Struct LocalWaker 

pub struct LocalWaker { /* private fields */ }

A single-threaded synchronization primitive for task wake-up.

Sometimes the task interested in a given event will change over time. A LocalWaker can coordinate notifications with the consumer potentially “updating” the underlying task to wake up. This is useful in scenarios where a computation completes in another task and wants to notify the consumer, but the consumer is in the process of being migrated to a new logical task.

Consumers should call register before checking the result of a computation and producers should call wake after producing the computation (this differs from the usual thread::park pattern). It is also permitted for wake to be called before register. This results in a no-op.

A single LocalWaker may be reused for any number of calls to register or wake.

The slot and its owned local handle must remain on their acquiring thread. Use take to transfer a registered standard waker instead.

fn assert_send<T: Send>() {}
assert_send::<ntex_util::task::LocalWaker>();

fn assert_sync<T: Sync>() {}
assert_sync::<ntex_util::task::LocalWaker>();

Implementations

impl LocalWaker

pub fn new() -> Self

Creates an empty LocalWaker.

pub fn with(waker: Option<Waker>) -> Self

Creates a LocalWaker with an optional initial waker.

pub fn register(&self, waker: &Waker) -> bool

Registers the waker to be notified on calls to wake.

Returns true if a waker was already registered.

If cloning the replacement panics, the previous registration is retained unless the clone callback itself changes the slot.

pub fn wake(&self)

Calls wake on the last Waker passed to register.

The waker is consumed, so a later wake does nothing until register is called again. If no waker is registered, this does nothing.

pub fn wake_checked(&self) -> bool

Calls wake on the last Waker passed to register.

Returns false if no waker is registered. Like wake, this consumes the registered waker.

pub fn take(&self) -> Option<Waker>

Returns the last Waker passed to register, so that the user can wake it.

This empties the slot and converts the owned handle into a thread-safe standard waker without cloning. If no waker is registered, returns None. Use take_local to retain native local operations.

pub fn take_local(&self) -> Option<LocalWaker>

Takes the registered wake handle, leaving the slot empty.

The returned handle retains native local operations and cannot be sent to another thread. If no waker is registered, returns None.

Trait Implementations

impl Clone for LocalWaker

Cloning creates an empty LocalWaker; the registered waker is not copied.

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LocalWaker

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

Formats the value using the given formatter.

impl Default for LocalWaker

fn default() -> Self

Returns the “default value” for a type.