void
nsBaseAppShell::NativeEventCallback()
{
PRInt32 hasPending = PR_AtomicSet(&mNativeEventPending, 0);
if (hasPending == 0)
return;
// If DoProcessNextNativeEvent is on the stack, then we assume that we can
// just unwind and let nsThread::ProcessNextEvent process the next event.
// However, if we are called from a nested native event loop (maybe via some
// plug-in or library function), then go ahead and process Gecko events now.
if (mEventloopNestingState == eEventloopXPCOM) {
mEventloopNestingState = eEventloopOther;
// XXX there is a tiny risk we will never get a new NativeEventCallback,
// XXX see discussion in bug 389931.
return;
}
// nsBaseAppShell::Run is not being used to pump events, so this may be
// our only opportunity to process pending gecko events.
nsIThread *thread = NS_GetCurrentThread();
PRBool prevBlockNativeEvent = mBlockNativeEvent;
if (mEventloopNestingState == eEventloopOther) {
if (!NS_HasPendingEvents(thread))
return;
// We're in a nested native event loop and have some gecko events to
// process. While doing that we block processing native events from the
// appshell - instead, we want to get back to the nested native event
// loop ASAP (bug 420148).
mBlockNativeEvent = PR_TRUE;
}
++mEventloopNestingLevel;
EventloopNestingState prevVal = mEventloopNestingState;
NS_ProcessPendingEvents(thread, THREAD_EVENT_STARVATION_LIMIT);
mEventloopNestingState = prevVal;
mBlockNativeEvent = prevBlockNativeEvent;
// Continue processing pending events later (we don't want to starve the
// embedders event loop).
if (NS_HasPendingEvents(thread))
OnDispatchedEvent(nsnull);
--mEventloopNestingLevel;
}
// Called from the main thread
NS_IMETHODIMP
nsBaseAppShell::OnProcessNextEvent(nsIThreadInternal *thr, bool mayWait,
uint32_t recursionDepth)
{
if (mBlockNativeEvent) {
if (!mayWait)
return NS_OK;
// Hmm, we're in a nested native event loop and would like to get
// back to it ASAP, but it seems a gecko event has caused us to
// spin up a nested XPCOM event loop (eg. modal window), so we
// really must start processing native events here again.
mBlockNativeEvent = false;
if (NS_HasPendingEvents(thr))
OnDispatchedEvent(thr); // in case we blocked it earlier
}
PRIntervalTime start = PR_IntervalNow();
PRIntervalTime limit = THREAD_EVENT_STARVATION_LIMIT;
// Unblock outer nested wait loop (below).
if (mBlockedWait)
*mBlockedWait = false;
bool *oldBlockedWait = mBlockedWait;
mBlockedWait = &mayWait;
// When mayWait is true, we need to make sure that there is an event in the
// thread's event queue before we return. Otherwise, the thread will block
// on its event queue waiting for an event.
bool needEvent = mayWait;
// Reset prior to invoking DoProcessNextNativeEvent which might cause
// NativeEventCallback to process gecko events.
mProcessedGeckoEvents = false;
if (mFavorPerf <= 0 && start > mSwitchTime + mStarvationDelay) {
// Favor pending native events
PRIntervalTime now = start;
bool keepGoing;
do {
mLastNativeEventTime = now;
keepGoing = DoProcessNextNativeEvent(false, recursionDepth);
} while (keepGoing && ((now = PR_IntervalNow()) - start) < limit);
} else {
// Avoid starving native events completely when in performance mode
if (start - mLastNativeEventTime > limit) {
mLastNativeEventTime = start;
DoProcessNextNativeEvent(false, recursionDepth);
}
}
while (!NS_HasPendingEvents(thr) && !mProcessedGeckoEvents) {
// If we have been asked to exit from Run, then we should not wait for
// events to process. Note that an inner nested event loop causes
// 'mayWait' to become false too, through 'mBlockedWait'.
if (mExiting)
mayWait = false;
mLastNativeEventTime = PR_IntervalNow();
if (!DoProcessNextNativeEvent(mayWait, recursionDepth) || !mayWait)
break;
}
mBlockedWait = oldBlockedWait;
// Make sure that the thread event queue does not block on its monitor, as
// it normally would do if it did not have any pending events. To avoid
// that, we simply insert a dummy event into its queue during shutdown.
if (needEvent && !mExiting && !NS_HasPendingEvents(thr)) {
DispatchDummyEvent(thr);
}
// We're about to run an event, so we're in a stable state.
RunSyncSections(true, recursionDepth);
return NS_OK;
}
// Note, this is currently overidden on windows, see comments in nsAppShell for
// details.
void
nsBaseAppShell::DoProcessMoreGeckoEvents()
{
OnDispatchedEvent(nullptr);
}
