JarCastinglru
A simple LRU cache supporting O(1) set, get and eviction of old keys
Installation
$ npm install lru
Example
var LRU = require('lru');
var cache = new LRU(2),
evicted
cache.on('evict',function(data) { evicted = data });
cache.set('foo', 'bar');
cache.get('foo'); //=> bar
cache.set('foo2', 'bar2');
cache.get('foo2'); //=> bar2
cache.set('foo3', 'bar3'); // => evicted = { key: 'foo', value: 'bar' }
cache.get('foo3'); // => 'bar3'
cache.remove('foo2') // => 'bar2'
cache.remove('foo4') // => undefined
cache.length // => 1
cache.keys // => ['foo3']
cache.clear() // => it will NOT emit the 'evict' event
cache.length // => 0
cache.keys // => []
API
LRU( length )
Create a new LRU cache that stores length elements before evicting the least recently used. Optionally you can pass an options map with additional options:
{
max: maxElementsToStore,
maxAge: maxAgeInMilliseconds
}
If you pass maxAge items will be evicted if they are older than maxAge when you access them.
Returns: the newly created LRU cache
Properties
.length
The number of keys currently in the cache.
.keys
Array of all the keys currently in the cache.
Methods
.set( key, value )
Set the value of the key and mark the key as most recently used.
Returns: value
.get( key )
Query the value of the key and mark the key as most recently used.
Returns: value of key if found; undefined otherwise.
.peek( key )
Query the value of the key without marking the key as most recently used.
Returns: value of key if found; undefined otherwise.
.remove( key )
Remove the value from the cache.
Returns: value of key if found; undefined otherwise.
.clear()
Clear the cache. This method does NOT emit the evict event.
.on( event, callback )
Respond to events. Currently only the evict event is implemented. When a key is evicted, the callback is executed with an associative array containing the evicted key: {key: key, value: value}.
Credits
A big thanks to Dusty Leary who finished the library.
License
MIT