| 1 | //! Atomic types. |
| 2 | //! |
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| 3 | //! * [`AtomicCell`], a thread-safe mutable memory location. |
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| 4 | //! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering. |
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| 5 | |
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| 6 | #[cfg (target_has_atomic = "ptr" )] |
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| 7 | #[cfg (not(crossbeam_loom))] |
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| 8 | cfg_if::cfg_if! { |
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| 9 | // Use "wide" sequence lock if the pointer width <= 32 for preventing its counter against wrap |
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| 10 | // around. |
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| 11 | // |
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| 12 | // We are ignoring too wide architectures (pointer width >= 256), since such a system will not |
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| 13 | // appear in a conceivable future. |
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| 14 | // |
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| 15 | // In narrow architectures (pointer width <= 16), the counter is still <= 32-bit and may be |
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| 16 | // vulnerable to wrap around. But it's mostly okay, since in such a primitive hardware, the |
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| 17 | // counter will not be increased that fast. |
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| 18 | if #[cfg(any(target_pointer_width = "64" , target_pointer_width = "128" ))] { |
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| 19 | mod seq_lock; |
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| 20 | } else { |
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| 21 | #[path = "seq_lock_wide.rs" ] |
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| 22 | mod seq_lock; |
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| 23 | } |
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| 24 | } |
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| 25 | |
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| 26 | #[cfg (target_has_atomic = "ptr" )] |
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| 27 | // We cannot provide AtomicCell under cfg(crossbeam_loom) because loom's atomic |
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| 28 | // types have a different in-memory representation than the underlying type. |
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| 29 | // TODO: The latest loom supports fences, so fallback using seqlock may be available. |
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| 30 | #[cfg (not(crossbeam_loom))] |
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| 31 | mod atomic_cell; |
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| 32 | mod consume; |
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| 33 | |
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| 34 | #[cfg (target_has_atomic = "ptr" )] |
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| 35 | #[cfg (not(crossbeam_loom))] |
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| 36 | pub use self::atomic_cell::AtomicCell; |
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| 37 | pub use self::consume::AtomicConsume; |
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| 38 | |
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