Struct futures_core::task::LocalKey

pub struct LocalKey<T> { /* fields omitted */ }

A key for task-local data stored in a future's task.

This type is generated by the task_local! macro and performs very similarly to the thread_local! macro and std::thread::LocalKey types. Data associated with a LocalKey<T> is stored inside of a future's task, and the data is destroyed when the future is completed and the task is destroyed.

Task-local data can migrate between threads and hence requires a Send bound. Additionally, task-local data also requires the 'static bound to ensure it lives long enough. When a key is accessed for the first time the task's data is initialized with the provided initialization expression to the macro.

Methods

impl<T: Send + 'static> LocalKey<T>

pub fn get_mut<'a>(&'static self, cx: &'a mut Context) -> &'a mut T

Access this task-local key.

This function will access this task-local key to retrieve the data associated with the current task and this key. If this is the first time this key has been accessed on this task, then the key will be initialized with the initialization expression provided at the time the task_local! macro was called.

Trait Implementations

impl<T: Debug> Debug for LocalKey<T>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.