lru-cache-node

    1.1.0 • Public • Published

    lru-cache-node

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    A lighting fast cache manager for node with least-recently-used policy.

    A super fast cache for node with LRU policy. Cache will keep on adding values until the maxSize is reached.

    After that it will start popping out the Least recently used/accessed value from the cache in order to set the new ones.

    Supports expiry and stale.

    Implemented using doubly-linked-list and hashmap with O(1) time complexity for gets and sets.

    Install

    $ npm install --save lru-cache-node
    

    Usage

    const Cache = require('lru-cache-node');
    
    let cache = new Cache(3); //set max size of cache as three
    
    cache.set('a', 7); //sets a value in cache with 'a' as key and 7 as value
    cache.set('b', 5);
    cache.set('c', 3); 
    /*
      [ { key: 'c', value: 3 },
        { key: 'b', value: 5 },
        { key: 'a', value: 7 } ]
     */
     
    cache.set('d', 10) // pops out a
    /*
      [ { key: 'd', value: 10 },
        { key: 'c', value: 3 },
        { key: 'b', value: 5 } ]
     */
     
    cache.get("b") //returns 5 and makes it most recently used
    /*
      [ { key: 'b', value: 5 },
        { key: 'd', value: 10 },
        { key: 'c', value: 3 } ]
     */
    
    cache.peek("d") //returns 10 but doesnt resets the order
    /*
      [ { key: 'b', value: 5 },
        { key: 'd', value: 10 },
        { key: 'c', value: 3 } ]
     */
    
    let cache = new Cache(3, 10); //Initialize Cache with size 3 and expiry for keys as 10ms
    const sleep = ms => new Promise(r => setTimeout(r, ms));
    
    cache.set('a', 7); //valid for 10ms
    cache.get('a'); //returns 7 and resets 10ms counter
    await sleep(15);
    cache.get('a'); //null
    
    cache.set('b', 5, 30); //overwrites cache's default expiry of 10ms and uses 30ms
    await sleep(15);
    cache.get('b'); //returns 5 and resets the expiry of b back to 30ms
    await sleep(35);
    cache.get('b'); //null

    API

    cache(maxSize, maxAge, stale)

    maxSize

    Type: Number
    Default: Infinity

    Maximum size of the cache.

    maxAge

    Type: Number
    Default: Infinity

    Default expiry for all keys for the cache. It does not proactively deletes expired keys, but will return null when an expired key is being accessed.

    stale

    Type: Boolean
    Default: false

    If set to true, will return the value of expired key before deleting it from cache.

    set(key, value, maxAge)

    key

    Key to be set.

    value

    Value for the key.

    maxAge

    Expiry of the key. Will override cache's maxAge if specified.

    get(key)

    Returns the value for the key. If not key does not exist will return null.

    Both set() and get() will update the "recently used"-ness and expiry of the key.

    peek(key)

    Returns the value for the key, without making the key most recently used. If not key does not exist will return null.

    delete(key)

    Deletes the key from the cache.

    contains(key)

    Returns a boolean indication if the value exists in cache or not.

    has(key)

    Alias for contains function.

    getSize()

    Returns the current size of cache.

    reset()

    Clears the whole cache and reinitialize it.

    toArray()

    Returns an array form of the catch.

    let cache = new Cache();
    cache.set("a", 5);
    cache.set("b", 4);
    cache.set("c", 0);
    cache.toArray()
    /*
    [ { key: 'c', value: 0 },
      { key: 'b', value: 4 },
      { key: 'a', value: 5 } ]
    */

    forEach(callback)

    Takes a function and iterates over all the keys in the cache, in order of recentness. Callback takes key, value and index as params.

    let cache = new Cache();
    cache.set("a", 1);
    cache.set("b", 2);
    cache.set("c", 3);
    cache.forEach((key, value, index) => {
    	console.log(key, value, index)
    })
    /*
    c 3 0
    b 2 1
    a 1 2
    */

    Keywords

    Install

    npm i lru-cache-node

    DownloadsWeekly Downloads

    1,859

    Version

    1.1.0

    License

    ISC

    Unpacked Size

    8.88 kB

    Total Files

    4

    Last publish

    Collaborators

    • arbazsiddiqui