Neutrinos Peludos Magnéticos


    0.5.2 • Public • Published


    According to NIST:

    hashbelt (data structure) :: Use a short list or array of hash tables to implement a hash table with aging to expire items. To expire items, add a new table at the head of the list and drop the oldest table, along with its contents. To find an item, search all the tables.


    npm install hashbelt


    import hashbelt from 'hashbelt'
    let belt = hashbelt({
      max: 4, // keep 4 belt entries (default)
      interval: 60000, // rotate every minute (default)
      step: Object, // create a new belt entry (default is {})
    // or pass a `step()` function
    let belt_map = hashbelt( () => new Map() )
    // or perhaps you'd like a WeakMap?
    let belt_weak = hashbelt( () => new WeakMap() )

    API of Hashbelt Result

    Expired entries will be pop()'d from the end of the belt. The first index is the most recent "tip" of the hashbelt.

    belt.rotate() // force a belt rotation
    belt.step() // create a belt entry (does not insert it)
    clearInterval(belt.tid) // belt.tid is the interval handle; unref'd by default
    Array.isArray(belt) // belt is just an array with extra attributes
    // use index 0 to access the tip
    belt[0]['my_key'] = 1942
    belt_map[0].set('my_key', 2042)
    // use array methods or iterate the belt to consult all entries
    belt.find(each => each['my_key'])
    belt_map.find(map => map.has('my_key'))

    2022 update (breaking changes)

    To make this module more generally useful, I've changed to a minimal hashbelt implementation ported from msg-fabric-core/code/timeouts.jsy. This change drops rarely used features such as copy forward caching and JS Map compatibility. In exchange, the library weighs in at ~300 bytes minified, and ~200 bytes with brotli.



    npm i hashbelt

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    • shanewholloway