netdev - Re: [PATCH v8 4/7] rust: time: Add wrapper for fsleep function

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Message-ID: <CAH5fLgiEqd6uAzx5bkSDzst6hB0Ap=FAB7tOs96+WBL-pHN+ZA@mail.gmail.com>
Date: Wed, 22 Jan 2025 11:47:38 +0100
From: Alice Ryhl <aliceryhl@...gle.com>
To: FUJITA Tomonori <fujita.tomonori@...il.com>
Cc: miguel.ojeda.sandonis@...il.com, linux-kernel@...r.kernel.org, 
	rust-for-linux@...r.kernel.org, netdev@...r.kernel.org, andrew@...n.ch, 
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Subject: Re: [PATCH v8 4/7] rust: time: Add wrapper for fsleep function

On Wed, Jan 22, 2025 at 11:44 AM FUJITA Tomonori
<fujita.tomonori@...il.com> wrote:
>
> >> >> A range can be used for a custom type?
> >> >
> >> > I was thinking of doing it through `as_nanos()`, but it may read
> >> > worse, so please ignore it if so.
> >>
> >> Ah, it might work. The following doesn't work. Seems that we need to
> >> add another const like MAX_DELTA_NANOS or something. No strong
> >> preference but I feel the current is simpler.
> >>
> >> let delta = match delta.as_nanos() {
> >>     0..=MAX_DELTA.as_nanos() as i32 => delta,
> >>     _ => MAX_DELTA,
> >> };
> >
> > Could you do Delta::min(delta, MAX_DELTA).as_nanos() ?
>
> We need Delta type here so you meant:
>
> let delta = std::cmp::min(delta, MAX_DELTA);

If `Delta` implements the `Ord` trait, then you can write `Delta::min`
to take the minimum of two deltas. It's equivalent to `std::cmp::min`,
of course.

> We also need to convert a negative delta to MAX_DELTA so we could do:
>
> let delta = if delta.is_negative() {
>     MAX_DELTA
> } else {
>     min(delta, MAX_DELTA)
> };
>
> looks a bit readable than the original code?

At that point we might as well write

    if delta.is_negative() || delta > MAX_DELTA

and skip the call to `min`.

Alice