1 files changed, 335 insertions, 0 deletions
diff --git a/remote/shared/Sync.sys.mjs b/remote/shared/Sync.sys.mjs
new file mode 100644
index 0000000000..7b14f8b2c8
--- /dev/null
+++ b/remote/shared/Sync.sys.mjs
@@ -0,0 +1,335 @@
+/* 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/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+});
+
+const { TYPE_ONE_SHOT, TYPE_REPEATING_SLACK } = Ci.nsITimer;
+
+ChromeUtils.defineLazyGetter(lazy, "logger", () =>
+  lazy.Log.get(lazy.Log.TYPES.REMOTE_AGENT)
+);
+
+/**
+ * Throttle until the `window` has performed an animation frame.
+ *
+ * @param {ChromeWindow} win
+ *     Window to request the animation frame from.
+ *
+ * @returns {Promise}
+ */
+export function AnimationFramePromise(win) {
+  const animationFramePromise = new Promise(resolve => {
+    win.requestAnimationFrame(resolve);
+  });
+
+  // Abort if the underlying window gets closed
+  const windowClosedPromise = new PollPromise(resolve => {
+    if (win.closed) {
+      resolve();
+    }
+  });
+
+  return Promise.race([animationFramePromise, windowClosedPromise]);
+}
+
+/**
+ * Create a helper object to defer a promise.
+ *
+ * @returns {object}
+ *     An object that returns the following properties:
+ *       - fulfilled Flag that indicates that the promise got resolved
+ *       - pending Flag that indicates a not yet fulfilled/rejected promise
+ *       - promise The actual promise
+ *       - reject Callback to reject the promise
+ *       - rejected Flag that indicates that the promise got rejected
+ *       - resolve Callback to resolve the promise
+ */
+export function Deferred() {
+  const deferred = {};
+
+  deferred.promise = new Promise((resolve, reject) => {
+    deferred.fulfilled = false;
+    deferred.pending = true;
+    deferred.rejected = false;
+
+    deferred.resolve = (...args) => {
+      deferred.fulfilled = true;
+      deferred.pending = false;
+      resolve(...args);
+    };
+
+    deferred.reject = (...args) => {
+      deferred.pending = false;
+      deferred.rejected = true;
+      reject(...args);
+    };
+  });
+
+  return deferred;
+}
+
+/**
+ * Wait for an event to be fired on a specified element.
+ *
+ * The returned promise is guaranteed to not resolve before the
+ * next event tick after the event listener is called, so that all
+ * other event listeners for the element are executed before the
+ * handler is executed.  For example:
+ *
+ *     const promise = new EventPromise(element, "myEvent");
+ *     // same event tick here
+ *     await promise;
+ *     // next event tick here
+ *
+ * @param {Element} subject
+ *     The element that should receive the event.
+ * @param {string} eventName
+ *     Case-sensitive string representing the event name to listen for.
+ * @param {object=} options
+ * @param {boolean=} options.capture
+ *     Indicates the event will be despatched to this subject,
+ *     before it bubbles down to any EventTarget beneath it in the
+ *     DOM tree. Defaults to false.
+ * @param {Function=} options.checkFn
+ *     Called with the Event object as argument, should return true if the
+ *     event is the expected one, or false if it should be ignored and
+ *     listening should continue. If not specified, the first event with
+ *     the specified name resolves the returned promise. Defaults to null.
+ * @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.
+ * @param {boolean=} options.mozSystemGroup
+ *     Determines whether to add listener to the system group. Defaults to
+ *     false.
+ * @param {boolean=} options.wantUntrusted
+ *     Receive synthetic events despatched by web content. Defaults to false.
+ *
+ * @returns {Promise<Event>}
+ *     Either fulfilled with the first described event, satisfying
+ *     options.checkFn if specified, or rejected with TimeoutError after
+ *     options.timeout milliseconds if specified.
+ *
+ * @throws {TypeError}
+ * @throws {RangeError}
+ */
+export function EventPromise(subject, eventName, options = {}) {
+  const {
+    capture = false,
+    checkFn = null,
+    timeout = null,
+    mozSystemGroup = false,
+    wantUntrusted = false,
+  } = options;
+  if (
+    !subject ||
+    !("addEventListener" in subject) ||
+    typeof eventName != "string" ||
+    typeof capture != "boolean" ||
+    (checkFn && typeof checkFn != "function") ||
+    (timeout !== null && typeof timeout != "number") ||
+    typeof mozSystemGroup != "boolean" ||
+    typeof wantUntrusted != "boolean"
+  ) {
+    throw new TypeError();
+  }
+  if (timeout < 0) {
+    throw new RangeError();
+  }
+
+  return new Promise((resolve, reject) => {
+    let timer;
+
+    function cleanUp() {
+      subject.removeEventListener(eventName, listener, capture);
+      timer?.cancel();
+    }
+
+    function listener(event) {
+      lazy.logger.trace(`Received DOM event ${event.type} for ${event.target}`);
+      try {
+        if (checkFn && !checkFn(event)) {
+          return;
+        }
+      } catch (e) {
+        // Treat an exception in the callback as a falsy value
+        lazy.logger.warn(`Event check failed: ${e.message}`);
+      }
+
+      cleanUp();
+      executeSoon(() => resolve(event));
+    }
+
+    subject.addEventListener(eventName, listener, {
+      capture,
+      mozSystemGroup,
+      wantUntrusted,
+    });
+
+    if (timeout !== null) {
+      timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+      timer.init(
+        () => {
+          cleanUp();
+          reject(
+            new lazy.error.TimeoutError(
+              `EventPromise timed out after ${timeout} ms`
+            )
+          );
+        },
+        timeout,
+        TYPE_ONE_SHOT
+      );
+    }
+  });
+}
+
+/**
+ * Wait for the next tick in the event loop to execute a callback.
+ *
+ * @param {Function} fn
+ *     Function to be executed.
+ */
+export function executeSoon(fn) {
+  if (typeof fn != "function") {
+    throw new TypeError();
+  }
+
+  Services.tm.dispatchToMainThread(fn);
+}
+
+/**
+ * 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 {string=} options.errorMessage
+ *     Message to use to send a warning if ``timeout`` is over.
+ *     Defaults to `PollPromise timed out`.
+ * @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, options = {}) {
+  const {
+    errorMessage = "PollPromise timed out",
+    interval = 10,
+    timeout = null,
+  } = options;
+  const timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+  let didTimeOut = false;
+
+  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 (typeof rejected != "undefined") {
+            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)
+          ) {
+            didTimeOut = true;
+            resolve(rejected);
+          }
+        })
+        .catch(reject);
+    };
+
+    // the repeating slack timer waits |interval|
+    // before invoking |evalFn|
+    evalFn();
+
+    timer.init(evalFn, interval, TYPE_REPEATING_SLACK);
+  }).then(
+    res => {
+      if (didTimeOut) {
+        lazy.logger.warn(`${errorMessage} after ${timeout} ms`);
+      }
+      timer.cancel();
+      return res;
+    },
+    err => {
+      timer.cancel();
+      throw err;
+    }
+  );
+}