1.0.0[−][src]Trait core::marker::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 Sync for AtomicBool
[src]
impl Sync for AtomicI128
[src]
impl Sync for AtomicI16
[src]
impl Sync for AtomicI32
[src]
impl Sync for AtomicI64
[src]
impl Sync for AtomicI8
[src]
impl Sync for AtomicIsize
[src]
impl Sync for AtomicU128
[src]
impl Sync for AtomicU16
[src]
impl Sync for AtomicU32
[src]
impl Sync for AtomicU64
[src]
impl Sync for AtomicU8
[src]
impl Sync for AtomicUsize
[src]
impl Sync for Waker
[src]
impl<'_, T: Sync> Sync for core::slice::Iter<'_, T>
[src]
impl<'_, T: Sync> Sync for core::slice::IterMut<'_, T>
[src]
impl<T> Sync for AtomicPtr<T>
[src]
impl<T: ?Sized> !Sync for *const T
[src]
impl<T: ?Sized> !Sync for *mut T
[src]
impl<T: ?Sized> !Sync for Cell<T>
[src]
impl<T: ?Sized> !Sync for RefCell<T>
[src]
impl<T: ?Sized> !Sync for UnsafeCell<T>
[src]
impl<T: ?Sized> !Sync for NonNull<T>
[src]
NonNull
pointers are not Sync
because the data they reference may be aliased.
Auto implementors
impl !Sync for Excess
impl !Sync for TraitObject
impl !Sync for RawWaker
impl Sync for core::cmp::Ordering
impl Sync for Infallible
impl Sync for c_void
impl Sync for Alignment
impl Sync for FpCategory
impl Sync for IntErrorKind
impl Sync for SearchStep
impl Sync for core::sync::atomic::Ordering
impl Sync for AllocErr
impl Sync for CannotReallocInPlace
impl Sync for Layout
impl Sync for LayoutErr
impl Sync for TypeId
impl Sync for float64x1_t
impl Sync for float64x2_t
impl Sync for int8x16x2_t
impl Sync for int8x16x3_t
impl Sync for int8x16x4_t
impl Sync for poly64x1_t
impl Sync for poly64x2_t
impl Sync for poly8x16x2_t
impl Sync for poly8x16x3_t
impl Sync for poly8x16x4_t
impl Sync for uint8x16x2_t
impl Sync for uint8x16x3_t
impl Sync for uint8x16x4_t
impl Sync for APSR
impl Sync for SY
impl Sync for float32x2_t
impl Sync for float32x4_t
impl Sync for int16x4_t
impl Sync for int16x8_t
impl Sync for int32x2_t
impl Sync for int32x4_t
impl Sync for int64x1_t
impl Sync for int64x2_t
impl Sync for int8x16_t
impl Sync for int8x8_t
impl Sync for int8x8x2_t
impl Sync for int8x8x3_t
impl Sync for int8x8x4_t
impl Sync for poly16x4_t
impl Sync for poly16x8_t
impl Sync for poly8x16_t
impl Sync for poly8x8_t
impl Sync for poly8x8x2_t
impl Sync for poly8x8x3_t
impl Sync for poly8x8x4_t
impl Sync for uint16x4_t
impl Sync for uint16x8_t
impl Sync for uint32x2_t
impl Sync for uint32x4_t
impl Sync for uint64x1_t
impl Sync for uint64x2_t
impl Sync for uint8x16_t
impl Sync for uint8x8_t
impl Sync for uint8x8x2_t
impl Sync for uint8x8x3_t
impl Sync for uint8x8x4_t
impl Sync for v16i8
impl Sync for v16u8
impl Sync for v2f64
impl Sync for v2i64
impl Sync for v2u64
impl Sync for v4f32
impl Sync for v4i32
impl Sync for v4u32
impl Sync for v8i16
impl Sync for v8u16
impl Sync for vector_bool_long
impl Sync for vector_double
impl Sync for vector_signed_long
impl Sync for vector_unsigned_long
impl Sync for v128
impl Sync for CpuidResult
impl Sync for __m128
impl Sync for __m128d
impl Sync for __m128i
impl Sync for __m256
impl Sync for __m256d
impl Sync for __m256i
impl Sync for __m512
impl Sync for __m512d
impl Sync for __m512i
impl Sync for __m64
impl Sync for TryFromSliceError
impl Sync for core::ascii::EscapeDefault
impl Sync for BorrowError
impl Sync for BorrowMutError
impl Sync for CharTryFromError
impl Sync for DecodeUtf16Error
impl Sync for core::char::EscapeDebug
impl Sync for core::char::EscapeDefault
impl Sync for core::char::EscapeUnicode
impl Sync for ParseCharError
impl Sync for ToLowercase
impl Sync for ToUppercase
impl Sync for UnicodeVersion
impl Sync for Error
impl Sync for SipHasher
impl Sync for PhantomPinned
impl Sync for NonZeroI128
impl Sync for NonZeroI16
impl Sync for NonZeroI32
impl Sync for NonZeroI64
impl Sync for NonZeroI8
impl Sync for NonZeroIsize
impl Sync for NonZeroU128
impl Sync for NonZeroU16
impl Sync for NonZeroU32
impl Sync for NonZeroU64
impl Sync for NonZeroU8
impl Sync for NonZeroUsize
impl Sync for ParseFloatError
impl Sync for ParseIntError
impl Sync for TryFromIntError
impl Sync for RangeFull
impl Sync for NoneError
impl Sync for Utf8Lossy
impl Sync for ParseBoolError
impl Sync for Utf8Error
impl Sync for RawWakerVTable
impl Sync for Duration
impl<'a> !Sync for VaList<'a>
impl<'a> !Sync for Arguments<'a>
impl<'a> !Sync for Formatter<'a>
impl<'a> !Sync for PanicInfo<'a>
impl<'a> Sync for Location<'a>
impl<'a> Sync for Utf8LossyChunk<'a>
impl<'a> Sync for Utf8LossyChunksIter<'a>
impl<'a> Sync for CharSearcher<'a>
impl<'a> Sync for Bytes<'a>
impl<'a> Sync for CharIndices<'a>
impl<'a> Sync for Chars<'a>
impl<'a> Sync for EncodeUtf16<'a>
impl<'a> Sync for core::str::EscapeDebug<'a>
impl<'a> Sync for core::str::EscapeDefault<'a>
impl<'a> Sync for core::str::EscapeUnicode<'a>
impl<'a> Sync for Lines<'a>
impl<'a> Sync for LinesAny<'a>
impl<'a> Sync for SplitAsciiWhitespace<'a>
impl<'a> Sync for SplitWhitespace<'a>
impl<'a> Sync for Context<'a>
impl<'a, 'b> !Sync for DebugList<'a, 'b>
impl<'a, 'b> !Sync for DebugMap<'a, 'b>
impl<'a, 'b> !Sync for DebugSet<'a, 'b>
impl<'a, 'b> !Sync for DebugStruct<'a, 'b>
impl<'a, 'b> !Sync for DebugTuple<'a, 'b>
impl<'a, 'b> Sync for CharSliceSearcher<'a, 'b>
impl<'a, 'b> Sync for StrSearcher<'a, 'b>
impl<'a, A> Sync for core::option::Iter<'a, A> where
A: Sync,
A: Sync,
impl<'a, A> Sync for core::option::IterMut<'a, A> where
A: Sync,
A: Sync,
impl<'a, F> Sync for CharPredicateSearcher<'a, F> where
F: MultiCharEq + Sync,
F: MultiCharEq + Sync,
impl<'a, P> Sync for MatchIndices<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for Matches<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for RMatchIndices<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for RMatches<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for core::str::RSplit<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for core::str::RSplitN<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for RSplitTerminator<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for core::str::Split<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for core::str::SplitN<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for SplitTerminator<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, T> Sync for core::result::Iter<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for core::result::IterMut<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for Chunks<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for ChunksExact<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for ChunksExactMut<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for ChunksMut<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for RChunks<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for RChunksExact<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for RChunksExactMut<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for RChunksMut<'a, T> where
T: Sync,
T: Sync,
impl<'a, T> Sync for Windows<'a, T> where
T: Sync,
T: Sync,
impl<'a, T, P> Sync for core::slice::RSplit<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for RSplitMut<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for core::slice::RSplitN<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for RSplitNMut<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for core::slice::Split<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for SplitMut<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for core::slice::SplitN<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'a, T, P> Sync for SplitNMut<'a, T, P> where
P: Sync,
T: Sync,
P: Sync,
T: Sync,
impl<'b, T> !Sync for Ref<'b, T>
impl<'b, T> !Sync for RefMut<'b, T>
impl<A> Sync for Repeat<A> where
A: Sync,
A: Sync,
impl<A> Sync for core::option::IntoIter<A> where
A: Sync,
A: Sync,
impl<A, B> Sync for Chain<A, B> where
A: Sync,
B: Sync,
A: Sync,
B: Sync,
impl<A, B> Sync for Zip<A, B> where
A: Sync,
B: Sync,
A: Sync,
B: Sync,
impl<F> Sync for FromFn<F> where
F: Sync,
F: Sync,
impl<F> Sync for OnceWith<F> where
F: Sync,
F: Sync,
impl<F> Sync for RepeatWith<F> where
F: Sync,
F: Sync,
impl<H> Sync for BuildHasherDefault<H> where
H: Sync,
H: Sync,
impl<I> Sync for DecodeUtf16<I> where
I: Sync,
I: Sync,
impl<I> Sync for Cloned<I> where
I: Sync,
I: Sync,
impl<I> Sync for Copied<I> where
I: Sync,
I: Sync,
impl<I> Sync for Cycle<I> where
I: Sync,
I: Sync,
impl<I> Sync for Enumerate<I> where
I: Sync,
I: Sync,
impl<I> Sync for Flatten<I> where
I: Sync,
<<I as Iterator>::Item as IntoIterator>::IntoIter: Sync,
I: Sync,
<<I as Iterator>::Item as IntoIterator>::IntoIter: Sync,
impl<I> Sync for Fuse<I> where
I: Sync,
I: Sync,
impl<I> Sync for Peekable<I> where
I: Sync,
<I as Iterator>::Item: Sync,
I: Sync,
<I as Iterator>::Item: Sync,
impl<I> Sync for Skip<I> where
I: Sync,
I: Sync,
impl<I> Sync for StepBy<I> where
I: Sync,
I: Sync,
impl<I> Sync for Take<I> where
I: Sync,
I: Sync,
impl<I, F> Sync for FilterMap<I, F> where
F: Sync,
I: Sync,
F: Sync,
I: Sync,
impl<I, F> Sync for Inspect<I, F> where
F: Sync,
I: Sync,
F: Sync,
I: Sync,
impl<I, F> Sync for Map<I, F> where
F: Sync,
I: Sync,
F: Sync,
I: Sync,
impl<I, P> Sync for Filter<I, P> where
I: Sync,
P: Sync,
I: Sync,
P: Sync,
impl<I, P> Sync for SkipWhile<I, P> where
I: Sync,
P: Sync,
I: Sync,
P: Sync,
impl<I, P> Sync for TakeWhile<I, P> where
I: Sync,
P: Sync,
I: Sync,
P: Sync,
impl<I, St, F> Sync for Scan<I, St, F> where
F: Sync,
I: Sync,
St: Sync,
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,
F: Sync,
I: Sync,
<U as IntoIterator>::IntoIter: Sync,
impl<Idx> Sync for Range<Idx> where
Idx: Sync,
Idx: Sync,
impl<Idx> Sync for RangeFrom<Idx> where
Idx: Sync,
Idx: Sync,
impl<Idx> Sync for RangeInclusive<Idx> where
Idx: Sync,
Idx: Sync,
impl<Idx> Sync for RangeTo<Idx> where
Idx: Sync,
Idx: Sync,
impl<Idx> Sync for RangeToInclusive<Idx> where
Idx: Sync,
Idx: Sync,
impl<P> Sync for Pin<P> where
P: Sync,
P: Sync,
impl<T> Sync for Bound<T> where
T: Sync,
T: Sync,
impl<T> Sync for Option<T> where
T: Sync,
T: Sync,
impl<T> Sync for Poll<T> where
T: Sync,
T: Sync,
impl<T> Sync for Reverse<T> where
T: Sync,
T: Sync,
impl<T> Sync for Empty<T> where
T: Sync,
T: Sync,
impl<T> Sync for Once<T> where
T: Sync,
T: Sync,
impl<T> Sync for Rev<T> where
T: Sync,
T: Sync,
impl<T> Sync for Discriminant<T>
impl<T> Sync for Wrapping<T> where
T: Sync,
T: Sync,
impl<T> Sync for core::result::IntoIter<T> where
T: Sync,
T: Sync,
impl<T> Sync for MaybeUninit<T> where
T: Sync,
T: Sync,
impl<T, E> Sync for Result<T, E> where
E: Sync,
T: Sync,
E: Sync,
T: Sync,
impl<T, F> Sync for Successors<T, F> where
F: Sync,
T: Sync,
F: Sync,
T: Sync,
impl<T: ?Sized> Sync for PhantomData<T> where
T: Sync,
T: Sync,
impl<T: ?Sized> Sync for ManuallyDrop<T> where
T: Sync,
T: Sync,
impl<Y, R> Sync for GeneratorState<Y, R> where
R: Sync,
Y: Sync,
R: Sync,
Y: Sync,