<!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/sys_common/poison.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>poison.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">error</span>::{<span class="ident">Error</span>};
<span class="kw">use</span> <span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">sync</span>::<span class="ident">atomic</span>::{<span class="ident">AtomicBool</span>, <span class="ident">Ordering</span>};
<span class="kw">use</span> <span class="ident">thread</span>;
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Flag</span> { <span class="ident">failed</span>: <span class="ident">AtomicBool</span> }
<span class="comment">// Note that the Ordering uses to access the `failed` field of `Flag` below is</span>
<span class="comment">// always `Relaxed`, and that's because this isn't actually protecting any data,</span>
<span class="comment">// it's just a flag whether we've panicked or not.</span>
<span class="comment">//</span>
<span class="comment">// The actual location that this matters is when a mutex is **locked** which is</span>
<span class="comment">// where we have external synchronization ensuring that we see memory</span>
<span class="comment">// reads/writes to this flag.</span>
<span class="comment">//</span>
<span class="comment">// As a result, if it matters, we should see the correct value for `failed` in</span>
<span class="comment">// all cases.</span>
<span class="kw">impl</span> <span class="ident">Flag</span> {
<span class="kw">pub</span> <span class="kw">const</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-></span> <span class="ident">Flag</span> {
<span class="ident">Flag</span> { <span class="ident">failed</span>: <span class="ident">AtomicBool</span>::<span class="ident">new</span>(<span class="bool-val">false</span>) }
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">borrow</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">Guard</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">ret</span> <span class="op">=</span> <span class="ident">Guard</span> { <span class="ident">panicking</span>: <span class="ident">thread</span>::<span class="ident">panicking</span>() };
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">get</span>() {
<span class="prelude-val">Err</span>(<span class="ident">PoisonError</span>::<span class="ident">new</span>(<span class="ident">ret</span>))
} <span class="kw">else</span> {
<span class="prelude-val">Ok</span>(<span class="ident">ret</span>)
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">done</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">guard</span>: <span class="kw-2">&</span><span class="ident">Guard</span>) {
<span class="kw">if</span> <span class="op">!</span><span class="ident">guard</span>.<span class="ident">panicking</span> <span class="op">&&</span> <span class="ident">thread</span>::<span class="ident">panicking</span>() {
<span class="self">self</span>.<span class="ident">failed</span>.<span class="ident">store</span>(<span class="bool-val">true</span>, <span class="ident">Ordering</span>::<span class="ident">Relaxed</span>);
}
}
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">get</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">failed</span>.<span class="ident">load</span>(<span class="ident">Ordering</span>::<span class="ident">Relaxed</span>)
}
}
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Guard</span> {
<span class="ident">panicking</span>: <span class="ident">bool</span>,
}
<span class="doccomment">/// A type of error which can be returned whenever a lock is acquired.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Both [`Mutex`]es and [`RwLock`]s are poisoned whenever a thread fails while the lock</span>
<span class="doccomment">/// is held. The precise semantics for when a lock is poisoned is documented on</span>
<span class="doccomment">/// each lock, but once a lock is poisoned then all future acquisitions will</span>
<span class="doccomment">/// return this error.</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(1));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // poison the mutex</span>
<span class="doccomment">/// let c_mutex = mutex.clone();</span>
<span class="doccomment">/// let _ = thread::spawn(move || {</span>
<span class="doccomment">/// let mut data = c_mutex.lock().unwrap();</span>
<span class="doccomment">/// *data = 2;</span>
<span class="doccomment">/// panic!();</span>
<span class="doccomment">/// }).join();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// match mutex.lock() {</span>
<span class="doccomment">/// Ok(_) => unreachable!(),</span>
<span class="doccomment">/// Err(p_err) => {</span>
<span class="doccomment">/// let data = p_err.get_ref();</span>
<span class="doccomment">/// println!("recovered: {}", data);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// };</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex`]: ../../std/sync/struct.Mutex.html</span>
<span class="doccomment">/// [`RwLock`]: ../../std/sync/struct.RwLock.html</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">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">guard</span>: <span class="ident">T</span>,
}
<span class="doccomment">/// An enumeration of possible errors associated with a [`TryLockResult`] which</span>
<span class="doccomment">/// can occur while trying to acquire a lock, from the [`try_lock`] method on a</span>
<span class="doccomment">/// [`Mutex`] or the [`try_read`] and [`try_write`] methods on an [`RwLock`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex`]: struct.Mutex.html</span>
<span class="doccomment">/// [`RwLock`]: struct.RwLock.html</span>
<span class="doccomment">/// [`TryLockResult`]: type.TryLockResult.html</span>
<span class="doccomment">/// [`try_lock`]: struct.Mutex.html#method.try_lock</span>
<span class="doccomment">/// [`try_read`]: struct.RwLock.html#method.try_read</span>
<span class="doccomment">/// [`try_write`]: struct.RwLock.html#method.try_write</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">enum</span> <span class="ident">TryLockError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// The lock could not be acquired because another thread failed while holding</span>
<span class="doccomment">/// the lock.</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="ident">Poisoned</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="ident">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>),
<span class="doccomment">/// The lock could not be acquired at this time because the operation would</span>
<span class="doccomment">/// otherwise block.</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="ident">WouldBlock</span>,
}
<span class="doccomment">/// A type alias for the result of a lock method which can be poisoned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The [`Ok`] variant of this result indicates that the primitive was not</span>
<span class="doccomment">/// poisoned, and the `Guard` is contained within. The [`Err`] variant indicates</span>
<span class="doccomment">/// that the primitive was poisoned. Note that the [`Err`] variant *also* carries</span>
<span class="doccomment">/// the associated guard, and it can be acquired through the [`into_inner`]</span>
<span class="doccomment">/// method.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Ok`]: ../../std/result/enum.Result.html#variant.Ok</span>
<span class="doccomment">/// [`Err`]: ../../std/result/enum.Result.html#variant.Err</span>
<span class="doccomment">/// [`into_inner`]: ../../std/sync/struct.PoisonError.html#method.into_inner</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">type</span> <span class="ident">LockResult</span><span class="op"><</span><span class="ident">Guard</span><span class="op">></span> <span class="op">=</span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Guard</span>, <span class="ident">PoisonError</span><span class="op"><</span><span class="ident">Guard</span><span class="op">>></span>;
<span class="doccomment">/// A type alias for the result of a nonblocking locking method.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// For more information, see [`LockResult`]. A `TryLockResult` doesn't</span>
<span class="doccomment">/// necessarily hold the associated guard in the [`Err`] type as the lock may not</span>
<span class="doccomment">/// have been acquired for other reasons.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`LockResult`]: ../../std/sync/type.LockResult.html</span>
<span class="doccomment">/// [`Err`]: ../../std/result/enum.Result.html#variant.Err</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">type</span> <span class="ident">TryLockResult</span><span class="op"><</span><span class="ident">Guard</span><span class="op">></span> <span class="op">=</span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Guard</span>, <span class="ident">TryLockError</span><span class="op"><</span><span class="ident">Guard</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">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">PoisonError</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="string">"PoisonError { inner: .. }"</span>.<span class="ident">fmt</span>(<span class="ident">f</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="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">PoisonError</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="string">"poisoned lock: another task failed inside"</span>.<span class="ident">fmt</span>(<span class="ident">f</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="op">></span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="string">"poisoned lock: another task failed inside"</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Creates a `PoisonError`.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is generally created by methods like [`Mutex::lock`] or [`RwLock::read`].</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex::lock`]: ../../std/sync/struct.Mutex.html#method.lock</span>
<span class="doccomment">/// [`RwLock::read`]: ../../std/sync/struct.RwLock.html#method.read</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">new</span>(<span class="ident">guard</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">PoisonError</span> { <span class="ident">guard</span>: <span class="ident">guard</span> }
}
<span class="doccomment">/// Consumes this error indicating that a lock is poisoned, returning the</span>
<span class="doccomment">/// underlying guard to allow access regardless.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use std::collections::HashSet;</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(HashSet::new()));</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // poison the mutex</span>
<span class="doccomment">/// let c_mutex = mutex.clone();</span>
<span class="doccomment">/// let _ = thread::spawn(move || {</span>
<span class="doccomment">/// let mut data = c_mutex.lock().unwrap();</span>
<span class="doccomment">/// data.insert(10);</span>
<span class="doccomment">/// panic!();</span>
<span class="doccomment">/// }).join();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let p_err = mutex.lock().unwrap_err();</span>
<span class="doccomment">/// let data = p_err.into_inner();</span>
<span class="doccomment">/// println!("recovered {} items", data.len());</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">"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">into_inner</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">T</span> { <span class="self">self</span>.<span class="ident">guard</span> }
<span class="doccomment">/// Reaches into this error indicating that a lock is poisoned, returning a</span>
<span class="doccomment">/// reference to the underlying guard to allow access regardless.</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">get_ref</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-2">&</span><span class="self">self</span>.<span class="ident">guard</span> }
<span class="doccomment">/// Reaches into this error indicating that a lock is poisoned, returning a</span>
<span class="doccomment">/// mutable reference to the underlying guard to allow access regardless.</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">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="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">T</span> { <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</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="ident">T</span><span class="op">></span> <span class="ident">From</span><span class="op"><</span><span class="ident">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> <span class="kw">for</span> <span class="ident">TryLockError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">from</span>(<span class="ident">err</span>: <span class="ident">PoisonError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">TryLockError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">TryLockError</span>::<span class="ident">Poisoned</span>(<span class="ident">err</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="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">TryLockError</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="kw-2">*</span><span class="self">self</span> {
<span class="ident">TryLockError</span>::<span class="ident">Poisoned</span>(..) <span class="op">=></span> <span class="string">"Poisoned(..)"</span>.<span class="ident">fmt</span>(<span class="ident">f</span>),
<span class="ident">TryLockError</span>::<span class="ident">WouldBlock</span> <span class="op">=></span> <span class="string">"WouldBlock"</span>.<span class="ident">fmt</span>(<span class="ident">f</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="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">TryLockError</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="kw-2">*</span><span class="self">self</span> {
<span class="ident">TryLockError</span>::<span class="ident">Poisoned</span>(..) <span class="op">=></span> <span class="string">"poisoned lock: another task failed inside"</span>,
<span class="ident">TryLockError</span>::<span class="ident">WouldBlock</span> <span class="op">=></span> <span class="string">"try_lock failed because the operation would block"</span>
}.<span class="ident">fmt</span>(<span class="ident">f</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="op">></span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">TryLockError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">TryLockError</span>::<span class="ident">Poisoned</span>(<span class="kw-2">ref</span> <span class="ident">p</span>) <span class="op">=></span> <span class="ident">p</span>.<span class="ident">description</span>(),
<span class="ident">TryLockError</span>::<span class="ident">WouldBlock</span> <span class="op">=></span> <span class="string">"try_lock failed because the operation would block"</span>
}
}
<span class="kw">fn</span> <span class="ident">cause</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">Error</span><span class="op">></span> {
<span class="kw">match</span> <span class="kw-2">*</span><span class="self">self</span> {
<span class="ident">TryLockError</span>::<span class="ident">Poisoned</span>(<span class="kw-2">ref</span> <span class="ident">p</span>) <span class="op">=></span> <span class="prelude-val">Some</span>(<span class="ident">p</span>),
<span class="kw">_</span> <span class="op">=></span> <span class="prelude-val">None</span>
}
}
}
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">map_result</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">U</span>, <span class="ident">F</span><span class="op">></span>(<span class="ident">result</span>: <span class="ident">LockResult</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">f</span>: <span class="ident">F</span>)
<span class="op">-></span> <span class="ident">LockResult</span><span class="op"><</span><span class="ident">U</span><span class="op">></span>
<span class="kw">where</span> <span class="ident">F</span>: <span class="ident">FnOnce</span>(<span class="ident">T</span>) <span class="op">-></span> <span class="ident">U</span> {
<span class="kw">match</span> <span class="ident">result</span> {
<span class="prelude-val">Ok</span>(<span class="ident">t</span>) <span class="op">=></span> <span class="prelude-val">Ok</span>(<span class="ident">f</span>(<span class="ident">t</span>)),
<span class="prelude-val">Err</span>(<span class="ident">PoisonError</span> { <span class="ident">guard</span> }) <span class="op">=></span> <span class="prelude-val">Err</span>(<span class="ident">PoisonError</span>::<span class="ident">new</span>(<span class="ident">f</span>(<span class="ident">guard</span>)))
}
}
</pre>
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