File Explorer

1'use strict'2 3const assert = require('node:assert')4 5/**6 * This takes care of revalidation requests we send to the origin. If we get7 *  a response indicating that what we have is cached (via a HTTP 304), we can8 *  continue using the cached value. Otherwise, we'll receive the new response9 *  here, which we then just pass on to the next handler (most likely a10 *  CacheHandler). Note that this assumes the proper headers were already11 *  included in the request to tell the origin that we want to revalidate the12 *  response (i.e. if-modified-since or if-none-match).13 *14 * @see https://www.rfc-editor.org/rfc/rfc9111.html#name-validation15 *16 * @implements {import('../../types/dispatcher.d.ts').default.DispatchHandler}17 */18class CacheRevalidationHandler {19  #successful = false20 21  /**22   * @type {((success: boolean, context?: any, statusCode?: number, headers?: import('../../types/header.d.ts').IncomingHttpHeaders) => void) | null}23   */24  #callback25 26  /**27   * @type {(import('../../types/dispatcher.d.ts').default.DispatchHandler)}28   */29  #handler30 31  #context32 33  /**34   * @type {boolean}35   */36  #allowErrorStatusCodes37 38  /**39   * @param {(success: boolean, context?: any, statusCode?: number, headers?: import('../../types/header.d.ts').IncomingHttpHeaders) => void} callback Function to call if the cached value is valid40   * @param {import('../../types/dispatcher.d.ts').default.DispatchHandlers} handler41   * @param {boolean} allowErrorStatusCodes42   */43  constructor (callback, handler, allowErrorStatusCodes) {44    if (typeof callback !== 'function') {45      throw new TypeError('callback must be a function')46    }47 48    this.#callback = callback49    this.#handler = handler50    this.#allowErrorStatusCodes = allowErrorStatusCodes51  }52 53  onRequestStart (_, context) {54    this.#successful = false55    this.#context = context56  }57 58  onRequestUpgrade (controller, statusCode, headers, socket) {59    this.#handler.onRequestUpgrade?.(controller, statusCode, headers, socket)60  }61 62  onResponseStart (63    controller,64    statusCode,65    headers,66    statusMessage67  ) {68    assert(this.#callback != null)69 70    // https://www.rfc-editor.org/rfc/rfc9111.html#name-handling-a-validation-respo71    // https://datatracker.ietf.org/doc/html/rfc5861#section-472    this.#successful = statusCode === 304 ||73      (this.#allowErrorStatusCodes && statusCode >= 500 && statusCode <= 504)74    this.#callback(this.#successful, this.#context, statusCode, headers)75    this.#callback = null76 77    if (this.#successful) {78      return true79    }80 81    this.#handler.onRequestStart?.(controller, this.#context)82    this.#handler.onResponseStart?.(83      controller,84      statusCode,85      headers,86      statusMessage87    )88  }89 90  onResponseData (controller, chunk) {91    if (this.#successful) {92      return93    }94 95    return this.#handler.onResponseData?.(controller, chunk)96  }97 98  onResponseEnd (controller, trailers) {99    if (this.#successful) {100      return101    }102 103    this.#handler.onResponseEnd?.(controller, trailers)104  }105 106  onResponseError (controller, err) {107    if (this.#successful) {108      return109    }110 111    if (this.#callback) {112      this.#callback(false)113      this.#callback = null114    }115 116    if (typeof this.#handler.onResponseError === 'function') {117      this.#handler.onResponseError(controller, err)118    } else {119      throw err120    }121  }122}123 124module.exports = CacheRevalidationHandler125