Trait core::marker::Sync 1.0.0[−][src]
#[lang = "sync"]pub unsafe auto trait Sync { }
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.
Types that are not Sync are those that have "interior
mutability" in a non-thread-safe form, such as cell::Cell
and cell::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::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<T: ?Sized> !Sync for NonNull<T>impl<T: ?Sized> !Sync for *const Timpl<T: ?Sized> !Sync for *mut Timpl Sync for AtomicBoolimpl<T> Sync for AtomicPtr<T>impl Sync for AtomicI8impl Sync for AtomicU8impl Sync for AtomicI16impl Sync for AtomicU16impl Sync for AtomicI32impl Sync for AtomicU32impl Sync for AtomicI64impl Sync for AtomicU64impl Sync for AtomicIsizeimpl Sync for AtomicUsizeimpl<T: ?Sized> !Sync for Cell<T>impl<T: ?Sized> !Sync for RefCell<T>impl<T: ?Sized> !Sync for UnsafeCell<T>impl<'a, T: Sync> Sync for core::slice::Iter<'a, T>impl<'a, T: Sync> Sync for core::slice::IterMut<'a, T>impl Sync for Wakerimpl !Sync for LocalWaker
Auto implementors
impl Sync for NonZeroU8impl Sync for NonZeroU16impl Sync for NonZeroU32impl Sync for NonZeroU64impl Sync for NonZeroU128impl Sync for NonZeroUsizeimpl<T> Sync for Wrapping<T> where
T: Sync,impl Sync for TryFromIntErrorimpl Sync for ParseIntErrorimpl Sync for ParseFloatErrorimpl Sync for FpCategoryimpl<T> Sync for Discriminant<T>impl<T> Sync for ManuallyDrop<T> where
T: Sync,impl<'a, T: ?Sized> Sync for PinMut<'a, T> where
T: Sync,impl<T: ?Sized> Sync for PhantomData<T> where
T: Sync,impl Sync for Pinnedimpl<Idx> Sync for Range<Idx> where
Idx: Sync,impl<Idx> Sync for RangeFrom<Idx> where
Idx: Sync,impl Sync for RangeFullimpl<Idx> Sync for RangeTo<Idx> where
Idx: Sync,impl<Idx> Sync for RangeInclusive<Idx> where
Idx: Sync,impl<Idx> Sync for RangeToInclusive<Idx> where
Idx: Sync,impl<T> Sync for Bound<T> where
T: Sync,impl<Y, R> Sync for GeneratorState<Y, R> where
R: Sync,
Y: Sync,impl<T> Sync for Reverse<T> where
T: Sync,impl Sync for core::cmp::Orderingimpl Sync for TypeIdimpl Sync for TryFromSliceErrorimpl Sync for core::ascii::EscapeDefaultimpl Sync for core::sync::atomic::Orderingimpl Sync for BorrowErrorimpl Sync for BorrowMutErrorimpl<'b, T> !Sync for Ref<'b, T>impl<'b, T> !Sync for RefMut<'b, T>impl Sync for ParseCharErrorimpl Sync for CharTryFromErrorimpl<I> Sync for DecodeUtf16<I> where
I: Sync,impl Sync for DecodeUtf16Errorimpl Sync for UnicodeVersionimpl<I> Sync for DecodeUtf8<I> where
I: Sync,impl Sync for InvalidSequenceimpl Sync for EscapeUnicodeimpl Sync for core::char::EscapeDefaultimpl Sync for EscapeDebugimpl Sync for ToLowercaseimpl Sync for ToUppercaseimpl<'a> !Sync for PanicInfo<'a>impl<'a> Sync for Location<'a>impl<A> Sync for Repeat<A> where
A: Sync,impl<F> Sync for RepeatWith<F> where
F: Sync,impl<T> Sync for Empty<T> where
T: Sync,impl<T> Sync for Once<T> where
T: Sync,impl<T> Sync for Rev<T> where
T: Sync,impl<I> Sync for Cloned<I> where
I: Sync,impl<I> Sync for Cycle<I> where
I: Sync,impl<I> Sync for StepBy<I> where
I: Sync,impl<A, B> Sync for Chain<A, B> where
A: Sync,
B: Sync,impl<A, B> Sync for Zip<A, B> where
A: Sync,
B: Sync,impl<I, F> Sync for Map<I, F> where
F: Sync,
I: Sync,impl<I, P> Sync for Filter<I, P> where
I: Sync,
P: Sync,impl<I, F> Sync for FilterMap<I, F> where
F: Sync,
I: Sync,impl<I> Sync for Enumerate<I> where
I: Sync,impl<I> Sync for Peekable<I> where
I: Sync,
<I as Iterator>::Item: Sync,impl<I, P> Sync for SkipWhile<I, P> where
I: Sync,
P: Sync,impl<I, P> Sync for TakeWhile<I, P> where
I: Sync,
P: Sync,impl<I> Sync for Skip<I> where
I: Sync,impl<I> Sync for Take<I> where
I: Sync,impl<I, St, F> Sync for Scan<I, St, F> where
F: Sync,
I: Sync,
St: Sync,impl<I, U, F> Sync for FlatMap<I, U, F> where
F: Sync,
I: Sync,
<U as IntoIterator>::IntoIter: Sync,impl<I> Sync for Flatten<I> where
I: Sync,
<<I as Iterator>::Item as IntoIterator>::IntoIter: Sync,impl<I> Sync for Fuse<I> where
I: Sync,impl<I, F> Sync for Inspect<I, F> where
F: Sync,
I: Sync,impl<'a, A> Sync for core::option::Iter<'a, A> where
A: Sync,impl<'a, A> Sync for core::option::IterMut<'a, A> where
A: Sync,impl<A> Sync for core::option::IntoIter<A> where
A: Sync,impl Sync for NoneErrorimpl<T> Sync for Option<T> where
T: Sync,impl !Sync for TraitObjectimpl<'a, T> Sync for core::result::Iter<'a, T> where
T: Sync,impl<'a, T> Sync for core::result::IterMut<'a, T> where
T: Sync,impl<T> Sync for core::result::IntoIter<T> where
T: Sync,impl<T, E> Sync for Result<T, E> where
E: Sync,
T: Sync,impl<'a, T, P> Sync for core::slice::Split<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for SplitMut<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for core::slice::RSplit<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for RSplitMut<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for core::slice::SplitN<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for core::slice::RSplitN<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for SplitNMut<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T, P> Sync for RSplitNMut<'a, T, P> where
P: Sync,
T: Sync,impl<'a, T> Sync for Windows<'a, T> where
T: Sync,impl<'a, T> Sync for Chunks<'a, T> where
T: Sync,impl<'a, T> Sync for ChunksMut<'a, T> where
T: Sync,impl<'a, T> Sync for ExactChunks<'a, T> where
T: Sync,impl<'a, T> Sync for ExactChunksMut<'a, T> where
T: Sync,impl Sync for ParseBoolErrorimpl Sync for Utf8Errorimpl<'a> Sync for Chars<'a>impl<'a> Sync for CharIndices<'a>impl<'a> Sync for Bytes<'a>impl<'a, P> Sync for core::str::Split<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for core::str::RSplit<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for SplitTerminator<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for RSplitTerminator<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for core::str::SplitN<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for core::str::RSplitN<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for MatchIndices<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for RMatchIndices<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for Matches<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a, P> Sync for RMatches<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,impl<'a> Sync for Lines<'a>impl<'a> Sync for LinesAny<'a>impl<'a> Sync for SplitWhitespace<'a>impl<'a> Sync for SplitAsciiWhitespace<'a>impl<'a> Sync for EncodeUtf16<'a>impl<'a> Sync for CharSearcher<'a>impl<'a, 'b> Sync for CharSliceSearcher<'a, 'b>impl<'a, F> Sync for CharPredicateSearcher<'a, F> where
F: Sync,impl<'a, 'b> Sync for StrSearcher<'a, 'b>impl Sync for SearchStepimpl Sync for Utf8Lossyimpl<'a> Sync for Utf8LossyChunksIter<'a>impl<'a> Sync for Utf8LossyChunk<'a>impl Sync for SipHasherimpl<H> Sync for BuildHasherDefault<H> where
H: Sync,impl<'a, 'b> !Sync for DebugStruct<'a, 'b>impl<'a, 'b> !Sync for DebugTuple<'a, 'b>impl<'a, 'b> !Sync for DebugSet<'a, 'b>impl<'a, 'b> !Sync for DebugList<'a, 'b>impl<'a, 'b> !Sync for DebugMap<'a, 'b>impl Sync for Errorimpl<'a> !Sync for Formatter<'a>impl<'a> !Sync for Arguments<'a>impl Sync for Alignmentimpl Sync for Durationimpl<'a, T> !Sync for FutureObj<'a, T>impl<'a, T> !Sync for LocalFutureObj<'a, T>impl<'a> !Sync for Context<'a>impl Sync for SpawnErrorKindimpl !Sync for SpawnObjErrorimpl !Sync for SpawnLocalObjErrorimpl !Sync for LocalWakerimpl<T> Sync for Poll<T> where
T: Sync,impl !Sync for Excessimpl Sync for Layoutimpl Sync for LayoutErrimpl Sync for AllocErrimpl Sync for CannotReallocInPlaceimpl Sync for __m64impl Sync for __m128iimpl Sync for __m128impl Sync for __m128dimpl Sync for __m256iimpl Sync for __m256impl Sync for __m256dimpl Sync for CpuidResultimpl Sync for float64x1_timpl Sync for float64x2_timpl Sync for int8x4_timpl Sync for uint8x4_timpl Sync for int16x2_timpl Sync for uint16x2_timpl Sync for int8x8_timpl Sync for uint8x8_timpl Sync for poly8x8_timpl Sync for int16x4_timpl Sync for uint16x4_timpl Sync for poly16x4_timpl Sync for int32x2_timpl Sync for uint32x2_timpl Sync for float32x2_timpl Sync for int64x1_timpl Sync for uint64x1_timpl Sync for int8x16_timpl Sync for uint8x16_timpl Sync for poly8x16_timpl Sync for int16x8_timpl Sync for uint16x8_timpl Sync for poly16x8_timpl Sync for int32x4_timpl Sync for uint32x4_timpl Sync for float32x4_timpl Sync for int64x2_timpl Sync for uint64x2_timpl Sync for i8x16impl Sync for vector_signed_longimpl Sync for vector_unsigned_longimpl Sync for vector_bool_longimpl Sync for vector_double