michael@0: /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  *
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "nsISupports.idl"
michael@0: 
michael@0: interface nsIRunnable;
michael@0: 
michael@0: /**
michael@0:  * Interface for the native event system layer.  This interface is designed
michael@0:  * to be used on the main application thread only.
michael@0:  */
michael@0: [uuid(2d10ca53-f143-439a-bb2e-c1fbc71f6a05)]
michael@0: interface nsIAppShell : nsISupports
michael@0: {
michael@0:   /**
michael@0:    * Enter an event loop.  Don't leave until exit() is called.
michael@0:    */
michael@0:   void run();
michael@0: 
michael@0:   /**
michael@0:    * Exit the handle event loop
michael@0:    */
michael@0:   void exit();
michael@0: 
michael@0:   /**
michael@0:    * Give hint to native event queue notification mechanism. If the native
michael@0:    * platform needs to tradeoff performance vs. native event starvation this
michael@0:    * hint tells the native dispatch code which to favor.  The default is to
michael@0:    * prevent native event starvation.
michael@0:    *
michael@0:    * Calls to this function may be nested. When the number of calls that pass
michael@0:    * PR_TRUE is subtracted from the number of calls that pass PR_FALSE is
michael@0:    * greater than 0, performance is given precedence over preventing event
michael@0:    * starvation.
michael@0:    *
michael@0:    * The starvationDelay arg is only used when favorPerfOverStarvation is
michael@0:    * PR_FALSE. It is the amount of time in milliseconds to wait before the
michael@0:    * PR_FALSE actually takes effect.
michael@0:    */
michael@0:   void favorPerformanceHint(in boolean favorPerfOverStarvation,
michael@0:                             in unsigned long starvationDelay);
michael@0: 
michael@0:   /**
michael@0:    * Suspends the use of additional platform-specific methods (besides the
michael@0:    * nsIAppShell->run() event loop) to run Gecko events on the main
michael@0:    * application thread.  Under some circumstances these "additional methods"
michael@0:    * can cause Gecko event handlers to be re-entered, sometimes leading to
michael@0:    * hangs and crashes.  Calls to suspendNative() and resumeNative() may be
michael@0:    * nested.  On some platforms (those that don't use any "additional
michael@0:    * methods") this will be a no-op.  Does not (in itself) stop Gecko events
michael@0:    * from being processed on the main application thread.  But if the
michael@0:    * nsIAppShell->run() event loop is blocked when this call is made, Gecko
michael@0:    * events will stop being processed until resumeNative() is called (even
michael@0:    * if a plugin or library is temporarily processing events on a nested
michael@0:    * event loop).
michael@0:    */
michael@0:   void suspendNative();
michael@0: 
michael@0:   /**
michael@0:    * Resumes the use of additional platform-specific methods to run Gecko
michael@0:    * events on the main application thread.  Calls to suspendNative() and
michael@0:    * resumeNative() may be nested.  On some platforms this will be a no-op.
michael@0:    */
michael@0:   void resumeNative();
michael@0: 
michael@0:   /**
michael@0:    * The current event loop nesting level.
michael@0:    */
michael@0:   readonly attribute unsigned long eventloopNestingLevel;
michael@0:   
michael@0:   /**
michael@0:    * Allows running of a "synchronous section", in the form of an nsIRunnable
michael@0:    * once the event loop has reached a "stable state". We've reached a stable
michael@0:    * state when the currently executing task/event has finished, see:
michael@0:    * http://www.whatwg.org/specs/web-apps/current-work/multipage/webappapis.html#synchronous-section
michael@0:    * In practice this runs aRunnable once the currently executing event
michael@0:    * finishes. If called multiple times per task/event, all the runnables will
michael@0:    * be executed, in the order in which runInStableState() was called.
michael@0:    */
michael@0:   void runInStableState(in nsIRunnable runnable);
michael@0: 
michael@0:   /**
michael@0:    * Run the given runnable before the next iteration of the event loop (this
michael@0:    * includes native events too). If a nested loop is spawned within the current
michael@0:    * event then the runnable will not be run until that loop has terminated.
michael@0:    */
michael@0:   void runBeforeNextEvent(in nsIRunnable runnable);
michael@0: };