Re: [PATCH v4] rust: add global lock support

Boqun Feng
2024-10-10T13:55:22Z

On Thu, Oct 10, 2024 at 12:53:00PM +0200, Alice Ryhl wrote:
[...]
> > > +#[macro_export]
> > > +macro_rules! global_lock {
> > > + {
> > > + $(#[$meta:meta])* $pub:vis static $name:ident: $kind:ident<$valuety:ty> = unsafe { uninit };
> > > + value: $value:expr;
> >
> > I would find it more natural to use `=` instead of `:` here, since then
> > it would read as a normal statement with the semicolon at the end.
> > Another alternative would be to use `,` instead of `;`, but that doesn't
> > work nicely with the static keyword above (although you could make the
> > user write it in another {}, but that also isn't ideal...).
> >
> > Using `=` instead of `:` makes my editor put the correct amount of
> > indentation there, `:` adds a lot of extra spaces.
>
> That seems sensible.
>

While we are at it, how about we make the syntax:

global_lock!{
static MY_LOCK: Mutex<u32> = unsafe { 0 };
}

or

global_lock!{
static MY_LOCK: Mutex<u32> = unsafe { uninit { 0 } };
}

?

i.e. instead of a "value" field, we put it in the "initialization
expression". To me, this make it more clear that "value" is the
initialized value protected by the lock. Thoughts?

Besides, instead of a "guard" type name, could you make a
generic guard type over the "locked_by" type? E.g.

struct GlobalGuard<L: GlobalLockedBy>(Guard<...>, PhantomData<*mut L>);

I feel like this could make the relationship between the guard type and
the locked_by type more obvious. But maybe there's something I'm
missing?

Regards,
Boqun …