Why does SetWinEventHook sometimes stop/pause monitoring events? - windows

Starting up a WinEventHook doesn't seem to be working reliably.
What would cause an event hook to only monitor events (or run the identified event proc function) sometimes?
ie. inside an IE8 BHO
HWINEVENTHOOK eHook = ::SetWinEventHook(EVENT_OBJECT_SHOW, EVENT_OBJECT_REORDER
, 0
, MSAALib_WinEventProc
, GetCurrentProcessId(), GetCurrentThreadId()
, WINEVENT_OUTOFCONTEXT );
I've been getting events quite regularly, but after a recent build it doesn't work except when I'm also running MS "Accessible event watcher", stopping and starting the event watcher also stops and starts my event proc being called.
I haven't changed the SetWinEventHook in any recent build so I do not believe this is the cause.
All the other thread/message pumping actions are taking place as expected so I do not believe failure to pump messages on the thread is the cause.
Testing getting reorder events using http://www.quirksmode.org/dom/events/tests/DOMtree.html and adding/removing test elements.
Edit:
Upon further testing it appears the change may have been that I stopped running the "Accessible event watcher" and not the build.
The range of events captured by the event hook without the "Accessible event watcher" appears to be [first, last) or eventMin to eventMax-1 which is not as per the doc SetWinEventHook when starting the "Accessible event watcher" the range changes and appears to be [first,last] so using an eventMax of EVENT_OBJECT_FOCUS seems to get the desired result of seeing EVENT_OBJECT_REORDER.
Is there something I'm missing here, or is the doc just wrong and the event watcher is doing something aswell?

Related

How to trigger the event in AnyLogic and then make it cyclic?

I would like to make the cyclic event. This event periodically calculates some parameters of the model. However, the event should be triggered once by a condition. I have no idea how to do that.
I tried to make the event.reset() at the beginning and then restart it after the appropriate condition is met.
However, I received the errors:" agent cannot be resolved to a variable"
If I delete the reset and restart functions for the event, everything will be ok. The event is cyclic and works fine.
The double click on the error shows the stings where the error is occurred (highlighted with red color):
On model start-up, suspend the event by using:
event.reset();
Once the condition you have is met, use:
event.restart();

Project reactor processors v3.X

We are trying to migrate from 2.X to 3.X.
https://github.com/reactor/reactor-core/issues/375
We have used the EventBus as event manager in our application(Low latency FX system) and it works very well for us.
After the change we decided to take every module and create his own processor to handle event.
1. Does this use seems to be correct from your point of view? Because lack of document at the current stage and after reviewing everything we could we don't really know what to do here
2. We have tried to use Flux in order to perform action every X interval
For example: Market is arriving 1000 for 1 second but we want to process an update only 4 time in a second. After upgrading we are using:
Processor with buffer and sending to another method.
In this method we have Flux that get list and try to work in parallel in order to complete his task.
We had 2 major problems:
1. Sometimes we received Null event which we cannot find that our system is sending to i suppose maybe we are miss using the processor
//Definition of processor
ReplayProcessor<Event> classAEventProcessor = ReplayProcessor.create();
//Event handler subscribing
public void onMyEventX(Consumer<Event> consumer) {
Flux<Event> handler = classAEventProcessor .filter(event -> event.getType().equals(EVENT_X));
handler.subscribe(consumer);
}
in the example above the event in the handler sometimes get null.. Once he does the stream stop working until we are restating server(Because only on restart we are doing creating processor)
2.We have tried to us parallel but sometimes some of the message were disappeared so maybe we are misusing the framework
//On constructor
tickProcessor.buffer(1024, Duration.of(250, ChronoUnit.MILLIS)).subscribe(markets ->
handleMarkets(markets));
//Handler
Flux.fromIterable(getListToProcess())
.parallel()
.runOn(Schedulers.parallel())
.doOnNext(entryMap -> {
DoBlockingWork(entryMap);
})
.sequential()
.subscribe();
The intention of this is that the processor will wakeup every 250ms and invoke the handler. The handler will work work with Flux parallel in order to make better and faster processing.
*In case that DoBlockingWork takes more than 250ms i couldn't understand what will be the behavior
UPDATE:
The EventBus was wrapped by us and every event subscribed throw the wrapped event manager.
Now we have tried to create event processor for every module but it works very slow. We have used TopicProcessor with ThreadExecutor and still very slow.. EventBus did the same work in high speed
Anyone has any idea? BTW when i tried to use DirectProcessor it seems to work much better that the TopicProcessor
Reactor 3 is built around the concept that you should avoid blocking as much as you can, so in your second snippet DoBlockingWork doesn't look good.
How are the events generated? Do you maybe have an listener-based asynchronous API to get them? If so, you could try using Flux.create.
For your use case of "we have 1000 events in 1 second, but only want to process 4", I'd chain a sample operator. For instance, sample(Duration.ofMillis(250)) will divide each second into 4 windows, from which it will only emit the last element.
The reference guide is being written, as well as a page where you can find links to external articles and learning material.There's a preview of the WIP reference guide here and the learning resources page here.

XCB event loop not getting any events

I am making an addon in Firefox, so I have a ChromeWorker - which is a privileged WebWorker. This is just a thread other then the mainthread.
In here I have no code but this (modified to make it look like not js-ctypes [which is the language for addons])
On startup I run this code, conn is a global variable:
conn = xcb_connect(null, null);
Then I run this in a 200ms interval:
evt = xcb_poll_for_event(conn);
console.log('evt:', evt);
if (!evt.isNull()) {
console.log('good got an event!!');
ostypes.API('free')(evt);
}
However evt is always null, I am never getting any events. My goal is to get all events on the system.
Anyone know what can cause something so simple to not work?
I have tried
xcb_change_window_attributes (conn, screens.data->root, XCB_CW_EVENT_MASK, values);
But this didn't fix it :(
The only way I can get it to work is by doing xcb_create_window xcb_map_window but then I get ONLY the events that happen in this created window.
You don't just magically get all events by opening a connection. There's only very few messages any client will receive, such as client messages, most others will only be sent to a client if it explicitly registered itself to receive them.
And yes, that means you have to register them on each and every window, which involves both crawling the tree and listening for windows being created, mapped, unmapped and destroyed and registering on them as well.
However, I would reconsider whether
My goal is to get all events on the system.
isn't an A-B problem. Why do you "need" all events? What do you actually want to do?

Subsequent events not triggering in while loop

I have a MAIN VI and a SUB VI which communicate events through control refnum. flow of events is as follows.
1) sub vi changes a value of its control and this event is handled in the main vi(this works).
2) main vi in response to the event changes one of its control and triggers an event from the event handler itself which is handled in the subvi event handler.(this also works).
The first phase is over. Now the main vi is running a while loop and the sub vi is running a while loop and main vi triggers an event every ~150ms. Which is to be handled in the subvi. This is the part which is not happening. I can see the main vi's control getting updated but the event(if generated) is not handled by the subvi. I'm using control's property node->Value(signalling) to change the value as well as trigger the event. What can be the possible cause?
note: the control (whose value is changed), event handler are the same as in the first phase.
Hope my question is clear.
i found the problem .
the subsequent events were not being handled because the loop in which the event handler ran looped once
i.e the initial condition was itself false so the loop only ran once.
this loop was controlled by stop if true. it had to be continue if true.
the boolean variable that controlled this loop was true. this should have been my first clue.

How to detect inactive user

How to detect inactive (idle) user in Windows application? I'd like to shutdown application when there hasn't been any input (keyboard, mouse) from user for certain period of time.
To track a user's idle time you could hook keyboard and mouse activity. Note, however, that installing a system-wide message hook is a very invasive thing to do and should be avoided if possible, since it will require your hook DLL to be loaded into all processes.
Another solution is to use the GetLastInputInfo API function (if your application is running on Win2000 (and up) machines).
GetLastInputInfo retrieves the time (in milliseconds) of the last input event (when the last detected user activity has been received, be it from keyboard or mouse).
Here's a simple example. The SecondsIdle function returns a number of second with no user activity (called in an OnTimer event of a TTimer component).
~~~~~~~~~~~~~~~~~~~~~~~~~
function SecondsIdle: DWord;
var
liInfo: TLastInputInfo;
begin
liInfo.cbSize := SizeOf(TLastInputInfo) ;
GetLastInputInfo(liInfo) ;
Result := (GetTickCount - liInfo.dwTime) DIV 1000;
end;
procedure TForm1.Timer1Timer(Sender: TObject) ;
begin
Caption := Format('System IDLE last %d seconds', [SecondsIdle]) ;
end;
http://delphi.about.com/od/adptips2004/a/bltip1104_4.htm
You might want to see the answer to this question: How to tell when Windows is inactive [1] it is basically same question the solution suggested is to use the GetLastInputInfo [2] API call.
This post explains some aspects as well: (The Code Project) How to check for user inactivity with and without platform invokes in C# [3]
[1] How to tell when Windows is inactive
[2] http://msdn.microsoft.com/en-us/library/ms646302%28VS.85%29.aspx
[3] http://www.codeproject.com/KB/cs/uim.aspx
Your application will get a WM_SYSCOMMAND message with SC_SCREENSAVE as a command id when the Screen Saver is about to kick in. Would that do? there's also the SC_MONITORPOWER command id when the monitor is about to blank (also a WM_SYSCOMMAND message).
Edit: looking at the comments, it appears that you don't care about whether the user is inative, but rather whether your application is inactive.
This is easy. If your app is minimized, then the user isn't interacting with it. If your app is not the foreground application, that's a good inicator as well.
You could also pay attention to messages in your pump to notice if there have been any user input messages to your app, In C++ adding code to the pump is trivial, in delphi you can use a WH_GETMESSAGE hook to monitor the pump hook into the message loop that TApplication implements. Or GetLastInputInfo
This SecondsIdle doens't work at all.
The way is to use a TTimer combined with a second variable that resets every time user inputs mouse or keyboard.

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