiter that can be used to control the rate of asynchronous operations. While it is not specifically designed for streams, it can be adapted to throttle stream operations. It offers advanced features like clustering and priority queues.

stream-meter

The 'stream-meter' package measures the rate of data flowing through a stream but does not throttle it. It can be used in conjunction with other packages to implement throttling based on the measured rate. It is useful for monitoring and logging purposes.

README

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 <[e-mail]>.