expiring-lru-cache

An expiring LRU cache module for node.js. This builds on the lru-cache module.

Usage

var Cache = require('expiring-lru-cache');

// Create a cache for up to 100 items (size). Items expire in 5 minutes
// (300,000ms expiry).
var accountCache = new Cache({size: 100, expiry: 300000});
accountCache.set('hamish', {...});
...
accountCache.get('hamish')    // => {...}

This also supports logging using Bunyan:

var Cache = require('expiring-lru-cache');
var Logger = require('bunyan');

var log = new Logger({name: 'myapp', level: 'trace'});

// 'name' is optional. It will be included in logging to help identify
// the cache.
var requestCache = new Cache({size: 50, expiry: 600000,
        log: log, name: 'request'});
requestCache.set('a', 1)
requestCache.get('a')       // => 1

This will then log at the TRACE level any cache usage:

$ node example-with-logging.js
{"name":"myapp","hostname":"banana.local","pid":44935,"level":10,"cache":{"name":"request","key":"a"},"msg":"cache set","time":"2012-03-07T22:28:40.317Z","v":0}
{"name":"myapp","hostname":"banana.local","pid":44935,"level":10,"cache":{"name":"request","key":"a"},"msg":"cache hit","time":"2012-03-07T22:28:40.319Z","v":0}

$ node example-with-logging.js | bunyan
[2012-03-07T22:28:43.724Z] TRACE: myapp/44945 on banana.local: cache set
    cache: {
      "name": "request",
      "key": "a"
    }
[2012-03-07T22:28:43.726Z] TRACE: myapp/44945 on banana.local: cache hit
    cache: {
      "name": "request",
      "key": "a"
    }

Installation

npm install expiring-lru-cache

Changelog

Changelog.

License

MIT. See LICENSE.txt.

API

var cache = new Cache({
    size: <integer number of max items>,
    expiry: <number of milliseconds expiry of items>,
    log: <optional Bunyan log>,
    name: <optional name used for logging only>
});
cache.set(key, value)
cache.get(key) -> value
cache.del(key)
cache.reset()