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sync: reorder const_new before new_with
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Darksonn committed Mar 12, 2024
1 parent b4ab647 commit 0974e1c
Showing 1 changed file with 40 additions and 40 deletions.
80 changes: 40 additions & 40 deletions tokio/src/sync/once_cell.rs
Original file line number Diff line number Diff line change
Expand Up @@ -132,36 +132,22 @@ impl<T> OnceCell<T> {
}
}

/// Creates a new `OnceCell` that contains the provided value, if any.
/// Creates a new empty `OnceCell` instance.
///
/// If the `Option` is `None`, this is equivalent to `OnceCell::new`.
/// Equivalent to `OnceCell::new`, except that it can be used in static
/// variables.
///
/// [`OnceCell::new`]: crate::sync::OnceCell::new
// Once https://github.com/rust-lang/rust/issues/73255 lands
// and tokio MSRV is bumped to the rustc version with it stablised,
// we can made this function available in const context,
// by creating `Semaphore::const_new_closed`.
pub fn new_with(value: Option<T>) -> Self {
if let Some(v) = value {
OnceCell::from(v)
} else {
OnceCell::new()
}
}

/// Creates a new `OnceCell` that contains the provided value.
/// When using the `tracing` [unstable feature], a `OnceCell` created with
/// `const_new` will not be instrumented. As such, it will not be visible
/// in [`tokio-console`]. Instead, [`OnceCell::new`] should be used to
/// create an instrumented object if that is needed.
///
/// # Example
///
/// When using the `tracing` [unstable feature], a `OnceCell` created with
/// `const_new_with` will not be instrumented. As such, it will not be
/// visible in [`tokio-console`]. Instead, [`OnceCell::new_with`] should be
/// used to create an instrumented object if that is needed.
///
/// ```
/// use tokio::sync::OnceCell;
///
/// static ONCE: OnceCell<u32> = OnceCell::const_new_with(1);
/// static ONCE: OnceCell<u32> = OnceCell::const_new();
///
/// async fn get_global_integer() -> &'static u32 {
/// ONCE.get_or_init(|| async {
Expand All @@ -172,37 +158,51 @@ impl<T> OnceCell<T> {
/// #[tokio::main]
/// async fn main() {
/// let result = get_global_integer().await;
/// assert_eq!(*result, 1);
/// assert_eq!(*result, 2);
/// }
/// ```
///
/// [`tokio-console`]: https://github.com/tokio-rs/console
/// [unstable feature]: crate#unstable-features
#[cfg(not(all(loom, test)))]
pub const fn const_new_with(value: T) -> Self {
pub const fn const_new() -> Self {
OnceCell {
value_set: AtomicBool::new(true),
value: UnsafeCell::new(MaybeUninit::new(value)),
semaphore: Semaphore::const_new_closed(),
value_set: AtomicBool::new(false),
value: UnsafeCell::new(MaybeUninit::uninit()),
semaphore: Semaphore::const_new(1),
}
}

/// Creates a new empty `OnceCell` instance.
/// Creates a new `OnceCell` that contains the provided value, if any.
///
/// Equivalent to `OnceCell::new`, except that it can be used in static
/// variables.
/// If the `Option` is `None`, this is equivalent to `OnceCell::new`.
///
/// When using the `tracing` [unstable feature], a `OnceCell` created with
/// `const_new` will not be instrumented. As such, it will not be visible
/// in [`tokio-console`]. Instead, [`OnceCell::new`] should be used to
/// create an instrumented object if that is needed.
/// [`OnceCell::new`]: crate::sync::OnceCell::new
// Once https://github.com/rust-lang/rust/issues/73255 lands
// and tokio MSRV is bumped to the rustc version with it stablised,
// we can made this function available in const context,
// by creating `Semaphore::const_new_closed`.
pub fn new_with(value: Option<T>) -> Self {
if let Some(v) = value {
OnceCell::from(v)
} else {
OnceCell::new()
}
}

/// Creates a new `OnceCell` that contains the provided value.
///
/// # Example
///
/// When using the `tracing` [unstable feature], a `OnceCell` created with
/// `const_new_with` will not be instrumented. As such, it will not be
/// visible in [`tokio-console`]. Instead, [`OnceCell::new_with`] should be
/// used to create an instrumented object if that is needed.
///
/// ```
/// use tokio::sync::OnceCell;
///
/// static ONCE: OnceCell<u32> = OnceCell::const_new();
/// static ONCE: OnceCell<u32> = OnceCell::const_new_with(1);
///
/// async fn get_global_integer() -> &'static u32 {
/// ONCE.get_or_init(|| async {
Expand All @@ -213,18 +213,18 @@ impl<T> OnceCell<T> {
/// #[tokio::main]
/// async fn main() {
/// let result = get_global_integer().await;
/// assert_eq!(*result, 2);
/// assert_eq!(*result, 1);
/// }
/// ```
///
/// [`tokio-console`]: https://github.com/tokio-rs/console
/// [unstable feature]: crate#unstable-features
#[cfg(not(all(loom, test)))]
pub const fn const_new() -> Self {
pub const fn const_new_with(value: T) -> Self {
OnceCell {
value_set: AtomicBool::new(false),
value: UnsafeCell::new(MaybeUninit::uninit()),
semaphore: Semaphore::const_new(1),
value_set: AtomicBool::new(true),
value: UnsafeCell::new(MaybeUninit::new(value)),
semaphore: Semaphore::const_new_closed(),
}
}

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