Trait frame_support::dispatch::marker::Send

1.0.0 · source ·
pub unsafe auto trait Send { }
Expand description

Types that can be transferred across thread boundaries.

This trait is automatically implemented when the compiler determines it’s appropriate.

An example of a non-Send type is the reference-counting pointer rc::Rc. If two threads attempt to clone Rcs that point to the same reference-counted value, they might try to update the reference count at the same time, which is undefined behavior because Rc doesn’t use atomic operations. Its cousin sync::Arc does use atomic operations (incurring some overhead) and thus is Send.

See the Nomicon for more details.


Dir implements Send but not Sync, because we use readdir which is not guaranteed to be thread-safe. Users can wrap this in a Mutex if they need Sync, which is effectively what’d need to do to implement Sync ourselves.

NonNull pointers are not Send because the data they reference may be aliased.

ThinBox<T> is Send if T is Send because the data is owned.

Auto implementors