Struct State

pub(super) struct State {
    val: AtomicUsize,
}

Fields

val: AtomicUsize

Implementations

impl State

All transitions are performed via RMW operations. This establishes an unambiguous modification order.

pub(super) fn new() -> State

Returns a task’s initial state.

pub(super) fn load(&self) -> Snapshot

Loads the current state, establishes Acquire ordering.

pub(super) fn transition_to_running(&self) -> TransitionToRunning

Attempts to transition the lifecycle to Running. This sets the notified bit to false so notifications during the poll can be detected.

pub(super) fn transition_to_idle(&self) -> TransitionToIdle

Transitions the task from Running -> Idle.

The transition to Idle fails if the task has been flagged to be cancelled.

pub(super) fn transition_to_complete(&self) -> Snapshot

Transitions the task from Running -> Complete.

pub(super) fn transition_to_terminal(&self, count: usize) -> bool

Transitions from Complete -> Terminal, decrementing the reference count the specified number of times.

Returns true if the task should be deallocated.

pub(super) fn transition_to_notified_by_val(&self) -> TransitionToNotifiedByVal

Transitions the state to NOTIFIED.

If no task needs to be submitted, a ref-count is consumed.

If a task needs to be submitted, the ref-count is incremented for the new Notified.

pub(super) fn transition_to_notified_by_ref(&self) -> TransitionToNotifiedByRef

Transitions the state to NOTIFIED.

pub(super) fn transition_to_notified_and_cancel(&self) -> bool

Sets the cancelled bit and transitions the state to NOTIFIED if idle.

Returns true if the task needs to be submitted to the pool for execution.

pub(super) fn transition_to_shutdown(&self) -> bool

Sets the CANCELLED bit and attempts to transition to Running.

Returns true if the transition to Running succeeded.

pub(super) fn drop_join_handle_fast(&self) -> Result<(), ()>

Optimistically tries to swap the state assuming the join handle is immediately dropped on spawn.

pub(super) fn transition_to_join_handle_dropped( &self, ) -> TransitionToJoinHandleDrop

Unsets the JOIN_INTEREST flag. If COMPLETE is not set, the JOIN_WAKER flag is also unset. The returned TransitionToJoinHandleDrop indicates whether the JoinHandle should drop the output of the future or the join waker after the transition.

pub(super) fn set_join_waker(&self) -> Result<Snapshot, Snapshot>

Sets the JOIN_WAKER bit.

Returns Ok if the bit is set, Err otherwise. This operation fails if the task has completed.

pub(super) fn unset_waker(&self) -> Result<Snapshot, Snapshot>

Unsets the JOIN_WAKER bit.

Returns Ok has been unset, Err otherwise. This operation fails if the task has completed.

pub(super) fn unset_waker_after_complete(&self) -> Snapshot

Unsets the JOIN_WAKER bit unconditionally after task completion.

This operation requires the task to be completed.

pub(super) fn ref_inc(&self)

pub(super) fn ref_dec(&self) -> bool

Returns true if the task should be released.

pub(super) fn ref_dec_twice(&self) -> bool

Returns true if the task should be released.

fn fetch_update_action<F, T>(&self, f: F) -> T

where F: FnMut(Snapshot) -> (T, Option<Snapshot>),

fn fetch_update<F>(&self, f: F) -> Result<Snapshot, Snapshot>

where F: FnMut(Snapshot) -> Option<Snapshot>,

Trait Implementations

impl Debug for State

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

Formats the value using the given formatter.