memcpy

node-memcpy

Copies data between node Buffers and/or ArrayBuffers up to ~75 times faster than in pure JS.

Wait, what?

node.js utilizes a non-standard concept of I/O buffers and thus has both its Buffer as well as ArrayBuffer support. While Buffers are nice because they are a lot faster than V8's ArrayBuffers, transferring data between those two types can be ridiculously slow. This is where a node module like memcpy comes into play.

 i memcpy.100k > cc Buffer -> Buffer: 22.222ms
 i memcpy.100k > cc Buffer -> ArrayBuffer: 23.548ms
 i memcpy.100k > cc ArrayBuffer -> Buffer: 22.108ms
 i memcpy.100k > cc ArrayBuffer -> ArrayBuffer: 21.778ms

 i memcpy.100k > js Buffer -> Buffer: 23.163ms
 i memcpy.100k > js Buffer -> ArrayBuffer: 1043.713ms
 i memcpy.100k > js ArrayBuffer -> Buffer: 1003.351ms
 i memcpy.100k > js ArrayBuffer -> ArrayBuffer: 1607.978ms

Breakdown

• Buffer to Buffer is about as fast as using Buffer#copy
• Buffer to ArrayBuffer is about 45 times faster
• ArrayBuffer to Buffer is about 45 times faster
• ArrayBuffer to ArrayBuffer is about 75 times faster

Usage

• npm install memcpy
• var memcpy = require("memcpy");
• memcpy(target[, targetStart=0], source[, sourceStart=0[, sourceEnd=source.length])

API

var memcpy = require("memcpy"), // C++ binding if available, else native JS
    memcpy_binding = memcpy.binding, // C++ binding or NULL if not available
    memcpy_native = memcpy.native; // Native JS
...

Please keep in mind that - besides the nice numbers - this is still to be considered experimental. I'd love if you'd review the C++ code to validate that it's safe. I can't yet think about a sane use case, though, as just sticking with Buffers on node.js and ArrayBuffers in the browser should be best practice.

License: Apache License, Version 2.0