lru cache cluster

cluster aware lru-cache - A cache object that deletes the least-recently-used items.

Usage:

Require lru-cache-cluster in master process

require('lru-cache-cluster');

In worker processes, require lru-cache-cluster and use as follows:

var LRU = require("lru-cache-cluster")
  , options = { max: 500
              , length: function (n) { return n * 2 }
              , dispose: function (key, n) { n.close() }
              , maxAge: 1000 * 60 * 60 }
  , cache = LRU(options)
  , otherCache = LRU(50) // sets just the max size

cache.set("key", "value")
cache.get("key", function(value){
	// "value"
})

If you put more stuff in it, then items will fall out.

If you try to put an oversized thing in it, then it'll fall out right away.

Options

• max The maximum size of the cache, checked by applying the length function to all values in the cache. Not setting this is kind of silly, since that's the whole purpose of this lib, but it defaults to Infinity.
• maxAge Maximum age in ms. Items are not pro-actively pruned out as they age, but if you try to get an item that is too old, it'll drop it and return undefined instead of giving it to you.
• length Function that is used to calculate the length of stored items. If you're storing strings or buffers, then you probably want to do something like function(n){return n.length}. The default is function(n){return 1}, which is fine if you want to store n like-sized things.
• dispose Function that is called on items when they are dropped from the cache. This can be handy if you want to close file descriptors or do other cleanup tasks when items are no longer accessible. Called with key, value. It's called before actually removing the item from the internal cache, so if you want to immediately put it back in, you'll have to do that in a nextTick or setTimeout callback or it won't do anything.
• stale By default, if you set a maxAge, it'll only actually pull stale items out of the cache when you get(key). (That is, it's not pre-emptively doing a setTimeout or anything.) If you set stale:true, it'll return the stale value before deleting it. If you don't set this, then it'll return undefined when you try to get a stale entry, as if it had already been deleted.