Ok, tthe TheInterruptSemaphore is signalled in checkForInterrupts() via usage of setInterruptPending().
As far as I know the only place that it is used is by the VM host platform keyboard handling logic only *IF* you are using an image that predates EventSensor (Aug 2000)
Now since most people use an image that has this class what happens is
(a) The process running EventSensor>>processEvent: looks at the incoming VM generated keyboard event and if it decides that the keys pressed meet it's criteria of what an interrupt is then it signals in the EventSensor interruptSemaphore That then wakes up the interrupt watcher process
InputSensor>>userInterruptWatcher running at Processor lowIOPriority.
This means of course the process that is running EventSensor>>processEvent: has to be able to run. You could simplify things here and fork off the userInterruptWatcher logic in EventSensor>>processEvent: and as I think Michael noticed rip out the InterruptWatcherProcess and InterruptSemaphore
On 20-Nov-08, at 7:18 AM, Igor Stasenko wrote:
2008/11/20 Michael Rueger m.rueger@acm.org:
Igor Stasenko wrote:
If i remember correctly, an interrupt semaphore is used to awake a process which watching for interrupts. And indeed, when key combination matching an interrupt key code, it calls setInterruptPending(), which is then eventually leads to signaling a semaphore which registered as interrupt semaphore. You can't handle it on image side, because you may not have chance to get to it (if there's another process running on same or higher priority than event ticker process). While in VM, regardless what image does, it periodically checks for interrupts, and during handling OS events, it checks if an interrupt key pressed, and if so, then signals the semaphore. At least, this is how it looks on Win32.
The question really was if it is in the VM but rather if it (still) should be in the VM. After some discussions with John I'm pretty sure we can remove the interrupt semaphore code from the VM. For now that would mean that the image code still referring to it should/can be removed.
In this case, i'd like to read John's reasoning, why its safe to remove it from VM.
From my perspective , it should stay, because you can't imitate same
behavior on language side safely.
Michael
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
-- Best regards, Igor Stasenko AKA sig.
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
-- = = = ======================================================================== John M. McIntosh johnmci@smalltalkconsulting.com Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com = = = ========================================================================
Hi John -
The reasoning sounds about right but you have to be *very* careful when making changes to that logic. As a simple example, fetchMoreEvents is not only called from the event tickler and consequently the interrupt handler might be forked at the priority of some random process using "Sensor anyButtonPressed" ;-) If I remember correctly, there were several other gotchas in this area (I tried changing some of this stuff in Croquet once) and since this is a place where screwing up will make a lot of people *very* unhappy I would advise extreme caution when making these changes.
Cheers, - Andreas
John M McIntosh wrote:
Ok, tthe TheInterruptSemaphore is signalled in checkForInterrupts() via usage of setInterruptPending().
As far as I know the only place that it is used is by the VM host platform keyboard handling logic only *IF* you are using an image that predates EventSensor (Aug 2000)
Now since most people use an image that has this class what happens is
(a) The process running EventSensor>>processEvent: looks at the incoming VM generated keyboard event and if it decides that the keys pressed meet it's criteria of what an interrupt is then it signals in the EventSensor interruptSemaphore That then wakes up the interrupt watcher process
InputSensor>>userInterruptWatcher running at Processor lowIOPriority.
This means of course the process that is running EventSensor>>processEvent: has to be able to run. You could simplify things here and fork off the userInterruptWatcher logic in EventSensor>>processEvent: and as I think Michael noticed rip out the InterruptWatcherProcess and InterruptSemaphore
On 20-Nov-08, at 7:18 AM, Igor Stasenko wrote:
2008/11/20 Michael Rueger m.rueger@acm.org:
Igor Stasenko wrote:
If i remember correctly, an interrupt semaphore is used to awake a process which watching for interrupts. And indeed, when key combination matching an interrupt key code, it calls setInterruptPending(), which is then eventually leads to signaling a semaphore which registered as interrupt semaphore. You can't handle it on image side, because you may not have chance to get to it (if there's another process running on same or higher priority than event ticker process). While in VM, regardless what image does, it periodically checks for interrupts, and during handling OS events, it checks if an interrupt key pressed, and if so, then signals the semaphore. At least, this is how it looks on Win32.
The question really was if it is in the VM but rather if it (still) should be in the VM. After some discussions with John I'm pretty sure we can remove the interrupt semaphore code from the VM. For now that would mean that the image code still referring to it should/can be removed.
In this case, i'd like to read John's reasoning, why its safe to remove it from VM.
From my perspective , it should stay, because you can't imitate same
behavior on language side safely.
Michael
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
-- Best regards, Igor Stasenko AKA sig.
Pharo-project mailing list Pharo-project@lists.gforge.inria.fr http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
--
John M. McIntosh johnmci@smalltalkconsulting.com Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ===========================================================================
Actually it's Michael who is messing in this area to improve the event handler for Pharo (and in general) as part of some funding from ESUG for the iPhone VM development work.
Me? I'm just an innocent bystander. I'd assume he has to fork off any logic with low io process priority which is what I think happens if you follow the bouncing ball by reviewing what installInterruptWatcher and handleUserInterrupt do. The key consideration is that fetchMoreEvents is the trigger, not the code in the VM.
On 20-Nov-08, at 10:58 AM, Andreas Raab wrote:
Hi John -
The reasoning sounds about right but you have to be *very* careful when making changes to that logic. As a simple example, fetchMoreEvents is not only called from the event tickler and consequently the interrupt handler might be forked at the priority of some random process using "Sensor anyButtonPressed" ;-) If I remember correctly, there were several other gotchas in this area (I tried changing some of this stuff in Croquet once) and since this is a place where screwing up will make a lot of people *very* unhappy I would advise extreme caution when making these changes.
Cheers,
- Andreas
-- = = = ======================================================================== John M. McIntosh johnmci@smalltalkconsulting.com Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com = = = ========================================================================
Oh, I'm sorry for the interference then. I thought you were digging around in this.
Cheers, - Andreas
John M McIntosh wrote:
Actually it's Michael who is messing in this area to improve the event handler for Pharo (and in general) as part of some funding from ESUG for the iPhone VM development work.
Me? I'm just an innocent bystander. I'd assume he has to fork off any logic with low io process priority which is what I think happens if you follow the bouncing ball by reviewing what installInterruptWatcher and handleUserInterrupt do. The key consideration is that fetchMoreEvents is the trigger, not the code in the VM.
On 20-Nov-08, at 10:58 AM, Andreas Raab wrote:
Hi John -
The reasoning sounds about right but you have to be *very* careful when making changes to that logic. As a simple example, fetchMoreEvents is not only called from the event tickler and consequently the interrupt handler might be forked at the priority of some random process using "Sensor anyButtonPressed" ;-) If I remember correctly, there were several other gotchas in this area (I tried changing some of this stuff in Croquet once) and since this is a place where screwing up will make a lot of people *very* unhappy I would advise extreme caution when making these changes.
Cheers,
- Andreas
--
John M. McIntosh johnmci@smalltalkconsulting.com Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ===========================================================================
2008/11/20 John M McIntosh johnmci@smalltalkconsulting.com:
Ok, tthe TheInterruptSemaphore is signalled in checkForInterrupts() via usage of setInterruptPending().
As far as I know the only place that it is used is by the VM host platform keyboard handling logic only *IF* you are using an image that predates EventSensor (Aug 2000)
Now since most people use an image that has this class what happens is
(a) The process running EventSensor>>processEvent: looks at the incoming VM generated keyboard event and if it decides that the keys pressed meet it's criteria of what an interrupt is then it signals in the EventSensor interruptSemaphore That then wakes up the interrupt watcher process
InputSensor>>userInterruptWatcher running at Processor lowIOPriority.
This means of course the process that is running EventSensor>>processEvent: has to be able to run. You could simplify things here and fork off the userInterruptWatcher logic in EventSensor>>processEvent: and as I think Michael noticed rip out the InterruptWatcherProcess and InterruptSemaphore
Good, it makes sense, if we provide enough guarantees that even ticker process is always running in warm & dry & safe conditions. :) This also makes 1 less process hanging around, because there is no need in setting up the userInterruptWatcher and semaphore for it once you can do it from event ticker like following:
(self isInterruptEvent: event) ifTrue: [ interruptHandler isAlreadyRunning ifFalse: [ [self handleInterrupt] forkAt: Processor severePriority ] ]
This makes it irrelevant, at which priority the current event handling running and safe from gotchas, pointed by Andreas (in numerous "Sensor anyFooBar" sends spreaded throughout the image).
Also, i think, it would be good to guarantee that there is only single Process which making calls to primitive and fetching events from VM - obviously the event ticker process. The rest processes should be allowed to talk with Sensor only through shared queue.
Igor Stasenko wrote:
This also makes 1 less process hanging around, because there is no need in setting up the userInterruptWatcher and semaphore for it once you can do it from event ticker like following:
(self isInterruptEvent: event) ifTrue: [ interruptHandler isAlreadyRunning ifFalse: [ [self handleInterrupt] forkAt: Processor severePriority ] ]
My memories of the previous attempt are coming back now ;-) The above is another one of 'em gotchas. If you have more than one process going wild you most definitely want to be able to fire off the interrupt handler multiple times. Which reminds me of yet another gotcha: "handlerBlock copy fixTemps" please or you are for a world of pain ;-)
Cheers, - Andreas
This makes it irrelevant, at which priority the current event handling running and safe from gotchas, pointed by Andreas (in numerous "Sensor anyFooBar" sends spreaded throughout the image).
Also, i think, it would be good to guarantee that there is only single Process which making calls to primitive and fetching events from VM - obviously the event ticker process. The rest processes should be allowed to talk with Sensor only through shared queue.
2008/11/20 Andreas Raab andreas.raab@gmx.de:
Igor Stasenko wrote:
This also makes 1 less process hanging around, because there is no need in setting up the userInterruptWatcher and semaphore for it once you can do it from event ticker like following:
(self isInterruptEvent: event) ifTrue: [ interruptHandler isAlreadyRunning ifFalse: [ [self handleInterrupt] forkAt: Processor severePriority ] ]
My memories of the previous attempt are coming back now ;-) The above is another one of 'em gotchas. If you have more than one process going wild you most definitely want to be able to fire off the interrupt handler multiple times. Which reminds me of yet another gotcha: "handlerBlock copy fixTemps" please or you are for a world of pain ;-)
It depends how long this process should live. I didn't examined how 'interrupting' works, just my guess that interrupt should be a short-term process which does a couple of hacky things and then terminates.
From this point, there is no need in spawning many of them, and
actually #isAlreadyRunning is to make sure that there is only single 'hacker' process running - to be sure that you don't need to protect your state with semaphores/mutexes and so on.
Cheers,
- Andreas
This makes it irrelevant, at which priority the current event handling running and safe from gotchas, pointed by Andreas (in numerous "Sensor anyFooBar" sends spreaded throughout the image).
Also, i think, it would be good to guarantee that there is only single Process which making calls to primitive and fetching events from VM - obviously the event ticker process. The rest processes should be allowed to talk with Sensor only through shared queue.
vm-dev@lists.squeakfoundation.org
-
Andreas Raab -
Igor Stasenko -
John M McIntosh