pub struct LocalKey<T: 'static> { /* private fields */ }
Expand description
A key for task-local data.
This type is generated by the task_local!
macro.
Unlike std::thread::LocalKey
, tokio::task::LocalKey
will
not lazily initialize the value on first access. Instead, the
value is first initialized when the future containing
the task-local is first polled by a futures executor, like Tokio.
Examples
tokio::task_local! {
static NUMBER: u32;
}
NUMBER.scope(1, async move {
assert_eq!(NUMBER.get(), 1);
}).await;
NUMBER.scope(2, async move {
assert_eq!(NUMBER.get(), 2);
NUMBER.scope(3, async move {
assert_eq!(NUMBER.get(), 3);
}).await;
}).await;
Implementations
sourceimpl<T: 'static> LocalKey<T>
impl<T: 'static> LocalKey<T>
sourcepub fn scope<F>(&'static self, value: T, f: F) -> TaskLocalFuture<T, F>ⓘNotable traits for TaskLocalFuture<T, F>impl<T: 'static, F: Future> Future for TaskLocalFuture<T, F> type Output = F::Output;
where
F: Future,
pub fn scope<F>(&'static self, value: T, f: F) -> TaskLocalFuture<T, F>ⓘNotable traits for TaskLocalFuture<T, F>impl<T: 'static, F: Future> Future for TaskLocalFuture<T, F> type Output = F::Output;
where
F: Future,
Sets a value T
as the task-local value for the future F
.
On completion of scope
, the task-local will be dropped.
Examples
tokio::task_local! {
static NUMBER: u32;
}
NUMBER.scope(1, async move {
println!("task local value: {}", NUMBER.get());
}).await;
sourcepub fn sync_scope<F, R>(&'static self, value: T, f: F) -> R where
F: FnOnce() -> R,
pub fn sync_scope<F, R>(&'static self, value: T, f: F) -> R where
F: FnOnce() -> R,
Sets a value T
as the task-local value for the closure F
.
On completion of scope
, the task-local will be dropped.
Examples
tokio::task_local! {
static NUMBER: u32;
}
NUMBER.sync_scope(1, || {
println!("task local value: {}", NUMBER.get());
});
Trait Implementations
Auto Trait Implementations
impl<T> RefUnwindSafe for LocalKey<T>
impl<T> Send for LocalKey<T>
impl<T> Sync for LocalKey<T>
impl<T> Unpin for LocalKey<T>
impl<T> UnwindSafe for LocalKey<T>
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more