sync.sys.mjs

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";

const lazy = {};

ChromeUtils.defineESModuleGetters(lazy, {
  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
  executeSoon: "chrome://remote/content/shared/Sync.sys.mjs",
  Log: "chrome://remote/content/shared/Log.sys.mjs",
});

ChromeUtils.defineLazyGetter(lazy, "logger", () =>
  lazy.Log.get(lazy.Log.TYPES.MARIONETTE)
);

const { TYPE_ONE_SHOT, TYPE_REPEATING_SLACK } = Ci.nsITimer;

const PROMISE_TIMEOUT = AppConstants.DEBUG ? 4500 : 1500;

/**
 * Runs a Promise-like function off the main thread until it is resolved
 * through ``resolve`` or ``rejected`` callbacks.  The function is
 * guaranteed to be run at least once, irregardless of the timeout.
 *
 * The ``func`` is evaluated every ``interval`` for as long as its
 * runtime duration does not exceed ``interval``.  Evaluations occur
 * sequentially, meaning that evaluations of ``func`` are queued if
 * the runtime evaluation duration of ``func`` is greater than ``interval``.
 *
 * ``func`` is given two arguments, ``resolve`` and ``reject``,
 * of which one must be called for the evaluation to complete.
 * Calling ``resolve`` with an argument indicates that the expected
 * wait condition was met and will return the passed value to the
 * caller.  Conversely, calling ``reject`` will evaluate ``func``
 * again until the ``timeout`` duration has elapsed or ``func`` throws.
 * The passed value to ``reject`` will also be returned to the caller
 * once the wait has expired.
 *
 * Usage::
 *
 *     let els = new PollPromise((resolve, reject) => {
 *       let res = document.querySelectorAll("p");
 *       if (res.length > 0) {
 *         resolve(Array.from(res));
 *       } else {
 *         reject([]);
 *       }
 *     }, {timeout: 1000});
 *
 * @param {Condition} func
 *     Function to run off the main thread.
 * @param {object=} options
 * @param {number=} options.timeout
 *     Desired timeout if wanted.  If 0 or less than the runtime evaluation
 *     time of ``func``, ``func`` is guaranteed to run at least once.
 *     Defaults to using no timeout.
 * @param {number=} options.interval
 *     Duration between each poll of ``func`` in milliseconds.
 *     Defaults to 10 milliseconds.
 *
 * @returns {Promise.<*>}
 *     Yields the value passed to ``func``'s
 *     ``resolve`` or ``reject`` callbacks.
 *
 * @throws {*}
 *     If ``func`` throws, its error is propagated.
 * @throws {TypeError}
 *     If `timeout` or `interval`` are not numbers.
 * @throws {RangeError}
 *     If `timeout` or `interval` are not unsigned integers.
 */
export function PollPromise(func, { timeout = null, interval = 10 } = {}) {
  const timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);

  if (typeof func != "function") {
    throw new TypeError();
  }
  if (timeout != null && typeof timeout != "number") {
    throw new TypeError();
  }
  if (typeof interval != "number") {
    throw new TypeError();
  }
  if (
    (timeout && (!Number.isInteger(timeout) || timeout < 0)) ||
    !Number.isInteger(interval) ||
    interval < 0
  ) {
    throw new RangeError();
  }

  return new Promise((resolve, reject) => {
    let start, end;

    if (Number.isInteger(timeout)) {
      start = new Date().getTime();
      end = start + timeout;
    }

    let evalFn = () => {
      new Promise(func)
        .then(resolve, rejected => {
          if (lazy.error.isError(rejected)) {
            throw rejected;
          }

          // return if there is a timeout and set to 0,
          // allowing |func| to be evaluated at least once
          if (
            typeof end != "undefined" &&
            (start == end || new Date().getTime() >= end)
          ) {
            resolve(rejected);
          }
        })
        .catch(reject);
    };

    // the repeating slack timer waits |interval|
    // before invoking |evalFn|
    evalFn();

    timer.init(evalFn, interval, TYPE_REPEATING_SLACK);
  }).then(
    res => {
      timer.cancel();
      return res;
    },
    err => {
      timer.cancel();
      throw err;
    }
  );
}

/**
 * Represents the timed, eventual completion (or failure) of an
 * asynchronous operation, and its resulting value.
 *
 * In contrast to a regular Promise, it times out after ``timeout``.
 *
 * @param {Function} fn
 *     Function to run, which will have its ``reject``
 *     callback invoked after the ``timeout`` duration is reached.
 *     It is given two callbacks: ``resolve(value)`` and
 *     ``reject(error)``.
 * @param {object=} options
 * @param {string} options.errorMessage
 *     Message to use for the thrown error.
 * @param {number=} options.timeout
 *     ``condition``'s ``reject`` callback will be called
 *     after this timeout, given in milliseconds.
 *     By default 1500 ms in an optimised build and 4500 ms in
 *     debug builds.
 * @param {Error=} options.throws
 *     When the ``timeout`` is hit, this error class will be
 *     thrown.  If it is null, no error is thrown and the promise is
 *     instead resolved on timeout with a TimeoutError.
 *
 * @returns {Promise.<*>}
 *     Timed promise.
 *
 * @throws {TypeError}
 *     If `timeout` is not a number.
 * @throws {RangeError}
 *     If `timeout` is not an unsigned integer.
 */
export function TimedPromise(fn, options = {}) {
  const {
    errorMessage = "TimedPromise timed out",
    timeout = PROMISE_TIMEOUT,
    throws = lazy.error.TimeoutError,
  } = options;

  const timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);

  if (typeof fn != "function") {
    throw new TypeError();
  }
  if (typeof timeout != "number") {
    throw new TypeError();
  }
  if (!Number.isInteger(timeout) || timeout < 0) {
    throw new RangeError();
  }

  return new Promise((resolve, reject) => {
    let trace;

    // Reject only if |throws| is given.  Otherwise it is assumed that
    // the user is OK with the promise timing out.
    let bail = () => {
      const message = `${errorMessage} after ${timeout} ms`;
      if (throws !== null) {
        let err = new throws(message);
        reject(err);
      } else {
        lazy.logger.warn(message, trace);
        resolve();
      }
    };

    trace = lazy.error.stack();
    timer.initWithCallback({ notify: bail }, timeout, TYPE_ONE_SHOT);

    try {
      fn(resolve, reject);
    } catch (e) {
      reject(e);
    }
  }).then(
    res => {
      timer.cancel();
      return res;
    },
    err => {
      timer.cancel();
      throw err;
    }
  );
}

/**
 * Pauses for the given duration.
 *
 * @param {number} timeout
 *     Duration to wait before fulfilling promise in milliseconds.
 *
 * @returns {Promise}
 *     Promise that fulfills when the `timeout` is elapsed.
 *
 * @throws {TypeError}
 *     If `timeout` is not a number.
 * @throws {RangeError}
 *     If `timeout` is not an unsigned integer.
 */
export function Sleep(timeout) {
  if (typeof timeout != "number") {
    throw new TypeError();
  }
  if (!Number.isInteger(timeout) || timeout < 0) {
    throw new RangeError();
  }

  return new Promise(resolve => {
    const timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
    timer.init(
      () => {
        // Bug 1663880 - Explicitely cancel the timer for now to prevent a hang
        timer.cancel();
        resolve();
      },
      timeout,
      TYPE_ONE_SHOT
    );
  });
}

/**
 * Detects when the specified message manager has been destroyed.
 *
 * One can observe the removal and detachment of a content browser
 * (`<xul:browser>`) or a chrome window by its message manager
 * disconnecting.
 *
 * When a browser is associated with a tab, this is safer than only
 * relying on the event `TabClose` which signalises the _intent to_
 * remove a tab and consequently would lead to the destruction of
 * the content browser and its browser message manager.
 *
 * When closing a chrome window it is safer than only relying on
 * the event 'unload' which signalises the _intent to_ close the
 * chrome window and consequently would lead to the destruction of
 * the window and its window message manager.
 *
 * @param {MessageListenerManager} messageManager
 *     The message manager to observe for its disconnect state.
 *     Use the browser message manager when closing a content browser,
 *     and the window message manager when closing a chrome window.
 *
 * @returns {Promise}
 *     A promise that resolves when the message manager has been destroyed.
 */
export function MessageManagerDestroyedPromise(messageManager) {
  return new Promise(resolve => {
    function observe(subject, topic) {
      lazy.logger.trace(`Received observer notification ${topic}`);

      if (subject == messageManager) {
        Services.obs.removeObserver(this, "message-manager-disconnect");
        resolve();
      }
    }

    Services.obs.addObserver(observe, "message-manager-disconnect");
  });
}

/**
 * Throttle until the main thread is idle and `window` has performed
 * an animation frame (in that order).
 *
 * @param {ChromeWindow} win
 *     Window to request the animation frame from.
 *
 * @returns {Promise}
 */
export function IdlePromise(win) {
  const animationFramePromise = new Promise(resolve => {
    lazy.executeSoon(() => {
      win.requestAnimationFrame(resolve);
    });
  });

  // Abort if the underlying window gets closed
  const windowClosedPromise = new PollPromise(resolve => {
    if (win.closed) {
      resolve();
    }
  });

  return Promise.race([animationFramePromise, windowClosedPromise]);
}

/**
 * Wraps a callback function, that, as long as it continues to be
 * invoked, will not be triggered.  The given function will be
 * called after the timeout duration is reached, after no more
 * events fire.
 *
 * This class implements the {@link EventListener} interface,
 * which means it can be used interchangably with `addEventHandler`.
 *
 * Debouncing events can be useful when dealing with e.g. DOM events
 * that fire at a high rate.  It is generally advisable to avoid
 * computationally expensive operations such as DOM modifications
 * under these circumstances.
 *
 * One such high frequenecy event is `resize` that can fire multiple
 * times before the window reaches its final dimensions.  In order
 * to delay an operation until the window has completed resizing,
 * it is possible to use this technique to only invoke the callback
 * after the last event has fired::
 *
 *     let cb = new DebounceCallback(event => {
 *       // fires after the final resize event
 *       console.log("resize", event);
 *     });
 *     window.addEventListener("resize", cb);
 *
 * Note that it is not possible to use this synchronisation primitive
 * with `addEventListener(..., {once: true})`.
 *
 * @param {function(Event): void} fn
 *     Callback function that is guaranteed to be invoked once only,
 *     after `timeout`.
 * @param {number=} [timeout = 250] timeout
 *     Time since last event firing, before `fn` will be invoked.
 */
export class DebounceCallback {
  constructor(fn, { timeout = 250 } = {}) {
    if (typeof fn != "function" || typeof timeout != "number") {
      throw new TypeError();
    }
    if (!Number.isInteger(timeout) || timeout < 0) {
      throw new RangeError();
    }

    this.fn = fn;
    this.timeout = timeout;
    this.timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
  }

  handleEvent(ev) {
    this.timer.cancel();
    this.timer.initWithCallback(
      () => {
        this.timer.cancel();
        this.fn(ev);
      },
      this.timeout,
      TYPE_ONE_SHOT
    );
  }
}

/**
 * Wait for a message to be fired from a particular message manager.
 *
 * This method has been duplicated from BrowserTestUtils.sys.mjs.
 *
 * @param {nsIMessageManager} messageManager
 *     The message manager that should be used.
 * @param {string} messageName
 *     The message to wait for.
 * @param {object=} options
 *     Extra options.
 * @param {function(Message): boolean=} options.checkFn
 *     Called with the ``Message`` object as argument, should return ``true``
 *     if the message is the expected one, or ``false`` if it should be
 *     ignored and listening should continue. If not specified, the first
 *     message with the specified name resolves the returned promise.
 *
 * @returns {Promise.<object>}
 *     Promise which resolves to the data property of the received
 *     ``Message``.
 */
export function waitForMessage(
  messageManager,
  messageName,
  { checkFn = undefined } = {}
) {
  if (messageManager == null || !("addMessageListener" in messageManager)) {
    throw new TypeError();
  }
  if (typeof messageName != "string") {
    throw new TypeError();
  }
  if (checkFn && typeof checkFn != "function") {
    throw new TypeError();
  }

  return new Promise(resolve => {
    messageManager.addMessageListener(messageName, function onMessage(msg) {
      lazy.logger.trace(`Received ${messageName} for ${msg.target}`);
      if (checkFn && !checkFn(msg)) {
        return;
      }
      messageManager.removeMessageListener(messageName, onMessage);
      resolve(msg.data);
    });
  });
}

/**
 * Wait for the specified observer topic to be observed.
 *
 * This method has been duplicated from TestUtils.sys.mjs.
 *
 * Because this function is intended for testing, any error in checkFn
 * will cause the returned promise to be rejected instead of waiting for
 * the next notification, since this is probably a bug in the test.
 *
 * @param {string} topic
 *     The topic to observe.
 * @param {object=} options
 *     Extra options.
 * @param {function(string, object): boolean=} options.checkFn
 *     Called with ``subject``, and ``data`` as arguments, should return true
 *     if the notification is the expected one, or false if it should be
 *     ignored and listening should continue. If not specified, the first
 *     notification for the specified topic resolves the returned promise.
 * @param {number=} options.timeout
 *     Timeout duration in milliseconds, if provided.
 *     If specified, then the returned promise will be rejected with
 *     TimeoutError, if not already resolved, after this duration has elapsed.
 *     If not specified, then no timeout is used. Defaults to null.
 *
 * @returns {Promise.<Array<string, object>>}
 *     Promise which is either resolved to an array of ``subject``, and ``data``
 *     from the observed notification, or rejected with TimeoutError after
 *     options.timeout milliseconds if specified.
 *
 * @throws {TypeError}
 * @throws {RangeError}
 */
export function waitForObserverTopic(topic, options = {}) {
  const { checkFn = null, timeout = null } = options;
  if (typeof topic != "string") {
    throw new TypeError();
  }
  if (
    (checkFn != null && typeof checkFn != "function") ||
    (timeout !== null && typeof timeout != "number")
  ) {
    throw new TypeError();
  }
  if (timeout && (!Number.isInteger(timeout) || timeout < 0)) {
    throw new RangeError();
  }

  return new Promise((resolve, reject) => {
    let timer;

    function cleanUp() {
      Services.obs.removeObserver(observer, topic);
      timer?.cancel();
    }

    function observer(subject, topic, data) {
      lazy.logger.trace(`Received observer notification ${topic}`);
      try {
        if (checkFn && !checkFn(subject, data)) {
          return;
        }
        cleanUp();
        resolve({ subject, data });
      } catch (ex) {
        cleanUp();
        reject(ex);
      }
    }

    Services.obs.addObserver(observer, topic);

    if (timeout !== null) {
      timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
      timer.init(
        () => {
          cleanUp();
          reject(
            new lazy.error.TimeoutError(
              `waitForObserverTopic timed out after ${timeout} ms`
            )
          );
        },
        timeout,
        TYPE_ONE_SHOT
      );
    }
  });
}