pub struct LocalKey<T> { /* private fields */ }
Expand description
A key for local data stored in a coroutine.
This type is generated by the coroutine_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 coroutine,
and the data is destroyed when the coroutine is completed.
coroutine-local data requires the 'static
bound to ensure it lives long
enough. When a key is accessed for the first time the coroutine’s data is
initialized with the provided initialization expression to the macro.
Implementations§
source§impl<T: 'static> LocalKey<T>
impl<T: 'static> LocalKey<T>
sourcepub fn with<F, R>(&'static self, f: F) -> Rwhere
F: FnOnce(&T) -> R,
pub fn with<F, R>(&'static self, f: F) -> Rwhere
F: FnOnce(&T) -> R,
Access this coroutine-local key, running the provided closure with a reference to the value.
This function will access this coroutine-local key to retrieve the data
associated with the current coroutine and this key. If this is the first
time this key has been accessed on this coroutine, then the key will be
initialized with the initialization expression provided at the time the
coroutine_local!
macro was called.
The provided closure will be provided a shared reference to the underlying data associated with this coroutine-local-key. The data itself is stored inside of the current coroutine.
if it’s not accessed in a coroutine context, it will use the thread local storage as a backend, so it’s safe to use it in thread context
Panics
This function can possibly panic for a number of reasons:
- If the initialization expression is run and it panics
- If the closure provided panics