@johngw/stream/dist/sources/CachableStream.js

Reactive programming tools using the WHATWG Streams API.

import { StorageCache } from '../storages/StorageCache.js';
import { CachableSource } from './CachableSource.js';
/**
 * An extension to the `ReadableStream` that queues items
 * only when a timed cache becomes invalid.
 *
 * @group Sources
 * @see {@link StorageCache}
 * @see {@link CachableSource:class}
 * @example
 * Caching for 30 minutes.
 *
 * ```
 * const cache = new StorageCache(
 *   localStorage,
 *   'my-cache',
 *   30 * 60_000
 * )
 *
 * let i = 0
 * const stream = new CachableStream<number>(
 *   cache,
 *   ['numbers'],
 *   () => ++i
 * )
 *
 * stream.pipeTo(write(console.info))
 * // 1
 *
 * await setTimeout(30 * 60_000))
 * // 2
 * ```
 * @example
 * Manually clearing cache.
 *
 * ```
 * const cache = new StorageCache(
 *   localStorage,
 *   'my-cache',
 *   30 * 60_000
 * )
 *
 * let i = 0
 * const stream = new CachableStream<number>(
 *   cache,
 *   ['numbers'],
 *   () => ++i
 * )
 *
 * stream.pipeTo(write(console.info))
 * // 1
 *
 * stream.clear()
 * // 2
 * ```
 */
export class CachableStream extends ReadableStream {
    #source;
    constructor(cache, path, pullItem, ms = cache.ms) {
        const source = new CachableSource(cache, path, pullItem, ms);
        super(source);
        this.#source = source;
    }
    clear() {
        this.#source.clear();
    }
    get sourceHasFinished() {
        return this.#source.sourceHasFinished;
    }
}
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