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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `C:\Users\zenn\.cargo\registry\src\index.crates.io-6f17d22bba15001f\critical-section-1.1.2\src\lib.rs`."><title>lib.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Bold-a2c9cd1067f8b328.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-cb6f1f67f1bcd037.css" id="mainThemeStyle"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="critical_section" data-themes="" data-resource-suffix="" data-rustdoc-version="1.73.0-nightly (8131b9774 2023-08-02)" data-channel="nightly" data-search-js="search-6dfdfced5eff6596.js" data-settings-js="settings-de11bff964e9d4e5.js" data-settings-css="settings-8c76f75bfb6bd192.css" data-theme-light-css="light-6d2c9675f3d09c26.css" data-theme-dark-css="dark-45ceb8f2e522f4d1.css" data-theme-ayu-css="ayu-fd19013d6ce078bf.css" ><script src="../../static.files/storage-db41da1a38ea3cb8.js"></script><script defer src="../../static.files/src-script-3280b574d94e47b4.js"></script><script defer src="../../src-files.js"></script><script defer src="../../static.files/main-0795b7d26be81095.js"></script><noscript><link rel="stylesheet" media="(prefers-color-scheme:light)" href="../../static.files/light-6d2c9675f3d09c26.css"><link rel="stylesheet" media="(prefers-color-scheme:dark)" href="../../static.files/dark-45ceb8f2e522f4d1.css"><link rel="stylesheet" href="../../static.files/noscript-cffde32267a19fd6.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc src"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"></nav><main><nav class="sub"><a class="sub-logo-container" href="../../critical_section/index.html"><img class="rust-logo" src="../../static.files/rust-logo-151179464ae7ed46.svg" alt="logo"></a><form class="search-form"><span></span><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><div data-nosnippet><pre class="src-line-numbers"><a href="#1" id="1">1</a>
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</pre></div><pre class="rust"><code><span class="attr">#![cfg_attr(not(feature = <span class="string">"std"</span>), no_std)]
|
||
#![doc = <span class="macro">include_str!</span>(<span class="string">"../README.md"</span>)]
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||
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||
</span><span class="kw">mod </span>mutex;
|
||
<span class="attr">#[cfg(feature = <span class="string">"std"</span>)]
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</span><span class="kw">mod </span>std;
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||
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||
<span class="kw">use </span>core::marker::PhantomData;
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||
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||
<span class="kw">pub use </span><span class="self">self</span>::mutex::Mutex;
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||
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||
<span class="doccomment">/// Critical section token.
|
||
///
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||
/// An instance of this type indicates that the current thread is executing code within a critical
|
||
/// section.
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||
</span><span class="attr">#[derive(Clone, Copy, Debug)]
|
||
</span><span class="kw">pub struct </span>CriticalSection<<span class="lifetime">'cs</span>> {
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||
_private: PhantomData<<span class="kw-2">&</span><span class="lifetime">'cs </span>()>,
|
||
}
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||
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||
<span class="kw">impl</span><<span class="lifetime">'cs</span>> CriticalSection<<span class="lifetime">'cs</span>> {
|
||
<span class="doccomment">/// Creates a critical section token.
|
||
///
|
||
/// This method is meant to be used to create safe abstractions rather than being directly used
|
||
/// in applications.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// This must only be called when the current thread is in a critical section. The caller must
|
||
/// ensure that the returned instance will not live beyond the end of the critical section.
|
||
///
|
||
/// The caller must use adequate fences to prevent the compiler from moving the
|
||
/// instructions inside the critical section to the outside of it. Sequentially consistent fences are
|
||
/// suggested immediately after entry and immediately before exit from the critical section.
|
||
///
|
||
/// Note that the lifetime `'cs` of the returned instance is unconstrained. User code must not
|
||
/// be able to influence the lifetime picked for this type, since that might cause it to be
|
||
/// inferred to `'static`.
|
||
</span><span class="attr">#[inline(always)]
|
||
</span><span class="kw">pub unsafe fn </span>new() -> <span class="self">Self </span>{
|
||
CriticalSection {
|
||
_private: PhantomData,
|
||
}
|
||
}
|
||
}
|
||
|
||
<span class="attr">#[cfg(any(
|
||
all(feature = <span class="string">"restore-state-none"</span>, feature = <span class="string">"restore-state-bool"</span>),
|
||
all(feature = <span class="string">"restore-state-none"</span>, feature = <span class="string">"restore-state-u8"</span>),
|
||
all(feature = <span class="string">"restore-state-none"</span>, feature = <span class="string">"restore-state-u16"</span>),
|
||
all(feature = <span class="string">"restore-state-none"</span>, feature = <span class="string">"restore-state-u32"</span>),
|
||
all(feature = <span class="string">"restore-state-none"</span>, feature = <span class="string">"restore-state-u64"</span>),
|
||
all(feature = <span class="string">"restore-state-bool"</span>, feature = <span class="string">"restore-state-u8"</span>),
|
||
all(feature = <span class="string">"restore-state-bool"</span>, feature = <span class="string">"restore-state-u16"</span>),
|
||
all(feature = <span class="string">"restore-state-bool"</span>, feature = <span class="string">"restore-state-u32"</span>),
|
||
all(feature = <span class="string">"restore-state-bool"</span>, feature = <span class="string">"restore-state-u64"</span>),
|
||
all(feature = <span class="string">"restore-state-u8"</span>, feature = <span class="string">"restore-state-u16"</span>),
|
||
all(feature = <span class="string">"restore-state-u8"</span>, feature = <span class="string">"restore-state-u32"</span>),
|
||
all(feature = <span class="string">"restore-state-u8"</span>, feature = <span class="string">"restore-state-u64"</span>),
|
||
all(feature = <span class="string">"restore-state-u16"</span>, feature = <span class="string">"restore-state-u32"</span>),
|
||
all(feature = <span class="string">"restore-state-u16"</span>, feature = <span class="string">"restore-state-u64"</span>),
|
||
all(feature = <span class="string">"restore-state-u32"</span>, feature = <span class="string">"restore-state-u64"</span>),
|
||
))]
|
||
</span><span class="macro">compile_error!</span>(<span class="string">"You must set at most one of these Cargo features: restore-state-none, restore-state-bool, restore-state-u8, restore-state-u16, restore-state-u32, restore-state-u64"</span>);
|
||
|
||
<span class="attr">#[cfg(not(any(
|
||
feature = <span class="string">"restore-state-bool"</span>,
|
||
feature = <span class="string">"restore-state-u8"</span>,
|
||
feature = <span class="string">"restore-state-u16"</span>,
|
||
feature = <span class="string">"restore-state-u32"</span>,
|
||
feature = <span class="string">"restore-state-u64"
|
||
</span>)))]
|
||
</span><span class="kw">type </span>RawRestoreStateInner = ();
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-bool"</span>)]
|
||
</span><span class="kw">type </span>RawRestoreStateInner = bool;
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u8"</span>)]
|
||
</span><span class="kw">type </span>RawRestoreStateInner = u8;
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u16"</span>)]
|
||
</span><span class="kw">type </span>RawRestoreStateInner = u16;
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u32"</span>)]
|
||
</span><span class="kw">type </span>RawRestoreStateInner = u32;
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u64"</span>)]
|
||
</span><span class="kw">type </span>RawRestoreStateInner = u64;
|
||
|
||
<span class="comment">// We have RawRestoreStateInner and RawRestoreState so that we don't have to copypaste the docs 5 times.
|
||
// In the docs this shows as `pub type RawRestoreState = u8` or whatever the selected type is, because
|
||
// the "inner" type alias is private.
|
||
|
||
</span><span class="doccomment">/// Raw, transparent "restore state".
|
||
///
|
||
/// This type changes based on which Cargo feature is selected, out of
|
||
/// - `restore-state-none` (default, makes the type be `()`)
|
||
/// - `restore-state-bool`
|
||
/// - `restore-state-u8`
|
||
/// - `restore-state-u16`
|
||
/// - `restore-state-u32`
|
||
/// - `restore-state-u64`
|
||
///
|
||
/// See [`RestoreState`].
|
||
///
|
||
/// User code uses [`RestoreState`] opaquely, critical section implementations
|
||
/// use [`RawRestoreState`] so that they can use the inner value.
|
||
</span><span class="kw">pub type </span>RawRestoreState = RawRestoreStateInner;
|
||
|
||
<span class="doccomment">/// Opaque "restore state".
|
||
///
|
||
/// Implementations use this to "carry over" information between acquiring and releasing
|
||
/// a critical section. For example, when nesting two critical sections of an
|
||
/// implementation that disables interrupts globally, acquiring the inner one won't disable
|
||
/// the interrupts since they're already disabled. The impl would use the restore state to "tell"
|
||
/// the corresponding release that it does *not* have to reenable interrupts yet, only the
|
||
/// outer release should do so.
|
||
///
|
||
/// User code uses [`RestoreState`] opaquely, critical section implementations
|
||
/// use [`RawRestoreState`] so that they can use the inner value.
|
||
</span><span class="attr">#[derive(Clone, Copy, Debug)]
|
||
</span><span class="kw">pub struct </span>RestoreState(RawRestoreState);
|
||
|
||
<span class="kw">impl </span>RestoreState {
|
||
<span class="doccomment">/// Create an invalid, dummy `RestoreState`.
|
||
///
|
||
/// This can be useful to avoid `Option` when storing a `RestoreState` in a
|
||
/// struct field, or a `static`.
|
||
///
|
||
/// Note that due to the safety contract of [`acquire`]/[`release`], you must not pass
|
||
/// a `RestoreState` obtained from this method to [`release`].
|
||
</span><span class="kw">pub const fn </span>invalid() -> <span class="self">Self </span>{
|
||
<span class="attr">#[cfg(not(any(
|
||
feature = <span class="string">"restore-state-bool"</span>,
|
||
feature = <span class="string">"restore-state-u8"</span>,
|
||
feature = <span class="string">"restore-state-u16"</span>,
|
||
feature = <span class="string">"restore-state-u32"</span>,
|
||
feature = <span class="string">"restore-state-u64"
|
||
</span>)))]
|
||
</span><span class="kw">return </span><span class="self">Self</span>(());
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-bool"</span>)]
|
||
</span><span class="kw">return </span><span class="self">Self</span>(<span class="bool-val">false</span>);
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u8"</span>)]
|
||
</span><span class="kw">return </span><span class="self">Self</span>(<span class="number">0</span>);
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u16"</span>)]
|
||
</span><span class="kw">return </span><span class="self">Self</span>(<span class="number">0</span>);
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u32"</span>)]
|
||
</span><span class="kw">return </span><span class="self">Self</span>(<span class="number">0</span>);
|
||
|
||
<span class="attr">#[cfg(feature = <span class="string">"restore-state-u64"</span>)]
|
||
</span><span class="kw">return </span><span class="self">Self</span>(<span class="number">0</span>);
|
||
}
|
||
}
|
||
|
||
<span class="doccomment">/// Acquire a critical section in the current thread.
|
||
///
|
||
/// This function is extremely low level. Strongly prefer using [`with`] instead.
|
||
///
|
||
/// Nesting critical sections is allowed. The inner critical sections
|
||
/// are mostly no-ops since they're already protected by the outer one.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// - Each `acquire` call must be paired with exactly one `release` call in the same thread.
|
||
/// - `acquire` returns a "restore state" that you must pass to the corresponding `release` call.
|
||
/// - `acquire`/`release` pairs must be "properly nested", ie it's not OK to do `a=acquire(); b=acquire(); release(a); release(b);`.
|
||
/// - It is UB to call `release` if the critical section is not acquired in the current thread.
|
||
/// - It is UB to call `release` with a "restore state" that does not come from the corresponding `acquire` call.
|
||
/// - It must provide ordering guarantees at least equivalent to a [`core::sync::atomic::Ordering::Acquire`]
|
||
/// on a memory location shared by all critical sections, on which the `release` call will do a
|
||
/// [`core::sync::atomic::Ordering::Release`] operation.
|
||
</span><span class="attr">#[inline(always)]
|
||
</span><span class="kw">pub unsafe fn </span>acquire() -> RestoreState {
|
||
<span class="kw">extern </span><span class="string">"Rust" </span>{
|
||
<span class="kw">fn </span>_critical_section_1_0_acquire() -> RawRestoreState;
|
||
}
|
||
|
||
<span class="attr">#[allow(clippy::unit_arg)]
|
||
</span>RestoreState(_critical_section_1_0_acquire())
|
||
}
|
||
|
||
<span class="doccomment">/// Release the critical section.
|
||
///
|
||
/// This function is extremely low level. Strongly prefer using [`with`] instead.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// See [`acquire`] for the safety contract description.
|
||
</span><span class="attr">#[inline(always)]
|
||
</span><span class="kw">pub unsafe fn </span>release(restore_state: RestoreState) {
|
||
<span class="kw">extern </span><span class="string">"Rust" </span>{
|
||
<span class="kw">fn </span>_critical_section_1_0_release(restore_state: RawRestoreState);
|
||
}
|
||
|
||
<span class="attr">#[allow(clippy::unit_arg)]
|
||
</span>_critical_section_1_0_release(restore_state.<span class="number">0</span>)
|
||
}
|
||
|
||
<span class="doccomment">/// Execute closure `f` in a critical section.
|
||
///
|
||
/// Nesting critical sections is allowed. The inner critical sections
|
||
/// are mostly no-ops since they're already protected by the outer one.
|
||
///
|
||
/// # Panics
|
||
///
|
||
/// This function panics if the given closure `f` panics. In this case
|
||
/// the critical section is released before unwinding.
|
||
</span><span class="attr">#[inline]
|
||
</span><span class="kw">pub fn </span>with<R>(f: <span class="kw">impl </span>FnOnce(CriticalSection) -> R) -> R {
|
||
<span class="comment">// Helper for making sure `release` is called even if `f` panics.
|
||
</span><span class="kw">struct </span>Guard {
|
||
state: RestoreState,
|
||
}
|
||
|
||
<span class="kw">impl </span>Drop <span class="kw">for </span>Guard {
|
||
<span class="attr">#[inline(always)]
|
||
</span><span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) {
|
||
<span class="kw">unsafe </span>{ release(<span class="self">self</span>.state) }
|
||
}
|
||
}
|
||
|
||
<span class="kw">let </span>state = <span class="kw">unsafe </span>{ acquire() };
|
||
<span class="kw">let </span>_guard = Guard { state };
|
||
|
||
<span class="kw">unsafe </span>{ f(CriticalSection::new()) }
|
||
}
|
||
|
||
<span class="doccomment">/// Methods required for a critical section implementation.
|
||
///
|
||
/// This trait is not intended to be used except when implementing a critical section.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Implementations must uphold the contract specified in [`crate::acquire`] and [`crate::release`].
|
||
</span><span class="kw">pub unsafe trait </span>Impl {
|
||
<span class="doccomment">/// Acquire the critical section.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Callers must uphold the contract specified in [`crate::acquire`] and [`crate::release`].
|
||
</span><span class="kw">unsafe fn </span>acquire() -> RawRestoreState;
|
||
|
||
<span class="doccomment">/// Release the critical section.
|
||
///
|
||
/// # Safety
|
||
///
|
||
/// Callers must uphold the contract specified in [`crate::acquire`] and [`crate::release`].
|
||
</span><span class="kw">unsafe fn </span>release(restore_state: RawRestoreState);
|
||
}
|
||
|
||
<span class="doccomment">/// Set the critical section implementation.
|
||
///
|
||
/// # Example
|
||
///
|
||
/// ```
|
||
/// # #[cfg(not(feature = "std"))] // needed for `cargo test --features std`
|
||
/// # mod no_std {
|
||
/// use critical_section::RawRestoreState;
|
||
///
|
||
/// struct MyCriticalSection;
|
||
/// critical_section::set_impl!(MyCriticalSection);
|
||
///
|
||
/// unsafe impl critical_section::Impl for MyCriticalSection {
|
||
/// unsafe fn acquire() -> RawRestoreState {
|
||
/// // ...
|
||
/// }
|
||
///
|
||
/// unsafe fn release(restore_state: RawRestoreState) {
|
||
/// // ...
|
||
/// }
|
||
/// }
|
||
/// # }
|
||
</span><span class="attr">#[macro_export]
|
||
</span><span class="macro">macro_rules! </span>set_impl {
|
||
(<span class="macro-nonterminal">$t</span>: ty) => {
|
||
<span class="attr">#[no_mangle]
|
||
</span><span class="kw">unsafe fn </span>_critical_section_1_0_acquire() -> <span class="macro-nonterminal">$crate::RawRestoreState </span>{
|
||
<<span class="macro-nonterminal">$t </span><span class="kw">as </span><span class="macro-nonterminal">$crate::Impl</span>>::acquire()
|
||
}
|
||
<span class="attr">#[no_mangle]
|
||
</span><span class="kw">unsafe fn </span>_critical_section_1_0_release(restore_state: <span class="macro-nonterminal">$crate::RawRestoreState</span>) {
|
||
<<span class="macro-nonterminal">$t </span><span class="kw">as </span><span class="macro-nonterminal">$crate::Impl</span>>::release(restore_state)
|
||
}
|
||
};
|
||
}
|
||
</code></pre></div></section></main></body></html> |