atomic_utilities 0.5.0

Basic utilities for fast atomics on multiple platforms
Documentation 
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//! This mod provides orderings to use with RMW operations
//! that optimally handle the case when all loads and stores
//! after an RMW operation must be ordered after the operation.
//! # Example:
//! ```
//! use std::sync::atomic::{AtomicUsize, fence, Ordering};
//! use atomic_utilities::fence_rmw::{RMWOrder, fence_rmw};
//!
//! let atomic_refcnt = AtomicUsize::new(0);
//! atomic_refcnt.fetch_add(1, RMWOrder);
//!
//! // ... do work here
//! // This will be ordered after the store of the fetch_add
//! // and will use minimal fences for various hardware platforms
//! atomic_refcnt.fetch_sub(1, Ordering::Release);
//! ```

use std::sync::atomic::Ordering;
#[cfg(any(target_platform = "x86", target_platform = "x86_64"))]
mod internal_ordering {
    use std::sync::atomic::Ordering;
    pub const RMW_O: Ordering = Ordering::Acquire;

    #[inline(always)]
    pub fn the_fence() {}
}

#[cfg(not(any(target_platform = "x86", target_platform = "x86_64")))]
mod internal_ordering {
    use std::sync::atomic::{Ordering, fence};
    pub const RMW_O: Ordering = Ordering::Relaxed;
    pub fn the_fence() {
        fence(Ordering::SeqCst)
    }
}

/// The ordering to be used for RMW operations in this fencing scheme
#[allow(non_upper_case_globals)]
pub const RMWOrder: Ordering = internal_ordering::RMW_O;

/// The fence to be used after the RMW
#[inline(always)]
pub fn fence_rmw() {
    internal_ordering::the_fence()
}