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serialized-lru-cache
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A cache object that deletes the least-recently-used items, with serialization support
A cache object that deletes the least-recently-used items, with serialization support.
This is a fork of the wonderful @isaacs node-lru-cache with several improvements
Get it from npm
npm install serialized-lru-cache
var LRUCache = require("lru-cache");
var cache = LRUCache(options);
or from bower
bower install serialized-lru-cache
<script type="text/javascript" src="bower_components/serialized-lru-cache/lib/lru-cache.js"></script>
<script type="text/javascript">
var cache = window.LRUCache(options);
</script>
var LRU = require("lru-cache")
, options = { max: 500
, length: function (n, key) { return n.length * 2 + key.length }
, 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") // "value"
cache.reset() // empty the cache
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.
You can save the current cache and load its entries in another cache instantiated with other options
var LRU = require("lru-cache")
, fs = require("fs")
, cache = LRU( {max: 500, maxAge: 60000})
, otherCache = LRU(50) // sets just the max size
cache.set("key", "value")
fs.writeFileSync("dump.json", JSON.stringify(cache));
otherCache.load(require("dump.json"));
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(v, k){return v.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.set(key, value)
get(key) => value
Both of these will update the "recently used"-ness of the key. They do what you think.
peek(key)
Returns the key value (or undefined
if not found) without
updating the "recently used"-ness of the key.
(If you find yourself using this a lot, you might be using the wrong sort of data structure, but there are some use cases where it's handy.)
del(key)
Deletes a key out of the cache.
reset()
Clear the cache entirely, throwing away all values.
has(key)
Check if a key is in the cache, without updating the recent-ness or deleting it for being stale.
forEach(function(value,key,cache), [thisp])
Just like Array.prototype.forEach
. Iterates over all the keys
in the cache, in order of recent-ness. (Ie, more recently used
items are iterated over first.)
keys()
Return an array of the keys in the cache.
values()
Return an array of the values in the cache.
toJSON()
Return an array of the cache entries ready for serialization.
load(cacheEntriesArray)
Loads another cache entries array, obtained with sourceCache.toJSON()
, into the cache. The destination cache
is reset before loading the new entries
FAQs
A cache object that deletes the least-recently-used items, with serialization support
We found that serialized-lru-cache demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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