124 lines
2.7 KiB
Rust
124 lines
2.7 KiB
Rust
//! Synchronization facade to choose between `core` primitives and `loom` primitives.
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#[cfg(all(feature = "portable-atomic", not(loom)))]
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mod sync_impl {
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pub(crate) use core::cell;
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pub(crate) use portable_atomic as atomic;
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#[cfg(not(feature = "std"))]
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pub(crate) use atomic::hint::spin_loop;
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#[cfg(feature = "std")]
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pub(crate) use std::thread::yield_now;
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}
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#[cfg(all(not(feature = "portable-atomic"), not(loom)))]
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mod sync_impl {
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pub(crate) use core::cell;
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pub(crate) use core::sync::atomic;
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#[cfg(not(feature = "std"))]
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#[inline]
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pub(crate) fn spin_loop() {
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#[allow(deprecated)]
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atomic::spin_loop_hint();
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}
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#[cfg(feature = "std")]
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pub(crate) use std::thread::yield_now;
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}
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#[cfg(loom)]
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mod sync_impl {
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pub(crate) use loom::cell;
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pub(crate) mod atomic {
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pub(crate) use core::sync::atomic::compiler_fence;
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pub(crate) use loom::sync::atomic::*;
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}
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pub(crate) use loom::thread::yield_now;
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}
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pub(crate) use sync_impl::*;
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/// Notify the CPU that we are currently busy-waiting.
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#[inline]
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pub(crate) fn busy_wait() {
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#[cfg(feature = "std")]
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yield_now();
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#[cfg(not(feature = "std"))]
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spin_loop();
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}
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#[cfg(loom)]
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pub(crate) mod prelude {}
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#[cfg(not(loom))]
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pub(crate) mod prelude {
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use super::{atomic, cell};
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/// Emulate `loom::UnsafeCell`'s API.
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pub(crate) trait UnsafeCellExt {
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type Value;
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fn with<R, F>(&self, f: F) -> R
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where
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F: FnOnce(*const Self::Value) -> R;
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fn with_mut<R, F>(&self, f: F) -> R
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where
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F: FnOnce(*mut Self::Value) -> R;
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}
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impl<T> UnsafeCellExt for cell::UnsafeCell<T> {
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type Value = T;
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fn with<R, F>(&self, f: F) -> R
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where
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F: FnOnce(*const Self::Value) -> R,
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{
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f(self.get())
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}
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fn with_mut<R, F>(&self, f: F) -> R
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where
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F: FnOnce(*mut Self::Value) -> R,
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{
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f(self.get())
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}
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}
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/// Emulate `loom::Atomic*`'s API.
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pub(crate) trait AtomicExt {
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type Value;
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fn with_mut<R, F>(&mut self, f: F) -> R
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where
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F: FnOnce(&mut Self::Value) -> R;
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}
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impl AtomicExt for atomic::AtomicUsize {
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type Value = usize;
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fn with_mut<R, F>(&mut self, f: F) -> R
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where
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F: FnOnce(&mut Self::Value) -> R,
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{
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f(self.get_mut())
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}
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}
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impl<T> AtomicExt for atomic::AtomicPtr<T> {
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type Value = *mut T;
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fn with_mut<R, F>(&mut self, f: F) -> R
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where
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F: FnOnce(&mut Self::Value) -> R,
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{
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f(self.get_mut())
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}
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}
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}
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