Trait concordium_std::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 Once

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

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

impl !Sync for Args

impl<T> !Sync for Receiver<T>

impl !Sync for ArgsOs

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

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

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

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

impl<T> Sync for JoinHandle<T>

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

impl<T> Sync for Key<T>

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

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

impl<T> !Sync for Sender<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, A> Sync for IntoIter<T, A> where
    A: Allocator,
    T: Sync, 

impl<'_> Sync for Drain<'_>

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

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

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

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

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

impl<'a> Sync for WeeAlloc<'a>

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<'_, T> Sync for concordium_std::collections::linked_list::Cursor<'_, T> where
    T: Sync, 

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

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

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

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

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

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

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Auto implementors

impl Sync for TryReserveError

impl Sync for Infallible

impl Sync for Address

impl Sync for AmountParseError

impl Sync for ParseDurationError

impl Sync for SeekFrom

impl Sync for Fields

impl Sync for SizeLength

impl Sync for Type

impl Sync for ActionsTree

impl Sync for DefaultHasher

impl Sync for RandomState

impl Sync for PhantomPinned

impl Sync for Contract

impl Sync for Module

impl Sync for AccountAddress

impl Sync for Action

impl Sync for Amount

impl Sync for AttributeTag

impl Sync for AttributesCursor

impl Sync for ChainMetadata

impl Sync for ContractAddress

impl Sync for ContractState

impl Sync for Duration

impl Sync for Logger

impl Sync for Parameter

impl Sync for ParseError

impl Sync for PoliciesIterator

impl Sync for Reject

impl Sync for Timestamp

impl Sync for ChainMetaTest

impl Sync for LogRecorder

impl Sync for TestPolicy

impl<'a, C> Sync for ContextTest<'a, C> where
    C: Sync, 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

impl<'a, K, V, F> Sync for concordium_std::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 concordium_std::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 concordium_std::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 concordium_std::collections::btree_set::Difference<'a, T> where
    T: Sync, 

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

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

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

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

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

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

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

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

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

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

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

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

impl<Attributes> Sync for Policy<Attributes> where
    Attributes: Sync, 

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

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

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

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

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

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

impl<K, V> Sync for concordium_std::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<T> Sync for Bound<T> where
    T: Sync, 

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

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

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

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

impl<T> Sync for Discriminant<T> where
    <T as DiscriminantKind>::Discriminant: Sync, 

impl<T> Sync for concordium_std::Cursor<T> where
    T: Sync, 

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

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