transitory/dist/types/cache/expiration/TimerWheel.d.ts

In-memory cache with high hit rates via LFU eviction. Supports time-based expiration, automatic loading and metrics.

import { CacheNode } from '../CacheNode';
import { KeyType } from '../KeyType';
import { Expirable } from './Expirable';
export declare type EvictionListener<K extends KeyType> = (keys: K[]) => void;
/**
 * A timer wheel for variable expiration of items in a cache. Stores items in
 * layers that are circular buffers that represent a time span.
 *
 * This implementation takes some extra care to work with Number as they are
 * actually doubles and shifting turns them into 32-bit ints. To represent
 * time we need more than 32-bits so to fully support things this implementation
 * uses a base which is removed from all of the numbers to make them fit into
 * 32-bits.
 *
 * Based on an idea by Ben Manes implemented in Caffeine.
 */
export declare class TimerWheel<K extends KeyType, V> {
    private evict;
    private time;
    private base;
    private layers;
    constructor(evict: EvictionListener<K>);
    get localTime(): number;
    private findBucket;
    advance(localTime?: number): void;
    /**
     * Create a node that that helps with tracking when a key and value
     * should be evicted.
     *
     * @param key -
     *   key to set
     * @param value -
     *   value to set
     * @returns
     *   node
     */
    node(key: K, value: V): TimerNode<K, V>;
    /**
     * Schedule eviction of the given node at the given timestamp.
     *
     * @param node -
     *   node to reschedule
     * @param time -
     *   new expiration time
     * @returns
     *   if the node was rescheduled
     */
    schedule(node: TimerNode<K, V>, time: number): boolean;
    deschedule(node: TimerNode<K, V>): void;
}
export declare class TimerNode<K extends KeyType, V> extends CacheNode<K, V> implements Expirable<V> {
    private wheel;
    time: number;
    constructor(wheel: TimerWheel<K, V>, key: K | null, value: V | null);
    isExpired(): boolean;
}