array-lru

A really fast LRU cache for array items (numeric keys)

npm install array-lru

Credit to @dominictarr for telling me about this neat algorithm for LRUs.

Usage

var alru = require('array-lru')
var lru = alru(512) // create a lru that can contain 512 values

lru.set(42, {hello: 'world'})
console.log(lru.get(42)) // {hello: 'world'}

It works similar to a normal hash table except when a bucket is full it will evict the oldest one from the bucket to make room for the new value.

API

var lru = alru(size, [options])

Create a new LRU instance. Options include:

{
  collisions: 4, // how many hash collisions before evicting (default 4)
  evict: fn, // call this function with (index, value) when someone is evicted
  indexedValues: false // set to true if your values has a .index property
}

Size should be a multiple of collisions. If not, it will be coerced into one.

var value = lru.get(index)

Get a value from the cache. If the index is not found, null is returned.

lru.set(index, value)

Insert a new value in the cache. If there is no room in the hash bucket that index maps to, the oldest value in the bucket will be evicted.

Performance

On my MacBook 12" I can set/get around 7.500.000 values per second, YMMV. Run the benchmark using npm run bench to test it for yourself.

License

MIT