<!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 to the Rust file `libstd/sync/mutex.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>mutex.rs.html -- source</title><link rel="stylesheet" type="text/css" href="../../../normalize.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../dark.css"><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><script src="../../../storage.js"></script><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></head><body class="rustdoc source"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">☰</div><a href='../../../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../../settings.html"><img src="../../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><pre class="rust ">
<span class="comment">// Copyright 2014 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class="comment">// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="kw">use</span> <span class="ident">cell</span>::<span class="ident">UnsafeCell</span>;
<span class="kw">use</span> <span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">mem</span>;
<span class="kw">use</span> <span class="ident">ops</span>::{<span class="ident">Deref</span>, <span class="ident">DerefMut</span>};
<span class="kw">use</span> <span class="ident">ptr</span>;
<span class="kw">use</span> <span class="ident">sys_common</span>::<span class="ident">mutex</span> <span class="kw">as</span> <span class="ident">sys</span>;
<span class="kw">use</span> <span class="ident">sys_common</span>::<span class="ident">poison</span>::{<span class="self">self</span>, <span class="ident">TryLockError</span>, <span class="ident">TryLockResult</span>, <span class="ident">LockResult</span>};
<span class="doccomment">/// A mutual exclusion primitive useful for protecting shared data</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This mutex will block threads waiting for the lock to become available. The</span>
<span class="doccomment">/// mutex can also be statically initialized or created via a [`new`]</span>
<span class="doccomment">/// constructor. Each mutex has a type parameter which represents the data that</span>
<span class="doccomment">/// it is protecting. The data can only be accessed through the RAII guards</span>
<span class="doccomment">/// returned from [`lock`] and [`try_lock`], which guarantees that the data is only</span>
<span class="doccomment">/// ever accessed when the mutex is locked.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Poisoning</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The mutexes in this module implement a strategy called "poisoning" where a</span>
<span class="doccomment">/// mutex is considered poisoned whenever a thread panics while holding the</span>
<span class="doccomment">/// mutex. Once a mutex is poisoned, all other threads are unable to access the</span>
<span class="doccomment">/// data by default as it is likely tainted (some invariant is not being</span>
<span class="doccomment">/// upheld).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// For a mutex, this means that the [`lock`] and [`try_lock`] methods return a</span>
<span class="doccomment">/// [`Result`] which indicates whether a mutex has been poisoned or not. Most</span>
<span class="doccomment">/// usage of a mutex will simply [`unwrap()`] these results, propagating panics</span>
<span class="doccomment">/// among threads to ensure that a possibly invalid invariant is not witnessed.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// A poisoned mutex, however, does not prevent all access to the underlying</span>
<span class="doccomment">/// data. The [`PoisonError`] type has an [`into_inner`] method which will return</span>
<span class="doccomment">/// the guard that would have otherwise been returned on a successful lock. This</span>
<span class="doccomment">/// allows access to the data, despite the lock being poisoned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`new`]: #method.new</span>
<span class="doccomment">/// [`lock`]: #method.lock</span>
<span class="doccomment">/// [`try_lock`]: #method.try_lock</span>
<span class="doccomment">/// [`Result`]: ../../std/result/enum.Result.html</span>
<span class="doccomment">/// [`unwrap()`]: ../../std/result/enum.Result.html#method.unwrap</span>
<span class="doccomment">/// [`PoisonError`]: ../../std/sync/struct.PoisonError.html</span>
<span class="doccomment">/// [`into_inner`]: ../../std/sync/struct.PoisonError.html#method.into_inner</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::{Arc, Mutex};</span>
<span class="doccomment">/// use std::thread;</span>
<span class="doccomment">/// use std::sync::mpsc::channel;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// const N: usize = 10;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Spawn a few threads to increment a shared variable (non-atomically), and</span>
<span class="doccomment">/// // let the main thread know once all increments are done.</span>
<span class="doccomment">/// //</span>
<span class="doccomment">/// // Here we're using an Arc to share memory among threads, and the data inside</span>
<span class="doccomment">/// // the Arc is protected with a mutex.</span>
<span class="doccomment">/// let data = Arc::new(Mutex::new(0));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let (tx, rx) = channel();</span>
<span class="doccomment">/// for _ in 0..N {</span>
<span class="doccomment">/// let (data, tx) = (data.clone(), tx.clone());</span>
<span class="doccomment">/// thread::spawn(move || {</span>
<span class="doccomment">/// // The shared state can only be accessed once the lock is held.</span>
<span class="doccomment">/// // Our non-atomic increment is safe because we're the only thread</span>
<span class="doccomment">/// // which can access the shared state when the lock is held.</span>
<span class="doccomment">/// //</span>
<span class="doccomment">/// // We unwrap() the return value to assert that we are not expecting</span>
<span class="doccomment">/// // threads to ever fail while holding the lock.</span>
<span class="doccomment">/// let mut data = data.lock().unwrap();</span>
<span class="doccomment">/// *data += 1;</span>
<span class="doccomment">/// if *data == N {</span>
<span class="doccomment">/// tx.send(()).unwrap();</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// // the lock is unlocked here when `data` goes out of scope.</span>
<span class="doccomment">/// });</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// rx.recv().unwrap();</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// To recover from a poisoned mutex:</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::{Arc, Mutex};</span>
<span class="doccomment">/// use std::thread;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let lock = Arc::new(Mutex::new(0_u32));</span>
<span class="doccomment">/// let lock2 = lock.clone();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let _ = thread::spawn(move || -> () {</span>
<span class="doccomment">/// // This thread will acquire the mutex first, unwrapping the result of</span>
<span class="doccomment">/// // `lock` because the lock has not been poisoned.</span>
<span class="doccomment">/// let _guard = lock2.lock().unwrap();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // This panic while holding the lock (`_guard` is in scope) will poison</span>
<span class="doccomment">/// // the mutex.</span>
<span class="doccomment">/// panic!();</span>
<span class="doccomment">/// }).join();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // The lock is poisoned by this point, but the returned result can be</span>
<span class="doccomment">/// // pattern matched on to return the underlying guard on both branches.</span>
<span class="doccomment">/// let mut guard = match lock.lock() {</span>
<span class="doccomment">/// Ok(guard) => guard,</span>
<span class="doccomment">/// Err(poisoned) => poisoned.into_inner(),</span>
<span class="doccomment">/// };</span>
<span class="doccomment">///</span>
<span class="doccomment">/// *guard += 1;</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> {
<span class="comment">// Note that this mutex is in a *box*, not inlined into the struct itself.</span>
<span class="comment">// Once a native mutex has been used once, its address can never change (it</span>
<span class="comment">// can't be moved). This mutex type can be safely moved at any time, so to</span>
<span class="comment">// ensure that the native mutex is used correctly we box the inner mutex to</span>
<span class="comment">// give it a constant address.</span>
<span class="ident">inner</span>: <span class="ident">Box</span><span class="op"><</span><span class="ident">sys</span>::<span class="ident">Mutex</span><span class="op">></span>,
<span class="ident">poison</span>: <span class="ident">poison</span>::<span class="ident">Flag</span>,
<span class="ident">data</span>: <span class="ident">UnsafeCell</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
}
<span class="comment">// these are the only places where `T: Send` matters; all other</span>
<span class="comment">// functionality works fine on a single thread.</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Send</span><span class="op">></span> <span class="ident">Send</span> <span class="kw">for</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> { }
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Send</span><span class="op">></span> <span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> { }
<span class="doccomment">/// An RAII implementation of a "scoped lock" of a mutex. When this structure is</span>
<span class="doccomment">/// dropped (falls out of scope), the lock will be unlocked.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The data protected by the mutex can be accessed through this guard via its</span>
<span class="doccomment">/// [`Deref`] and [`DerefMut`] implementations.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This structure is created by the [`lock`] and [`try_lock`] methods on</span>
<span class="doccomment">/// [`Mutex`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Deref`]: ../../std/ops/trait.Deref.html</span>
<span class="doccomment">/// [`DerefMut`]: ../../std/ops/trait.DerefMut.html</span>
<span class="doccomment">/// [`lock`]: struct.Mutex.html#method.lock</span>
<span class="doccomment">/// [`try_lock`]: struct.Mutex.html#method.try_lock</span>
<span class="doccomment">/// [`Mutex`]: struct.Mutex.html</span>
<span class="attribute">#[<span class="ident">must_use</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="lifetime">'a</span><span class="op">></span> {
<span class="comment">// funny underscores due to how Deref/DerefMut currently work (they</span>
<span class="comment">// disregard field privacy).</span>
<span class="ident">__lock</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
<span class="ident">__poison</span>: <span class="ident">poison</span>::<span class="ident">Guard</span>,
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="op">!</span><span class="ident">Send</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> { }
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"mutexguard"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.19.0"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Sync</span><span class="op">></span> <span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> { }
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Creates a new mutex in an unlocked state ready for use.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::Mutex;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex = Mutex::new(0);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">t</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Mutex</span> {
<span class="ident">inner</span>: <span class="kw">box</span> <span class="ident">sys</span>::<span class="ident">Mutex</span>::<span class="ident">new</span>(),
<span class="ident">poison</span>: <span class="ident">poison</span>::<span class="ident">Flag</span>::<span class="ident">new</span>(),
<span class="ident">data</span>: <span class="ident">UnsafeCell</span>::<span class="ident">new</span>(<span class="ident">t</span>),
};
<span class="kw">unsafe</span> {
<span class="ident">m</span>.<span class="ident">inner</span>.<span class="ident">init</span>();
}
<span class="ident">m</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Acquires a mutex, blocking the current thread until it is able to do so.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function will block the local thread until it is available to acquire</span>
<span class="doccomment">/// the mutex. Upon returning, the thread is the only thread with the lock</span>
<span class="doccomment">/// held. An RAII guard is returned to allow scoped unlock of the lock. When</span>
<span class="doccomment">/// the guard goes out of scope, the mutex will be unlocked.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The exact behavior on locking a mutex in the thread which already holds</span>
<span class="doccomment">/// the lock is left unspecified. However, this function will not return on</span>
<span class="doccomment">/// the second call (it might panic or deadlock, for example).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Errors</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If another user of this mutex panicked while holding the mutex, then</span>
<span class="doccomment">/// this call will return an error once the mutex is acquired.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function might panic when called if the lock is already held by</span>
<span class="doccomment">/// the current thread.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::{Arc, Mutex};</span>
<span class="doccomment">/// use std::thread;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex = Arc::new(Mutex::new(0));</span>
<span class="doccomment">/// let c_mutex = mutex.clone();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// thread::spawn(move || {</span>
<span class="doccomment">/// *c_mutex.lock().unwrap() = 10;</span>
<span class="doccomment">/// }).join().expect("thread::spawn failed");</span>
<span class="doccomment">/// assert_eq!(*mutex.lock().unwrap(), 10);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">lock</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">LockResult</span><span class="op"><</span><span class="ident">MutexGuard</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">MutexGuard</span>::<span class="ident">new</span>(<span class="self">self</span>)
}
}
<span class="doccomment">/// Attempts to acquire this lock.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If the lock could not be acquired at this time, then [`Err`] is returned.</span>
<span class="doccomment">/// Otherwise, an RAII guard is returned. The lock will be unlocked when the</span>
<span class="doccomment">/// guard is dropped.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function does not block.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Errors</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If another user of this mutex panicked while holding the mutex, then</span>
<span class="doccomment">/// this call will return failure if the mutex would otherwise be</span>
<span class="doccomment">/// acquired.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Err`]: ../../std/result/enum.Result.html#variant.Err</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::{Arc, Mutex};</span>
<span class="doccomment">/// use std::thread;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex = Arc::new(Mutex::new(0));</span>
<span class="doccomment">/// let c_mutex = mutex.clone();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// thread::spawn(move || {</span>
<span class="doccomment">/// let mut lock = c_mutex.try_lock();</span>
<span class="doccomment">/// if let Ok(ref mut mutex) = lock {</span>
<span class="doccomment">/// **mutex = 10;</span>
<span class="doccomment">/// } else {</span>
<span class="doccomment">/// println!("try_lock failed");</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// }).join().expect("thread::spawn failed");</span>
<span class="doccomment">/// assert_eq!(*mutex.lock().unwrap(), 10);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">try_lock</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">TryLockResult</span><span class="op"><</span><span class="ident">MutexGuard</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="kw">unsafe</span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">try_lock</span>() {
<span class="prelude-val">Ok</span>(<span class="ident">MutexGuard</span>::<span class="ident">new</span>(<span class="self">self</span>)<span class="question-mark">?</span>)
} <span class="kw">else</span> {
<span class="prelude-val">Err</span>(<span class="ident">TryLockError</span>::<span class="ident">WouldBlock</span>)
}
}
}
<span class="doccomment">/// Determines whether the mutex is poisoned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If another thread is active, the mutex can still become poisoned at any</span>
<span class="doccomment">/// time. You should not trust a `false` value for program correctness</span>
<span class="doccomment">/// without additional synchronization.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::{Arc, Mutex};</span>
<span class="doccomment">/// use std::thread;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex = Arc::new(Mutex::new(0));</span>
<span class="doccomment">/// let c_mutex = mutex.clone();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let _ = thread::spawn(move || {</span>
<span class="doccomment">/// let _lock = c_mutex.lock().unwrap();</span>
<span class="doccomment">/// panic!(); // the mutex gets poisoned</span>
<span class="doccomment">/// }).join();</span>
<span class="doccomment">/// assert_eq!(mutex.is_poisoned(), true);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"sync_poison"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.2.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">is_poisoned</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="ident">poison</span>.<span class="ident">get</span>()
}
<span class="doccomment">/// Consumes this mutex, returning the underlying data.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Errors</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If another user of this mutex panicked while holding the mutex, then</span>
<span class="doccomment">/// this call will return an error instead.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::Mutex;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex = Mutex::new(0);</span>
<span class="doccomment">/// assert_eq!(mutex.into_inner().unwrap(), 0);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"mutex_into_inner"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.6.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">into_inner</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">LockResult</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">where</span> <span class="ident">T</span>: <span class="ident">Sized</span> {
<span class="comment">// We know statically that there are no outstanding references to</span>
<span class="comment">// `self` so there's no need to lock the inner mutex.</span>
<span class="comment">//</span>
<span class="comment">// To get the inner value, we'd like to call `data.into_inner()`,</span>
<span class="comment">// but because `Mutex` impl-s `Drop`, we can't move out of it, so</span>
<span class="comment">// we'll have to destructure it manually instead.</span>
<span class="kw">unsafe</span> {
<span class="comment">// Like `let Mutex { inner, poison, data } = self`.</span>
<span class="kw">let</span> (<span class="ident">inner</span>, <span class="ident">poison</span>, <span class="ident">data</span>) <span class="op">=</span> {
<span class="kw">let</span> <span class="ident">Mutex</span> { <span class="kw-2">ref</span> <span class="ident">inner</span>, <span class="kw-2">ref</span> <span class="ident">poison</span>, <span class="kw-2">ref</span> <span class="ident">data</span> } <span class="op">=</span> <span class="self">self</span>;
(<span class="ident">ptr</span>::<span class="ident">read</span>(<span class="ident">inner</span>), <span class="ident">ptr</span>::<span class="ident">read</span>(<span class="ident">poison</span>), <span class="ident">ptr</span>::<span class="ident">read</span>(<span class="ident">data</span>))
};
<span class="ident">mem</span>::<span class="ident">forget</span>(<span class="self">self</span>);
<span class="ident">inner</span>.<span class="ident">destroy</span>(); <span class="comment">// Keep in sync with the `Drop` impl.</span>
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="ident">poison</span>::<span class="ident">map_result</span>(<span class="ident">poison</span>.<span class="ident">borrow</span>(), <span class="op">|</span><span class="kw">_</span><span class="op">|</span> <span class="ident">data</span>.<span class="ident">into_inner</span>())
}
}
<span class="doccomment">/// Returns a mutable reference to the underlying data.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Since this call borrows the `Mutex` mutably, no actual locking needs to</span>
<span class="doccomment">/// take place---the mutable borrow statically guarantees no locks exist.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Errors</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If another user of this mutex panicked while holding the mutex, then</span>
<span class="doccomment">/// this call will return an error instead.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::sync::Mutex;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mut mutex = Mutex::new(0);</span>
<span class="doccomment">/// *mutex.get_mut().unwrap() = 10;</span>
<span class="doccomment">/// assert_eq!(*mutex.lock().unwrap(), 10);</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"mutex_get_mut"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.6.0"</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">LockResult</span><span class="op"><</span><span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span><span class="op">></span> {
<span class="comment">// We know statically that there are no other references to `self`, so</span>
<span class="comment">// there's no need to lock the inner mutex.</span>
<span class="kw">let</span> <span class="ident">data</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">data</span>.<span class="ident">get</span>() };
<span class="ident">poison</span>::<span class="ident">map_result</span>(<span class="self">self</span>.<span class="ident">poison</span>.<span class="ident">borrow</span>(), <span class="op">|</span><span class="kw">_</span><span class="op">|</span> <span class="ident">data</span> )
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op"><</span><span class="attribute">#[<span class="ident">may_dangle</span>]</span> <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="comment">// This is actually safe b/c we know that there is no further usage of</span>
<span class="comment">// this mutex (it's up to the user to arrange for a mutex to get</span>
<span class="comment">// dropped, that's not our job)</span>
<span class="comment">//</span>
<span class="comment">// IMPORTANT: This code must be kept in sync with `Mutex::into_inner`.</span>
<span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">destroy</span>() }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"mutex_from"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.24.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">for</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Creates a new mutex in an unlocked state ready for use.</span>
<span class="doccomment">/// This is equivalent to [`Mutex::new`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex::new`]: #method.new</span>
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">t</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">t</span>)
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"mutex_default"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.10.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">Default</span><span class="op">></span> <span class="ident">Default</span> <span class="kw">for</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Creates a `Mutex<T>`, with the `Default` value for T.</span>
<span class="kw">fn</span> <span class="ident">default</span>() <span class="op">-></span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">Default</span>::<span class="ident">default</span>())
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Debug</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">try_lock</span>() {
<span class="prelude-val">Ok</span>(<span class="ident">guard</span>) <span class="op">=></span> <span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Mutex"</span>).<span class="ident">field</span>(<span class="string">"data"</span>, <span class="op">&&</span><span class="kw-2">*</span><span class="ident">guard</span>).<span class="ident">finish</span>(),
<span class="prelude-val">Err</span>(<span class="ident">TryLockError</span>::<span class="ident">Poisoned</span>(<span class="ident">err</span>)) <span class="op">=></span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Mutex"</span>).<span class="ident">field</span>(<span class="string">"data"</span>, <span class="op">&&</span><span class="kw-2">*</span><span class="kw-2">*</span><span class="ident">err</span>.<span class="ident">get_ref</span>()).<span class="ident">finish</span>()
},
<span class="prelude-val">Err</span>(<span class="ident">TryLockError</span>::<span class="ident">WouldBlock</span>) <span class="op">=></span> {
<span class="kw">struct</span> <span class="ident">LockedPlaceholder</span>;
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">LockedPlaceholder</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> { <span class="ident">f</span>.<span class="ident">write_str</span>(<span class="string">"<locked>"</span>) }
}
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Mutex"</span>).<span class="ident">field</span>(<span class="string">"data"</span>, <span class="kw-2">&</span><span class="ident">LockedPlaceholder</span>).<span class="ident">finish</span>()
}
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">lock</span>: <span class="kw-2">&</span><span class="lifetime">'mutex</span> <span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">LockResult</span><span class="op"><</span><span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span><span class="op">>></span> {
<span class="ident">poison</span>::<span class="ident">map_result</span>(<span class="ident">lock</span>.<span class="ident">poison</span>.<span class="ident">borrow</span>(), <span class="op">|</span><span class="ident">guard</span><span class="op">|</span> {
<span class="ident">MutexGuard</span> {
<span class="ident">__lock</span>: <span class="ident">lock</span>,
<span class="ident">__poison</span>: <span class="ident">guard</span>,
}
})
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Deref</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Target</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">fn</span> <span class="ident">deref</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">T</span> {
<span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">*</span><span class="self">self</span>.<span class="ident">__lock</span>.<span class="ident">data</span>.<span class="ident">get</span>() }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">DerefMut</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'mutex</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">deref_mut</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span> {
<span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">__lock</span>.<span class="ident">data</span>.<span class="ident">get</span>() }
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"rust1"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.0.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">__lock</span>.<span class="ident">poison</span>.<span class="ident">done</span>(<span class="kw-2">&</span><span class="self">self</span>.<span class="ident">__poison</span>);
<span class="self">self</span>.<span class="ident">__lock</span>.<span class="ident">inner</span>.<span class="ident">unlock</span>();
}
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"std_debug"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.16.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Debug</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"MutexGuard"</span>)
.<span class="ident">field</span>(<span class="string">"lock"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">__lock</span>)
.<span class="ident">finish</span>()
}
}
<span class="attribute">#[<span class="ident">stable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"std_guard_impls"</span>, <span class="ident">since</span> <span class="op">=</span> <span class="string">"1.20.0"</span>)]</span>
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span> <span class="op">+</span> <span class="ident">fmt</span>::<span class="ident">Display</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
(<span class="kw-2">*</span><span class="kw-2">*</span><span class="self">self</span>).<span class="ident">fmt</span>(<span class="ident">f</span>)
}
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">guard_lock</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span>(<span class="ident">guard</span>: <span class="kw-2">&</span><span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">sys</span>::<span class="ident">Mutex</span> {
<span class="kw-2">&</span><span class="ident">guard</span>.<span class="ident">__lock</span>.<span class="ident">inner</span>
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">guard_poison</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span>(<span class="ident">guard</span>: <span class="kw-2">&</span><span class="ident">MutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">poison</span>::<span class="ident">Flag</span> {
<span class="kw-2">&</span><span class="ident">guard</span>.<span class="ident">__lock</span>.<span class="ident">poison</span>
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">test</span>, <span class="ident">not</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>)))]</span>
<span class="kw">mod</span> <span class="ident">tests</span> {
<span class="kw">use</span> <span class="ident">sync</span>::<span class="ident">mpsc</span>::<span class="ident">channel</span>;
<span class="kw">use</span> <span class="ident">sync</span>::{<span class="ident">Arc</span>, <span class="ident">Mutex</span>, <span class="ident">Condvar</span>};
<span class="kw">use</span> <span class="ident">sync</span>::<span class="ident">atomic</span>::{<span class="ident">AtomicUsize</span>, <span class="ident">Ordering</span>};
<span class="kw">use</span> <span class="ident">thread</span>;
<span class="kw">struct</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Arc</span><span class="op"><</span>(<span class="ident">Mutex</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">Condvar</span>)<span class="op">></span>);
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Eq</span>, <span class="ident">PartialEq</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">NonCopy</span>(<span class="ident">i32</span>);
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">smoke</span>() {
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Mutex</span>::<span class="ident">new</span>(());
<span class="ident">drop</span>(<span class="ident">m</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>());
<span class="ident">drop</span>(<span class="ident">m</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">lots_and_lots</span>() {
<span class="kw">const</span> <span class="ident">J</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="number">1000</span>;
<span class="kw">const</span> <span class="ident">K</span>: <span class="ident">u32</span> <span class="op">=</span> <span class="number">3</span>;
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="number">0</span>));
<span class="kw">fn</span> <span class="ident">inc</span>(<span class="ident">m</span>: <span class="kw-2">&</span><span class="ident">Mutex</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span>) {
<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">J</span> {
<span class="kw-2">*</span><span class="ident">m</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>() <span class="op">+=</span> <span class="number">1</span>;
}
}
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel</span>();
<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">K</span> {
<span class="kw">let</span> <span class="ident">tx2</span> <span class="op">=</span> <span class="ident">tx</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="ident">m2</span> <span class="op">=</span> <span class="ident">m</span>.<span class="ident">clone</span>();
<span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span><span class="op">||</span> { <span class="ident">inc</span>(<span class="kw-2">&</span><span class="ident">m2</span>); <span class="ident">tx2</span>.<span class="ident">send</span>(()).<span class="ident">unwrap</span>(); });
<span class="kw">let</span> <span class="ident">tx2</span> <span class="op">=</span> <span class="ident">tx</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="ident">m2</span> <span class="op">=</span> <span class="ident">m</span>.<span class="ident">clone</span>();
<span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span><span class="op">||</span> { <span class="ident">inc</span>(<span class="kw-2">&</span><span class="ident">m2</span>); <span class="ident">tx2</span>.<span class="ident">send</span>(()).<span class="ident">unwrap</span>(); });
}
<span class="ident">drop</span>(<span class="ident">tx</span>);
<span class="kw">for</span> <span class="kw">_</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">2</span> <span class="op">*</span> <span class="ident">K</span> {
<span class="ident">rx</span>.<span class="ident">recv</span>().<span class="ident">unwrap</span>();
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">m</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>(), <span class="ident">J</span> <span class="op">*</span> <span class="ident">K</span> <span class="op">*</span> <span class="number">2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">try_lock</span>() {
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Mutex</span>::<span class="ident">new</span>(());
<span class="kw-2">*</span><span class="ident">m</span>.<span class="ident">try_lock</span>().<span class="ident">unwrap</span>() <span class="op">=</span> ();
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_into_inner</span>() {
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">NonCopy</span>(<span class="number">10</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">m</span>.<span class="ident">into_inner</span>().<span class="ident">unwrap</span>(), <span class="ident">NonCopy</span>(<span class="number">10</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_into_inner_drop</span>() {
<span class="kw">struct</span> <span class="ident">Foo</span>(<span class="ident">Arc</span><span class="op"><</span><span class="ident">AtomicUsize</span><span class="op">></span>);
<span class="kw">impl</span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Foo</span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">fetch_add</span>(<span class="number">1</span>, <span class="ident">Ordering</span>::<span class="ident">SeqCst</span>);
}
}
<span class="kw">let</span> <span class="ident">num_drops</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">AtomicUsize</span>::<span class="ident">new</span>(<span class="number">0</span>));
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">Foo</span>(<span class="ident">num_drops</span>.<span class="ident">clone</span>()));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">num_drops</span>.<span class="ident">load</span>(<span class="ident">Ordering</span>::<span class="ident">SeqCst</span>), <span class="number">0</span>);
{
<span class="kw">let</span> <span class="ident">_inner</span> <span class="op">=</span> <span class="ident">m</span>.<span class="ident">into_inner</span>().<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">num_drops</span>.<span class="ident">load</span>(<span class="ident">Ordering</span>::<span class="ident">SeqCst</span>), <span class="number">0</span>);
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">num_drops</span>.<span class="ident">load</span>(<span class="ident">Ordering</span>::<span class="ident">SeqCst</span>), <span class="number">1</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_into_inner_poison</span>() {
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">NonCopy</span>(<span class="number">10</span>)));
<span class="kw">let</span> <span class="ident">m2</span> <span class="op">=</span> <span class="ident">m</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">||</span> {
<span class="kw">let</span> <span class="ident">_lock</span> <span class="op">=</span> <span class="ident">m2</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="macro">panic</span><span class="macro">!</span>(<span class="string">"test panic in inner thread to poison mutex"</span>);
}).<span class="ident">join</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">m</span>.<span class="ident">is_poisoned</span>());
<span class="kw">match</span> <span class="ident">Arc</span>::<span class="ident">try_unwrap</span>(<span class="ident">m</span>).<span class="ident">unwrap</span>().<span class="ident">into_inner</span>() {
<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=></span> <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">e</span>.<span class="ident">into_inner</span>(), <span class="ident">NonCopy</span>(<span class="number">10</span>)),
<span class="prelude-val">Ok</span>(<span class="ident">x</span>) <span class="op">=></span> <span class="macro">panic</span><span class="macro">!</span>(<span class="string">"into_inner of poisoned Mutex is Ok: {:?}"</span>, <span class="ident">x</span>),
}
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_get_mut</span>() {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">NonCopy</span>(<span class="number">10</span>));
<span class="kw-2">*</span><span class="ident">m</span>.<span class="ident">get_mut</span>().<span class="ident">unwrap</span>() <span class="op">=</span> <span class="ident">NonCopy</span>(<span class="number">20</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">m</span>.<span class="ident">into_inner</span>().<span class="ident">unwrap</span>(), <span class="ident">NonCopy</span>(<span class="number">20</span>));
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_get_mut_poison</span>() {
<span class="kw">let</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">NonCopy</span>(<span class="number">10</span>)));
<span class="kw">let</span> <span class="ident">m2</span> <span class="op">=</span> <span class="ident">m</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">||</span> {
<span class="kw">let</span> <span class="ident">_lock</span> <span class="op">=</span> <span class="ident">m2</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="macro">panic</span><span class="macro">!</span>(<span class="string">"test panic in inner thread to poison mutex"</span>);
}).<span class="ident">join</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">m</span>.<span class="ident">is_poisoned</span>());
<span class="kw">match</span> <span class="ident">Arc</span>::<span class="ident">try_unwrap</span>(<span class="ident">m</span>).<span class="ident">unwrap</span>().<span class="ident">get_mut</span>() {
<span class="prelude-val">Err</span>(<span class="ident">e</span>) <span class="op">=></span> <span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">e</span>.<span class="ident">into_inner</span>(), <span class="ident">NonCopy</span>(<span class="number">10</span>)),
<span class="prelude-val">Ok</span>(<span class="ident">x</span>) <span class="op">=></span> <span class="macro">panic</span><span class="macro">!</span>(<span class="string">"get_mut of poisoned Mutex is Ok: {:?}"</span>, <span class="ident">x</span>),
}
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_mutex_arc_condvar</span>() {
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="ident">Packet</span>(<span class="ident">Arc</span>::<span class="ident">new</span>((<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="bool-val">false</span>), <span class="ident">Condvar</span>::<span class="ident">new</span>())));
<span class="kw">let</span> <span class="ident">packet2</span> <span class="op">=</span> <span class="ident">Packet</span>(<span class="ident">packet</span>.<span class="number">0</span>.<span class="ident">clone</span>());
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel</span>();
<span class="kw">let</span> <span class="ident">_t</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span><span class="op">||</span> {
<span class="comment">// wait until parent gets in</span>
<span class="ident">rx</span>.<span class="ident">recv</span>().<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="kw-2">&</span>(<span class="kw-2">ref</span> <span class="ident">lock</span>, <span class="kw-2">ref</span> <span class="ident">cvar</span>) <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">packet2</span>.<span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">lock</span> <span class="op">=</span> <span class="ident">lock</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="kw-2">*</span><span class="ident">lock</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="ident">cvar</span>.<span class="ident">notify_one</span>();
});
<span class="kw">let</span> <span class="kw-2">&</span>(<span class="kw-2">ref</span> <span class="ident">lock</span>, <span class="kw-2">ref</span> <span class="ident">cvar</span>) <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">packet</span>.<span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">lock</span> <span class="op">=</span> <span class="ident">lock</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="ident">tx</span>.<span class="ident">send</span>(()).<span class="ident">unwrap</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="kw-2">*</span><span class="ident">lock</span>);
<span class="kw">while</span> <span class="op">!</span><span class="kw-2">*</span><span class="ident">lock</span> {
<span class="ident">lock</span> <span class="op">=</span> <span class="ident">cvar</span>.<span class="ident">wait</span>(<span class="ident">lock</span>).<span class="ident">unwrap</span>();
}
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_arc_condvar_poison</span>() {
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="ident">Packet</span>(<span class="ident">Arc</span>::<span class="ident">new</span>((<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="number">1</span>), <span class="ident">Condvar</span>::<span class="ident">new</span>())));
<span class="kw">let</span> <span class="ident">packet2</span> <span class="op">=</span> <span class="ident">Packet</span>(<span class="ident">packet</span>.<span class="number">0</span>.<span class="ident">clone</span>());
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel</span>();
<span class="kw">let</span> <span class="ident">_t</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">||</span> <span class="op">-></span> () {
<span class="ident">rx</span>.<span class="ident">recv</span>().<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="kw-2">&</span>(<span class="kw-2">ref</span> <span class="ident">lock</span>, <span class="kw-2">ref</span> <span class="ident">cvar</span>) <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">packet2</span>.<span class="number">0</span>;
<span class="kw">let</span> <span class="ident">_g</span> <span class="op">=</span> <span class="ident">lock</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="ident">cvar</span>.<span class="ident">notify_one</span>();
<span class="comment">// Parent should fail when it wakes up.</span>
<span class="macro">panic</span><span class="macro">!</span>();
});
<span class="kw">let</span> <span class="kw-2">&</span>(<span class="kw-2">ref</span> <span class="ident">lock</span>, <span class="kw-2">ref</span> <span class="ident">cvar</span>) <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">packet</span>.<span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">lock</span> <span class="op">=</span> <span class="ident">lock</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="ident">tx</span>.<span class="ident">send</span>(()).<span class="ident">unwrap</span>();
<span class="kw">while</span> <span class="kw-2">*</span><span class="ident">lock</span> <span class="op">==</span> <span class="number">1</span> {
<span class="kw">match</span> <span class="ident">cvar</span>.<span class="ident">wait</span>(<span class="ident">lock</span>) {
<span class="prelude-val">Ok</span>(<span class="ident">l</span>) <span class="op">=></span> {
<span class="ident">lock</span> <span class="op">=</span> <span class="ident">l</span>;
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">lock</span>, <span class="number">1</span>);
}
<span class="prelude-val">Err</span>(..) <span class="op">=></span> <span class="kw">break</span>,
}
}
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_mutex_arc_poison</span>() {
<span class="kw">let</span> <span class="ident">arc</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="number">1</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">arc</span>.<span class="ident">is_poisoned</span>());
<span class="kw">let</span> <span class="ident">arc2</span> <span class="op">=</span> <span class="ident">arc</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span><span class="op">||</span> {
<span class="kw">let</span> <span class="ident">lock</span> <span class="op">=</span> <span class="ident">arc2</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">lock</span>, <span class="number">2</span>);
}).<span class="ident">join</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">arc</span>.<span class="ident">lock</span>().<span class="ident">is_err</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">arc</span>.<span class="ident">is_poisoned</span>());
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_mutex_arc_nested</span>() {
<span class="comment">// Tests nested mutexes and access</span>
<span class="comment">// to underlying data.</span>
<span class="kw">let</span> <span class="ident">arc</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="number">1</span>));
<span class="kw">let</span> <span class="ident">arc2</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="ident">arc</span>));
<span class="kw">let</span> (<span class="ident">tx</span>, <span class="ident">rx</span>) <span class="op">=</span> <span class="ident">channel</span>();
<span class="kw">let</span> <span class="ident">_t</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span><span class="op">||</span> {
<span class="kw">let</span> <span class="ident">lock</span> <span class="op">=</span> <span class="ident">arc2</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">lock2</span> <span class="op">=</span> <span class="ident">lock</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">lock2</span>, <span class="number">1</span>);
<span class="ident">tx</span>.<span class="ident">send</span>(()).<span class="ident">unwrap</span>();
});
<span class="ident">rx</span>.<span class="ident">recv</span>().<span class="ident">unwrap</span>();
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_mutex_arc_access_in_unwind</span>() {
<span class="kw">let</span> <span class="ident">arc</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>(<span class="ident">Mutex</span>::<span class="ident">new</span>(<span class="number">1</span>));
<span class="kw">let</span> <span class="ident">arc2</span> <span class="op">=</span> <span class="ident">arc</span>.<span class="ident">clone</span>();
<span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span><span class="op">||</span> <span class="op">-></span> () {
<span class="kw">struct</span> <span class="ident">Unwinder</span> {
<span class="ident">i</span>: <span class="ident">Arc</span><span class="op"><</span><span class="ident">Mutex</span><span class="op"><</span><span class="ident">i32</span><span class="op">>></span>,
}
<span class="kw">impl</span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Unwinder</span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">i</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>() <span class="op">+=</span> <span class="number">1</span>;
}
}
<span class="kw">let</span> <span class="ident">_u</span> <span class="op">=</span> <span class="ident">Unwinder</span> { <span class="ident">i</span>: <span class="ident">arc2</span> };
<span class="macro">panic</span><span class="macro">!</span>();
}).<span class="ident">join</span>();
<span class="kw">let</span> <span class="ident">lock</span> <span class="op">=</span> <span class="ident">arc</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">*</span><span class="ident">lock</span>, <span class="number">2</span>);
}
<span class="attribute">#[<span class="ident">test</span>]</span>
<span class="kw">fn</span> <span class="ident">test_mutex_unsized</span>() {
<span class="kw">let</span> <span class="ident">mutex</span>: <span class="kw-2">&</span><span class="ident">Mutex</span><span class="op"><</span>[<span class="ident">i32</span>]<span class="op">></span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">Mutex</span>::<span class="ident">new</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
{
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw-2">*</span><span class="ident">mutex</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>();
<span class="ident">b</span>[<span class="number">0</span>] <span class="op">=</span> <span class="number">4</span>;
<span class="ident">b</span>[<span class="number">2</span>] <span class="op">=</span> <span class="number">5</span>;
}
<span class="kw">let</span> <span class="ident">comp</span>: <span class="kw-2">&</span>[<span class="ident">i32</span>] <span class="op">=</span> <span class="kw-2">&</span>[<span class="number">4</span>, <span class="number">2</span>, <span class="number">5</span>];
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="kw-2">*</span><span class="ident">mutex</span>.<span class="ident">lock</span>().<span class="ident">unwrap</span>(), <span class="ident">comp</span>);
}
}
</pre>
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