[vbox-dev] Passive event handling

[Nikolay Igotti]

     Hi Ian,

  Think your question is mostly about locking, and my understanding is 
that there's no need
to lock the VM. Genereally, as Klaus pointed out, event source holds 
reference to object which
produces events for it, shall it be Console, Machine or VirtualBox instance.
  So your code could be significantly simplified.
vboxshell.py contains reasonable (for the moment I wrote it) usecase of 
event sources, including
filtering and aggregation.


  Thanks,
      Nikolay

On 10/01/2012 04:58 PM, Ian Moore wrote:
> Hello,
>
> I'm having some trouble following the passive event mechanism logic. 
> I'm working on a web application and it will periodically poll 
> vboxwebsrv for events. While this works well with the vbox event 
> source, I'm not quite sure how to implement this for individual 
> machine console events. Should it go like this:
>
> 1. Create an event listener when a running machine is selected
> --- machine = vbox->findMachine(...)
> --- session = websessionManager->getSessionObject()
> --- listener = session->console->eventSource->createListener()
> --- session->console->eventSource->registerListener(listener,...,false)
> --- session->unlock(machine)
>
> 2. Then periodically poll for events. Each poll cycle would
> --- machine = vbox->findMachine(...)
> --- session = websessionManager->getSessionObject()
> --- while(event = session->console->eventSource->getEvent(listener 
> created in step #1)) { ... }
> --- session->unlock(machine)
>
> Should I leave the shared lock in place (leaving session->console 
> available) until the machine is deselected or stopped? I tried looking 
> through the VirtualBox source, but was unable to determine how it 
> should work.
>
> Thank you for any help!
>
>
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