| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/crossbeam-utils-0.8.15/src/thread.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>thread.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../crossbeam_utils/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../crossbeam_utils/index.html"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="doccomment">//! Threads that can borrow variables from the stack. |
| //! |
| //! Create a scope when spawned threads need to access variables on the stack: |
| //! |
| //! ``` |
| //! use crossbeam_utils::thread; |
| //! |
| //! let people = vec![ |
| //! "Alice".to_string(), |
| //! "Bob".to_string(), |
| //! "Carol".to_string(), |
| //! ]; |
| //! |
| //! thread::scope(|s| { |
| //! for person in &people { |
| //! s.spawn(move |_| { |
| //! println!("Hello, {}!", person); |
| //! }); |
| //! } |
| //! }).unwrap(); |
| //! ``` |
| //! |
| //! # Why scoped threads? |
| //! |
| //! Suppose we wanted to re-write the previous example using plain threads: |
| //! |
| //! ```compile_fail,E0597 |
| //! use std::thread; |
| //! |
| //! let people = vec![ |
| //! "Alice".to_string(), |
| //! "Bob".to_string(), |
| //! "Carol".to_string(), |
| //! ]; |
| //! |
| //! let mut threads = Vec::new(); |
| //! |
| //! for person in &people { |
| //! threads.push(thread::spawn(move || { |
| //! println!("Hello, {}!", person); |
| //! })); |
| //! } |
| //! |
| //! for thread in threads { |
| //! thread.join().unwrap(); |
| //! } |
| //! ``` |
| //! |
| //! This doesn't work because the borrow checker complains about `people` not living long enough: |
| //! |
| //! ```text |
| //! error[E0597]: `people` does not live long enough |
| //! --> src/main.rs:12:20 |
| //! | |
| //! 12 | for person in &people { |
| //! | ^^^^^^ borrowed value does not live long enough |
| //! ... |
| //! 21 | } |
| //! | - borrowed value only lives until here |
| //! | |
| //! = note: borrowed value must be valid for the static lifetime... |
| //! ``` |
| //! |
| //! The problem here is that spawned threads are not allowed to borrow variables on stack because |
| //! the compiler cannot prove they will be joined before `people` is destroyed. |
| //! |
| //! Scoped threads are a mechanism to guarantee to the compiler that spawned threads will be joined |
| //! before the scope ends. |
| //! |
| //! # How scoped threads work |
| //! |
| //! If a variable is borrowed by a thread, the thread must complete before the variable is |
| //! destroyed. Threads spawned using [`std::thread::spawn`] can only borrow variables with the |
| //! `'static` lifetime because the borrow checker cannot be sure when the thread will complete. |
| //! |
| //! A scope creates a clear boundary between variables outside the scope and threads inside the |
| //! scope. Whenever a scope spawns a thread, it promises to join the thread before the scope ends. |
| //! This way we guarantee to the borrow checker that scoped threads only live within the scope and |
| //! can safely access variables outside it. |
| //! |
| //! # Nesting scoped threads |
| //! |
| //! Sometimes scoped threads need to spawn more threads within the same scope. This is a little |
| //! tricky because argument `s` lives *inside* the invocation of `thread::scope()` and as such |
| //! cannot be borrowed by scoped threads: |
| //! |
| //! ```compile_fail,E0373,E0521 |
| //! use crossbeam_utils::thread; |
| //! |
| //! thread::scope(|s| { |
| //! s.spawn(|_| { |
| //! // Not going to compile because we're trying to borrow `s`, |
| //! // which lives *inside* the scope! :( |
| //! s.spawn(|_| println!("nested thread")); |
| //! }); |
| //! }); |
| //! ``` |
| //! |
| //! Fortunately, there is a solution. Every scoped thread is passed a reference to its scope as an |
| //! argument, which can be used for spawning nested threads: |
| //! |
| //! ``` |
| //! use crossbeam_utils::thread; |
| //! |
| //! thread::scope(|s| { |
| //! // Note the `|s|` here. |
| //! s.spawn(|s| { |
| //! // Yay, this works because we're using a fresh argument `s`! :) |
| //! s.spawn(|_| println!("nested thread")); |
| //! }); |
| //! }).unwrap(); |
| //! ``` |
| |
| </span><span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::marker::PhantomData; |
| <span class="kw">use </span>std::mem; |
| <span class="kw">use </span>std::panic; |
| <span class="kw">use </span>std::sync::{Arc, Mutex}; |
| <span class="kw">use </span>std::thread; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::sync::WaitGroup; |
| <span class="kw">use </span>cfg_if::cfg_if; |
| |
| <span class="kw">type </span>SharedVec<T> = Arc<Mutex<Vec<T>>>; |
| <span class="kw">type </span>SharedOption<T> = Arc<Mutex<<span class="prelude-ty">Option</span><T>>>; |
| |
| <span class="doccomment">/// Creates a new scope for spawning threads. |
| /// |
| /// All child threads that haven't been manually joined will be automatically joined just before |
| /// this function invocation ends. If all joined threads have successfully completed, `Ok` is |
| /// returned with the return value of `f`. If any of the joined threads has panicked, an `Err` is |
| /// returned containing errors from panicked threads. Note that if panics are implemented by |
| /// aborting the process, no error is returned; see the notes of [std::panic::catch_unwind]. |
| /// |
| /// **Note:** Since Rust 1.63, this function is soft-deprecated in favor of the more efficient [`std::thread::scope`]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// let var = vec![1, 2, 3]; |
| /// |
| /// thread::scope(|s| { |
| /// s.spawn(|_| { |
| /// println!("A child thread borrowing `var`: {:?}", var); |
| /// }); |
| /// }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>scope<<span class="lifetime">'env</span>, F, R>(f: F) -> thread::Result<R> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&</span>Scope<<span class="lifetime">'env</span>>) -> R, |
| { |
| <span class="kw">let </span>wg = WaitGroup::new(); |
| <span class="kw">let </span>scope = Scope::<<span class="lifetime">'env</span>> { |
| handles: SharedVec::default(), |
| wait_group: wg.clone(), |
| _marker: PhantomData, |
| }; |
| |
| <span class="comment">// Execute the scoped function, but catch any panics. |
| </span><span class="kw">let </span>result = panic::catch_unwind(panic::AssertUnwindSafe(|| f(<span class="kw-2">&</span>scope))); |
| |
| <span class="comment">// Wait until all nested scopes are dropped. |
| </span>drop(scope.wait_group); |
| wg.wait(); |
| |
| <span class="comment">// Join all remaining spawned threads. |
| </span><span class="kw">let </span>panics: Vec<<span class="kw">_</span>> = scope |
| .handles |
| .lock() |
| .unwrap() |
| <span class="comment">// Filter handles that haven't been joined, join them, and collect errors. |
| </span>.drain(..) |
| .filter_map(|handle| handle.lock().unwrap().take()) |
| .filter_map(|handle| handle.join().err()) |
| .collect(); |
| |
| <span class="comment">// If `f` has panicked, resume unwinding. |
| // If any of the child threads have panicked, return the panic errors. |
| // Otherwise, everything is OK and return the result of `f`. |
| </span><span class="kw">match </span>result { |
| <span class="prelude-val">Err</span>(err) => panic::resume_unwind(err), |
| <span class="prelude-val">Ok</span>(res) => { |
| <span class="kw">if </span>panics.is_empty() { |
| <span class="prelude-val">Ok</span>(res) |
| } <span class="kw">else </span>{ |
| <span class="prelude-val">Err</span>(Box::new(panics)) |
| } |
| } |
| } |
| } |
| |
| <span class="doccomment">/// A scope for spawning threads. |
| </span><span class="kw">pub struct </span>Scope<<span class="lifetime">'env</span>> { |
| <span class="doccomment">/// The list of the thread join handles. |
| </span>handles: SharedVec<SharedOption<thread::JoinHandle<()>>>, |
| |
| <span class="doccomment">/// Used to wait until all subscopes all dropped. |
| </span>wait_group: WaitGroup, |
| |
| <span class="doccomment">/// Borrows data with invariant lifetime `'env`. |
| </span>_marker: PhantomData<<span class="kw-2">&</span><span class="lifetime">'env </span><span class="kw-2">mut &</span><span class="lifetime">'env </span>()>, |
| } |
| |
| <span class="kw">unsafe impl </span>Sync <span class="kw">for </span>Scope<<span class="lifetime">'_</span>> {} |
| |
| <span class="kw">impl</span><<span class="lifetime">'env</span>> Scope<<span class="lifetime">'env</span>> { |
| <span class="doccomment">/// Spawns a scoped thread. |
| /// |
| /// This method is similar to the [`spawn`] function in Rust's standard library. The difference |
| /// is that this thread is scoped, meaning it's guaranteed to terminate before the scope exits, |
| /// allowing it to reference variables outside the scope. |
| /// |
| /// The scoped thread is passed a reference to this scope as an argument, which can be used for |
| /// spawning nested threads. |
| /// |
| /// The returned [handle](ScopedJoinHandle) can be used to manually |
| /// [join](ScopedJoinHandle::join) the thread before the scope exits. |
| /// |
| /// This will create a thread using default parameters of [`ScopedThreadBuilder`], if you want to specify the |
| /// stack size or the name of the thread, use this API instead. |
| /// |
| /// [`spawn`]: std::thread::spawn |
| /// |
| /// # Panics |
| /// |
| /// Panics if the OS fails to create a thread; use [`ScopedThreadBuilder::spawn`] |
| /// to recover from such errors. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// let handle = s.spawn(|_| { |
| /// println!("A child thread is running"); |
| /// 42 |
| /// }); |
| /// |
| /// // Join the thread and retrieve its result. |
| /// let res = handle.join().unwrap(); |
| /// assert_eq!(res, 42); |
| /// }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>spawn<<span class="lifetime">'scope</span>, F, T>(<span class="kw-2">&</span><span class="lifetime">'scope </span><span class="self">self</span>, f: F) -> ScopedJoinHandle<<span class="lifetime">'scope</span>, T> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&</span>Scope<<span class="lifetime">'env</span>>) -> T, |
| F: Send + <span class="lifetime">'env</span>, |
| T: Send + <span class="lifetime">'env</span>, |
| { |
| <span class="self">self</span>.builder() |
| .spawn(f) |
| .expect(<span class="string">"failed to spawn scoped thread"</span>) |
| } |
| |
| <span class="doccomment">/// Creates a builder that can configure a thread before spawning. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// s.builder() |
| /// .spawn(|_| println!("A child thread is running")) |
| /// .unwrap(); |
| /// }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>builder<<span class="lifetime">'scope</span>>(<span class="kw-2">&</span><span class="lifetime">'scope </span><span class="self">self</span>) -> ScopedThreadBuilder<<span class="lifetime">'scope</span>, <span class="lifetime">'env</span>> { |
| ScopedThreadBuilder { |
| scope: <span class="self">self</span>, |
| builder: thread::Builder::new(), |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Scope<<span class="lifetime">'_</span>> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.pad(<span class="string">"Scope { .. }"</span>) |
| } |
| } |
| |
| <span class="doccomment">/// Configures the properties of a new thread. |
| /// |
| /// The two configurable properties are: |
| /// |
| /// - [`name`]: Specifies an [associated name for the thread][naming-threads]. |
| /// - [`stack_size`]: Specifies the [desired stack size for the thread][stack-size]. |
| /// |
| /// The [`spawn`] method will take ownership of the builder and return an [`io::Result`] of the |
| /// thread handle with the given configuration. |
| /// |
| /// The [`Scope::spawn`] method uses a builder with default configuration and unwraps its return |
| /// value. You may want to use this builder when you want to recover from a failure to launch a |
| /// thread. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// s.builder() |
| /// .spawn(|_| println!("Running a child thread")) |
| /// .unwrap(); |
| /// }).unwrap(); |
| /// ``` |
| /// |
| /// [`name`]: ScopedThreadBuilder::name |
| /// [`stack_size`]: ScopedThreadBuilder::stack_size |
| /// [`spawn`]: ScopedThreadBuilder::spawn |
| /// [`io::Result`]: std::io::Result |
| /// [naming-threads]: std::thread#naming-threads |
| /// [stack-size]: std::thread#stack-size |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>ScopedThreadBuilder<<span class="lifetime">'scope</span>, <span class="lifetime">'env</span>> { |
| scope: <span class="kw-2">&</span><span class="lifetime">'scope </span>Scope<<span class="lifetime">'env</span>>, |
| builder: thread::Builder, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'scope</span>, <span class="lifetime">'env</span>> ScopedThreadBuilder<<span class="lifetime">'scope</span>, <span class="lifetime">'env</span>> { |
| <span class="doccomment">/// Sets the name for the new thread. |
| /// |
| /// The name must not contain null bytes (`\0`). |
| /// |
| /// For more information about named threads, see [here][naming-threads]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// use std::thread::current; |
| /// |
| /// thread::scope(|s| { |
| /// s.builder() |
| /// .name("my thread".to_string()) |
| /// .spawn(|_| assert_eq!(current().name(), Some("my thread"))) |
| /// .unwrap(); |
| /// }).unwrap(); |
| /// ``` |
| /// |
| /// [naming-threads]: std::thread#naming-threads |
| </span><span class="kw">pub fn </span>name(<span class="kw-2">mut </span><span class="self">self</span>, name: String) -> ScopedThreadBuilder<<span class="lifetime">'scope</span>, <span class="lifetime">'env</span>> { |
| <span class="self">self</span>.builder = <span class="self">self</span>.builder.name(name); |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Sets the size of the stack for the new thread. |
| /// |
| /// The stack size is measured in bytes. |
| /// |
| /// For more information about the stack size for threads, see [here][stack-size]. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// s.builder() |
| /// .stack_size(32 * 1024) |
| /// .spawn(|_| println!("Running a child thread")) |
| /// .unwrap(); |
| /// }).unwrap(); |
| /// ``` |
| /// |
| /// [stack-size]: std::thread#stack-size |
| </span><span class="kw">pub fn </span>stack_size(<span class="kw-2">mut </span><span class="self">self</span>, size: usize) -> ScopedThreadBuilder<<span class="lifetime">'scope</span>, <span class="lifetime">'env</span>> { |
| <span class="self">self</span>.builder = <span class="self">self</span>.builder.stack_size(size); |
| <span class="self">self |
| </span>} |
| |
| <span class="doccomment">/// Spawns a scoped thread with this configuration. |
| /// |
| /// The scoped thread is passed a reference to this scope as an argument, which can be used for |
| /// spawning nested threads. |
| /// |
| /// The returned handle can be used to manually join the thread before the scope exits. |
| /// |
| /// # Errors |
| /// |
| /// Unlike the [`Scope::spawn`] method, this method yields an |
| /// [`io::Result`] to capture any failure to create the thread at |
| /// the OS level. |
| /// |
| /// [`io::Result`]: std::io::Result |
| /// |
| /// # Panics |
| /// |
| /// Panics if a thread name was set and it contained null bytes. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// let handle = s.builder() |
| /// .spawn(|_| { |
| /// println!("A child thread is running"); |
| /// 42 |
| /// }) |
| /// .unwrap(); |
| /// |
| /// // Join the thread and retrieve its result. |
| /// let res = handle.join().unwrap(); |
| /// assert_eq!(res, 42); |
| /// }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>spawn<F, T>(<span class="self">self</span>, f: F) -> io::Result<ScopedJoinHandle<<span class="lifetime">'scope</span>, T>> |
| <span class="kw">where |
| </span>F: FnOnce(<span class="kw-2">&</span>Scope<<span class="lifetime">'env</span>>) -> T, |
| F: Send + <span class="lifetime">'env</span>, |
| T: Send + <span class="lifetime">'env</span>, |
| { |
| <span class="comment">// The result of `f` will be stored here. |
| </span><span class="kw">let </span>result = SharedOption::default(); |
| |
| <span class="comment">// Spawn the thread and grab its join handle and thread handle. |
| </span><span class="kw">let </span>(handle, thread) = { |
| <span class="kw">let </span>result = Arc::clone(<span class="kw-2">&</span>result); |
| |
| <span class="comment">// A clone of the scope that will be moved into the new thread. |
| </span><span class="kw">let </span>scope = Scope::<<span class="lifetime">'env</span>> { |
| handles: Arc::clone(<span class="kw-2">&</span><span class="self">self</span>.scope.handles), |
| wait_group: <span class="self">self</span>.scope.wait_group.clone(), |
| _marker: PhantomData, |
| }; |
| |
| <span class="comment">// Spawn the thread. |
| </span><span class="kw">let </span>handle = { |
| <span class="kw">let </span>closure = <span class="kw">move </span>|| { |
| <span class="comment">// Make sure the scope is inside the closure with the proper `'env` lifetime. |
| </span><span class="kw">let </span>scope: Scope<<span class="lifetime">'env</span>> = scope; |
| |
| <span class="comment">// Run the closure. |
| </span><span class="kw">let </span>res = f(<span class="kw-2">&</span>scope); |
| |
| <span class="comment">// Store the result if the closure didn't panic. |
| </span><span class="kw-2">*</span>result.lock().unwrap() = <span class="prelude-val">Some</span>(res); |
| }; |
| |
| <span class="comment">// Allocate `closure` on the heap and erase the `'env` bound. |
| </span><span class="kw">let </span>closure: Box<<span class="kw">dyn </span>FnOnce() + Send + <span class="lifetime">'env</span>> = Box::new(closure); |
| <span class="kw">let </span>closure: Box<<span class="kw">dyn </span>FnOnce() + Send + <span class="lifetime">'static</span>> = |
| <span class="kw">unsafe </span>{ mem::transmute(closure) }; |
| |
| <span class="comment">// Finally, spawn the closure. |
| </span><span class="self">self</span>.builder.spawn(closure)<span class="question-mark">? |
| </span>}; |
| |
| <span class="kw">let </span>thread = handle.thread().clone(); |
| <span class="kw">let </span>handle = Arc::new(Mutex::new(<span class="prelude-val">Some</span>(handle))); |
| (handle, thread) |
| }; |
| |
| <span class="comment">// Add the handle to the shared list of join handles. |
| </span><span class="self">self</span>.scope.handles.lock().unwrap().push(Arc::clone(<span class="kw-2">&</span>handle)); |
| |
| <span class="prelude-val">Ok</span>(ScopedJoinHandle { |
| handle, |
| result, |
| thread, |
| _marker: PhantomData, |
| }) |
| } |
| } |
| |
| <span class="kw">unsafe impl</span><T> Send <span class="kw">for </span>ScopedJoinHandle<<span class="lifetime">'_</span>, T> {} |
| <span class="kw">unsafe impl</span><T> Sync <span class="kw">for </span>ScopedJoinHandle<<span class="lifetime">'_</span>, T> {} |
| |
| <span class="doccomment">/// A handle that can be used to join its scoped thread. |
| /// |
| /// This struct is created by the [`Scope::spawn`] method and the |
| /// [`ScopedThreadBuilder::spawn`] method. |
| </span><span class="kw">pub struct </span>ScopedJoinHandle<<span class="lifetime">'scope</span>, T> { |
| <span class="doccomment">/// A join handle to the spawned thread. |
| </span>handle: SharedOption<thread::JoinHandle<()>>, |
| |
| <span class="doccomment">/// Holds the result of the inner closure. |
| </span>result: SharedOption<T>, |
| |
| <span class="doccomment">/// A handle to the the spawned thread. |
| </span>thread: thread::Thread, |
| |
| <span class="doccomment">/// Borrows the parent scope with lifetime `'scope`. |
| </span>_marker: PhantomData<<span class="kw-2">&</span><span class="lifetime">'scope </span>()>, |
| } |
| |
| <span class="kw">impl</span><T> ScopedJoinHandle<<span class="lifetime">'_</span>, T> { |
| <span class="doccomment">/// Waits for the thread to finish and returns its result. |
| /// |
| /// If the child thread panics, an error is returned. Note that if panics are implemented by |
| /// aborting the process, no error is returned; see the notes of [std::panic::catch_unwind]. |
| /// |
| /// # Panics |
| /// |
| /// This function may panic on some platforms if a thread attempts to join itself or otherwise |
| /// may create a deadlock with joining threads. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// let handle1 = s.spawn(|_| println!("I'm a happy thread :)")); |
| /// let handle2 = s.spawn(|_| panic!("I'm a sad thread :(")); |
| /// |
| /// // Join the first thread and verify that it succeeded. |
| /// let res = handle1.join(); |
| /// assert!(res.is_ok()); |
| /// |
| /// // Join the second thread and verify that it panicked. |
| /// let res = handle2.join(); |
| /// assert!(res.is_err()); |
| /// }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>join(<span class="self">self</span>) -> thread::Result<T> { |
| <span class="comment">// Take out the handle. The handle will surely be available because the root scope waits |
| // for nested scopes before joining remaining threads. |
| </span><span class="kw">let </span>handle = <span class="self">self</span>.handle.lock().unwrap().take().unwrap(); |
| |
| <span class="comment">// Join the thread and then take the result out of its inner closure. |
| </span>handle |
| .join() |
| .map(|()| <span class="self">self</span>.result.lock().unwrap().take().unwrap()) |
| } |
| |
| <span class="doccomment">/// Returns a handle to the underlying thread. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use crossbeam_utils::thread; |
| /// |
| /// thread::scope(|s| { |
| /// let handle = s.spawn(|_| println!("A child thread is running")); |
| /// println!("The child thread ID: {:?}", handle.thread().id()); |
| /// }).unwrap(); |
| /// ``` |
| </span><span class="kw">pub fn </span>thread(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span>thread::Thread { |
| <span class="kw-2">&</span><span class="self">self</span>.thread |
| } |
| } |
| |
| <span class="macro">cfg_if! </span>{ |
| <span class="kw">if </span><span class="attribute">#[cfg(unix)] </span>{ |
| <span class="kw">use </span>std::os::unix::thread::{JoinHandleExt, RawPthread}; |
| |
| <span class="kw">impl</span><T> JoinHandleExt <span class="kw">for </span>ScopedJoinHandle<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>as_pthread_t(<span class="kw-2">&</span><span class="self">self</span>) -> RawPthread { |
| <span class="comment">// Borrow the handle. The handle will surely be available because the root scope waits |
| // for nested scopes before joining remaining threads. |
| </span><span class="kw">let </span>handle = <span class="self">self</span>.handle.lock().unwrap(); |
| handle.as_ref().unwrap().as_pthread_t() |
| } |
| <span class="kw">fn </span>into_pthread_t(<span class="self">self</span>) -> RawPthread { |
| <span class="self">self</span>.as_pthread_t() |
| } |
| } |
| } <span class="kw">else if </span><span class="attribute">#[cfg(windows)] </span>{ |
| <span class="kw">use </span>std::os::windows::io::{AsRawHandle, IntoRawHandle, RawHandle}; |
| |
| <span class="kw">impl</span><T> AsRawHandle <span class="kw">for </span>ScopedJoinHandle<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>as_raw_handle(<span class="kw-2">&</span><span class="self">self</span>) -> RawHandle { |
| <span class="comment">// Borrow the handle. The handle will surely be available because the root scope waits |
| // for nested scopes before joining remaining threads. |
| </span><span class="kw">let </span>handle = <span class="self">self</span>.handle.lock().unwrap(); |
| handle.as_ref().unwrap().as_raw_handle() |
| } |
| } |
| |
| <span class="kw">impl</span><T> IntoRawHandle <span class="kw">for </span>ScopedJoinHandle<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>into_raw_handle(<span class="self">self</span>) -> RawHandle { |
| <span class="self">self</span>.as_raw_handle() |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T> fmt::Debug <span class="kw">for </span>ScopedJoinHandle<<span class="lifetime">'_</span>, T> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.pad(<span class="string">"ScopedJoinHandle { .. }"</span>) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="crossbeam_utils" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
