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42 lines
1.2 KiB
Markdown
42 lines
1.2 KiB
Markdown
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# Examples
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## `Send + Sync`
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Most types you come across are `Send + Sync`:
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* `i8`, `f32`, `bool`, `char`, `&str`, ...
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* `(T1, T2)`, `[T; N]`, `&[T]`, `struct { x: T }`, ...
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* `String`, `Option<T>`, `Vec<T>`, `Box<T>`, ...
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* `Arc<T>`: Explicitly thread-safe via atomic reference count.
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* `Mutex<T>`: Explicitly thread-safe via internal locking.
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* `AtomicBool`, `AtomicU8`, ...: Uses special atomic instructions.
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The generic types are typically `Send + Sync` when the type parameters are
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`Send + Sync`.
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## `Send + !Sync`
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These types can be moved to other threads, but they're not thread-safe.
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Typically because of interior mutability:
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* `mpsc::Sender<T>`
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* `mpsc::Receiver<T>`
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* `Cell<T>`
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* `RefCell<T>`
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## `!Send + Sync`
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These types are thread-safe, but they cannot be moved to another thread:
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* `MutexGuard<T>`: Uses OS level primitives which must be deallocated on the
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thread which created them.
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## `!Send + !Sync`
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These types are not thread-safe and cannot be moved to other threads:
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* `Rc<T>`: each `Rc<T>` has a reference to an `RcBox<T>`, which contains a
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non-atomic reference count.
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* `*const T`, `*mut T`: Rust that there are special lifetime considerations for the
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pointer.
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