chriso/lru

A simple LRU cache

lru's Issues

return value in cache.set(key, value)

This way one can write:

var value = cache.get(key) || cache.set(key, read_from_database(key));

Document all features

Only documentation is example; events not currently documented.

Clear with option to call evict on all entries?

It'd be quite nice to be able to call the evict event on all entries upon clearing the cache.

This would have the benefit of being able to do something like the following:

process.on('exit', () => cache.vacate());

Differences/benefits to lru-cache

Hey,

I've always been using https://github.com/isaacs/node-lru-cache for when I need a in-memory lru cache. But now I found this.

Any reason I should change and use this instead of lru-cache? :)

.remove returns element

Currently lru.remove(key) returns the element and not the value. I think it would be more consistent if just returned the value like set/get.

TypeError: Cannot set property 'prev' of undefined

/home/substack/projects/kd-tree-store/node_modules/lru/index.js:33
            this.cache[this.tail].prev = null;
                                       ^

TypeError: Cannot set property 'prev' of undefined
    at LRU.remove (/home/substack/projects/kd-tree-store/node_modules/lru/index.js:33:40)
    at LRU.evict (/home/substack/projects/kd-tree-store/node_modules/lru/index.js:121:29)
    at LRU.set (/home/substack/projects/kd-tree-store/node_modules/lru/index.js:66:18)
    at build (/home/substack/projects/kd-tree-store/index.js:35:17)
    at write (/home/substack/projects/kd-tree-store/index.js:53:9)
    at build (/home/substack/projects/kd-tree-store/index.js:42:7)
    at write (/home/substack/projects/kd-tree-store/index.js:59:9)
    at /home/substack/projects/kd-tree-store/index.js:38:14
    at FSReqWrap.wrapper [as oncomplete] (fs.js:667:5)

Respect maxAge on keys property

Just a though about keys property, don't you think it should evict old elements and return only valid keys regarding maxAge?

This will clean the cache more aggressively but getting the keys would be a little longer.

What do you think @chriso @mafintosh @DiegoRBaquero ?

Edit: same could apply to length property

.get doesn't consider most-recently-read access

Hi, in function get I see it calculates whether an element's modified field is set in such way that its difference with Date.now() is more than maxAge, and if so it removes that key and returns undefined.
However, it does not consider the most-recent time where an element was read, i.e. was accessed with a previous get: the modified property is set only inside function set.
This is in contrast to the documentation and to general LRU expected behavior AFAIK.

Change module.exports.LRU = … to module.exports = …

Since the module only has one export, would be simpler to just do var lru = require('lru'), but now I'm just being pedantic about it. Would be a major version update, but otherwise trivial.

backed by external service

I'm loving this LRU cache implementation, but I need use it out of my main node process.

I'm playing with the idea of move the cache in a redis service, so I want to ask: do you think that could be more or less easy create a memory laye abtraction, using memory as default, but making possible use specific implementation like redis? 😄

Add more control on `maxAge` eviction

Hello,
The rule maxAge being checked only on get calls is a bit restrictive to me. In my use case. I use peek to select some elements and then I really use only some of them and call get.

In this way, I keep the last used date accurate to evict the oldest when max is reached.
Now most of my elements are never accessed using get and maxAge is not triggered.

What do you think about adding a method to check availability or adding a parameter to get or peek to control maxAge eviction?

It would prevent me for doing this:

// Check manually if the peer is active
if (peers.maxAge && (Date.now() - peers.cache[peerId].modified) > peers.maxAge) {
  peers.remove(peerId)
  continue
}
// Don't mark the peer as most recently used on announce
var peer = this.peers.peek(peerId)

I can propose a PR in this way if you want to.

How can I keep the most recently used *unique* items?

Hello, I have a use case where I'm querying an API that tells browsers not to cache its responses. As a user bounces around from page to page in my application, the browser makes a fresh request each time, even if you're hitting "back" and "forward" repeatedly. I'd like to use a cache to save the most recent, say, 5 requests. But it should be the most recent unique requests; otherwise if you hit "back" and "forward" repeatedly, your cache will only contain those 2 pages and knock out any others you recently hit.

Is there a way to consider the uniqueness of items in an LRU like this one? Or am I thinking about it all wrong?

Thanks for your time.

Memory fragmentation

Deleting and Recreating the object each time you read, lead to a lot of memory fragmentation. You do not have to recreate the object on read. Just move the pointers in the queue.