memcpy

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

node-memcpy

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

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.

// C++ binding
 
 i memcpy.100k > cc Buffer -> Buffer: 22.756ms
 i memcpy.100k > cc Buffer -> ArrayBuffer: 23.861ms
 i memcpy.100k > cc Buffer -> Uint8Array: 22.953ms
 
 i memcpy.100k > cc ArrayBuffer -> Buffer: 22.955ms
 i memcpy.100k > cc ArrayBuffer -> ArrayBuffer: 23.273ms
 i memcpy.100k > cc ArrayBuffer -> Uint8Array: 22.685ms
 
 i memcpy.100k > cc Uint8Array -> Buffer: 23.472ms
 i memcpy.100k > cc Uint8Array -> ArrayBuffer: 22.975ms
 i memcpy.100k > cc Uint8Array -> Uint8Array: 22.953ms
 
// Native JS
 
 i memcpy.100k > js Buffer -> Buffer: 21.617ms
 i memcpy.100k > js Buffer -> ArrayBuffer: 993.361ms
 i memcpy.100k > js Buffer -> Uint8Array: 410.010ms
 
 i memcpy.100k > js ArrayBuffer -> Buffer: 940.273ms
 i memcpy.100k > js ArrayBuffer -> ArrayBuffer: 1626.182ms
 i memcpy.100k > js ArrayBuffer -> Uint8Array: 1084.790ms
 
 i memcpy.100k > js Uint8Array -> Buffer: 386.218ms
 i memcpy.100k > js Uint8Array -> ArrayBuffer: 1107.530ms
 i memcpy.100k > js Uint8Array -> Uint8Array: 502.653ms
ArgumentTypeOptionalDescription
targetBuffer | ArrayBuffer | Uint8ArrayTarget buffer to copy to
targetStartnumberomittableTarget offset to begin copying to, defaults to 0
sourceBuffer | ArrayBuffer | Uint8ArraySource buffer to copy from
sourceStartnumberoptionalSource offset to begin copying from, defaults to 0
sourceEndnumberoptionalSource offset to end copying from, defaults ot source.length
@returnsnumberNumber of bytes copied

Source and target regions may overlap.

  • npm install memcpy
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 of a sane use case, though, as just sticking with Buffers on node.js and ArrayBuffers in the browser should be best practice.

Denys Khanzhiyev (node 0.11.13+ support with nan)

License: Apache License, Version 2.0