Bachir Soussi Chiadmi cefd1c2ad0 updated sys and created publi | 7 년 전 | |
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lib | 7 년 전 | |
test | 7 년 전 | |
.npmignore | 7 년 전 | |
.travis.yml | 7 년 전 | |
CONTRIBUTORS | 7 년 전 | |
LICENSE | 7 년 전 | |
README.md | 7 년 전 | |
package.json | 7 년 전 |
A cache object that deletes the least-recently-used items.
var LRU = require("lru-cache")
, 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") // "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.
Note: this module will print warnings to console.error
if you use a
key that is not a String or Number. Because items are stored in an
object, which coerces keys to a string, it won't go well for you if
you try to use a key that is not a unique string, it'll cause surprise
collisions. For example:
// Bad Example! Dont' do this!
var cache = LRU()
var a = {}
var b = {}
cache.set(a, 'this is a')
cache.set(b, 'this is b')
console.log(cache.get(a)) // prints: 'this is b'
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 max
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, maxAge)
get(key) => value
Both of these will update the "recently used"-ness of the key.
They do what you think. max
is optional and overrides the
cache max
option if provided.
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.
length()
Return total length of objects in cache taking into account
length
options function.
itemCount
Return total quantity of objects currently in cache. Note, that
stale
(see options) items are returned as part of this item
count.
dump()
Return an array of the cache entries ready for serialization and usage with 'destinationCache.load(arr)`.
load(cacheEntriesArray)
Loads another cache entries array, obtained with sourceCache.dump()
,
into the cache. The destination cache is reset before loading new entries