Struct JoinFuture 

pub(crate) struct JoinFuture<'a, 'b, Q: ?Sized, Key, Val, We, B, L> {
    lifecycle: &'a L,
    shard: &'a RwLock<CacheShard<Key, Val, We, B, L, Arc<Placeholder<Val>>>>,
    hash: u64,
    key: &'b Q,
    state: JoinFutureState<Val>,
    notified: AtomicBool,
    _pin: PhantomPinned,
}

Future that checks for an existing placeholder and waits for it to be filled.

The shard lock is acquired as a local variable inside poll, never stored in the future state, so the future remains Send.

Pin safety

This future is !Unpin because poll registers &self.notified as a raw pointer in the placeholder’s waiter list. Pin guarantees the future won’t be moved after the first poll, keeping that pointer valid. The pointer is cleaned up in drop_pending_waiter before the struct is destroyed.

Fields

lifecycle: &'a L

shard: &'a RwLock<CacheShard<Key, Val, We, B, L, Arc<Placeholder<Val>>>>

hash: u64

key: &'b Q

state: JoinFutureState<Val>

notified: AtomicBool

_pin: PhantomPinned

Implementations

impl<'a, 'b, Q: ?Sized, Key, Val, We, B, L> JoinFuture<'a, 'b, Q, Key, Val, We, B, L>

pub(crate) fn new( lifecycle: &'a L, shard: &'a RwLock<CacheShard<Key, Val, We, B, L, Arc<Placeholder<Val>>>>, hash: u64, key: &'b Q, ) -> Self

impl<Q: ?Sized, Key, Val, We, B, L> JoinFuture<'_, '_, Q, Key, Val, We, B, L>

fn drop_pending_waiter(&mut self)

Trait Implementations

impl<Q: ?Sized, Key, Val, We, B, L> Drop for JoinFuture<'_, '_, Q, Key, Val, We, B, L>

fn drop(&mut self)

Executes the destructor for this type.

impl<'a, Key: Eq + Hash, Q: Hash + Equivalent<Key> + ToOwned<Owned = Key> + ?Sized, Val, We: Weighter<Key, Val>, B: BuildHasher, L: Lifecycle<Key, Val>> Future for JoinFuture<'a, '_, Q, Key, Val, We, B, L>

type Output = JoinResult<'a, Key, Val, We, B, L>

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.