pub(crate) struct AutoBox<T>(PhantomData<T>);Expand description
Decides whether a future or closure of type T is boxed before it is
turned into a task, based on BOX_FUTURE_THRESHOLD.
The decision is an associated constant rather than a runtime
comparison of std::mem::size_of::<T>() so that only the taken branch
is instantiated. With a runtime if, both branches are instantiated
for every T (one task harness for T, one for Pin<Box<T>>),
doubling the generated code for every spawned future in a crate. A
branch on a constant that is known once T is known is pruned by the
monomorphization collector, so only the harness that is actually used
is generated.
Tuple Fields§
§0: PhantomData<T>Implementations§
Source§impl<T> AutoBox<T>
impl<T> AutoBox<T>
Sourcepub(crate) const SHOULD_BOX: bool
pub(crate) const SHOULD_BOX: bool
true if a value of type T is larger than BOX_FUTURE_THRESHOLD.
Auto Trait Implementations§
impl<T> Freeze for AutoBox<T>
impl<T> RefUnwindSafe for AutoBox<T>where
T: RefUnwindSafe,
impl<T> Send for AutoBox<T>where
T: Send,
impl<T> Sync for AutoBox<T>where
T: Sync,
impl<T> Unpin for AutoBox<T>where
T: Unpin,
impl<T> UnsafeUnpin for AutoBox<T>
impl<T> UnwindSafe for AutoBox<T>where
T: UnwindSafe,
Blanket Implementations§
Source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
Source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more