MIDI devices are closed before the shutdown script is run

[Sean M. Pappalardo]

For PortMIDI devices at least, the MidiDevice is close()d before the MidiScriptEngine is shut down, preventing any shutdown script code from sending anything to the device. This happens when disabling the device in the prefs or closing Mixxx.

Not sure when this happened but it's been in trunk since at least r2544. Will try to track it down.

[Albert Santoni (gamegod)]

I added a sendInhibit flag to fix a race condition on shutdown. The problem
might be caused by that.
On 2010-11-16 7:05 AM, "Sean M. Pappalardo" <email address hidden>
wrote:
> Public bug reported:
>
> For PortMIDI devices at least, the MidiDevice is close()d before the
> MidiScriptEngine is shut down, preventing any shutdown script code from
> sending anything to the device. This happens when disabling the device
> in the prefs or closing Mixxx.
>
> Not sure when this happened but it's been in trunk since at least r2544.
> Will try to track it down.
>
> ** Affects: mixxx
> Importance: Low
> Status: Confirmed
>
> ** Affects: mixxx/1.9
> Importance: Low
> Status: Confirmed
>
>
> ** Tags: midi
>
> ** Also affects: mixxx/1.9
> Importance: Undecided
> Status: New
>
> ** Changed in: mixxx/1.9
> Status: New => Confirmed
>
> ** Changed in: mixxx/1.9
> Importance: Undecided => Low
>
> ** Changed in: mixxx/1.9
> Milestone: None => 1.9.0
>
> --
> MIDI devices are closed before the shutdown script is run
> https://bugs.launchpad.net/bugs/676086
> You received this bug notification because you are a member of Mixxx
> Development Team, which is subscribed to Mixxx.

[Sean M. Pappalardo (pegasus-renegadetech)]

Interesting...FWIW, I now sometimes get deadlocks on shutdown in recent trunk. I thought I correctly handled deadlocking at shutdown before you added the sendInhibit by having the MidiDevice wait for the MSE's gracefulShutdown() to finish.

I'm convinced that all the locking we currently do was an incorrect way to solve the original problems. Since I've set it up awhile ago so that only the MSE thread will call MSE functions, (using signals to communicate between the MidiDevice and its MSE,) the safe* functions and much of the locks can be removed. (We can just ASSERT that each function is being called from the MSE thread if you like.)

[Sean M. Pappalardo (pegasus-renegadetech)]

I reverted the sendInhibit flag in r2592 of trunk which fixes this bug. (I was getting a deadlock on shutdown sometimes even when it was there.) We have too many mutexes in the MIDI subsystem and I plan to fix that before v1.10.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/5659