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 and the Sync trait for more details.
Implementors§
impl !Send for Args
impl !Send for ArgsOs
impl Send for TableElementwhere VMExternRef: Send,
impl Send for Bump
impl Send for Bytes
impl Send for BytesMut
impl Send for Select<'_>
impl Send for Collector
impl Send for Parker
impl Send for Unparker
impl Send for AtomicWaker
impl Send for rustix::backend::fs::dir::Dir
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.
impl Send for rustix::backend::fs::dir::Dir
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.
impl Send for GdbJitImageRegistration
impl Send for ExportFunction
impl Send for ExportGlobal
impl Send for ExportMemory
impl Send for ExportTable
impl Send for VMExternRef
impl Send for InstanceHandle
impl Send for VMCallerCheckedAnyfunc
impl Send for VMFunctionImport
impl Send for VMGlobalImport
impl Send for VMMemoryImport
impl Send for VMRuntimeLimits
impl Send for VMTableImport
impl Send for VMHostFuncContext
impl Send for DCtx<'_>
impl Send for alloc::string::Drain<'_>
impl Send for Waker
impl<'a> Send for CCtx<'a>
impl<'a> Send for CDict<'a>
impl<'a> Send for DDict<'a>
impl<'a> Send for IoSlice<'a>
impl<'a> Send for IoSliceMut<'a>
impl<'a, 'b, K, Q, V, S, A> Send for OccupiedEntryRef<'a, 'b, K, Q, V, S, A>where K: Send, Q: Sync + ?Sized, V: Send, S: Send, A: Send + Allocator + Clone,
impl<'a, A> Send for arrayvec::Drain<'a, A>where A: Array + Send,
impl<'a, K, V> Send for lru::Iter<'a, K, V>where K: Send, V: Send,
impl<'a, K, V> Send for lru::IterMut<'a, K, V>where K: Send, V: Send,
impl<'a, R, T> Send for lock_api::mutex::MappedMutexGuard<'a, R, T>where R: RawMutex + 'a, T: Send + 'a + ?Sized, <R as RawMutex>::GuardMarker: Send,
impl<'a, R, T> Send for MappedRwLockReadGuard<'a, R, T>where R: RawRwLock + 'a, T: Sync + 'a + ?Sized, <R as RawRwLock>::GuardMarker: Send,
impl<'a, R, T> Send for MappedRwLockWriteGuard<'a, R, T>where R: RawRwLock + 'a, T: Send + 'a + ?Sized, <R as RawRwLock>::GuardMarker: Send,
impl<'a, T> Send for smallvec::Drain<'a, T>where T: Send + Array,
impl<'a, T, O> Send for bitvec::slice::iter::Iter<'a, T, O>where T: BitStore, O: BitOrder, &'a mut BitSlice<T, O>: Send,
impl<'a, T, O> Send for bitvec::slice::iter::IterMut<'a, T, O>where T: BitStore, O: BitOrder, &'a mut BitSlice<T, O>: Send,
impl<'a, T, const CAP: usize> Send for arrayvec::arrayvec::Drain<'a, T, CAP>where T: Send,
impl<A> Send for SmallVec<A>where A: Array, <A as Array>::Item: Send,
impl<C> Send for Secp256k1<C>where C: Context,
impl<Dyn> Send for DynMetadata<Dyn>where Dyn: ?Sized,
impl<Fut> Send for futures_util::stream::futures_unordered::iter::IntoIter<Fut>where Fut: Send + Unpin,
impl<Fut> Send for IterPinMut<'_, Fut>where Fut: Send,
impl<Fut> Send for IterPinRef<'_, Fut>where Fut: Send,
impl<Fut> Send for FuturesUnordered<Fut>where Fut: Send,
impl<K, V> Send for hashbrown::map::IterMut<'_, K, V>where K: Send, V: Send,
impl<K, V, S> Send for LruCache<K, V, S>where K: Send, V: Send, S: Send,
impl<K, V, S, A> Send for OccupiedEntry<'_, K, V, S, A>where K: Send, V: Send, S: Send, A: Send + Allocator + Clone,
impl<K, V, S, A> Send for RawOccupiedEntryMut<'_, K, V, S, A>where K: Send, V: Send, S: Send, A: Send + Allocator + Clone,
impl<M, T, O> Send for BitRef<'_, M, T, O>where M: Mutability, T: BitStore + Sync, O: BitOrder,
impl<R, G> Send for RawReentrantMutex<R, G>where R: RawMutex + Send, G: GetThreadId + Send,
impl<R, G, T> Send for ReentrantMutex<R, G, T>where R: RawMutex + Send, G: GetThreadId + Send, T: Send + ?Sized,
impl<R, T> Send for lock_api::mutex::Mutex<R, T>where R: RawMutex + Send, T: Send + ?Sized,
impl<R, T> Send for lock_api::rwlock::RwLock<R, T>where R: RawRwLock + Send, T: Send + ?Sized,
impl<T> !Send for *const Twhere T: ?Sized,
impl<T> !Send for *mut Twhere T: ?Sized,
impl<T> !Send for Rc<T>where T: ?Sized,
impl<T> !Send for alloc::rc::Weak<T>where 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::MutexGuard<'_, 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 &Twhere T: Sync + ?Sized,
impl<T> Send for MisalignError<T>
impl<T> Send for crossbeam_channel::channel::Receiver<T>where T: Send,
impl<T> Send for crossbeam_channel::channel::Sender<T>where T: Send,
impl<T> Send for Injector<T>where T: Send,
impl<T> Send for Stealer<T>where T: Send,
impl<T> Send for Worker<T>where T: Send,
impl<T> Send for Atomic<T>where T: Pointable + Send + Sync + ?Sized,
impl<T> Send for AtomicCell<T>where T: Send,
impl<T> Send for CachePadded<T>where T: Send,
impl<T> Send for ShardedLock<T>where T: Send + ?Sized,
impl<T> Send for ScopedJoinHandle<'_, T>
impl<T> Send for FutureObj<'_, T>
impl<T> Send for futures_util::lock::mutex::Mutex<T>where T: Send + ?Sized,
impl<T> Send for futures_util::lock::mutex::MutexGuard<'_, T>where T: Send + ?Sized,
impl<T> Send for MutexLockFuture<'_, T>where T: Send + ?Sized,
impl<T> Send for OwnedMutexGuard<T>where T: Send + ?Sized,
impl<T> Send for OwnedMutexLockFuture<T>where T: Send + ?Sized,
impl<T> Send for Bucket<T>
impl<T> Send for ThinBox<T>where T: Send + ?Sized,
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 Arc<T>where T: Sync + Send + ?Sized,
impl<T> Send for alloc::sync::Weak<T>where T: Sync + Send + ?Sized,
impl<T> Send for Cell<T>where T: Send + ?Sized,
impl<T> Send for RefCell<T>where T: Send + ?Sized,
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::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>where T: Send + ?Sized,
impl<T> Send for OnceLock<T>where T: Send,
impl<T> Send for std::sync::rwlock::RwLock<T>where T: Send + ?Sized,
impl<T> Send for JoinHandle<T>
impl<T, A> Send for RawDrain<'_, T, A>where A: Allocator + Copy + Send, T: Send,
impl<T, A> Send for RawIntoIter<T, A>where A: Allocator + Clone + Send, T: Send,
impl<T, A> Send for RawTable<T, A>where A: Allocator + Clone + Send, T: Send,
impl<T, A> Send for Cursor<'_, T, A>where T: Sync, A: Allocator + Sync,
impl<T, A> Send for CursorMut<'_, T, A>where T: Send, A: Allocator + Send,
impl<T, A> Send for LinkedList<T, A>where T: Send, A: Allocator + Send,
impl<T, A> Send for alloc::collections::vec_deque::drain::Drain<'_, T, A>where T: Send, A: Allocator + Send,
impl<T, A> Send for alloc::vec::drain::Drain<'_, T, A>where T: Send, A: Send + Allocator,
impl<T, A> Send for alloc::vec::into_iter::IntoIter<T, A>where T: Send, A: Allocator + Send,
impl<T, C> Send for OwnedRef<T, C>where T: Sync + Clear + Default, C: Config,
impl<T, C> Send for OwnedRefMut<T, C>where T: Sync + Clear + Default, C: Config,
impl<T, C> Send for Pool<T, C>where T: Send + Clear + Default, C: Config,
impl<T, C> Send for OwnedEntry<T, C>where T: Sync, C: Config,
impl<T, C> Send for Slab<T, C>where T: Send, C: Config,
impl<T, N> Send for generic_array::GenericArray<T, N>where T: Send, N: ArrayLength<T>,
impl<T, N> Send for generic_array::GenericArray<T, N>where T: Send, N: ArrayLength<T>,
impl<T, O> Send for bitvec::boxed::iter::IntoIter<T, O>where T: BitStore + Sync, O: BitOrder,
impl<T, O> Send for BitBox<T, O>where T: BitStore, O: BitOrder,
impl<T, O> Send for BitSlice<T, O>where T: BitStore + Sync, O: BitOrder,
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.