On Sun, Dec 29, 2024 at 01:02:13PM +0100, René Scharfe wrote:
> Synchronization Barriers were added with Windows 8 and Windows Server
> 2012, Git for Windows requires higher versions, so this native
> mechanism should be usable. Relevant links:
> [...]
> However, macOS doesn't have pthread barriers. Here's an implementation
> that had to be fixed to satisfy Coverity, so it might be good now?
Yep, that matches what I'd found so far.
One of the reasons I hadn't sent anything is that I was waffling between
two approaches:
- implement barriers everywhere and just use them. More work, but we'd
have the tool if we wanted to use it later, and all builds behave
the same.
- make a "maybe_barrier" interface that might be a noop, and let most
platforms compile without them. They are not needed for correct
operation in most cases, but only to work around a sanitizer problem.
And it is not even a problem that comes up frequently; it is a race
that we occasionally see in CI. So enabling it only for our
linux-leaks CI job would be enough to dull the pain.
And there is no risk of any portability or run-time issues, because
the code is a noop for most builds.
> https://github.com/libusb/hidapi/blob/master/mac/hid.c
>
> Perhaps that implementation could be used for Windows as well? All
> functions it uses are provided by compat/win32/pthread.h; not sure if
> they are sufficiently fleshed out, though.
Yeah, I found a similar one. I think it's an undergrad OS assignment to
implement barriers using semaphores, but probably building on a mutex
and cond is less horrible. ;)
-Peff
