Handling ports disconnecting

[6r1d]

As it is, RMR does not track ports disconnecting; I have to add some utility code for that.

I am not sure what indicators of disconnection are available.
Are connections and disconnections described by SND_SEQ_EVENT_PORT_SUBSCRIBED and SND_SEQ_EVENT_PORT_UNSUBSCRIBED events?

[6r1d]

I did a tiny test with VMPK.

When I pick a port in a dialog and enter it, I catch a SND_SEQ_EVENT_PORT_SUBSCRIBED event in alsa_MIDI_handler.
When I exit VMPK, I catch a SND_SEQ_EVENT_PORT_UNSUBSCRIBED event in alsa_MIDI_handler.
I also catch ``SND_SEQ_EVENT_PORT_SUBSCRIBED` when I reopen VMPK.

Then I repeated it with RMR (virtual input and normal output) and the result is the same. It subscribes, unsibscribes, no "SND_SEQ_EVENT_PORT_EXIT".

Trying to catch exit, I tried RMR yet again, now with virtual output and normal input modes.
When I close a virtual output port, it "unsubscribes", no "SND_SEQ_EVENT_PORT_EXIT" firing. Now that is interesting!

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I think all these events are related to the port only, not to a client. Next thing to do is to try and intercept SND_SEQ_EVENT_CLIENT_START and SND_SEQ_EVENT_CLIENT_EXIT.

[6r1d]

I tried to catch a SND_SEQ_EVENT_CLIENT_START and SND_SEQ_EVENT_CLIENT_EXIT events with a "virtual output to input" mode. It failed.

Then I tried "output to virtual input" configuration.
It also throws port subscription / unsibscription events.

My current conclusion: I'll have to redesign the output to run in a duplex mode later so I can know if I can detect SND_SEQ_EVENT_CLIENT_START and SND_SEQ_EVENT_CLIENT_EXIT events, but I am currently not sure that has any worth. Alternatively, I can try this alsa example to see if it shows how SND_SEQ_EVENT_CLIENT_EXIT event is thrown: seq-decoder.c.