pub unsafe auto trait Sync { }Available on crate feature
std only.Expand description
Types for which it is safe to share references between threads.
This trait is automatically implemented when the compiler determines it’s appropriate.
The precise definition is: a type T is Sync if and only if &T is
Send. In other words, if there is no possibility of
undefined behavior (including data races) when passing
&T references between threads.
As one would expect, primitive types like u8 and f64
are all Sync, and so are simple aggregate types containing them,
like tuples, structs and enums. More examples of basic Sync
types include “immutable” types like &T, and those with simple
inherited mutability, such as Box<T>, Vec<T> and
most other collection types. (Generic parameters need to be Sync
for their container to be Sync.)
A somewhat surprising consequence of the definition is that &mut T
is Sync (if T is Sync) even though it seems like that might
provide unsynchronized mutation. The trick is that a mutable
reference behind a shared reference (that is, & &mut T)
becomes read-only, as if it were a & &T. Hence there is no risk
of a data race.
A shorter overview of how Sync and Send relate to referencing:
&TisSendif and only ifTisSync&mut TisSendif and only ifTisSend&Tand&mut TareSyncif and only ifTisSync
Types that are not Sync are those that have “interior
mutability” in a non-thread-safe form, such as Cell
and RefCell. These types allow for mutation of
their contents even through an immutable, shared reference. For
example the set method on Cell<T> takes &self, so it requires
only a shared reference &Cell<T>. The method performs no
synchronization, thus Cell cannot be Sync.
Another example of a non-Sync type is the reference-counting
pointer Rc. Given any reference &Rc<T>, you can clone
a new Rc<T>, modifying the reference counts in a non-atomic way.
For cases when one does need thread-safe interior mutability,
Rust provides atomic data types, as well as explicit locking via
sync::Mutex and sync::RwLock. These types
ensure that any mutation cannot cause data races, hence the types
are Sync. Likewise, sync::Arc provides a thread-safe
analogue of Rc.
Any types with interior mutability must also use the
cell::UnsafeCell wrapper around the value(s) which
can be mutated through a shared reference. Failing to doing this is
undefined behavior. For example, transmute-ing
from &T to &mut T is invalid.
See the Nomicon for more details about Sync.
Implementors§
impl !Sync for LocalWaker
impl !Sync for Arguments<'_>
impl !Sync for Args
impl !Sync for ArgsOs
impl Sync for ExampleEnumIntU8
Available on
doc only.impl Sync for RawId
impl Sync for devela::_core::ffi::c_str::Bytes<'_>
impl Sync for devela::_core::sync::atomic::AtomicBool
impl Sync for devela::_core::sync::atomic::AtomicI8
impl Sync for devela::_core::sync::atomic::AtomicI16
impl Sync for devela::_core::sync::atomic::AtomicI32
impl Sync for devela::_core::sync::atomic::AtomicI64
impl Sync for devela::_core::sync::atomic::AtomicIsize
impl Sync for devela::_core::sync::atomic::AtomicU8
impl Sync for devela::_core::sync::atomic::AtomicU16
impl Sync for devela::_core::sync::atomic::AtomicU32
impl Sync for devela::_core::sync::atomic::AtomicU64
impl Sync for devela::_core::sync::atomic::AtomicUsize
impl Sync for devela::work::AtomicBool
impl Sync for Waker
impl Sync for devela::_dep::_alloc::string::Drain<'_>
impl Sync for PyDateTime_CAPI
impl Sync for PyBackedBytes
impl Sync for PyBackedStr
impl Sync for devela::_dep::rodio::cpal::platform::AlsaDevices
impl Sync for Bytes
impl Sync for BytesMut
impl Sync for Collector
impl Sync for GuardNoSend
impl Sync for Scope<'_>
impl Sync for Unparker
impl<'a> Sync for IoSlice<'a>
impl<'a> Sync for IoSliceMut<'a>
impl<'a, 'bump> Sync for devela::_dep::bumpalo::collections::string::Drain<'a, 'bump>
impl<'a, 'bump, T> Sync for devela::_dep::bumpalo::collections::vec::Drain<'a, 'bump, T>where
T: Sync,
impl<'a, R, G, T> Sync for MappedReentrantMutexGuard<'a, R, G, T>
impl<'a, R, G, T> Sync for ReentrantMutexGuard<'a, R, G, T>
impl<'a, R, T> Sync for MappedMutexGuard<'a, R, T>
impl<'a, R, T> Sync for MappedRwLockReadGuard<'a, R, T>
impl<'a, R, T> Sync for MappedRwLockWriteGuard<'a, R, T>
impl<'a, R, T> Sync for MutexGuard<'a, R, T>
impl<'a, R, T> Sync for RwLockUpgradableReadGuard<'a, R, T>
impl<'a, T> Sync for Drain<'a, T>where
T: Sync + Array,
impl<'a, T> Sync for OnceRef<'a, T>where
T: Sync,
impl<'a, T, const CAP: usize> Sync for arrayvec::arrayvec::Drain<'a, T, CAP>where
T: Sync,
impl<'bump, T> Sync for devela::_dep::bumpalo::collections::vec::IntoIter<'bump, T>where
T: Sync,
impl<Dyn> Sync for devela::_core::ptr::DynMetadata<Dyn>where
Dyn: ?Sized,
impl<Dyn> Sync for devela::_dep::rkyv::ptr_meta::DynMetadata<Dyn>where
Dyn: ?Sized,
impl<K, V, S, A> Sync for devela::_dep::hashbrown::hash_map::OccupiedEntry<'_, K, V, S, A>
impl<K, V, S, A> Sync for devela::_dep::hashbrown::hash_map::RawOccupiedEntryMut<'_, K, V, S, A>
impl<R, G> Sync for RawReentrantMutex<R, G>
impl<R, G, T> Sync for ReentrantMutex<R, G, T>
impl<R, T> Sync for Mutex<R, T>
impl<R, T> Sync for RwLock<R, T>
impl<R, T> Sync for RwLockReadGuard<'_, R, T>
impl<R, T> Sync for RwLockWriteGuard<'_, R, T>
impl<T> !Sync for *const Twhere
T: ?Sized,
impl<T> !Sync for *mut Twhere
T: ?Sized,
impl<T> !Sync for Cell<T>where
T: ?Sized,
impl<T> !Sync for OnceCell<T>
impl<T> !Sync for NonNull<T>where
T: ?Sized,
NonNull pointers are not Sync because the data they reference may be aliased.
impl<T> !Sync for RefCell<T>where
T: ?Sized,
impl<T> !Sync for UnsafeCell<T>where
T: ?Sized,
impl<T> !Sync for devela::_dep::_std::sync::mpsc::Receiver<T>
impl<T> Sync for SyncUnsafeCell<T>
impl<T> Sync for devela::_core::slice::ChunksExactMut<'_, T>where
T: Sync,
impl<T> Sync for devela::_core::slice::ChunksMut<'_, T>where
T: Sync,
impl<T> Sync for devela::_core::slice::Iter<'_, T>where
T: Sync,
impl<T> Sync for devela::_core::slice::IterMut<'_, T>where
T: Sync,
impl<T> Sync for devela::_core::slice::RChunksExactMut<'_, T>where
T: Sync,
impl<T> Sync for devela::_core::slice::RChunksMut<'_, T>where
T: Sync,
impl<T> Sync for devela::_core::sync::atomic::AtomicPtr<T>
impl<T> Sync for Exclusive<T>where
T: ?Sized,
impl<T> Sync for NonZero<T>where
T: ZeroablePrimitive + Sync,
impl<T> Sync for devela::work::Atomic<T>
impl<T> Sync for devela::work::Mutex<T>
impl<T> Sync for devela::work::MutexGuard<'_, T>
impl<T> Sync for OnceLock<T>
impl<T> Sync for devela::work::RwLock<T>
impl<T> Sync for devela::work::RwLockReadGuard<'_, T>
impl<T> Sync for devela::work::RwLockWriteGuard<'_, T>
impl<T> Sync for JoinHandle<T>
impl<T> Sync for ThinBox<T>
ThinBox<T> is Sync if T is Sync because the data is owned.
impl<T> Sync for devela::_dep::_alloc::collections::linked_list::Iter<'_, T>where
T: Sync,
impl<T> Sync for devela::_dep::_alloc::collections::linked_list::IterMut<'_, T>where
T: Sync,
impl<T> Sync for PyBuffer<T>
impl<T> Sync for Py<T>
impl<T> Sync for GILOnceCell<T>
impl<T> Sync for GILProtected<T>where
T: Send,
impl<T> Sync for SerVec<T>where
T: Sync,
impl<T> Sync for ReadHalf<T>where
T: Sync,
impl<T> Sync for WriteHalf<T>where
T: Sync,
impl<T> Sync for devela::_dep::_std::sync::mpmc::Receiver<T>where
T: Send,
impl<T> Sync for devela::_dep::_std::sync::mpmc::Sender<T>where
T: Send,
impl<T> Sync for devela::_dep::_std::sync::mpsc::Sender<T>where
T: Send,
impl<T> Sync for devela::_dep::_std::sync::MappedMutexGuard<'_, T>
impl<T> Sync for devela::_dep::_std::sync::MappedRwLockReadGuard<'_, T>
impl<T> Sync for devela::_dep::_std::sync::MappedRwLockWriteGuard<'_, T>
impl<T> Sync for ReentrantLock<T>
impl<T> Sync for ReentrantLockGuard<'_, T>
impl<T> Sync for Atomic<T>
impl<T> Sync for AtomicCell<T>where
T: Send,
impl<T> Sync for CachePadded<T>where
T: Sync,
impl<T> Sync for Channel<T>where
T: Send,
impl<T> Sync for Injector<T>where
T: Send,
impl<T> Sync for OnceBox<T>
impl<T> Sync for ScopedJoinHandle<'_, T>
impl<T> Sync for ShardedLock<T>
impl<T> Sync for ShardedLockReadGuard<'_, T>
impl<T> Sync for ShardedLockWriteGuard<'_, T>
impl<T> Sync for Stealer<T>where
T: Send,
impl<T, A> !Sync for Rc<T, A>
impl<T, A> !Sync for devela::all::RcWeak<T, A>
impl<T, A> !Sync for UniqueRc<T, A>
impl<T, A> Sync for LinkedList<T, A>
impl<T, A> Sync for Arc<T, A>
impl<T, A> Sync for devela::work::ArcWeak<T, A>
impl<T, A> Sync for devela::_dep::_alloc::collections::linked_list::Cursor<'_, T, A>
impl<T, A> Sync for devela::_dep::_alloc::collections::linked_list::CursorMut<'_, T, A>
impl<T, A> Sync for devela::_dep::_alloc::collections::vec_deque::Drain<'_, T, A>
impl<T, A> Sync for devela::_dep::_alloc::vec::Drain<'_, T, A>
impl<T, A> Sync for devela::_dep::_alloc::vec::IntoIter<T, A>
impl<T, A> Sync for devela::_dep::hashbrown::hash_table::OccupiedEntry<'_, T, A>
impl<T, F> Sync for LazyLock<T, F>
impl<T, F> Sync for Lazy<T, F>
impl<T, F, S> Sync for ScopeGuard<T, F, S>
impl<T, const N: usize> Sync for InlineVec<T, N>where
T: Sync,
impl<T: Sync> Sync for BareBox<T>
Available on crate feature
unsafe_sync only.impl<T: Sync> Sync for CacheAlign<T>
Available on crate feature
unsafe_sync only.