1 //! Atomic types.
2 //!
3 //! * [`AtomicCell`], a thread-safe mutable memory location.
4 //! * [`AtomicConsume`], for reading from primitive atomic types with "consume" ordering.
5 
6 #[cfg(target_has_atomic = "ptr")]
7 #[cfg(not(crossbeam_loom))]
8 // Use "wide" sequence lock if the pointer width <= 32 for preventing its counter against wrap
9 // around.
10 //
11 // In narrow architectures (pointer width <= 16), the counter is still <= 32-bit and may be
12 // vulnerable to wrap around. But it's mostly okay, since in such a primitive hardware, the
13 // counter will not be increased that fast.
14 // Note that Rust (and C99) pointers must be at least 16-bit (i.e., 8-bit targets are impossible): https://github.com/rust-lang/rust/pull/49305
15 #[cfg_attr(
16     any(target_pointer_width = "16", target_pointer_width = "32"),
17     path = "seq_lock_wide.rs"
18 )]
19 mod seq_lock;
20 
21 #[cfg(target_has_atomic = "ptr")]
22 // We cannot provide AtomicCell under cfg(crossbeam_loom) because loom's atomic
23 // types have a different in-memory representation than the underlying type.
24 // TODO: The latest loom supports fences, so fallback using seqlock may be available.
25 #[cfg(not(crossbeam_loom))]
26 mod atomic_cell;
27 #[cfg(target_has_atomic = "ptr")]
28 #[cfg(not(crossbeam_loom))]
29 pub use atomic_cell::AtomicCell;
30 
31 mod consume;
32 pub use consume::AtomicConsume;
33