| <!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 `/root/.cargo/git/checkouts/tokio-377c595163f99a10/dfe252d/tokio/src/sync/mutex.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mutex.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../tokio/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../tokio/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" 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="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| <span id="1020">1020</span> |
| <span id="1021">1021</span> |
| <span id="1022">1022</span> |
| <span id="1023">1023</span> |
| <span id="1024">1024</span> |
| <span id="1025">1025</span> |
| </pre><pre class="rust"><code><span class="attribute">#![cfg_attr(not(feature = <span class="string">"sync"</span>), allow(unreachable_pub, dead_code))] |
| |
| </span><span class="kw">use </span><span class="kw">crate</span>::sync::batch_semaphore <span class="kw">as </span>semaphore; |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="kw">use </span><span class="kw">crate</span>::util::trace; |
| |
| <span class="kw">use </span>std::cell::UnsafeCell; |
| <span class="kw">use </span>std::error::Error; |
| <span class="kw">use </span>std::ops::{Deref, DerefMut}; |
| <span class="kw">use </span>std::sync::Arc; |
| <span class="kw">use </span>std::{fmt, marker, mem}; |
| |
| <span class="doccomment">/// An asynchronous `Mutex`-like type. |
| /// |
| /// This type acts similarly to [`std::sync::Mutex`], with two major |
| /// differences: [`lock`] is an async method so does not block, and the lock |
| /// guard is designed to be held across `.await` points. |
| /// |
| /// # Which kind of mutex should you use? |
| /// |
| /// Contrary to popular belief, it is ok and often preferred to use the ordinary |
| /// [`Mutex`][std] from the standard library in asynchronous code. |
| /// |
| /// The feature that the async mutex offers over the blocking mutex is the |
| /// ability to keep it locked across an `.await` point. This makes the async |
| /// mutex more expensive than the blocking mutex, so the blocking mutex should |
| /// be preferred in the cases where it can be used. The primary use case for the |
| /// async mutex is to provide shared mutable access to IO resources such as a |
| /// database connection. If the value behind the mutex is just data, it's |
| /// usually appropriate to use a blocking mutex such as the one in the standard |
| /// library or [`parking_lot`]. |
| /// |
| /// Note that, although the compiler will not prevent the std `Mutex` from holding |
| /// its guard across `.await` points in situations where the task is not movable |
| /// between threads, this virtually never leads to correct concurrent code in |
| /// practice as it can easily lead to deadlocks. |
| /// |
| /// A common pattern is to wrap the `Arc<Mutex<...>>` in a struct that provides |
| /// non-async methods for performing operations on the data within, and only |
| /// lock the mutex inside these methods. The [mini-redis] example provides an |
| /// illustration of this pattern. |
| /// |
| /// Additionally, when you _do_ want shared access to an IO resource, it is |
| /// often better to spawn a task to manage the IO resource, and to use message |
| /// passing to communicate with that task. |
| /// |
| /// [std]: std::sync::Mutex |
| /// [`parking_lot`]: https://docs.rs/parking_lot |
| /// [mini-redis]: https://github.com/tokio-rs/mini-redis/blob/master/src/db.rs |
| /// |
| /// # Examples: |
| /// |
| /// ```rust,no_run |
| /// use tokio::sync::Mutex; |
| /// use std::sync::Arc; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let data1 = Arc::new(Mutex::new(0)); |
| /// let data2 = Arc::clone(&data1); |
| /// |
| /// tokio::spawn(async move { |
| /// let mut lock = data2.lock().await; |
| /// *lock += 1; |
| /// }); |
| /// |
| /// let mut lock = data1.lock().await; |
| /// *lock += 1; |
| /// } |
| /// ``` |
| /// |
| /// |
| /// ```rust,no_run |
| /// use tokio::sync::Mutex; |
| /// use std::sync::Arc; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let count = Arc::new(Mutex::new(0)); |
| /// |
| /// for i in 0..5 { |
| /// let my_count = Arc::clone(&count); |
| /// tokio::spawn(async move { |
| /// for j in 0..10 { |
| /// let mut lock = my_count.lock().await; |
| /// *lock += 1; |
| /// println!("{} {} {}", i, j, lock); |
| /// } |
| /// }); |
| /// } |
| /// |
| /// loop { |
| /// if *count.lock().await >= 50 { |
| /// break; |
| /// } |
| /// } |
| /// println!("Count hit 50."); |
| /// } |
| /// ``` |
| /// There are a few things of note here to pay attention to in this example. |
| /// 1. The mutex is wrapped in an [`Arc`] to allow it to be shared across |
| /// threads. |
| /// 2. Each spawned task obtains a lock and releases it on every iteration. |
| /// 3. Mutation of the data protected by the Mutex is done by de-referencing |
| /// the obtained lock as seen on lines 12 and 19. |
| /// |
| /// Tokio's Mutex works in a simple FIFO (first in, first out) style where all |
| /// calls to [`lock`] complete in the order they were performed. In that way the |
| /// Mutex is "fair" and predictable in how it distributes the locks to inner |
| /// data. Locks are released and reacquired after every iteration, so basically, |
| /// each thread goes to the back of the line after it increments the value once. |
| /// Note that there's some unpredictability to the timing between when the |
| /// threads are started, but once they are going they alternate predictably. |
| /// Finally, since there is only a single valid lock at any given time, there is |
| /// no possibility of a race condition when mutating the inner value. |
| /// |
| /// Note that in contrast to [`std::sync::Mutex`], this implementation does not |
| /// poison the mutex when a thread holding the [`MutexGuard`] panics. In such a |
| /// case, the mutex will be unlocked. If the panic is caught, this might leave |
| /// the data protected by the mutex in an inconsistent state. |
| /// |
| /// [`Mutex`]: struct@Mutex |
| /// [`MutexGuard`]: struct@MutexGuard |
| /// [`Arc`]: struct@std::sync::Arc |
| /// [`std::sync::Mutex`]: struct@std::sync::Mutex |
| /// [`Send`]: trait@std::marker::Send |
| /// [`lock`]: method@Mutex::lock |
| </span><span class="kw">pub struct </span>Mutex<T: <span class="question-mark">?</span>Sized> { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span: tracing::Span, |
| s: semaphore::Semaphore, |
| c: UnsafeCell<T>, |
| } |
| |
| <span class="doccomment">/// A handle to a held `Mutex`. The guard can be held across any `.await` point |
| /// as it is [`Send`]. |
| /// |
| /// As long as you have this guard, you have exclusive access to the underlying |
| /// `T`. The guard internally borrows the `Mutex`, so the mutex will not be |
| /// dropped while a guard exists. |
| /// |
| /// The lock is automatically released whenever the guard is dropped, at which |
| /// point `lock` will succeed yet again. |
| </span><span class="attribute">#[must_use = <span class="string">"if unused the Mutex will immediately unlock"</span>] |
| </span><span class="kw">pub struct </span>MutexGuard<<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span: tracing::Span, |
| lock: <span class="kw-2">&</span><span class="lifetime">'a </span>Mutex<T>, |
| } |
| |
| <span class="doccomment">/// An owned handle to a held `Mutex`. |
| /// |
| /// This guard is only available from a `Mutex` that is wrapped in an [`Arc`]. It |
| /// is identical to `MutexGuard`, except that rather than borrowing the `Mutex`, |
| /// it clones the `Arc`, incrementing the reference count. This means that |
| /// unlike `MutexGuard`, it will have the `'static` lifetime. |
| /// |
| /// As long as you have this guard, you have exclusive access to the underlying |
| /// `T`. The guard internally keeps a reference-counted pointer to the original |
| /// `Mutex`, so even if the lock goes away, the guard remains valid. |
| /// |
| /// The lock is automatically released whenever the guard is dropped, at which |
| /// point `lock` will succeed yet again. |
| /// |
| /// [`Arc`]: std::sync::Arc |
| </span><span class="kw">pub struct </span>OwnedMutexGuard<T: <span class="question-mark">?</span>Sized> { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span: tracing::Span, |
| lock: Arc<Mutex<T>>, |
| } |
| |
| <span class="doccomment">/// A handle to a held `Mutex` that has had a function applied to it via [`MutexGuard::map`]. |
| /// |
| /// This can be used to hold a subfield of the protected data. |
| /// |
| /// [`MutexGuard::map`]: method@MutexGuard::map |
| </span><span class="attribute">#[must_use = <span class="string">"if unused the Mutex will immediately unlock"</span>] |
| </span><span class="kw">pub struct </span>MappedMutexGuard<<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> { |
| s: <span class="kw-2">&</span><span class="lifetime">'a </span>semaphore::Semaphore, |
| data: <span class="kw-2">*mut </span>T, |
| <span class="comment">// Needed to tell the borrow checker that we are holding a `&mut T` |
| </span>marker: marker::PhantomData<<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>T>, |
| } |
| |
| <span class="comment">// As long as T: Send, it's fine to send and share Mutex<T> between threads. |
| // If T was not Send, sending and sharing a Mutex<T> would be bad, since you can |
| // access T through Mutex<T>. |
| </span><span class="kw">unsafe impl</span><T> Send <span class="kw">for </span>Mutex<T> <span class="kw">where </span>T: <span class="question-mark">?</span>Sized + Send {} |
| <span class="kw">unsafe impl</span><T> Sync <span class="kw">for </span>Mutex<T> <span class="kw">where </span>T: <span class="question-mark">?</span>Sized + Send {} |
| <span class="kw">unsafe impl</span><T> Sync <span class="kw">for </span>MutexGuard<<span class="lifetime">'_</span>, T> <span class="kw">where </span>T: <span class="question-mark">?</span>Sized + Send + Sync {} |
| <span class="kw">unsafe impl</span><T> Sync <span class="kw">for </span>OwnedMutexGuard<T> <span class="kw">where </span>T: <span class="question-mark">?</span>Sized + Send + Sync {} |
| <span class="kw">unsafe impl</span><<span class="lifetime">'a</span>, T> Sync <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> <span class="kw">where </span>T: <span class="question-mark">?</span>Sized + Sync + <span class="lifetime">'a </span>{} |
| <span class="kw">unsafe impl</span><<span class="lifetime">'a</span>, T> Send <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> <span class="kw">where </span>T: <span class="question-mark">?</span>Sized + Send + <span class="lifetime">'a </span>{} |
| |
| <span class="doccomment">/// Error returned from the [`Mutex::try_lock`], [`RwLock::try_read`] and |
| /// [`RwLock::try_write`] functions. |
| /// |
| /// `Mutex::try_lock` operation will only fail if the mutex is already locked. |
| /// |
| /// `RwLock::try_read` operation will only fail if the lock is currently held |
| /// by an exclusive writer. |
| /// |
| /// `RwLock::try_write` operation will only fail if the lock is currently held |
| /// by any reader or by an exclusive writer. |
| /// |
| /// [`Mutex::try_lock`]: Mutex::try_lock |
| /// [`RwLock::try_read`]: fn@super::RwLock::try_read |
| /// [`RwLock::try_write`]: fn@super::RwLock::try_write |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>TryLockError(<span class="kw">pub</span>(<span class="kw">super</span>) ()); |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>TryLockError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, fmt: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="macro">write!</span>(fmt, <span class="string">"operation would block"</span>) |
| } |
| } |
| |
| <span class="kw">impl </span>Error <span class="kw">for </span>TryLockError {} |
| |
| <span class="attribute">#[test] |
| #[cfg(not(loom))] |
| </span><span class="kw">fn </span>bounds() { |
| <span class="kw">fn </span>check_send<T: Send>() {} |
| <span class="kw">fn </span>check_unpin<T: Unpin>() {} |
| <span class="comment">// This has to take a value, since the async fn's return type is unnameable. |
| </span><span class="kw">fn </span>check_send_sync_val<T: Send + Sync>(_t: T) {} |
| <span class="kw">fn </span>check_send_sync<T: Send + Sync>() {} |
| <span class="kw">fn </span>check_static<T: <span class="lifetime">'static</span>>() {} |
| <span class="kw">fn </span>check_static_val<T: <span class="lifetime">'static</span>>(_t: T) {} |
| |
| check_send::<MutexGuard<<span class="lifetime">'_</span>, u32>>(); |
| check_send::<OwnedMutexGuard<u32>>(); |
| check_unpin::<Mutex<u32>>(); |
| check_send_sync::<Mutex<u32>>(); |
| check_static::<OwnedMutexGuard<u32>>(); |
| |
| <span class="kw">let </span>mutex = Mutex::new(<span class="number">1</span>); |
| check_send_sync_val(mutex.lock()); |
| <span class="kw">let </span>arc_mutex = Arc::new(Mutex::new(<span class="number">1</span>)); |
| check_send_sync_val(arc_mutex.clone().lock_owned()); |
| check_static_val(arc_mutex.lock_owned()); |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> Mutex<T> { |
| <span class="doccomment">/// Creates a new lock in an unlocked state ready for use. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// |
| /// let lock = Mutex::new(5); |
| /// ``` |
| </span><span class="attribute">#[track_caller] |
| </span><span class="kw">pub fn </span>new(t: T) -> <span class="self">Self |
| </span><span class="kw">where |
| </span>T: Sized, |
| { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="kw">let </span>resource_span = { |
| <span class="kw">let </span>location = std::panic::Location::caller(); |
| |
| <span class="macro">tracing::trace_span!</span>( |
| <span class="string">"runtime.resource"</span>, |
| concrete_type = <span class="string">"Mutex"</span>, |
| kind = <span class="string">"Sync"</span>, |
| loc.file = location.file(), |
| loc.line = location.line(), |
| loc.col = location.column(), |
| ) |
| }; |
| |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="kw">let </span>s = resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">false</span>, |
| ); |
| semaphore::Semaphore::new(<span class="number">1</span>) |
| }); |
| |
| <span class="attribute">#[cfg(any(not(tokio_unstable), not(feature = <span class="string">"tracing"</span>)))] |
| </span><span class="kw">let </span>s = semaphore::Semaphore::new(<span class="number">1</span>); |
| |
| <span class="self">Self </span>{ |
| c: UnsafeCell::new(t), |
| s, |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span, |
| } |
| } |
| |
| <span class="doccomment">/// Creates a new lock in an unlocked state ready for use. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// |
| /// static LOCK: Mutex<i32> = Mutex::const_new(5); |
| /// ``` |
| </span><span class="attribute">#[cfg(all(feature = <span class="string">"parking_lot"</span>, not(all(loom, test)),))] |
| #[cfg_attr(docsrs, doc(cfg(feature = <span class="string">"parking_lot"</span>)))] |
| </span><span class="kw">pub const fn </span>const_new(t: T) -> <span class="self">Self |
| </span><span class="kw">where |
| </span>T: Sized, |
| { |
| <span class="self">Self </span>{ |
| c: UnsafeCell::new(t), |
| s: semaphore::Semaphore::const_new(<span class="number">1</span>), |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span: tracing::Span::none(), |
| } |
| } |
| |
| <span class="doccomment">/// Locks this mutex, causing the current task to yield until the lock has |
| /// been acquired. When the lock has been acquired, function returns a |
| /// [`MutexGuard`]. |
| /// |
| /// # Cancel safety |
| /// |
| /// This method uses a queue to fairly distribute locks in the order they |
| /// were requested. Cancelling a call to `lock` makes you lose your place in |
| /// the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mutex = Mutex::new(1); |
| /// |
| /// let mut n = mutex.lock().await; |
| /// *n = 2; |
| /// } |
| /// ``` |
| </span><span class="kw">pub async fn </span>lock(<span class="kw-2">&</span><span class="self">self</span>) -> MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>trace::async_op( |
| || <span class="self">self</span>.acquire(), |
| <span class="self">self</span>.resource_span.clone(), |
| <span class="string">"Mutex::lock"</span>, |
| <span class="string">"poll"</span>, |
| <span class="bool-val">false</span>, |
| ) |
| .<span class="kw">await</span>; |
| |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="self">self</span>.resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">true</span>, |
| ); |
| }); |
| |
| <span class="attribute">#[cfg(any(not(tokio_unstable), not(feature = <span class="string">"tracing"</span>)))] |
| </span><span class="self">self</span>.acquire().<span class="kw">await</span>; |
| |
| MutexGuard { |
| lock: <span class="self">self</span>, |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span: <span class="self">self</span>.resource_span.clone(), |
| } |
| } |
| |
| <span class="doccomment">/// Blockingly locks this `Mutex`. When the lock has been acquired, function returns a |
| /// [`MutexGuard`]. |
| /// |
| /// This method is intended for use cases where you |
| /// need to use this mutex in asynchronous code as well as in synchronous code. |
| /// |
| /// # Panics |
| /// |
| /// This function panics if called within an asynchronous execution context. |
| /// |
| /// - If you find yourself in an asynchronous execution context and needing |
| /// to call some (synchronous) function which performs one of these |
| /// `blocking_` operations, then consider wrapping that call inside |
| /// [`spawn_blocking()`][crate::runtime::Handle::spawn_blocking] |
| /// (or [`block_in_place()`][crate::task::block_in_place]). |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::Arc; |
| /// use tokio::sync::Mutex; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mutex = Arc::new(Mutex::new(1)); |
| /// let lock = mutex.lock().await; |
| /// |
| /// let mutex1 = Arc::clone(&mutex); |
| /// let blocking_task = tokio::task::spawn_blocking(move || { |
| /// // This shall block until the `lock` is released. |
| /// let mut n = mutex1.blocking_lock(); |
| /// *n = 2; |
| /// }); |
| /// |
| /// assert_eq!(*lock, 1); |
| /// // Release the lock. |
| /// drop(lock); |
| /// |
| /// // Await the completion of the blocking task. |
| /// blocking_task.await.unwrap(); |
| /// |
| /// // Assert uncontended. |
| /// let n = mutex.try_lock().unwrap(); |
| /// assert_eq!(*n, 2); |
| /// } |
| /// |
| /// ``` |
| </span><span class="attribute">#[track_caller] |
| #[cfg(feature = <span class="string">"sync"</span>)] |
| </span><span class="kw">pub fn </span>blocking_lock(<span class="kw-2">&</span><span class="self">self</span>) -> MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="kw">crate</span>::future::block_on(<span class="self">self</span>.lock()) |
| } |
| |
| <span class="doccomment">/// Blockingly locks this `Mutex`. When the lock has been acquired, function returns an |
| /// [`OwnedMutexGuard`]. |
| /// |
| /// This method is identical to [`Mutex::blocking_lock`], except that the returned |
| /// guard references the `Mutex` with an [`Arc`] rather than by borrowing |
| /// it. Therefore, the `Mutex` must be wrapped in an `Arc` to call this |
| /// method, and the guard will live for the `'static` lifetime, as it keeps |
| /// the `Mutex` alive by holding an `Arc`. |
| /// |
| /// # Panics |
| /// |
| /// This function panics if called within an asynchronous execution context. |
| /// |
| /// - If you find yourself in an asynchronous execution context and needing |
| /// to call some (synchronous) function which performs one of these |
| /// `blocking_` operations, then consider wrapping that call inside |
| /// [`spawn_blocking()`][crate::runtime::Handle::spawn_blocking] |
| /// (or [`block_in_place()`][crate::task::block_in_place]). |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use std::sync::Arc; |
| /// use tokio::sync::Mutex; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mutex = Arc::new(Mutex::new(1)); |
| /// let lock = mutex.lock().await; |
| /// |
| /// let mutex1 = Arc::clone(&mutex); |
| /// let blocking_task = tokio::task::spawn_blocking(move || { |
| /// // This shall block until the `lock` is released. |
| /// let mut n = mutex1.blocking_lock_owned(); |
| /// *n = 2; |
| /// }); |
| /// |
| /// assert_eq!(*lock, 1); |
| /// // Release the lock. |
| /// drop(lock); |
| /// |
| /// // Await the completion of the blocking task. |
| /// blocking_task.await.unwrap(); |
| /// |
| /// // Assert uncontended. |
| /// let n = mutex.try_lock().unwrap(); |
| /// assert_eq!(*n, 2); |
| /// } |
| /// |
| /// ``` |
| </span><span class="attribute">#[track_caller] |
| #[cfg(feature = <span class="string">"sync"</span>)] |
| </span><span class="kw">pub fn </span>blocking_lock_owned(<span class="self">self</span>: Arc<<span class="self">Self</span>>) -> OwnedMutexGuard<T> { |
| <span class="kw">crate</span>::future::block_on(<span class="self">self</span>.lock_owned()) |
| } |
| |
| <span class="doccomment">/// Locks this mutex, causing the current task to yield until the lock has |
| /// been acquired. When the lock has been acquired, this returns an |
| /// [`OwnedMutexGuard`]. |
| /// |
| /// This method is identical to [`Mutex::lock`], except that the returned |
| /// guard references the `Mutex` with an [`Arc`] rather than by borrowing |
| /// it. Therefore, the `Mutex` must be wrapped in an `Arc` to call this |
| /// method, and the guard will live for the `'static` lifetime, as it keeps |
| /// the `Mutex` alive by holding an `Arc`. |
| /// |
| /// # Cancel safety |
| /// |
| /// This method uses a queue to fairly distribute locks in the order they |
| /// were requested. Cancelling a call to `lock_owned` makes you lose your |
| /// place in the queue. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// use std::sync::Arc; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mutex = Arc::new(Mutex::new(1)); |
| /// |
| /// let mut n = mutex.clone().lock_owned().await; |
| /// *n = 2; |
| /// } |
| /// ``` |
| /// |
| /// [`Arc`]: std::sync::Arc |
| </span><span class="kw">pub async fn </span>lock_owned(<span class="self">self</span>: Arc<<span class="self">Self</span>>) -> OwnedMutexGuard<T> { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>trace::async_op( |
| || <span class="self">self</span>.acquire(), |
| <span class="self">self</span>.resource_span.clone(), |
| <span class="string">"Mutex::lock_owned"</span>, |
| <span class="string">"poll"</span>, |
| <span class="bool-val">false</span>, |
| ) |
| .<span class="kw">await</span>; |
| |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="self">self</span>.resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">true</span>, |
| ); |
| }); |
| |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="kw">let </span>resource_span = <span class="self">self</span>.resource_span.clone(); |
| |
| <span class="attribute">#[cfg(any(not(tokio_unstable), not(feature = <span class="string">"tracing"</span>)))] |
| </span><span class="self">self</span>.acquire().<span class="kw">await</span>; |
| |
| OwnedMutexGuard { |
| lock: <span class="self">self</span>, |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span, |
| } |
| } |
| |
| <span class="kw">async fn </span>acquire(<span class="kw-2">&</span><span class="self">self</span>) { |
| <span class="self">self</span>.s.acquire(<span class="number">1</span>).<span class="kw">await</span>.unwrap_or_else(|<span class="kw">_</span>| { |
| <span class="comment">// The semaphore was closed. but, we never explicitly close it, and |
| // we own it exclusively, which means that this can never happen. |
| </span><span class="macro">unreachable!</span>() |
| }); |
| } |
| |
| <span class="doccomment">/// Attempts to acquire the lock, and returns [`TryLockError`] if the |
| /// lock is currently held somewhere else. |
| /// |
| /// [`TryLockError`]: TryLockError |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// # async fn dox() -> Result<(), tokio::sync::TryLockError> { |
| /// |
| /// let mutex = Mutex::new(1); |
| /// |
| /// let n = mutex.try_lock()?; |
| /// assert_eq!(*n, 1); |
| /// # Ok(()) |
| /// # } |
| /// ``` |
| </span><span class="kw">pub fn </span>try_lock(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Result</span><MutexGuard<<span class="lifetime">'_</span>, T>, TryLockError> { |
| <span class="kw">match </span><span class="self">self</span>.s.try_acquire(<span class="number">1</span>) { |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="self">self</span>.resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">true</span>, |
| ); |
| }); |
| |
| <span class="prelude-val">Ok</span>(MutexGuard { |
| lock: <span class="self">self</span>, |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span: <span class="self">self</span>.resource_span.clone(), |
| }) |
| } |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="prelude-val">Err</span>(TryLockError(())), |
| } |
| } |
| |
| <span class="doccomment">/// Returns a mutable reference to the underlying data. |
| /// |
| /// Since this call borrows the `Mutex` mutably, no actual locking needs to |
| /// take place -- the mutable borrow statically guarantees no locks exist. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// |
| /// fn main() { |
| /// let mut mutex = Mutex::new(1); |
| /// |
| /// let n = mutex.get_mut(); |
| /// *n = 2; |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>get_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span>T { |
| <span class="kw">unsafe </span>{ |
| <span class="comment">// Safety: This is https://github.com/rust-lang/rust/pull/76936 |
| </span><span class="kw-2">&mut *</span><span class="self">self</span>.c.get() |
| } |
| } |
| |
| <span class="doccomment">/// Attempts to acquire the lock, and returns [`TryLockError`] if the lock |
| /// is currently held somewhere else. |
| /// |
| /// This method is identical to [`Mutex::try_lock`], except that the |
| /// returned guard references the `Mutex` with an [`Arc`] rather than by |
| /// borrowing it. Therefore, the `Mutex` must be wrapped in an `Arc` to call |
| /// this method, and the guard will live for the `'static` lifetime, as it |
| /// keeps the `Mutex` alive by holding an `Arc`. |
| /// |
| /// [`TryLockError`]: TryLockError |
| /// [`Arc`]: std::sync::Arc |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// use std::sync::Arc; |
| /// # async fn dox() -> Result<(), tokio::sync::TryLockError> { |
| /// |
| /// let mutex = Arc::new(Mutex::new(1)); |
| /// |
| /// let n = mutex.clone().try_lock_owned()?; |
| /// assert_eq!(*n, 1); |
| /// # Ok(()) |
| /// # } |
| </span><span class="kw">pub fn </span>try_lock_owned(<span class="self">self</span>: Arc<<span class="self">Self</span>>) -> <span class="prelude-ty">Result</span><OwnedMutexGuard<T>, TryLockError> { |
| <span class="kw">match </span><span class="self">self</span>.s.try_acquire(<span class="number">1</span>) { |
| <span class="prelude-val">Ok</span>(<span class="kw">_</span>) => { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="self">self</span>.resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">true</span>, |
| ); |
| }); |
| |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="kw">let </span>resource_span = <span class="self">self</span>.resource_span.clone(); |
| |
| <span class="prelude-val">Ok</span>(OwnedMutexGuard { |
| lock: <span class="self">self</span>, |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span>resource_span, |
| }) |
| } |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => <span class="prelude-val">Err</span>(TryLockError(())), |
| } |
| } |
| |
| <span class="doccomment">/// Consumes the mutex, returning the underlying data. |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::Mutex; |
| /// |
| /// #[tokio::main] |
| /// async fn main() { |
| /// let mutex = Mutex::new(1); |
| /// |
| /// let n = mutex.into_inner(); |
| /// assert_eq!(n, 1); |
| /// } |
| /// ``` |
| </span><span class="kw">pub fn </span>into_inner(<span class="self">self</span>) -> T |
| <span class="kw">where |
| </span>T: Sized, |
| { |
| <span class="self">self</span>.c.into_inner() |
| } |
| } |
| |
| <span class="kw">impl</span><T> From<T> <span class="kw">for </span>Mutex<T> { |
| <span class="kw">fn </span>from(s: T) -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new(s) |
| } |
| } |
| |
| <span class="kw">impl</span><T> Default <span class="kw">for </span>Mutex<T> |
| <span class="kw">where |
| </span>T: Default, |
| { |
| <span class="kw">fn </span>default() -> <span class="self">Self </span>{ |
| <span class="self">Self</span>::new(T::default()) |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> std::fmt::Debug <span class="kw">for </span>Mutex<T> |
| <span class="kw">where |
| </span>T: std::fmt::Debug, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>std::fmt::Formatter<<span class="lifetime">'_</span>>) -> std::fmt::Result { |
| <span class="kw">let </span><span class="kw-2">mut </span>d = f.debug_struct(<span class="string">"Mutex"</span>); |
| <span class="kw">match </span><span class="self">self</span>.try_lock() { |
| <span class="prelude-val">Ok</span>(inner) => d.field(<span class="string">"data"</span>, &&<span class="kw-2">*</span>inner), |
| <span class="prelude-val">Err</span>(<span class="kw">_</span>) => d.field(<span class="string">"data"</span>, <span class="kw-2">&</span><span class="macro">format_args!</span>(<span class="string">"<locked>"</span>)), |
| }; |
| d.finish() |
| } |
| } |
| |
| <span class="comment">// === impl MutexGuard === |
| |
| </span><span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> MutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="doccomment">/// Makes a new [`MappedMutexGuard`] for a component of the locked data. |
| /// |
| /// This operation cannot fail as the [`MutexGuard`] passed in already locked the mutex. |
| /// |
| /// This is an associated function that needs to be used as `MutexGuard::map(...)`. A method |
| /// would interfere with methods of the same name on the contents of the locked data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::{Mutex, MutexGuard}; |
| /// |
| /// #[derive(Debug, Clone, Copy, PartialEq, Eq)] |
| /// struct Foo(u32); |
| /// |
| /// # #[tokio::main] |
| /// # async fn main() { |
| /// let foo = Mutex::new(Foo(1)); |
| /// |
| /// { |
| /// let mut mapped = MutexGuard::map(foo.lock().await, |f| &mut f.0); |
| /// *mapped = 2; |
| /// } |
| /// |
| /// assert_eq!(Foo(2), *foo.lock().await); |
| /// # } |
| /// ``` |
| /// |
| /// [`MutexGuard`]: struct@MutexGuard |
| /// [`MappedMutexGuard`]: struct@MappedMutexGuard |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>map<U, F>(<span class="kw-2">mut </span>this: <span class="self">Self</span>, f: F) -> MappedMutexGuard<<span class="lifetime">'a</span>, U> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&mut </span>T) -> <span class="kw-2">&mut </span>U, |
| { |
| <span class="kw">let </span>data = f(<span class="kw-2">&mut *</span>this) <span class="kw">as </span><span class="kw-2">*mut </span>U; |
| <span class="kw">let </span>s = <span class="kw-2">&</span>this.lock.s; |
| mem::forget(this); |
| MappedMutexGuard { |
| s, |
| data, |
| marker: marker::PhantomData, |
| } |
| } |
| |
| <span class="doccomment">/// Attempts to make a new [`MappedMutexGuard`] for a component of the locked data. The |
| /// original guard is returned if the closure returns `None`. |
| /// |
| /// This operation cannot fail as the [`MutexGuard`] passed in already locked the mutex. |
| /// |
| /// This is an associated function that needs to be used as `MutexGuard::try_map(...)`. A |
| /// method would interfere with methods of the same name on the contents of the locked data. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use tokio::sync::{Mutex, MutexGuard}; |
| /// |
| /// #[derive(Debug, Clone, Copy, PartialEq, Eq)] |
| /// struct Foo(u32); |
| /// |
| /// # #[tokio::main] |
| /// # async fn main() { |
| /// let foo = Mutex::new(Foo(1)); |
| /// |
| /// { |
| /// let mut mapped = MutexGuard::try_map(foo.lock().await, |f| Some(&mut f.0)) |
| /// .expect("should not fail"); |
| /// *mapped = 2; |
| /// } |
| /// |
| /// assert_eq!(Foo(2), *foo.lock().await); |
| /// # } |
| /// ``` |
| /// |
| /// [`MutexGuard`]: struct@MutexGuard |
| /// [`MappedMutexGuard`]: struct@MappedMutexGuard |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>try_map<U, F>(<span class="kw-2">mut </span>this: <span class="self">Self</span>, f: F) -> <span class="prelude-ty">Result</span><MappedMutexGuard<<span class="lifetime">'a</span>, U>, <span class="self">Self</span>> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&mut </span>T) -> <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>U>, |
| { |
| <span class="kw">let </span>data = <span class="kw">match </span>f(<span class="kw-2">&mut *</span>this) { |
| <span class="prelude-val">Some</span>(data) => data <span class="kw">as </span><span class="kw-2">*mut </span>U, |
| <span class="prelude-val">None </span>=> <span class="kw">return </span><span class="prelude-val">Err</span>(this), |
| }; |
| <span class="kw">let </span>s = <span class="kw-2">&</span>this.lock.s; |
| mem::forget(this); |
| <span class="prelude-val">Ok</span>(MappedMutexGuard { |
| s, |
| data, |
| marker: marker::PhantomData, |
| }) |
| } |
| |
| <span class="doccomment">/// Returns a reference to the original `Mutex`. |
| /// |
| /// ``` |
| /// use tokio::sync::{Mutex, MutexGuard}; |
| /// |
| /// async fn unlock_and_relock<'l>(guard: MutexGuard<'l, u32>) -> MutexGuard<'l, u32> { |
| /// println!("1. contains: {:?}", *guard); |
| /// let mutex = MutexGuard::mutex(&guard); |
| /// drop(guard); |
| /// let guard = mutex.lock().await; |
| /// println!("2. contains: {:?}", *guard); |
| /// guard |
| /// } |
| /// # |
| /// # #[tokio::main] |
| /// # async fn main() { |
| /// # let mutex = Mutex::new(0u32); |
| /// # let guard = mutex.lock().await; |
| /// # let _guard = unlock_and_relock(guard).await; |
| /// # } |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>mutex(this: <span class="kw-2">&</span><span class="self">Self</span>) -> <span class="kw-2">&</span><span class="lifetime">'a </span>Mutex<T> { |
| this.lock |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> Drop <span class="kw">for </span>MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="self">self</span>.resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">false</span>, |
| ); |
| }); |
| <span class="self">self</span>.lock.s.release(<span class="number">1</span>); |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> Deref <span class="kw">for </span>MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="kw">type </span>Target = T; |
| <span class="kw">fn </span>deref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="self">Self</span>::Target { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&*</span><span class="self">self</span>.lock.c.get() } |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> DerefMut <span class="kw">for </span>MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>deref_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self</span>::Target { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span><span class="self">self</span>.lock.c.get() } |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized + fmt::Debug> fmt::Debug <span class="kw">for </span>MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt::Debug::fmt(<span class="kw-2">&**</span><span class="self">self</span>, f) |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized + fmt::Display> fmt::Display <span class="kw">for </span>MutexGuard<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt::Display::fmt(<span class="kw-2">&**</span><span class="self">self</span>, f) |
| } |
| } |
| |
| <span class="comment">// === impl OwnedMutexGuard === |
| |
| </span><span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> OwnedMutexGuard<T> { |
| <span class="doccomment">/// Returns a reference to the original `Arc<Mutex>`. |
| /// |
| /// ``` |
| /// use std::sync::Arc; |
| /// use tokio::sync::{Mutex, OwnedMutexGuard}; |
| /// |
| /// async fn unlock_and_relock(guard: OwnedMutexGuard<u32>) -> OwnedMutexGuard<u32> { |
| /// println!("1. contains: {:?}", *guard); |
| /// let mutex: Arc<Mutex<u32>> = OwnedMutexGuard::mutex(&guard).clone(); |
| /// drop(guard); |
| /// let guard = mutex.lock_owned().await; |
| /// println!("2. contains: {:?}", *guard); |
| /// guard |
| /// } |
| /// # |
| /// # #[tokio::main] |
| /// # async fn main() { |
| /// # let mutex = Arc::new(Mutex::new(0u32)); |
| /// # let guard = mutex.lock_owned().await; |
| /// # unlock_and_relock(guard).await; |
| /// # } |
| /// ``` |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>mutex(this: <span class="kw-2">&</span><span class="self">Self</span>) -> <span class="kw-2">&</span>Arc<Mutex<T>> { |
| <span class="kw-2">&</span>this.lock |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> Drop <span class="kw">for </span>OwnedMutexGuard<T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">"tracing"</span>))] |
| </span><span class="self">self</span>.resource_span.in_scope(|| { |
| <span class="macro">tracing::trace!</span>( |
| target: <span class="string">"runtime::resource::state_update"</span>, |
| locked = <span class="bool-val">false</span>, |
| ); |
| }); |
| <span class="self">self</span>.lock.s.release(<span class="number">1</span>) |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> Deref <span class="kw">for </span>OwnedMutexGuard<T> { |
| <span class="kw">type </span>Target = T; |
| <span class="kw">fn </span>deref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="self">Self</span>::Target { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&*</span><span class="self">self</span>.lock.c.get() } |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized> DerefMut <span class="kw">for </span>OwnedMutexGuard<T> { |
| <span class="kw">fn </span>deref_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self</span>::Target { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span><span class="self">self</span>.lock.c.get() } |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized + fmt::Debug> fmt::Debug <span class="kw">for </span>OwnedMutexGuard<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt::Debug::fmt(<span class="kw-2">&**</span><span class="self">self</span>, f) |
| } |
| } |
| |
| <span class="kw">impl</span><T: <span class="question-mark">?</span>Sized + fmt::Display> fmt::Display <span class="kw">for </span>OwnedMutexGuard<T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt::Display::fmt(<span class="kw-2">&**</span><span class="self">self</span>, f) |
| } |
| } |
| |
| <span class="comment">// === impl MappedMutexGuard === |
| |
| </span><span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> MappedMutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="doccomment">/// Makes a new [`MappedMutexGuard`] for a component of the locked data. |
| /// |
| /// This operation cannot fail as the [`MappedMutexGuard`] passed in already locked the mutex. |
| /// |
| /// This is an associated function that needs to be used as `MappedMutexGuard::map(...)`. A |
| /// method would interfere with methods of the same name on the contents of the locked data. |
| /// |
| /// [`MappedMutexGuard`]: struct@MappedMutexGuard |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>map<U, F>(<span class="kw-2">mut </span>this: <span class="self">Self</span>, f: F) -> MappedMutexGuard<<span class="lifetime">'a</span>, U> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&mut </span>T) -> <span class="kw-2">&mut </span>U, |
| { |
| <span class="kw">let </span>data = f(<span class="kw-2">&mut *</span>this) <span class="kw">as </span><span class="kw-2">*mut </span>U; |
| <span class="kw">let </span>s = this.s; |
| mem::forget(this); |
| MappedMutexGuard { |
| s, |
| data, |
| marker: marker::PhantomData, |
| } |
| } |
| |
| <span class="doccomment">/// Attempts to make a new [`MappedMutexGuard`] for a component of the locked data. The |
| /// original guard is returned if the closure returns `None`. |
| /// |
| /// This operation cannot fail as the [`MappedMutexGuard`] passed in already locked the mutex. |
| /// |
| /// This is an associated function that needs to be used as `MappedMutexGuard::try_map(...)`. A |
| /// method would interfere with methods of the same name on the contents of the locked data. |
| /// |
| /// [`MappedMutexGuard`]: struct@MappedMutexGuard |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>try_map<U, F>(<span class="kw-2">mut </span>this: <span class="self">Self</span>, f: F) -> <span class="prelude-ty">Result</span><MappedMutexGuard<<span class="lifetime">'a</span>, U>, <span class="self">Self</span>> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&mut </span>T) -> <span class="prelude-ty">Option</span><<span class="kw-2">&mut </span>U>, |
| { |
| <span class="kw">let </span>data = <span class="kw">match </span>f(<span class="kw-2">&mut *</span>this) { |
| <span class="prelude-val">Some</span>(data) => data <span class="kw">as </span><span class="kw-2">*mut </span>U, |
| <span class="prelude-val">None </span>=> <span class="kw">return </span><span class="prelude-val">Err</span>(this), |
| }; |
| <span class="kw">let </span>s = this.s; |
| mem::forget(this); |
| <span class="prelude-val">Ok</span>(MappedMutexGuard { |
| s, |
| data, |
| marker: marker::PhantomData, |
| }) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> Drop <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="kw">fn </span>drop(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="self">self</span>.s.release(<span class="number">1</span>) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> Deref <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="kw">type </span>Target = T; |
| <span class="kw">fn </span>deref(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="self">Self</span>::Target { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&*</span><span class="self">self</span>.data } |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized> DerefMut <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="kw">fn </span>deref_mut(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="kw-2">&mut </span><span class="self">Self</span>::Target { |
| <span class="kw">unsafe </span>{ <span class="kw-2">&mut *</span><span class="self">self</span>.data } |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized + fmt::Debug> fmt::Debug <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt::Debug::fmt(<span class="kw-2">&**</span><span class="self">self</span>, f) |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, T: <span class="question-mark">?</span>Sized + fmt::Display> fmt::Display <span class="kw">for </span>MappedMutexGuard<<span class="lifetime">'a</span>, T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| fmt::Display::fmt(<span class="kw-2">&**</span><span class="self">self</span>, f) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="tokio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |