wait-for-stream

npm install wait-for-stream

A small utility to get exactly the amount of data you need from a stream. Instead of repeatedly calling read until the amount of data you wanted shows up, this does the waiting for you.

methods

new Waiter(stream)

Creates a new Waiter on a stream.

wait.getBytes(length, cb)

Waits until length bytes are available on the stream, and calls cb with those bytes.

wait.getLength(lengthBytes, cb)

Helper function which gets lengthBytes bytes and uses them as a big-endian, unsigned length to get some data. For example, if a TCP stream sends a 32 bit length followed by data of that length, wait.getLength(4, ...) will get the data for you. Valid values for lengthBytes are 1, 2, and 4. I decided to leave out 64 bit lengths as the loss of precision when converting to a JS number may result in intermittant errors. Plus, if you're waiting for more than 4GB of data on a stream, you should probably be using some other method...

examples

var Waiter = require('wait-for-stream');
 
var stream = net.connect(); // or something
var wait = new Waiter(stream);
 
wait.getBytes(12, function(data) {
    console.log(data); // Twelve bytes from the stream
});
 
wait.getLength(2, function(data) { // Get a 2 byte length
    console.log(data); // 55 bytes of stuff
});

Notes

Calling the methods repeatedly without waiting for earlier callbacks to return is perfectly safe. Just remember that the callbacks will get their data in the order the original calls were made.