Trait futures_util::task::UnsafeFutureObj

pub unsafe trait UnsafeFutureObj<'a, T>: 'a {
    // Required methods
    fn into_raw(self) -> *mut dyn Future<Output = T> + 'a;
    unsafe fn drop(ptr: *mut dyn Future<Output = T> + 'a);
}

A custom implementation of a future trait object for FutureObj, providing a vtable with drop support.

This custom representation is typically used only in no_std contexts, where the default Box-based implementation is not available.

Safety

See the safety notes on individual methods for what guarantees an implementor must provide.

Required Methods

fn into_raw(self) -> *mut dyn Future<Output = T> + 'a

Convert an owned instance into a (conceptually owned) fat pointer.

Safety

Implementor

The trait implementor must guarantee that it is safe to convert the provided *mut (dyn Future<Output = T> + 'a) into a Pin<&mut (dyn Future<Output = T> + 'a)> and call methods on it, non-reentrantly, until UnsafeFutureObj::drop is called with it.

unsafe fn drop(ptr: *mut dyn Future<Output = T> + 'a)

Drops the future represented by the given fat pointer.

Safety

Implementor

The trait implementor must guarantee that it is safe to call this function once per into_raw invocation.

Caller

The caller must ensure:

• the pointer passed was obtained from an into_raw invocation from this same trait object
• the pointer is not currently in use as a Pin<&mut (dyn Future<Output = T> + 'a)>
• the pointer must not be used again after this function is called

Object Safety

This trait is not object safe.

Implementations on Foreign Types

impl<'a, T> UnsafeFutureObj<'a, T> for &'a mut (dyn Future<Output = T> + Unpin)

fn into_raw(self) -> *mut dyn Future<Output = T> + 'a

unsafe fn drop(_ptr: *mut dyn Future<Output = T> + 'a)

impl<'a, T> UnsafeFutureObj<'a, T> for Pin<&'a mut dyn Future<Output = T>>

fn into_raw(self) -> *mut dyn Future<Output = T> + 'a

unsafe fn drop(_ptr: *mut dyn Future<Output = T> + 'a)

impl<'a, T, F> UnsafeFutureObj<'a, T> for &'a mut F

where F: Future<Output = T> + Unpin + 'a,

fn into_raw(self) -> *mut dyn Future<Output = T> + 'a

unsafe fn drop(_ptr: *mut dyn Future<Output = T> + 'a)

impl<'a, T, F> UnsafeFutureObj<'a, T> for Pin<&'a mut F>

where F: Future<Output = T> + 'a,

fn into_raw(self) -> *mut dyn Future<Output = T> + 'a

unsafe fn drop(_ptr: *mut dyn Future<Output = T> + 'a)

Implementors