mirror of
https://github.com/mozilla/gecko-dev.git
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ef3d0f1c2e
MozReview-Commit-ID: 1QBmqfgY6WI
350 lines
9.8 KiB
C++
350 lines
9.8 KiB
C++
/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "base/message_loop.h"
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#include "nsBaseAppShell.h"
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#if defined(MOZ_CRASHREPORTER)
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#include "nsExceptionHandler.h"
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#endif
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#include "nsThreadUtils.h"
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#include "nsIObserverService.h"
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#include "nsServiceManagerUtils.h"
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#include "mozilla/Services.h"
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// When processing the next thread event, the appshell may process native
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// events (if not in performance mode), which can result in suppressing the
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// next thread event for at most this many ticks:
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#define THREAD_EVENT_STARVATION_LIMIT PR_MillisecondsToInterval(10)
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NS_IMPL_ISUPPORTS(nsBaseAppShell, nsIAppShell, nsIThreadObserver, nsIObserver)
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nsBaseAppShell::nsBaseAppShell()
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: mSuspendNativeCount(0)
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, mEventloopNestingLevel(0)
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, mBlockedWait(nullptr)
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, mFavorPerf(0)
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, mNativeEventPending(false)
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, mStarvationDelay(0)
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, mSwitchTime(0)
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, mLastNativeEventTime(0)
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, mEventloopNestingState(eEventloopNone)
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, mRunning(false)
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, mExiting(false)
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, mBlockNativeEvent(false)
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{
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}
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nsBaseAppShell::~nsBaseAppShell()
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{
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}
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nsresult
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nsBaseAppShell::Init()
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{
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// Configure ourselves as an observer for the current thread:
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nsCOMPtr<nsIThreadInternal> threadInt =
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do_QueryInterface(NS_GetCurrentThread());
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NS_ENSURE_STATE(threadInt);
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threadInt->SetObserver(this);
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nsCOMPtr<nsIObserverService> obsSvc =
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mozilla::services::GetObserverService();
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if (obsSvc)
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obsSvc->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
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return NS_OK;
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}
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// Called by nsAppShell's native event callback
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void
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nsBaseAppShell::NativeEventCallback()
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{
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if (!mNativeEventPending.exchange(false))
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return;
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// If DoProcessNextNativeEvent is on the stack, then we assume that we can
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// just unwind and let nsThread::ProcessNextEvent process the next event.
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// However, if we are called from a nested native event loop (maybe via some
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// plug-in or library function), then go ahead and process Gecko events now.
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if (mEventloopNestingState == eEventloopXPCOM) {
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mEventloopNestingState = eEventloopOther;
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// XXX there is a tiny risk we will never get a new NativeEventCallback,
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// XXX see discussion in bug 389931.
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return;
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}
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// nsBaseAppShell::Run is not being used to pump events, so this may be
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// our only opportunity to process pending gecko events.
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nsIThread *thread = NS_GetCurrentThread();
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bool prevBlockNativeEvent = mBlockNativeEvent;
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if (mEventloopNestingState == eEventloopOther) {
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if (!NS_HasPendingEvents(thread))
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return;
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// We're in a nested native event loop and have some gecko events to
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// process. While doing that we block processing native events from the
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// appshell - instead, we want to get back to the nested native event
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// loop ASAP (bug 420148).
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mBlockNativeEvent = true;
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}
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IncrementEventloopNestingLevel();
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EventloopNestingState prevVal = mEventloopNestingState;
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NS_ProcessPendingEvents(thread, THREAD_EVENT_STARVATION_LIMIT);
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mProcessedGeckoEvents = true;
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mEventloopNestingState = prevVal;
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mBlockNativeEvent = prevBlockNativeEvent;
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// Continue processing pending events later (we don't want to starve the
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// embedders event loop).
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if (NS_HasPendingEvents(thread))
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DoProcessMoreGeckoEvents();
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DecrementEventloopNestingLevel();
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}
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// Note, this is currently overidden on windows, see comments in nsAppShell for
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// details.
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void
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nsBaseAppShell::DoProcessMoreGeckoEvents()
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{
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OnDispatchedEvent(nullptr);
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}
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// Main thread via OnProcessNextEvent below
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bool
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nsBaseAppShell::DoProcessNextNativeEvent(bool mayWait)
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{
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// The next native event to be processed may trigger our NativeEventCallback,
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// in which case we do not want it to process any thread events since we'll
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// do that when this function returns.
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//
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// If the next native event is not our NativeEventCallback, then we may end
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// up recursing into this function.
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//
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// However, if the next native event is not our NativeEventCallback, but it
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// results in another native event loop, then our NativeEventCallback could
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// fire and it will see mEventloopNestingState as eEventloopOther.
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//
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EventloopNestingState prevVal = mEventloopNestingState;
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mEventloopNestingState = eEventloopXPCOM;
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IncrementEventloopNestingLevel();
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bool result = ProcessNextNativeEvent(mayWait);
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DecrementEventloopNestingLevel();
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mEventloopNestingState = prevVal;
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return result;
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}
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//-------------------------------------------------------------------------
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// nsIAppShell methods:
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NS_IMETHODIMP
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nsBaseAppShell::Run(void)
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{
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NS_ENSURE_STATE(!mRunning); // should not call Run twice
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mRunning = true;
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nsIThread *thread = NS_GetCurrentThread();
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MessageLoop::current()->Run();
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NS_ProcessPendingEvents(thread);
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mRunning = false;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsBaseAppShell::Exit(void)
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{
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if (mRunning && !mExiting) {
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MessageLoop::current()->Quit();
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}
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mExiting = true;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsBaseAppShell::FavorPerformanceHint(bool favorPerfOverStarvation,
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uint32_t starvationDelay)
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{
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mStarvationDelay = PR_MillisecondsToInterval(starvationDelay);
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if (favorPerfOverStarvation) {
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++mFavorPerf;
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} else {
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--mFavorPerf;
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mSwitchTime = PR_IntervalNow();
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}
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return NS_OK;
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}
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NS_IMETHODIMP
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nsBaseAppShell::SuspendNative()
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{
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++mSuspendNativeCount;
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return NS_OK;
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}
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NS_IMETHODIMP
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nsBaseAppShell::ResumeNative()
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{
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--mSuspendNativeCount;
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NS_ASSERTION(mSuspendNativeCount >= 0, "Unbalanced call to nsBaseAppShell::ResumeNative!");
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return NS_OK;
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}
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NS_IMETHODIMP
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nsBaseAppShell::GetEventloopNestingLevel(uint32_t* aNestingLevelResult)
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{
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NS_ENSURE_ARG_POINTER(aNestingLevelResult);
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*aNestingLevelResult = mEventloopNestingLevel;
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return NS_OK;
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}
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//-------------------------------------------------------------------------
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// nsIThreadObserver methods:
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// Called from any thread
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NS_IMETHODIMP
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nsBaseAppShell::OnDispatchedEvent(nsIThreadInternal *thr)
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{
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if (mBlockNativeEvent)
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return NS_OK;
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if (mNativeEventPending.exchange(true))
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return NS_OK;
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// Returns on the main thread in NativeEventCallback above
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ScheduleNativeEventCallback();
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return NS_OK;
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}
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// Called from the main thread
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NS_IMETHODIMP
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nsBaseAppShell::OnProcessNextEvent(nsIThreadInternal *thr, bool mayWait)
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{
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if (mBlockNativeEvent) {
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if (!mayWait)
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return NS_OK;
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// Hmm, we're in a nested native event loop and would like to get
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// back to it ASAP, but it seems a gecko event has caused us to
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// spin up a nested XPCOM event loop (eg. modal window), so we
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// really must start processing native events here again.
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mBlockNativeEvent = false;
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if (NS_HasPendingEvents(thr))
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OnDispatchedEvent(thr); // in case we blocked it earlier
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}
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PRIntervalTime start = PR_IntervalNow();
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PRIntervalTime limit = THREAD_EVENT_STARVATION_LIMIT;
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// Unblock outer nested wait loop (below).
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if (mBlockedWait)
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*mBlockedWait = false;
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bool *oldBlockedWait = mBlockedWait;
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mBlockedWait = &mayWait;
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// When mayWait is true, we need to make sure that there is an event in the
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// thread's event queue before we return. Otherwise, the thread will block
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// on its event queue waiting for an event.
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bool needEvent = mayWait;
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// Reset prior to invoking DoProcessNextNativeEvent which might cause
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// NativeEventCallback to process gecko events.
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mProcessedGeckoEvents = false;
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if (mFavorPerf <= 0 && start > mSwitchTime + mStarvationDelay) {
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// Favor pending native events
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PRIntervalTime now = start;
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bool keepGoing;
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do {
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mLastNativeEventTime = now;
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keepGoing = DoProcessNextNativeEvent(false);
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} while (keepGoing && ((now = PR_IntervalNow()) - start) < limit);
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} else {
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// Avoid starving native events completely when in performance mode
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if (start - mLastNativeEventTime > limit) {
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mLastNativeEventTime = start;
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DoProcessNextNativeEvent(false);
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}
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}
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while (!NS_HasPendingEvents(thr) && !mProcessedGeckoEvents) {
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// If we have been asked to exit from Run, then we should not wait for
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// events to process. Note that an inner nested event loop causes
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// 'mayWait' to become false too, through 'mBlockedWait'.
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if (mExiting)
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mayWait = false;
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mLastNativeEventTime = PR_IntervalNow();
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if (!DoProcessNextNativeEvent(mayWait) || !mayWait)
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break;
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}
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mBlockedWait = oldBlockedWait;
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// Make sure that the thread event queue does not block on its monitor, as
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// it normally would do if it did not have any pending events. To avoid
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// that, we simply insert a dummy event into its queue during shutdown.
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if (needEvent && !mExiting && !NS_HasPendingEvents(thr)) {
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DispatchDummyEvent(thr);
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}
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return NS_OK;
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}
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bool
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nsBaseAppShell::DispatchDummyEvent(nsIThread* aTarget)
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{
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NS_ASSERTION(NS_IsMainThread(), "Wrong thread!");
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if (!mDummyEvent)
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mDummyEvent = new mozilla::Runnable("DummyEvent");
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return NS_SUCCEEDED(aTarget->Dispatch(mDummyEvent, NS_DISPATCH_NORMAL));
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}
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void
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nsBaseAppShell::IncrementEventloopNestingLevel()
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{
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++mEventloopNestingLevel;
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#if defined(MOZ_CRASHREPORTER)
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CrashReporter::SetEventloopNestingLevel(mEventloopNestingLevel);
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#endif
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}
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void
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nsBaseAppShell::DecrementEventloopNestingLevel()
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{
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--mEventloopNestingLevel;
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#if defined(MOZ_CRASHREPORTER)
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CrashReporter::SetEventloopNestingLevel(mEventloopNestingLevel);
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#endif
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}
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// Called from the main thread
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NS_IMETHODIMP
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nsBaseAppShell::AfterProcessNextEvent(nsIThreadInternal *thr,
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bool eventWasProcessed)
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{
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return NS_OK;
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}
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NS_IMETHODIMP
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nsBaseAppShell::Observe(nsISupports *subject, const char *topic,
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const char16_t *data)
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{
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NS_ASSERTION(!strcmp(topic, NS_XPCOM_SHUTDOWN_OBSERVER_ID), "oops");
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Exit();
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return NS_OK;
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}
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