Nibbler

/nɪb(ə)lə/ is a tool for cutting sheet metal with minimal distortion.

If you're like me you've probably encountered this error message:

Error: EMFILE, too many open files

There are dime dozen solutions online but I find some of them a bit hard to fit into my workflow. A library/module should be easy enough to drop in and re-use my existing logic, IMHO.

This module uses the queue function from Async to process each file bit by bit at your disposal.

Rather than poking around your file systems file descriptor limit - let's get rid of that route and instead do the less severe way by using queue at the user-space level. This is not perfect - I must say but somehow it helped me.

Install

From a technical point of view the code is pretty small, just copy/paste and you are done however do the steps below if you want to proceed.

NPM

$> npm install file-nibbler

Yarn

$> yarn add file-nibbler

Usage

var fileNibbler = require('file-nibbler').nibbler;
var MILLION_FILES_DIR = 'full/path/to/my/files/';

// This is your callback method for processing each file.
// Note that it should return a Promise so that `file-nibbler` knows
// when to call or process the next task from the queue
function myFileProcessor(pathToFile) {
    return new Promise(function(resolve, reject) {
        // do some work on the file, and resolve it once done
        resolve();
    });
}

fileNibbler(MILLION_FILES_DIR, myFileProcessor)
.then(function() {
    // done, do your post processing
})
.catch(function(error) {
    // when an error occurs
});

API

nibbler(path, [opts], callback(string))

Returns a Promise.

path

String, path to files folder

opts - Object, optional flags for various flags

opts.filterBy is a string, for filtering out specific file(s) from the path. It only accepts regex-based string eg: ^((?!flash.exe).)*$, which returns all the files except flash.exe.

Default: all files

opts.concurrencyLevel is a number for setting up the concurrency level.

Default 5

callback

Object, required callback method wrapped in Promise. Nibbler calls this function once the item is in queue and passes the full path of the file as the first argument.

Note

The module at its core is pretty basic but I'm using on production for munching thousands and gigabytes of data on low end EC2 machine.

Todo

• ~~better handling of async and sync processing of file/queue. Current use-case is sync-mode for my callback~~
• Webpack
• Test
• Hook with TravisCI
• Auto-publish to NPM, NuGet, Bower
• ES6-ify
• TypeScript definition file

References

• Async#queue

License

MIT