[openbeos-midi] Re: midi_server surviving app crash
- From: Philippe Houdoin <philippe.houdoin@xxxxxxx>
- To: openbeos-midi@xxxxxxxxxxxxx
- Date: Fri, 11 Oct 2002 00:23:06 +0200 (MEST)
En réponse à Michael Pfeiffer:
> Imagine the following scenario: An application A registers a
> BMidiConsumer at the midi_server. Another app B connects
> a BMidiProducer to the consumer and starts sending
> Midi messages to the producer. Suddenly app A crashes.
Brrr, it sounds like drama!
;-)
> How treats the midi_server such a situation?
Well, the IPC used by midikit2 seems to be ports, looking at some private
members of BMidiConsummer and BMidiRoster private methods.
BeOS kernel automagicly delete ports owned by dying teams.
I guess midi_server/BMidi* classes just take care to always check
port i/o routines for B_BAD_PORT_ID return code, and this case close any active
connection made on this endpoint & remove all dead midi endpoint(s).
> I think it survives the app crash.
Absolutly. How neat it that :-).
> What happens with app B that still wants to send
> messages to the consumer of the now not existing
> app A?
write_port[_etc]() will return B_BAD_PORT_ID.
> How realises the midi_server that a registered BMidiNode has
> "died" because its app has crashed?
Any SprayEvent() (private method of BMidiProducer) will fail internaly on
write_port[_etc]().
Again, it's only *my* speculation on how the midi_server and MidiKit2 could
works.
But, you're right, looking at how Marcus's media kit handle this scenario could
help here...
-Philippe.
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