advanced-throttle v1.3.3
node-advanced-throttle
Node.js Transform stream that passes data through at n bytes per second and can be paused.
This module offers a Throttle passthrough stream class, it allows you to write data to it and it will be passed through in n bytes per second. It is also possible to pause and resume the steam. This can be used to send PCM Data to a speaker module in realtime.
Installation
$ npm install advanced-throttle
Example
Here's an example of throttling a file readstream at 80 bytes per second and outputting the data to stdout:
var Throttle = require('advanced-throttle');
var fs = require('fs');
// create a "Throttle" instance that reads at 80 bytes per second
var throttle = new Throttle(80);
var in = fs.createReadStream('data.txt');
in.pipe(throttle).pipe(process.stdout);
// initialize the break after 80 bytes
setTimeout(function() {
wait();
}, 1000);
// after 80 bytes wait 1 second for the user to read the text
function wait() {
if (throttle.isStreamPaused()) {
throttle.resumeStream();
} else {
throttle.pauseStream();
}
// either wait 1 second for the 80 bytes to be written or give the user the opportunity to read the text.
setTimeout(function() {
wait();
}, 1000);
}
API
Throttle()
The Throttle
passthrough stream class is very similar to the node core
stream.Passthrough
stream, except that you specify a bps
"bytes per
second" option and data will not be passed through faster than the byte
value you specify.
You can invoke with just a bps
Number and get the rest of the default
options. This should be more common:
process.stdin.pipe(new Throttle(100 * 1024)).pipe(process.stdout);
Or you can pass an options
Object in, with a bps
value specified along with
other options:
var t = new Throttle({ bps: 100 * 1024, chunkSize: 100, highWaterMark: 500 });
.pauseStream() : void
Pauses the stream but keeps storing data in the internal buffer.
.resumeStream() : void
Resumes the stream which will cause all stored data to be written out at the throttled speed.
.isStreamPaused() : boolean
Returns whether the stream is currently paused or running.