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 /* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */

 /* 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/. */

 #ifndef nsBaseAppShell_h__

 #define nsBaseAppShell_h__

 #include "mozilla/Atomics.h"

 #include "nsIAppShell.h"

 #include "nsIThreadInternal.h"

 #include "nsIObserver.h"

 #include "nsIRunnable.h"

 #include "nsCOMPtr.h"

 #include "nsTArray.h"

 #include "prinrval.h"

 /**

  * A singleton that manages the UI thread's event queue.  Subclass this class

  * to enable platform-specific event queue support.

  */

 class nsBaseAppShell : public nsIAppShell, public nsIThreadObserver,

                        public nsIObserver

 {

 public:

   NS_DECL_THREADSAFE_ISUPPORTS

   NS_DECL_NSIAPPSHELL

   NS_DECL_NSITHREADOBSERVER

   NS_DECL_NSIOBSERVER

   nsBaseAppShell();

 protected:

   virtual ~nsBaseAppShell();

   /**

    * This method is called by subclasses when the app shell singleton is

    * instantiated.

    */

   nsresult Init();

   /**

    * Called by subclasses from a native event. See ScheduleNativeEventCallback.

    */

   void NativeEventCallback();

   /**

    * Make a decision as to whether or not NativeEventCallback will

    * trigger gecko event processing when there are pending gecko

    * events.

    */

   virtual void DoProcessMoreGeckoEvents();

   /**

    * Implemented by subclasses.  Invoke NativeEventCallback from a native

    * event.  This method may be called on any thread.

    */

   virtual void ScheduleNativeEventCallback() = 0;

   /**

    * Implemented by subclasses.  Process the next native event.  Only wait for

    * the next native event if mayWait is true.  This method is only called on

    * the main application thread.

    *

    * @param mayWait

    *   If "true", then this method may wait if necessary for the next available

    *   native event.  DispatchNativeEvent may be called to unblock a call to

    *   ProcessNextNativeEvent that is waiting.

    * @return

    *   This method returns "true" if a native event was processed.

    */

   virtual bool ProcessNextNativeEvent(bool mayWait) = 0;

   int32_t mSuspendNativeCount;

   uint32_t mEventloopNestingLevel;

 private:

   bool DoProcessNextNativeEvent(bool mayWait, uint32_t recursionDepth);

   bool DispatchDummyEvent(nsIThread* target);

   void IncrementEventloopNestingLevel();

   void DecrementEventloopNestingLevel();

   /**

    * Runs all synchronous sections which are queued up in mSyncSections.

    */

   void RunSyncSectionsInternal(bool stable, uint32_t threadRecursionLevel);

   void RunSyncSections(bool stable, uint32_t threadRecursionLevel)

   {

     if (!mSyncSections.IsEmpty()) {

       RunSyncSectionsInternal(stable, threadRecursionLevel);

     }

   }

   void ScheduleSyncSection(nsIRunnable* runnable, bool stable);

   struct SyncSection {

     SyncSection()

     : mStable(false), mEventloopNestingLevel(0), mThreadRecursionLevel(0)

     { }

     void Forget(SyncSection* other) {

       other->mStable = mStable;

       other->mEventloopNestingLevel = mEventloopNestingLevel;

       other->mThreadRecursionLevel = mThreadRecursionLevel;

       other->mRunnable = mRunnable.forget();

     }

     bool mStable;

     uint32_t mEventloopNestingLevel;

     uint32_t mThreadRecursionLevel;

     nsCOMPtr<nsIRunnable> mRunnable;

   };

   nsCOMPtr<nsIRunnable> mDummyEvent;

   /**

    * mBlockedWait points back to a slot that controls the wait loop in

    * an outer OnProcessNextEvent invocation.  Nested calls always set

    * it to false to unblock an outer loop, since all events may

    * have been consumed by the inner event loop(s).

    */

   bool *mBlockedWait;

   int32_t mFavorPerf;

   mozilla::Atomic<bool> mNativeEventPending;

   PRIntervalTime mStarvationDelay;

   PRIntervalTime mSwitchTime;

   PRIntervalTime mLastNativeEventTime;

   enum EventloopNestingState {

     eEventloopNone,  // top level thread execution

     eEventloopXPCOM, // innermost native event loop is ProcessNextNativeEvent

     eEventloopOther  // innermost native event loop is a native library/plugin etc

   };

   EventloopNestingState mEventloopNestingState;

   nsTArray<SyncSection> mSyncSections;

   bool mRunning;

   bool mExiting;

   /**

    * mBlockNativeEvent blocks the appshell from processing native events.

    * It is set to true while a nested native event loop (eEventloopOther)

    * is processing gecko events in NativeEventCallback(), thus queuing up

    * native events until we return to that loop (bug 420148).

    * We force mBlockNativeEvent to false in case handling one of the gecko

    * events spins up a nested XPCOM event loop (eg. modal window) which would

    * otherwise lead to a "deadlock" where native events aren't processed at all.

    */

   bool mBlockNativeEvent;

   /**

    * Tracks whether we have processed any gecko events in NativeEventCallback so

    * that we can avoid erroneously entering a blocking loop waiting for gecko

    * events to show up during OnProcessNextEvent.  This is required because on

    * OS X ProcessGeckoEvents may be invoked inside the context of

    * ProcessNextNativeEvent and may result in NativeEventCallback being invoked

    * and in turn invoking NS_ProcessPendingEvents.  Because

    * ProcessNextNativeEvent may be invoked prior to the NS_HasPendingEvents

    * waiting loop, this is the only way to make the loop aware that events may

    * have been processed.

    *

    * This variable is set to false in OnProcessNextEvent prior to the first

    * call to DoProcessNextNativeEvent.  It is set to true by

    * NativeEventCallback after calling NS_ProcessPendingEvents.

    */

   bool mProcessedGeckoEvents;

 };

 #endif // nsBaseAppShell_h__