Struct tokio::task::LocalKey [−][src]
pub struct LocalKey<T: 'static> { /* fields omitted */ }
This is supported on crate feature
rt
only.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
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,
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,
Notable traits for TaskLocalFuture<T, F>
impl<T: 'static, F: Future> Future for TaskLocalFuture<T, F> type Output = F::Output;
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;
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()); });
Accesses the current task-local and runs the provided closure.
Panics
This function will panic if not called within the context of a future containing a task-local with the corresponding key.