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 Rc
s 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 and the Sync
trait for more details.
Implementors§
impl !Send for Arguments<'_>
impl !Send for LocalWaker
impl !Send for Args
impl !Send for ArgsOs
impl Send for AllocScratchError
impl Send for ArchiveError
impl Send for alloc::string::Drain<'_>
impl Send for Bytes<'_>
impl Send for Waker
impl Send for Bump
impl Send for Atom
Immutable, so it’s safe to be shared between threads
impl Send for AllocScratch
impl Send for AlignedVec
impl Send for PrefixRange
impl Send for SuffixRange
impl<'a> Send for IoSlice<'a>
impl<'a> Send for IoSliceMut<'a>
impl<'a> Send for ArchiveValidator<'a>
impl<'a, 'b, K, Q, V, S, A> Send for hashbrown::map::OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
impl<'a, 'b, K, Q, V, S, A> Send for hashbrown::map::OccupiedEntryRef<'a, 'b, K, Q, V, S, A>
impl<'a, 'bump> Send for bumpalo::collections::string::Drain<'a, 'bump>
impl<'a, 'bump, T> Send for bumpalo::collections::vec::Drain<'a, 'bump, T>where
T: Send,
impl<'a, R, T> Send for lock_api::mutex::MappedMutexGuard<'a, R, T>
impl<'a, R, T> Send for lock_api::rwlock::MappedRwLockReadGuard<'a, R, T>
impl<'a, R, T> Send for lock_api::rwlock::MappedRwLockWriteGuard<'a, R, T>
impl<'a, T> Send for smallvec::Drain<'a, T>
impl<'a, T> Send for ArcBorrow<'a, T>
impl<'a, T> Send for ZeroVec<'a, T>
impl<'a, T, O> Send for bitvec::slice::iter::Iter<'a, T, O>
impl<'a, T, O> Send for bitvec::slice::iter::IterMut<'a, T, O>
impl<'bump, T> Send for bumpalo::collections::vec::IntoIter<'bump, T>where
T: Send,
impl<A> Send for SmallVec<A>
impl<A, B> Send for ArcUnion<A, B>
impl<C> Send for CartableOptionPointer<C>where
C: Sync + CartablePointerLike,
impl<Dyn> Send for core::ptr::metadata::DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Send for ptr_meta::DynMetadata<Dyn>where
Dyn: ?Sized,
impl<H, T> Send for ThinArc<H, T>
impl<K, V> Send for hashbrown::map::IterMut<'_, K, V>
impl<K, V> Send for hashbrown::map::IterMut<'_, K, V>
impl<K, V, S, A> Send for hashbrown::map::OccupiedEntry<'_, K, V, S, A>
impl<K, V, S, A> Send for hashbrown::map::OccupiedEntry<'_, K, V, S, A>
impl<K, V, S, A> Send for hashbrown::map::RawOccupiedEntryMut<'_, K, V, S, A>
impl<K, V, S, A> Send for hashbrown::map::RawOccupiedEntryMut<'_, K, V, S, A>
impl<M, T, O> Send for BitRef<'_, M, T, O>
impl<R, G> Send for RawReentrantMutex<R, G>
impl<R, G, T> Send for ReentrantMutex<R, G, T>
impl<R, T> Send for lock_api::mutex::Mutex<R, T>
impl<R, T> Send for lock_api::rwlock::RwLock<R, T>
impl<T> !Send for *const Twhere
T: ?Sized,
impl<T> !Send for *mut Twhere
T: ?Sized,
impl<T> !Send for NonNull<T>where
T: ?Sized,
NonNull
pointers are not Send
because the data they reference may be aliased.
impl<T> !Send for std::sync::mutex::MappedMutexGuard<'_, T>where
T: ?Sized,
impl<T> !Send for MutexGuard<'_, T>where
T: ?Sized,
impl<T> !Send for ReentrantLockGuard<'_, T>where
T: ?Sized,
impl<T> !Send for std::sync::rwlock::MappedRwLockReadGuard<'_, T>where
T: ?Sized,
impl<T> !Send for std::sync::rwlock::MappedRwLockWriteGuard<'_, T>where
T: ?Sized,
impl<T> !Send for RwLockReadGuard<'_, T>where
T: ?Sized,
impl<T> !Send for RwLockWriteGuard<'_, T>where
T: ?Sized,
impl<T> Send for BitSpanError<T>where
T: BitStore,
impl<T> Send for &T
impl<T> Send for ThinBox<T>
ThinBox<T>
is Send
if T
is Send
because the data is owned.
impl<T> Send for alloc::collections::linked_list::Iter<'_, T>where
T: Sync,
impl<T> Send for alloc::collections::linked_list::IterMut<'_, T>where
T: Send,
impl<T> Send for Cell<T>
impl<T> Send for RefCell<T>
impl<T> Send for NonZero<T>where
T: ZeroablePrimitive + Send,
impl<T> Send for ChunksExactMut<'_, T>where
T: Send,
impl<T> Send for ChunksMut<'_, T>where
T: Send,
impl<T> Send for core::slice::iter::Iter<'_, T>where
T: Sync,
impl<T> Send for core::slice::iter::IterMut<'_, T>where
T: Send,
impl<T> Send for RChunksExactMut<'_, T>where
T: Send,
impl<T> Send for RChunksMut<'_, T>where
T: Send,
impl<T> Send for AtomicPtr<T>
impl<T> Send for std::sync::mpmc::Receiver<T>where
T: Send,
impl<T> Send for std::sync::mpmc::Sender<T>where
T: Send,
impl<T> Send for std::sync::mpsc::Receiver<T>where
T: Send,
impl<T> Send for std::sync::mpsc::Sender<T>where
T: Send,
impl<T> Send for SyncSender<T>where
T: Send,
impl<T> Send for std::sync::mutex::Mutex<T>
impl<T> Send for OnceLock<T>where
T: Send,
impl<T> Send for ReentrantLock<T>
impl<T> Send for std::sync::rwlock::RwLock<T>
impl<T> Send for JoinHandle<T>
impl<T> Send for MisalignError<T>
impl<T> Send for OutBuf<'_, T>where
T: Send,
impl<T> Send for OutRef<'_, T>where
T: Send,
impl<T> Send for BufferScratch<T>where
T: Send,
impl<T> Send for ScratchVec<T>where
T: Send,
impl<T> Send for triomphe::arc::Arc<T>
impl<T> Send for OffsetArc<T>
impl<T> Send for UniqueArc<T>
impl<T, A> !Send for Rc<T, A>
impl<T, A> !Send for alloc::rc::Weak<T, A>
impl<T, A> Send for Cursor<'_, T, A>
impl<T, A> Send for CursorMut<'_, T, A>
impl<T, A> Send for LinkedList<T, A>
impl<T, A> Send for alloc::collections::vec_deque::drain::Drain<'_, T, A>
impl<T, A> Send for alloc::sync::Weak<T, A>
impl<T, A> Send for alloc::vec::drain::Drain<'_, T, A>
impl<T, A> Send for alloc::vec::into_iter::IntoIter<T, A>
impl<T, A> Send for Box<T, A>
impl<T, A> Send for allocator_api2::stable::vec::drain::Drain<'_, T, A>
impl<T, A> Send for allocator_api2::stable::vec::into_iter::IntoIter<T, A>
impl<T, A> Send for hashbrown::table::OccupiedEntry<'_, T, A>
impl<T, A> Send for swc_common::sync::Lrc<T, A>
impl<T, O> Send for bitvec::boxed::iter::IntoIter<T, O>
impl<T, O> Send for BitBox<T, O>
impl<T, O> Send for BitSlice<T, O>
§Bit-Slice Thread Safety
This allows bit-slice references to be moved across thread boundaries only when
the underlying T
element can tolerate concurrency.
All BitSlice
references, shared or exclusive, are only threadsafe if the T
element type is Send
, because any given bit-slice reference may only have
partial control of a memory element that is also being shared by a bit-slice
reference on another thread. As such, this is never implemented for Cell<U>
,
but always implemented for AtomicU
and U
for a given unsigned integer type
U
.
Atomic integers safely handle concurrent writes, cells do not allow concurrency
at all, so the only missing piece is &mut BitSlice<_, U: Unsigned>
. This is
handled by the aliasing system that the mutable splitters employ: a mutable
reference to an unsynchronized bit-slice can only cross threads when no other
handle is able to exist to the elements it governs. Splitting a mutable
bit-slice causes the split halves to change over to either atomics or cells, so
concurrency is either safe or impossible.