Trait scale_info::prelude::marker::Sync

#[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 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 Argument

impl Sync for FormatSpec

impl Sync for Alignment

impl Sync for Count

impl<'_, T> Sync for RwLockWriteGuard<'_, T> where
    T: Sync + ?Sized, 

impl Sync for Once

impl<'a> Sync for IoSliceMut<'a>

impl<T> Sync for RwLock<T> where
    T: Send + Sync + ?Sized, 

impl<T> Sync for SyncOnceCell<T> where
    T: Send + Sync, 

impl<T> !Sync for Sender<T>

impl<'_, T> Sync for MutexGuard<'_, T> where
    T: Sync + ?Sized, 

impl !Sync for Args

impl<T, F> Sync for SyncLazy<T, F> where
    F: Send,
    SyncOnceCell<T>: Sync, 

impl<'a> Sync for IoSlice<'a>

impl<T> Sync for Mutex<T> where
    T: Send + ?Sized, 

impl<T> Sync for Key<T>

impl !Sync for ArgsOs

impl<'_, T> Sync for RwLockReadGuard<'_, T> where
    T: Sync + ?Sized, 

impl<T> !Sync for Receiver<T>

impl<T> Sync for JoinHandle<T>

impl Sync for Waker

impl Sync for AtomicI16

impl Sync for AtomicI32

impl<T> !Sync for UnsafeCell<T> where
    T: ?Sized, 

impl<'_, T> Sync for Iter<'_, T> where
    T: Sync, 

impl Sync for AtomicBool

impl Sync for AtomicU8

impl Sync for AtomicU32

impl Sync for AtomicI64

impl<T> Sync for Empty<T>

impl<T> Sync for AtomicPtr<T>

impl<T> !Sync for *const T where
    T: ?Sized, 

impl Sync for AtomicUsize

impl<T> !Sync for Cell<T> where
    T: ?Sized, 

impl<'_, T> Sync for IterMut<'_, T> where
    T: Sync, 

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 Sync for AtomicU64

impl Sync for AtomicIsize

impl<T> !Sync for *mut T where
    T: ?Sized, 

impl Sync for AtomicU16

impl Sync for AtomicI8

impl<T> Sync for Weak<T> where
    T: Send + Sync + ?Sized, 

impl<T> !Sync for Rc<T> where
    T: ?Sized, 

impl<T> !Sync for Weak<T> where
    T: ?Sized, 

impl<T> Sync for Arc<T> where
    T: Send + Sync + ?Sized, 

impl<'a, A> Sync for Drain<'a, A> where
    A: Array + Sync, 

impl Sync for isize

impl<T> Sync for [T] where
    T: Sync, 

impl Sync for [u8]

impl Sync for char

impl Sync for u128

impl Sync for u16

impl Sync for i128

impl Sync for i16

impl Sync for str

impl Sync for f64

impl Sync for u64

impl Sync for u8

impl Sync for i64

impl Sync for i8

impl<T, const N: usize> Sync for [T; N] where
    T: Sync, 

impl Sync for bool

impl Sync for f32

impl Sync for u32

impl Sync for usize

impl Sync for i32

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Implementors

impl<'_> Sync for scale_info::prelude::string::Drain<'_>

impl<'_, T> Sync for Cursor<'_, T> where
    T: Sync, 

impl<'_, T> Sync for CursorMut<'_, T> where
    T: Sync, 

impl<'_, T> Sync for scale_info::prelude::collections::linked_list::Iter<'_, T> where
    T: Sync, 

impl<'_, T> Sync for scale_info::prelude::collections::linked_list::IterMut<'_, T> where
    T: Sync, 

impl<'_, T> Sync for scale_info::prelude::collections::vec_deque::Drain<'_, T> where
    T: Sync, 

impl<'_, T> Sync for scale_info::prelude::collections::vec_deque::IterMut<'_, T> where
    T: Sync, 

impl<'_, T, A> Sync for scale_info::prelude::vec::Drain<'_, T, A> where
    T: Sync,
    A: Sync + Allocator, 

impl<T> Sync for LinkedList<T> where
    T: Sync, 

impl<T, A> Sync for scale_info::prelude::vec::IntoIter<T, A> where
    T: Sync,
    A: Allocator, 

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Auto implementors

impl Sync for Fieldless

impl Sync for Fields

impl Sync for NamedFields

impl Sync for NoFields

impl Sync for NoVariants

impl Sync for UnnamedFields

impl Sync for VariantFields

impl Sync for Variants

impl Sync for PathAssigned

impl Sync for PathNotAssigned

impl Sync for PathError

impl Sync for TypeDefPrimitive

impl Sync for MetaForm

impl Sync for Ordering

impl Sync for TryReserveError

impl Sync for scale_info::prelude::fmt::Alignment

impl Sync for FpCategory

impl Sync for IntErrorKind

impl Sync for TypeId

impl Sync for DefaultHasher

impl Sync for RandomState

impl Sync for Error

impl Sync for SipHasher

impl Sync for PhantomPinned

impl Sync for NonZeroI8

impl Sync for NonZeroI16

impl Sync for NonZeroI32

impl Sync for NonZeroI64

impl Sync for NonZeroI128

impl Sync for NonZeroIsize

impl Sync for NonZeroU8

impl Sync for NonZeroU16

impl Sync for NonZeroU32

impl Sync for NonZeroU64

impl Sync for NonZeroU128

impl Sync for NonZeroUsize

impl Sync for ParseFloatError

impl Sync for ParseIntError

impl Sync for TryFromIntError

impl Sync for FromUtf8Error

impl Sync for FromUtf16Error

impl Sync for String

impl Sync for MetaType

impl Sync for Registry

impl<'a> !Sync for Arguments<'a>

impl<'a> !Sync for Formatter<'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, I, A> Sync for Splice<'a, I, A> where
    A: Sync,
    I: Sync,
    <I as Iterator>::Item: Sync, 

impl<'a, K> Sync for scale_info::prelude::collections::hash_set::Drain<'a, K> where
    K: Sync, 

impl<'a, K> Sync for scale_info::prelude::collections::hash_set::Iter<'a, K> where
    K: Sync, 

impl<'a, K, F> Sync for scale_info::prelude::collections::hash_set::DrainFilter<'a, K, F> where
    F: Sync,
    K: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::Entry<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::Entry<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::Iter<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::IterMut<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::Keys<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::OccupiedEntry<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::Range<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for RangeMut<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::VacantEntry<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::Values<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::btree_map::ValuesMut<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::Drain<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::Iter<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::IterMut<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::Keys<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::OccupiedEntry<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::VacantEntry<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::Values<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V> Sync for scale_info::prelude::collections::hash_map::ValuesMut<'a, K, V> where
    K: Sync,
    V: Sync, 

impl<'a, K, V, F> Sync for scale_info::prelude::collections::btree_map::DrainFilter<'a, K, V, F> where
    F: Sync,
    K: Sync,
    V: Sync, 

impl<'a, K, V, F> Sync for scale_info::prelude::collections::hash_map::DrainFilter<'a, K, V, F> where
    F: Sync,
    K: Sync,
    V: Sync, 

impl<'a, K, V, S> Sync for RawEntryMut<'a, K, V, S> where
    K: Sync,
    S: Sync,
    V: Sync, 

impl<'a, K, V, S> Sync for RawEntryBuilder<'a, K, V, S> where
    K: Sync,
    S: Sync,
    V: Sync, 

impl<'a, K, V, S> Sync for RawEntryBuilderMut<'a, K, V, S> where
    K: Sync,
    S: Sync,
    V: Sync, 

impl<'a, K, V, S> Sync for RawOccupiedEntryMut<'a, K, V, S> where
    K: Sync,
    S: Sync,
    V: Sync, 

impl<'a, K, V, S> Sync for RawVacantEntryMut<'a, K, V, S> where
    K: Sync,
    S: Sync,
    V: Sync, 

impl<'a, T> Sync for Symbol<'a, T>

impl<'a, T> Sync for scale_info::prelude::collections::binary_heap::Drain<'a, T> where
    T: Sync, 

impl<'a, T> Sync for DrainSorted<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::binary_heap::Iter<'a, T> where
    T: Sync, 

impl<'a, T> Sync for PeekMut<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::btree_set::Difference<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::btree_set::Intersection<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::btree_set::Iter<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::btree_set::Range<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::btree_set::SymmetricDifference<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::btree_set::Union<'a, T> where
    T: Sync, 

impl<'a, T> Sync for scale_info::prelude::collections::vec_deque::Iter<'a, T> where
    T: Sync, 

impl<'a, T, F> !Sync for scale_info::prelude::collections::linked_list::DrainFilter<'a, T, F>

impl<'a, T, F> Sync for scale_info::prelude::collections::btree_set::DrainFilter<'a, T, F> where
    F: Sync,
    T: Sync, 

impl<'a, T, F, A> Sync for scale_info::prelude::vec::DrainFilter<'a, T, F, A> where
    A: Sync,
    F: Sync,
    T: Sync, 

impl<'a, T, S> Sync for scale_info::prelude::collections::hash_set::Difference<'a, T, S> where
    S: Sync,
    T: Sync, 

impl<'a, T, S> Sync for scale_info::prelude::collections::hash_set::Intersection<'a, T, S> where
    S: Sync,
    T: Sync, 

impl<'a, T, S> Sync for scale_info::prelude::collections::hash_set::SymmetricDifference<'a, T, S> where
    S: Sync,
    T: Sync, 

impl<'a, T, S> Sync for scale_info::prelude::collections::hash_set::Union<'a, T, S> where
    S: Sync,
    T: Sync, 

impl<H> Sync for BuildHasherDefault<H> where
    H: Sync, 

impl<K> Sync for scale_info::prelude::collections::hash_set::IntoIter<K> where
    K: Sync, 

impl<K, V> Sync for scale_info::prelude::collections::btree_map::IntoIter<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V> Sync for scale_info::prelude::collections::btree_map::IntoKeys<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V> Sync for scale_info::prelude::collections::btree_map::IntoValues<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V> Sync for scale_info::prelude::collections::hash_map::IntoIter<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V> Sync for scale_info::prelude::collections::hash_map::IntoKeys<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V> Sync for scale_info::prelude::collections::hash_map::IntoValues<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V> Sync for BTreeMap<K, V> where
    K: Sync,
    V: Sync, 

impl<K, V, S> Sync for HashMap<K, V, S> where
    K: Sync,
    S: Sync,
    V: Sync, 

impl<S> Sync for TypeBuilder<S>

impl<S> Sync for PortableForm<S> where
    S: Sync, 

impl<S> Sync for PortableRegistry<S> where
    S: Sync, 

impl<T> Sync for TypeDef<T> where
    <T as Form>::String: Sync,
    <T as Form>::Type: Sync, 

impl<T> Sync for Bound<T> where
    T: Sync, 

impl<T> Sync for FieldsBuilder<T>

impl<T> Sync for VariantsBuilder<T>

impl<T> Sync for Interner<T> where
    T: Sync, 

impl<T> Sync for UntrackedSymbol<T>

impl<T> Sync for Reverse<T> where
    T: Sync, 

impl<T> Sync for scale_info::prelude::collections::binary_heap::IntoIter<T> where
    T: Sync, 

impl<T> Sync for IntoIterSorted<T> where
    T: Sync, 

impl<T> Sync for scale_info::prelude::collections::btree_set::IntoIter<T> where
    T: Sync, 

impl<T> Sync for scale_info::prelude::collections::linked_list::IntoIter<T> where
    T: Sync, 

impl<T> Sync for BTreeSet<T> where
    T: Sync, 

impl<T> Sync for BinaryHeap<T> where
    T: Sync, 

impl<T> Sync for VecDeque<T> where
    T: Sync, 

impl<T> Sync for scale_info::prelude::collections::vec_deque::IntoIter<T> where
    T: Sync, 

impl<T> Sync for Discriminant<T>

impl<T> Sync for Wrapping<T> where
    T: Sync, 

impl<T> Sync for Field<T> where
    <T as Form>::String: Sync,
    <T as Form>::Type: Sync, 

impl<T> Sync for Path<T> where
    <T as Form>::String: Sync, 

impl<T> Sync for Type<T> where
    <T as Form>::String: Sync,
    <T as Form>::Type: Sync, 

impl<T> Sync for TypeDefArray<T> where
    <T as Form>::Type: Sync, 

impl<T> Sync for TypeDefComposite<T> where
    <T as Form>::String: Sync,
    <T as Form>::Type: Sync, 

impl<T> Sync for TypeDefPhantom<T> where
    <T as Form>::Type: Sync, 

impl<T> Sync for TypeDefSequence<T> where
    <T as Form>::Type: Sync, 

impl<T> Sync for TypeDefTuple<T> where
    <T as Form>::Type: Sync, 

impl<T> Sync for TypeDefVariant<T> where
    <T as Form>::String: Sync,
    <T as Form>::Type: Sync, 

impl<T> Sync for Variant<T> where
    <T as Form>::String: Sync,
    <T as Form>::Type: Sync, 

impl<T> Sync for MaybeUninit<T> where
    T: Sync, 

impl<T, A> Sync for Vec<T, A> where
    A: Sync,
    T: Sync, 

impl<T, S> Sync for HashSet<T, S> where
    S: Sync,
    T: Sync, 

impl<T: ?Sized> Sync for PhantomData<T> where
    T: Sync, 

impl<T: ?Sized> Sync for ManuallyDrop<T> where
    T: Sync, 

impl<T: ?Sized, A> Sync for Box<T, A> where
    A: Sync,
    T: Sync, 

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