rust-lang/rust
1
0
Fork 0
Code Issues Pull Requests Actions 1 Packages Projects Releases Wiki Activity

Stabilize LazyCell and LazyLock (lazy_cell)

Browse Source
This commit is contained in:
Peter Jaszkowiak
2024-02-20 20:55:13 -07:00
parent 0b2f194b83
commit 4913ab8f77
34 changed files with 60 additions and 82 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
library/std/src/sync/lazy_lock.rs
View File

@@ -31,8 +31,6 @@ union Data<T, F> {
/// Initialize static variables with `LazyLock`.
///
/// ```
/// #![feature(lazy_cell)]
///
/// use std::collections::HashMap;
///
/// use std::sync::LazyLock;
@@ -61,8 +59,6 @@ union Data<T, F> {
/// ```
/// Initialize fields with `LazyLock`.
/// ```
/// #![feature(lazy_cell)]
///
/// use std::sync::LazyLock;
///
/// #[derive(Debug)]
@@ -76,8 +72,7 @@ union Data<T, F> {
/// println!("{}", *data.number);
/// }
/// ```
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
pub struct LazyLock<T, F = fn() -> T> {
once: Once,
data: UnsafeCell<Data<T, F>>,
@@ -85,8 +80,21 @@ pub struct LazyLock<T, F = fn() -> T> {
impl<T, F: FnOnce() -> T> LazyLock<T, F> {
/// Creates a new lazy value with the given initializing function.
///
/// # Examples
///
/// ```
/// use std::sync::LazyLock;
///
/// let hello = "Hello, World!".to_string();
///
/// let lazy = LazyLock::new(|| hello.to_uppercase());
///
/// assert_eq!(&*lazy, "HELLO, WORLD!");
/// ```
#[inline]
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
#[rustc_const_stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
pub const fn new(f: F) -> LazyLock<T, F> {
LazyLock { once: Once::new(), data: UnsafeCell::new(Data { f: ManuallyDrop::new(f) }) }
}
@@ -107,7 +115,6 @@ impl<T, F: FnOnce() -> T> LazyLock<T, F> {
/// # Examples
///
/// ```
/// #![feature(lazy_cell)]
/// #![feature(lazy_cell_consume)]
///
/// use std::sync::LazyLock;
@@ -145,8 +152,6 @@ impl<T, F: FnOnce() -> T> LazyLock<T, F> {
/// # Examples
///
/// ```
/// #![feature(lazy_cell)]
///
/// use std::sync::LazyLock;
///
/// let lazy = LazyLock::new(|| 92);
@@ -155,7 +160,7 @@ impl<T, F: FnOnce() -> T> LazyLock<T, F> {
/// assert_eq!(&*lazy, &92);
/// ```
#[inline]
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
pub fn force(this: &LazyLock<T, F>) -> &T {
this.once.call_once(|| {
// SAFETY: `call_once` only runs this closure once, ever.
@@ -191,7 +196,7 @@ impl<T, F> LazyLock<T, F> {
}
}
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
impl<T, F> Drop for LazyLock<T, F> {
fn drop(&mut self) {
match self.once.state() {
@@ -204,7 +209,7 @@ impl<T, F> Drop for LazyLock<T, F> {
}
}
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
impl<T, F: FnOnce() -> T> Deref for LazyLock<T, F> {
type Target = T;
@@ -219,7 +224,7 @@ impl<T, F: FnOnce() -> T> Deref for LazyLock<T, F> {
}
}
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
impl<T: Default> Default for LazyLock<T> {
/// Creates a new lazy value using `Default` as the initializing function.
#[inline]
@@ -228,7 +233,7 @@ impl<T: Default> Default for LazyLock<T> {
}
}
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
impl<T: fmt::Debug, F> fmt::Debug for LazyLock<T, F> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut d = f.debug_tuple("LazyLock");
@@ -242,13 +247,13 @@ impl<T: fmt::Debug, F> fmt::Debug for LazyLock<T, F> {
// We never create a `&F` from a `&LazyLock<T, F>` so it is fine
// to not impl `Sync` for `F`.
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
unsafe impl<T: Sync + Send, F: Send> Sync for LazyLock<T, F> {}
// auto-derived `Send` impl is OK.
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
impl<T: RefUnwindSafe + UnwindSafe, F: UnwindSafe> RefUnwindSafe for LazyLock<T, F> {}
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
impl<T: UnwindSafe, F: UnwindSafe> UnwindSafe for LazyLock<T, F> {}
#[cfg(test)]

2
library/std/src/sync/mod.rs
View File

@@ -179,7 +179,7 @@ pub use self::rwlock::{MappedRwLockReadGuard, MappedRwLockWriteGuard};
#[stable(feature = "rust1", since = "1.0.0")]
pub use self::rwlock::{RwLock, RwLockReadGuard, RwLockWriteGuard};
#[unstable(feature = "lazy_cell", issue = "109736")]
#[stable(feature = "lazy_cell", since = "CURRENT_RUSTC_VERSION")]
pub use self::lazy_lock::LazyLock;
#[stable(feature = "once_cell", since = "1.70.0")]
pub use self::once_lock::OnceLock;