readcache

readcache is a module to keep the contents of a file cached in memory until it's modified. This is done by comparing the file's fs.Stats.mtime.

Originally meant to be used with JSON files, but anything else will do. It will save you a bunch of fs.readFile until it's actually necessary, and it's less "persistent" than loading JSON files using require.

Installation

Using npm:

npm install readcache

Reference

readcache.readfile (path, [options], [callback])

Gets the contents of the file at path.

If the file is not cached yet, or if the file has been modified since the time it was cached, the file will be read and its contents cached. Otherwise, you will get the cached contents.

var readcache = require('readcache');

readcache('/path/to/file', function (err, data, stats) {
    console.log(data); // Contents of the file
    console.log(stats); // { "hit": false, "mtime": 1439974339996 }
        
    // The file is cached now, so this time the contents will be coming from 
    // memory, instead of reading the file again
    readcache('/path/to/file', function (err, data, stats) {
        console.log(stats); // { "hit": true, "mtime": 1439974339996 }
    });
});

Arguments

• options - Optional set of options passed to fs.readFile
  • encoding - The string encoding, defaults to utf8
  • flag - Defaults to r
• callback - Optional callback function with signature (err, data, stats)
  • err - Error, if any
  • data - The contents of the file
  • stats - Statistics object
    • hit - true when the cache was hit, false otherwise
    • mtime - The last known modification time of the cached file

Testing

Run the unit tests with gulp test.

Benchmarking

Run the benchmark suite with gulp benchmark.

On Node.js v5.0.0, readcache is slightly faster than require and fs.readFile.

Starting 'benchmark'...
    readcache x 667 ops/sec ±3.78% (81 runs sampled)
    readFile x 661 ops/sec ±1.06% (74 runs sampled)
    require x 579 ops/sec ±1.99% (36 runs sampled)
    Passed:
      'readcache' is etalon
      'readFile' at 1.01x slower
      'require' at 1.15x slower
Finished 'benchmark' after 18 s

On Node.js v4.2.1, readcache is slightly faster than require and fs.readFile.

Starting 'benchmark'...
    readcache x 738 ops/sec ±1.46% (84 runs sampled)
    readFile x 693 ops/sec ±1.76% (74 runs sampled)
    require x 711 ops/sec ±1.64% (77 runs sampled)
    Passed:
      'readcache' is etalon
      'require' at 1.04x slower
      'readFile' at 1.06x slower
Finished 'benchmark' after 19 s

On Node.js 0.12.7, readcache is faster than its fs.readFile counterpart, but slower than require.

Starting 'benchmark'...
    readcache x 690 ops/sec ±1.10% (80 runs sampled)
    readFile x 614 ops/sec ±1.15% (80 runs sampled)
    require x 714 ops/sec ±1.13% (47 runs sampled)
    Passed:
      'require' at 1.04x faster
      'readcache' is etalon
      'readFile' at 1.12x slower
Finished 'benchmark' after 18 s

On older Node.js versions like 0.10.28, readcache is even faster than require:

Starting 'benchmark'...
    readcache x 723 ops/sec ±1.93% (82 runs sampled)
    readFile x 645 ops/sec ±2.23% (84 runs sampled)
    require x 625 ops/sec ±3.03% (38 runs sampled)
    Passed:
      'readcache' is etalon
      'readFile' at 1.12x slower
      'require' at 1.16x slower
Finished 'benchmark' after 18 s

License

The MIT License (MIT)

Copyright (c) 2015 Arturo Martínez

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.