Changeset 93188 in vbox for trunk/src

Timestamp:

Jan 11, 2022 9:28:09 PM (3 years ago)

Author:

vboxsync

Message:

Main/Event: defunct passive event listeners prevent subsequent vetoable
events from being processed bugref:10000

If a passive event listener has registered an interest in a vetoable
event and subsequently disappears then any later passive event listeners
which are interested in the same vetoable event won't ever see
IEvent::setProcessed() called. The most common scenario where this is
seen is when the VBox GUI crashes and restarts during the same VBoxSVC
instance after which any time an OnExtraDataCanChange event is
triggered, such as by clicking a VM's name, it incurs a three second
timeout where nothing can be done in the GUI during that time. The fix
removes OnExtraDataCanChange from the unresponsive passive event
listener's list of interested events after it times out the first time
which means that the annoying three seconds of GUI inactivity will only
be seen once.

File:

• trunk/src/VBox/Main/src-all/EventImpl.cpp (modified) (2 diffs)

trunk/src/VBox/Main/src-all/EventImpl.cpp

@@ -229 +229 @@
     {
         *aResult = FALSE;
+        /*
+         * If we timed out then one or more passive listeners didn't process this event
+         * within the time limit most likely due to the listener no longer being alive (e.g.
+         * the VirtualBox GUI crashed) so we flag this to our caller so it can remove this
+         * event from the list of events the passive listener is interested in.  This avoids
+         * incurring this timeout every time the event is fired.
+         */
+        if (vrc == VERR_TIMEOUT)
+            return E_ABORT;
     }
 
@@ -1176 +1185 @@
 
     if (fWaitable)
+    {
         hrc = aEvent->WaitProcessed(aTimeout, aResult);
+
+        /*
+         * If a passive listener times out without processing a vetoable event then we
+         * remove that event from the list of events this listener is interested in.
+         */
+        if (!*aResult && hrc == E_ABORT && implies(VBoxEventType_Vetoable, evType))
+        {
+            AutoWriteLock alock(this COMMA_LOCKVAL_SRC_POS);
+
+            EventMapList &listeners = m->mEvMap[(int)evType - FirstEvent];
+            for (EventMapList::iterator it = listeners.begin();
+                 it != listeners.end();
+                 ++it)
+            {
+                RecordHolder<ListenerRecord> record(*it);
+                if (record.obj()->mQueue.size() != 0 && record.obj()->mQueue.back() == aEvent)
+                    m->mEvMap[(int)evType - FirstEvent].remove(record.obj());
+            }
+
+            PendingEventsMap::iterator pit = m->mPendingMap.find(aEvent);
+            if (pit != m->mPendingMap.end())
+                m->mPendingMap.erase(pit);
+
+            /*
+             * VBoxEventDesc::fire() requires TRUE to be returned so it can handle
+             * vetoable events.
+             */
+            return S_OK;
+        }
+    }
     else
         *aResult = TRUE;