Re: [PATCH v13 2/7] net/vmnet: add vmnet backends to qapi/net

[Peter Maydell <peter.maydell@linaro.org>]

On Tue, 25 Jan 2022 at 04:14, Akihiko Odaki <akihiko.odaki@gmail.com> wrote:
> I'm neutral about the decision. I think QEMU should avoid using
> Objective-C code except for interactions with Apple's APIs, and .c is
> superior in terms of that as it would prevent accidental introduction
> of Objective-C code. On the other hand, naming them .m will allow the
> introduction of Automatic Reference Counting to manage dispatch queue
> objects. In fact, I have found a few memory leaks in vmnet in the last
> review and ui/cocoa.m has a suspicious construction of the object
> management (Particularly it has asynchronous dispatches wrapped with
> NSAutoreleasePool, which does not make sense).

I think those are probably my fault -- in commit 6e657e64cd (in 2013)
we added NSAutoReleasePools to fix leaks that happened because
we were calling into Cocoa APIs from threads other than the UI
thread that didn't have their own automatically created autorelease
pool. Much later in commit 5588840ff778 (in 2019) we put in the
dispatch_async stuff because newer macOS was stricter about
requiring Cocoa API calls to be only on the UI thread. So
I think that means the requirement for the autorelease pools
has now gone away in those functions and we could simply delete
them -- does that sound right? (I freely admit that I'm not a macOS
expert -- I just look stuff up in the documentation; historically
we haven't really had many expert macOS people around to work on
cocoa.m...)

On the subject of cocoa.m, while we have various macOS-interested
people in this thread, can I ask if anybody would like to
review a couple of patches that came in at the beginning of the
year?

https://patchew.org/QEMU/20220102174153.70043-1-carwynellis@gmail.com/
("ui/cocoa: Add option to disable left command and hide cursor on click")
and
https://patchew.org/QEMU/20220103114515.24020-1-carwynellis@gmail.com/
("Show/hide the menu bar in fullscreen on mouse")

either from the point of view of "is this a sensible change to
the macOS UI experience" or for the actual code changes, or both.

We've been very short on upstream macOS code reviewers so if people
interested in that host platform are able to chip in by
reviewing each others' code that helps a lot.

thanks
-- PMM