1.0.0[−][src]Trait ontio_std::prelude::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
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
.
Implementations on Foreign Types
impl Sync for AtomicU8
[src]
impl Sync for AtomicBool
[src]
impl<T> !Sync for RefCell<T> where
T: ?Sized,
[src]
T: ?Sized,
impl Sync for AtomicI64
[src]
impl<T> Sync for AtomicPtr<T>
[src]
impl Sync for AtomicU128
[src]
impl<T> !Sync for NonNull<T> where
T: ?Sized,
[src]
T: ?Sized,
NonNull
pointers are not Sync
because the data they reference may be aliased.
impl<T> Sync for Empty<T>
[src]
impl Sync for AtomicIsize
[src]
impl<T> !Sync for Cell<T> where
T: ?Sized,
[src]
T: ?Sized,
impl<'_, T> Sync for IterMut<'_, T> where
T: Sync,
[src]
T: Sync,
impl<'_, T> Sync for Iter<'_, T> where
T: Sync,
[src]
T: Sync,
impl<T> !Sync for UnsafeCell<T> where
T: ?Sized,
[src]
T: ?Sized,
impl Sync for AtomicI16
[src]
impl Sync for Waker
[src]
impl Sync for AtomicU64
[src]
impl Sync for AtomicI128
[src]
impl Sync for AtomicU16
[src]
impl Sync for AtomicI32
[src]
impl Sync for AtomicI8
[src]
impl Sync for AtomicUsize
[src]
impl Sync for AtomicU32
[src]
impl<T> Sync for LinkedList<T> where
T: Sync,
[src]
T: Sync,
impl<'_, T> Sync for IterMut<'_, T> where
T: Sync,
[src]
T: Sync,
impl<T> !Sync for Rc<T> where
T: ?Sized,
[src]
T: ?Sized,
impl<'_, T> Sync for CursorMut<'_, T> where
T: Sync,
[src]
T: Sync,
impl<T> !Sync for Weak<T> where
T: ?Sized,
[src]
T: ?Sized,
impl<T> Sync for Weak<T> where
T: Send + Sync + ?Sized,
[src]
T: Send + Sync + ?Sized,
impl<'_, T> Sync for IterMut<'_, T> where
T: Sync,
[src]
T: Sync,
impl<T> Sync for Arc<T> where
T: Send + Sync + ?Sized,
[src]
T: Send + Sync + ?Sized,
impl<'_, T> Sync for Iter<'_, T> where
T: Sync,
[src]
T: Sync,
impl<'_, T> Sync for Drain<'_, T> where
T: Sync,
[src]
T: Sync,
impl<'_, T> Sync for Cursor<'_, T> where
T: Sync,
[src]
T: Sync,
impl<'a> Sync for WeeAlloc<'a>
[src]
Loading content...Implementors
impl<'_> Sync for ontio_std::prelude::string::Drain<'_>
[src]
impl<'_, T, A> Sync for ontio_std::prelude::vec::Drain<'_, T, A> where
A: Sync + Allocator,
T: Sync,
[src]
A: Sync + Allocator,
T: Sync,
impl<T> !Sync for *const T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> !Sync for *mut T where
T: ?Sized,
[src]
T: ?Sized,
impl<T, A> Sync for IntoIter<T, A> where
A: Allocator,
T: Sync,
[src]
A: Allocator,
T: Sync,
Auto implementors
impl Sync for Error
impl Sync for Ordering
impl Sync for SearchStep
impl Sync for EventBuilder
impl Sync for Sink
impl Sync for VmValueBuilder
impl Sync for DDOAttribute
impl Sync for Group
impl Sync for Signer
impl Sync for TransferParam
impl Sync for ParseBoolError
impl Sync for Utf8Error
impl Sync for FromUtf8Error
impl Sync for FromUtf16Error
impl Sync for I128
impl Sync for String
impl Sync for U128
impl Sync for H160
impl Sync for H256
impl Sync for U256
impl Sync for [u8]
impl Sync for bool
impl Sync for char
impl Sync for f32
impl Sync for f64
impl Sync for i8
impl Sync for i16
impl Sync for i32
impl Sync for i64
impl Sync for i128
impl Sync for isize
impl Sync for str
impl Sync for u8
impl Sync for u16
impl Sync for u32
impl Sync for u64
impl Sync for u128
impl Sync for usize
impl<'a> Sync for Source<'a>
impl<'a> Sync for VmValueParser<'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 EscapeDebug<'a>
impl<'a> Sync for EscapeDefault<'a>
impl<'a> Sync for 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, 'b> Sync for CharSliceSearcher<'a, 'b>
impl<'a, 'b> Sync for StrSearcher<'a, 'b>
impl<'a, F> Sync for CharPredicateSearcher<'a, F> where
F: MultiCharEq + Sync,
F: MultiCharEq + Sync,
impl<'a, I, A> Sync for Splice<'a, I, A> where
A: Sync,
I: Sync,
<I as Iterator>::Item: Sync,
A: Sync,
I: Sync,
<I as Iterator>::Item: 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 RSplit<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for 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 Split<'a, P> where
<P as Pattern<'a>>::Searcher: Sync,
<P as Pattern<'a>>::Searcher: Sync,
impl<'a, P> Sync for 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, F, A> Sync for DrainFilter<'a, T, F, A> where
A: Sync,
F: Sync,
T: Sync,
A: Sync,
F: Sync,
T: Sync,
impl<T> Sync for Option<T> where
T: Sync,
T: Sync,
impl<T> Sync for ListStore<T> where
T: Sync,
T: Sync,
impl<T> Sync for Reverse<T> where
T: Sync,
T: Sync,
impl<T> Sync for [T] where
T: Sync,
T: Sync,
impl<T, A> Sync for Vec<T, A> where
A: Sync,
T: Sync,
A: Sync,
T: Sync,
impl<T, E> Sync for Result<T, E> where
E: Sync,
T: Sync,
E: Sync,
T: Sync,
impl<T, const N: usize> Sync for [T; N] where
T: Sync,
T: Sync,
impl<T: ?Sized, A> Sync for Box<T, A> where
A: Sync,
T: Sync,
A: Sync,
T: Sync,