3 //! ## The threading model
5 //! An executing Rust program consists of a collection of native OS threads,
6 //! each with their own stack and local state. Threads can be named, and
7 //! provide some built-in support for low-level synchronization.
9 //! Communication between threads can be done through
10 //! [channels], Rust's message-passing types, along with [other forms of thread
11 //! synchronization](../../std/sync/index.html) and shared-memory data
12 //! structures. In particular, types that are guaranteed to be
13 //! threadsafe are easily shared between threads using the
14 //! atomically-reference-counted container, [`Arc`].
16 //! Fatal logic errors in Rust cause *thread panic*, during which
17 //! a thread will unwind the stack, running destructors and freeing
18 //! owned resources. While not meant as a 'try/catch' mechanism, panics
19 //! in Rust can nonetheless be caught (unless compiling with `panic=abort`) with
20 //! [`catch_unwind`](../../std/panic/fn.catch_unwind.html) and recovered
21 //! from, or alternatively be resumed with
22 //! [`resume_unwind`](../../std/panic/fn.resume_unwind.html). If the panic
23 //! is not caught the thread will exit, but the panic may optionally be
24 //! detected from a different thread with [`join`]. If the main thread panics
25 //! without the panic being caught, the application will exit with a
26 //! non-zero exit code.
28 //! When the main thread of a Rust program terminates, the entire program shuts
29 //! down, even if other threads are still running. However, this module provides
30 //! convenient facilities for automatically waiting for the termination of a
31 //! child thread (i.e., join).
33 //! ## Spawning a thread
35 //! A new thread can be spawned using the [`thread::spawn`][`spawn`] function:
40 //! thread::spawn(move || {
45 //! In this example, the spawned thread is "detached" from the current
46 //! thread. This means that it can outlive its parent (the thread that spawned
47 //! it), unless this parent is the main thread.
49 //! The parent thread can also wait on the completion of the child
50 //! thread; a call to [`spawn`] produces a [`JoinHandle`], which provides
51 //! a `join` method for waiting:
56 //! let child = thread::spawn(move || {
60 //! let res = child.join();
63 //! The [`join`] method returns a [`thread::Result`] containing [`Ok`] of the final
64 //! value produced by the child thread, or [`Err`] of the value given to
65 //! a call to [`panic!`] if the child panicked.
67 //! ## Configuring threads
69 //! A new thread can be configured before it is spawned via the [`Builder`] type,
70 //! which currently allows you to set the name and stack size for the child thread:
73 //! # #![allow(unused_must_use)]
76 //! thread::Builder::new().name("child1".to_string()).spawn(move || {
77 //! println!("Hello, world!");
81 //! ## The `Thread` type
83 //! Threads are represented via the [`Thread`] type, which you can get in one of
86 //! * By spawning a new thread, e.g., using the [`thread::spawn`][`spawn`]
87 //! function, and calling [`thread`][`JoinHandle::thread`] on the [`JoinHandle`].
88 //! * By requesting the current thread, using the [`thread::current`] function.
90 //! The [`thread::current`] function is available even for threads not spawned
91 //! by the APIs of this module.
93 //! ## Thread-local storage
95 //! This module also provides an implementation of thread-local storage for Rust
96 //! programs. Thread-local storage is a method of storing data into a global
97 //! variable that each thread in the program will have its own copy of.
98 //! Threads do not share this data, so accesses do not need to be synchronized.
100 //! A thread-local key owns the value it contains and will destroy the value when the
101 //! thread exits. It is created with the [`thread_local!`] macro and can contain any
102 //! value that is `'static` (no borrowed pointers). It provides an accessor function,
103 //! [`with`], that yields a shared reference to the value to the specified
104 //! closure. Thread-local keys allow only shared access to values, as there would be no
105 //! way to guarantee uniqueness if mutable borrows were allowed. Most values
106 //! will want to make use of some form of **interior mutability** through the
107 //! [`Cell`] or [`RefCell`] types.
109 //! ## Naming threads
111 //! Threads are able to have associated names for identification purposes. By default, spawned
112 //! threads are unnamed. To specify a name for a thread, build the thread with [`Builder`] and pass
113 //! the desired thread name to [`Builder::name`]. To retrieve the thread name from within the
114 //! thread, use [`Thread::name`]. A couple examples of where the name of a thread gets used:
116 //! * If a panic occurs in a named thread, the thread name will be printed in the panic message.
117 //! * The thread name is provided to the OS where applicable (e.g., `pthread_setname_np` in
118 //! unix-like platforms).
122 //! The default stack size for spawned threads is 2 MiB, though this particular stack size is
123 //! subject to change in the future. There are two ways to manually specify the stack size for
126 //! * Build the thread with [`Builder`] and pass the desired stack size to [`Builder::stack_size`].
127 //! * Set the `RUST_MIN_STACK` environment variable to an integer representing the desired stack
128 //! size (in bytes). Note that setting [`Builder::stack_size`] will override this.
130 //! Note that the stack size of the main thread is *not* determined by Rust.
132 //! [channels]: ../../std/sync/mpsc/index.html
133 //! [`Arc`]: ../../std/sync/struct.Arc.html
134 //! [`spawn`]: ../../std/thread/fn.spawn.html
135 //! [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html
136 //! [`JoinHandle::thread`]: ../../std/thread/struct.JoinHandle.html#method.thread
137 //! [`join`]: ../../std/thread/struct.JoinHandle.html#method.join
138 //! [`Result`]: ../../std/result/enum.Result.html
139 //! [`Ok`]: ../../std/result/enum.Result.html#variant.Ok
140 //! [`Err`]: ../../std/result/enum.Result.html#variant.Err
141 //! [`panic!`]: ../../std/macro.panic.html
142 //! [`Builder`]: ../../std/thread/struct.Builder.html
143 //! [`Builder::stack_size`]: ../../std/thread/struct.Builder.html#method.stack_size
144 //! [`Builder::name`]: ../../std/thread/struct.Builder.html#method.name
145 //! [`thread::current`]: ../../std/thread/fn.current.html
146 //! [`thread::Result`]: ../../std/thread/type.Result.html
147 //! [`Thread`]: ../../std/thread/struct.Thread.html
148 //! [`park`]: ../../std/thread/fn.park.html
149 //! [`unpark`]: ../../std/thread/struct.Thread.html#method.unpark
150 //! [`Thread::name`]: ../../std/thread/struct.Thread.html#method.name
151 //! [`thread::park_timeout`]: ../../std/thread/fn.park_timeout.html
152 //! [`Cell`]: ../cell/struct.Cell.html
153 //! [`RefCell`]: ../cell/struct.RefCell.html
154 //! [`thread_local!`]: ../macro.thread_local.html
155 //! [`with`]: struct.LocalKey.html#method.with
157 #![stable(feature = "rust1", since = "1.0.0")]
160 use crate::boxed::FnBox;
161 use crate::cell::UnsafeCell;
162 use crate::ffi::{CStr, CString};
167 use crate::panicking;
169 use crate::sync::{Mutex, Condvar, Arc};
170 use crate::sync::atomic::AtomicUsize;
171 use crate::sync::atomic::Ordering::SeqCst;
172 use crate::sys::thread as imp;
173 use crate::sys_common::mutex;
174 use crate::sys_common::thread_info;
175 use crate::sys_common::thread;
176 use crate::sys_common::{AsInner, IntoInner};
177 use crate::time::Duration;
179 ////////////////////////////////////////////////////////////////////////////////
180 // Thread-local storage
181 ////////////////////////////////////////////////////////////////////////////////
183 #[macro_use] mod local;
185 #[stable(feature = "rust1", since = "1.0.0")]
186 pub use self::local::{LocalKey, AccessError};
188 // The types used by the thread_local! macro to access TLS keys. Note that there
189 // are two types, the "OS" type and the "fast" type. The OS thread local key
190 // type is accessed via platform-specific API calls and is slow, while the fast
191 // key type is accessed via code generated via LLVM, where TLS keys are set up
192 // by the elf linker. Note that the OS TLS type is always available: on macOS
193 // the standard library is compiled with support for older platform versions
194 // where fast TLS was not available; end-user code is compiled with fast TLS
195 // where available, but both are needed.
197 #[unstable(feature = "libstd_thread_internals", issue = "0")]
198 #[cfg(all(target_arch = "wasm32", not(target_feature = "atomics")))]
199 #[doc(hidden)] pub use self::local::statik::Key as __StaticLocalKeyInner;
200 #[unstable(feature = "libstd_thread_internals", issue = "0")]
201 #[cfg(target_thread_local)]
202 #[doc(hidden)] pub use self::local::fast::Key as __FastLocalKeyInner;
203 #[unstable(feature = "libstd_thread_internals", issue = "0")]
204 #[doc(hidden)] pub use self::local::os::Key as __OsLocalKeyInner;
206 ////////////////////////////////////////////////////////////////////////////////
208 ////////////////////////////////////////////////////////////////////////////////
210 /// Thread factory, which can be used in order to configure the properties of
213 /// Methods can be chained on it in order to configure it.
215 /// The two configurations available are:
217 /// - [`name`]: specifies an [associated name for the thread][naming-threads]
218 /// - [`stack_size`]: specifies the [desired stack size for the thread][stack-size]
220 /// The [`spawn`] method will take ownership of the builder and create an
221 /// [`io::Result`] to the thread handle with the given configuration.
223 /// The [`thread::spawn`] free function uses a `Builder` with default
224 /// configuration and [`unwrap`]s its return value.
226 /// You may want to use [`spawn`] instead of [`thread::spawn`], when you want
227 /// to recover from a failure to launch a thread, indeed the free function will
228 /// panic where the `Builder` method will return a [`io::Result`].
235 /// let builder = thread::Builder::new();
237 /// let handler = builder.spawn(|| {
241 /// handler.join().unwrap();
244 /// [`thread::spawn`]: ../../std/thread/fn.spawn.html
245 /// [`stack_size`]: ../../std/thread/struct.Builder.html#method.stack_size
246 /// [`name`]: ../../std/thread/struct.Builder.html#method.name
247 /// [`spawn`]: ../../std/thread/struct.Builder.html#method.spawn
248 /// [`io::Result`]: ../../std/io/type.Result.html
249 /// [`unwrap`]: ../../std/result/enum.Result.html#method.unwrap
250 /// [naming-threads]: ./index.html#naming-threads
251 /// [stack-size]: ./index.html#stack-size
252 #[stable(feature = "rust1", since = "1.0.0")]
255 // A name for the thread-to-be, for identification in panic messages
256 name: Option<String>,
257 // The size of the stack for the spawned thread in bytes
258 stack_size: Option<usize>,
262 /// Generates the base configuration for spawning a thread, from which
263 /// configuration methods can be chained.
270 /// let builder = thread::Builder::new()
271 /// .name("foo".into())
274 /// let handler = builder.spawn(|| {
278 /// handler.join().unwrap();
280 #[stable(feature = "rust1", since = "1.0.0")]
281 pub fn new() -> Builder {
288 /// Names the thread-to-be. Currently the name is used for identification
289 /// only in panic messages.
291 /// The name must not contain null bytes (`\0`).
293 /// For more information about named threads, see
294 /// [this module-level documentation][naming-threads].
301 /// let builder = thread::Builder::new()
302 /// .name("foo".into());
304 /// let handler = builder.spawn(|| {
305 /// assert_eq!(thread::current().name(), Some("foo"))
308 /// handler.join().unwrap();
311 /// [naming-threads]: ./index.html#naming-threads
312 #[stable(feature = "rust1", since = "1.0.0")]
313 pub fn name(mut self, name: String) -> Builder {
314 self.name = Some(name);
318 /// Sets the size of the stack (in bytes) for the new thread.
320 /// The actual stack size may be greater than this value if
321 /// the platform specifies a minimal stack size.
323 /// For more information about the stack size for threads, see
324 /// [this module-level documentation][stack-size].
331 /// let builder = thread::Builder::new().stack_size(32 * 1024);
334 /// [stack-size]: ./index.html#stack-size
335 #[stable(feature = "rust1", since = "1.0.0")]
336 pub fn stack_size(mut self, size: usize) -> Builder {
337 self.stack_size = Some(size);
341 /// Spawns a new thread by taking ownership of the `Builder`, and returns an
342 /// [`io::Result`] to its [`JoinHandle`].
344 /// The spawned thread may outlive the caller (unless the caller thread
345 /// is the main thread; the whole process is terminated when the main
346 /// thread finishes). The join handle can be used to block on
347 /// termination of the child thread, including recovering its panics.
349 /// For a more complete documentation see [`thread::spawn`][`spawn`].
353 /// Unlike the [`spawn`] free function, this method yields an
354 /// [`io::Result`] to capture any failure to create the thread at
357 /// [`spawn`]: ../../std/thread/fn.spawn.html
358 /// [`io::Result`]: ../../std/io/type.Result.html
359 /// [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html
363 /// Panics if a thread name was set and it contained null bytes.
370 /// let builder = thread::Builder::new();
372 /// let handler = builder.spawn(|| {
376 /// handler.join().unwrap();
378 #[stable(feature = "rust1", since = "1.0.0")]
379 pub fn spawn<F, T>(self, f: F) -> io::Result<JoinHandle<T>> where
380 F: FnOnce() -> T, F: Send + 'static, T: Send + 'static
382 unsafe { self.spawn_unchecked(f) }
385 /// Spawns a new thread without any lifetime restrictions by taking ownership
386 /// of the `Builder`, and returns an [`io::Result`] to its [`JoinHandle`].
388 /// The spawned thread may outlive the caller (unless the caller thread
389 /// is the main thread; the whole process is terminated when the main
390 /// thread finishes). The join handle can be used to block on
391 /// termination of the child thread, including recovering its panics.
393 /// This method is identical to [`thread::Builder::spawn`][`Builder::spawn`],
394 /// except for the relaxed lifetime bounds, which render it unsafe.
395 /// For a more complete documentation see [`thread::spawn`][`spawn`].
399 /// Unlike the [`spawn`] free function, this method yields an
400 /// [`io::Result`] to capture any failure to create the thread at
405 /// Panics if a thread name was set and it contained null bytes.
409 /// The caller has to ensure that no references in the supplied thread closure
410 /// or its return type can outlive the spawned thread's lifetime. This can be
411 /// guaranteed in two ways:
413 /// - ensure that [`join`][`JoinHandle::join`] is called before any referenced
415 /// - use only types with `'static` lifetime bounds, i.e., those with no or only
416 /// `'static` references (both [`thread::Builder::spawn`][`Builder::spawn`]
417 /// and [`thread::spawn`][`spawn`] enforce this property statically)
422 /// #![feature(thread_spawn_unchecked)]
425 /// let builder = thread::Builder::new();
428 /// let thread_x = &x;
430 /// let handler = unsafe {
431 /// builder.spawn_unchecked(move || {
432 /// println!("x = {}", *thread_x);
436 /// // caller has to ensure `join()` is called, otherwise
437 /// // it is possible to access freed memory if `x` gets
438 /// // dropped before the thread closure is executed!
439 /// handler.join().unwrap();
442 /// [`spawn`]: ../../std/thread/fn.spawn.html
443 /// [`Builder::spawn`]: ../../std/thread/struct.Builder.html#method.spawn
444 /// [`io::Result`]: ../../std/io/type.Result.html
445 /// [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html
446 #[unstable(feature = "thread_spawn_unchecked", issue = "55132")]
447 pub unsafe fn spawn_unchecked<'a, F, T>(self, f: F) -> io::Result<JoinHandle<T>> where
448 F: FnOnce() -> T, F: Send + 'a, T: Send + 'a
450 let Builder { name, stack_size } = self;
452 let stack_size = stack_size.unwrap_or_else(thread::min_stack);
454 let my_thread = Thread::new(name);
455 let their_thread = my_thread.clone();
457 let my_packet : Arc<UnsafeCell<Option<Result<T>>>>
458 = Arc::new(UnsafeCell::new(None));
459 let their_packet = my_packet.clone();
462 if let Some(name) = their_thread.cname() {
463 imp::Thread::set_name(name);
466 thread_info::set(imp::guard::current(), their_thread);
467 #[cfg(feature = "backtrace")]
468 let try_result = panic::catch_unwind(panic::AssertUnwindSafe(|| {
469 crate::sys_common::backtrace::__rust_begin_short_backtrace(f)
471 #[cfg(not(feature = "backtrace"))]
472 let try_result = panic::catch_unwind(panic::AssertUnwindSafe(f));
473 *their_packet.get() = Some(try_result);
476 Ok(JoinHandle(JoinInner {
477 // `imp::Thread::new` takes a closure with a `'static` lifetime, since it's passed
478 // through FFI or otherwise used with low-level threading primitives that have no
479 // notion of or way to enforce lifetimes.
481 // As mentioned in the `Safety` section of this function's documentation, the caller of
482 // this function needs to guarantee that the passed-in lifetime is sufficiently long
483 // for the lifetime of the thread.
485 // Similarly, the `sys` implementation must guarantee that no references to the closure
486 // exist after the thread has terminated, which is signaled by `Thread::join`
488 native: Some(imp::Thread::new(
490 mem::transmute::<Box<dyn FnBox() + 'a>, Box<dyn FnBox() + 'static>>(Box::new(main))
493 packet: Packet(my_packet),
498 ////////////////////////////////////////////////////////////////////////////////
500 ////////////////////////////////////////////////////////////////////////////////
502 /// Spawns a new thread, returning a [`JoinHandle`] for it.
504 /// The join handle will implicitly *detach* the child thread upon being
505 /// dropped. In this case, the child thread may outlive the parent (unless
506 /// the parent thread is the main thread; the whole process is terminated when
507 /// the main thread finishes). Additionally, the join handle provides a [`join`]
508 /// method that can be used to join the child thread. If the child thread
509 /// panics, [`join`] will return an [`Err`] containing the argument given to
512 /// This will create a thread using default parameters of [`Builder`], if you
513 /// want to specify the stack size or the name of the thread, use this API
516 /// As you can see in the signature of `spawn` there are two constraints on
517 /// both the closure given to `spawn` and its return value, let's explain them:
519 /// - The `'static` constraint means that the closure and its return value
520 /// must have a lifetime of the whole program execution. The reason for this
521 /// is that threads can `detach` and outlive the lifetime they have been
523 /// Indeed if the thread, and by extension its return value, can outlive their
524 /// caller, we need to make sure that they will be valid afterwards, and since
525 /// we *can't* know when it will return we need to have them valid as long as
526 /// possible, that is until the end of the program, hence the `'static`
528 /// - The [`Send`] constraint is because the closure will need to be passed
529 /// *by value* from the thread where it is spawned to the new thread. Its
530 /// return value will need to be passed from the new thread to the thread
531 /// where it is `join`ed.
532 /// As a reminder, the [`Send`] marker trait expresses that it is safe to be
533 /// passed from thread to thread. [`Sync`] expresses that it is safe to have a
534 /// reference be passed from thread to thread.
538 /// Panics if the OS fails to create a thread; use [`Builder::spawn`]
539 /// to recover from such errors.
543 /// Creating a thread.
548 /// let handler = thread::spawn(|| {
552 /// handler.join().unwrap();
555 /// As mentioned in the module documentation, threads are usually made to
556 /// communicate using [`channels`], here is how it usually looks.
558 /// This example also shows how to use `move`, in order to give ownership
559 /// of values to a thread.
563 /// use std::sync::mpsc::channel;
565 /// let (tx, rx) = channel();
567 /// let sender = thread::spawn(move || {
568 /// tx.send("Hello, thread".to_owned())
569 /// .expect("Unable to send on channel");
572 /// let receiver = thread::spawn(move || {
573 /// let value = rx.recv().expect("Unable to receive from channel");
574 /// println!("{}", value);
577 /// sender.join().expect("The sender thread has panicked");
578 /// receiver.join().expect("The receiver thread has panicked");
581 /// A thread can also return a value through its [`JoinHandle`], you can use
582 /// this to make asynchronous computations (futures might be more appropriate
588 /// let computation = thread::spawn(|| {
589 /// // Some expensive computation.
593 /// let result = computation.join().unwrap();
594 /// println!("{}", result);
597 /// [`channels`]: ../../std/sync/mpsc/index.html
598 /// [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html
599 /// [`join`]: ../../std/thread/struct.JoinHandle.html#method.join
600 /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
601 /// [`panic`]: ../../std/macro.panic.html
602 /// [`Builder::spawn`]: ../../std/thread/struct.Builder.html#method.spawn
603 /// [`Builder`]: ../../std/thread/struct.Builder.html
604 /// [`Send`]: ../../std/marker/trait.Send.html
605 /// [`Sync`]: ../../std/marker/trait.Sync.html
606 #[stable(feature = "rust1", since = "1.0.0")]
607 pub fn spawn<F, T>(f: F) -> JoinHandle<T> where
608 F: FnOnce() -> T, F: Send + 'static, T: Send + 'static
610 Builder::new().spawn(f).expect("failed to spawn thread")
613 /// Gets a handle to the thread that invokes it.
617 /// Getting a handle to the current thread with `thread::current()`:
622 /// let handler = thread::Builder::new()
623 /// .name("named thread".into())
625 /// let handle = thread::current();
626 /// assert_eq!(handle.name(), Some("named thread"));
630 /// handler.join().unwrap();
632 #[stable(feature = "rust1", since = "1.0.0")]
633 pub fn current() -> Thread {
634 thread_info::current_thread().expect("use of std::thread::current() is not \
635 possible after the thread's local \
636 data has been destroyed")
639 /// Cooperatively gives up a timeslice to the OS scheduler.
641 /// This is used when the programmer knows that the thread will have nothing
642 /// to do for some time, and thus avoid wasting computing time.
644 /// For example when polling on a resource, it is common to check that it is
645 /// available, and if not to yield in order to avoid busy waiting.
647 /// Thus the pattern of `yield`ing after a failed poll is rather common when
648 /// implementing low-level shared resources or synchronization primitives.
650 /// However programmers will usually prefer to use [`channel`]s, [`Condvar`]s,
651 /// [`Mutex`]es or [`join`] for their synchronization routines, as they avoid
652 /// thinking about thread scheduling.
654 /// Note that [`channel`]s for example are implemented using this primitive.
655 /// Indeed when you call `send` or `recv`, which are blocking, they will yield
656 /// if the channel is not available.
663 /// thread::yield_now();
666 /// [`channel`]: ../../std/sync/mpsc/index.html
667 /// [`spawn`]: ../../std/thread/fn.spawn.html
668 /// [`join`]: ../../std/thread/struct.JoinHandle.html#method.join
669 /// [`Mutex`]: ../../std/sync/struct.Mutex.html
670 /// [`Condvar`]: ../../std/sync/struct.Condvar.html
671 #[stable(feature = "rust1", since = "1.0.0")]
673 imp::Thread::yield_now()
676 /// Determines whether the current thread is unwinding because of panic.
678 /// A common use of this feature is to poison shared resources when writing
679 /// unsafe code, by checking `panicking` when the `drop` is called.
681 /// This is usually not needed when writing safe code, as [`Mutex`es][Mutex]
682 /// already poison themselves when a thread panics while holding the lock.
684 /// This can also be used in multithreaded applications, in order to send a
685 /// message to other threads warning that a thread has panicked (e.g., for
686 /// monitoring purposes).
693 /// struct SomeStruct;
695 /// impl Drop for SomeStruct {
696 /// fn drop(&mut self) {
697 /// if thread::panicking() {
698 /// println!("dropped while unwinding");
700 /// println!("dropped while not unwinding");
707 /// let a = SomeStruct;
712 /// let b = SomeStruct;
717 /// [Mutex]: ../../std/sync/struct.Mutex.html
719 #[stable(feature = "rust1", since = "1.0.0")]
720 pub fn panicking() -> bool {
721 panicking::panicking()
724 /// Puts the current thread to sleep for at least the specified amount of time.
726 /// The thread may sleep longer than the duration specified due to scheduling
727 /// specifics or platform-dependent functionality. It will never sleep less.
729 /// # Platform-specific behavior
731 /// On Unix platforms, the underlying syscall may be interrupted by a
732 /// spurious wakeup or signal handler. To ensure the sleep occurs for at least
733 /// the specified duration, this function may invoke that system call multiple
741 /// // Let's sleep for 2 seconds:
742 /// thread::sleep_ms(2000);
744 #[stable(feature = "rust1", since = "1.0.0")]
745 #[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::thread::sleep`")]
746 pub fn sleep_ms(ms: u32) {
747 sleep(Duration::from_millis(ms as u64))
750 /// Puts the current thread to sleep for at least the specified amount of time.
752 /// The thread may sleep longer than the duration specified due to scheduling
753 /// specifics or platform-dependent functionality. It will never sleep less.
755 /// # Platform-specific behavior
757 /// On Unix platforms, the underlying syscall may be interrupted by a
758 /// spurious wakeup or signal handler. To ensure the sleep occurs for at least
759 /// the specified duration, this function may invoke that system call multiple
761 /// Platforms which do not support nanosecond precision for sleeping will
762 /// have `dur` rounded up to the nearest granularity of time they can sleep for.
767 /// use std::{thread, time};
769 /// let ten_millis = time::Duration::from_millis(10);
770 /// let now = time::Instant::now();
772 /// thread::sleep(ten_millis);
774 /// assert!(now.elapsed() >= ten_millis);
776 #[stable(feature = "thread_sleep", since = "1.4.0")]
777 pub fn sleep(dur: Duration) {
778 imp::Thread::sleep(dur)
781 // constants for park/unpark
782 const EMPTY: usize = 0;
783 const PARKED: usize = 1;
784 const NOTIFIED: usize = 2;
786 /// Blocks unless or until the current thread's token is made available.
788 /// A call to `park` does not guarantee that the thread will remain parked
789 /// forever, and callers should be prepared for this possibility.
791 /// # park and unpark
793 /// Every thread is equipped with some basic low-level blocking support, via the
794 /// [`thread::park`][`park`] function and [`thread::Thread::unpark`][`unpark`]
795 /// method. [`park`] blocks the current thread, which can then be resumed from
796 /// another thread by calling the [`unpark`] method on the blocked thread's
799 /// Conceptually, each [`Thread`] handle has an associated token, which is
800 /// initially not present:
802 /// * The [`thread::park`][`park`] function blocks the current thread unless or
803 /// until the token is available for its thread handle, at which point it
804 /// atomically consumes the token. It may also return *spuriously*, without
805 /// consuming the token. [`thread::park_timeout`] does the same, but allows
806 /// specifying a maximum time to block the thread for.
808 /// * The [`unpark`] method on a [`Thread`] atomically makes the token available
809 /// if it wasn't already. Because the token is initially absent, [`unpark`]
810 /// followed by [`park`] will result in the second call returning immediately.
812 /// In other words, each [`Thread`] acts a bit like a spinlock that can be
813 /// locked and unlocked using `park` and `unpark`.
815 /// Notice that being unblocked does not imply any synchronization with someone
816 /// that unparked this thread, it could also be spurious.
817 /// For example, it would be a valid, but inefficient, implementation to make both [`park`] and
818 /// [`unpark`] return immediately without doing anything.
820 /// The API is typically used by acquiring a handle to the current thread,
821 /// placing that handle in a shared data structure so that other threads can
822 /// find it, and then `park`ing in a loop. When some desired condition is met, another
823 /// thread calls [`unpark`] on the handle.
825 /// The motivation for this design is twofold:
827 /// * It avoids the need to allocate mutexes and condvars when building new
828 /// synchronization primitives; the threads already provide basic
829 /// blocking/signaling.
831 /// * It can be implemented very efficiently on many platforms.
837 /// use std::sync::{Arc, atomic::{Ordering, AtomicBool}};
838 /// use std::time::Duration;
840 /// let flag = Arc::new(AtomicBool::new(false));
841 /// let flag2 = Arc::clone(&flag);
843 /// let parked_thread = thread::spawn(move || {
844 /// // We want to wait until the flag is set. We *could* just spin, but using
845 /// // park/unpark is more efficient.
846 /// while !flag2.load(Ordering::Acquire) {
847 /// println!("Parking thread");
849 /// // We *could* get here spuriously, i.e., way before the 10ms below are over!
850 /// // But that is no problem, we are in a loop until the flag is set anyway.
851 /// println!("Thread unparked");
853 /// println!("Flag received");
856 /// // Let some time pass for the thread to be spawned.
857 /// thread::sleep(Duration::from_millis(10));
859 /// // Set the flag, and let the thread wake up.
860 /// // There is no race condition here, if `unpark`
861 /// // happens first, `park` will return immediately.
862 /// // Hence there is no risk of a deadlock.
863 /// flag.store(true, Ordering::Release);
864 /// println!("Unpark the thread");
865 /// parked_thread.thread().unpark();
867 /// parked_thread.join().unwrap();
870 /// [`Thread`]: ../../std/thread/struct.Thread.html
871 /// [`park`]: ../../std/thread/fn.park.html
872 /// [`unpark`]: ../../std/thread/struct.Thread.html#method.unpark
873 /// [`thread::park_timeout`]: ../../std/thread/fn.park_timeout.html
875 // The implementation currently uses the trivial strategy of a Mutex+Condvar
876 // with wakeup flag, which does not actually allow spurious wakeups. In the
877 // future, this will be implemented in a more efficient way, perhaps along the lines of
878 // http://cr.openjdk.java.net/~stefank/6989984.1/raw_files/new/src/os/linux/vm/os_linux.cpp
879 // or futuxes, and in either case may allow spurious wakeups.
880 #[stable(feature = "rust1", since = "1.0.0")]
882 let thread = current();
884 // If we were previously notified then we consume this notification and
886 if thread.inner.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst).is_ok() {
890 // Otherwise we need to coordinate going to sleep
891 let mut m = thread.inner.lock.lock().unwrap();
892 match thread.inner.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) {
895 // We must read here, even though we know it will be `NOTIFIED`.
896 // This is because `unpark` may have been called again since we read
897 // `NOTIFIED` in the `compare_exchange` above. We must perform an
898 // acquire operation that synchronizes with that `unpark` to observe
899 // any writes it made before the call to unpark. To do that we must
900 // read from the write it made to `state`.
901 let old = thread.inner.state.swap(EMPTY, SeqCst);
902 assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
904 } // should consume this notification, so prohibit spurious wakeups in next park.
905 Err(_) => panic!("inconsistent park state"),
908 m = thread.inner.cvar.wait(m).unwrap();
909 match thread.inner.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst) {
910 Ok(_) => return, // got a notification
911 Err(_) => {} // spurious wakeup, go back to sleep
916 /// Use [`park_timeout`].
918 /// Blocks unless or until the current thread's token is made available or
919 /// the specified duration has been reached (may wake spuriously).
921 /// The semantics of this function are equivalent to [`park`] except
922 /// that the thread will be blocked for roughly no longer than `dur`. This
923 /// method should not be used for precise timing due to anomalies such as
924 /// preemption or platform differences that may not cause the maximum
925 /// amount of time waited to be precisely `ms` long.
927 /// See the [park documentation][`park`] for more detail.
929 /// [`park_timeout`]: fn.park_timeout.html
930 /// [`park`]: ../../std/thread/fn.park.html
931 #[stable(feature = "rust1", since = "1.0.0")]
932 #[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::thread::park_timeout`")]
933 pub fn park_timeout_ms(ms: u32) {
934 park_timeout(Duration::from_millis(ms as u64))
937 /// Blocks unless or until the current thread's token is made available or
938 /// the specified duration has been reached (may wake spuriously).
940 /// The semantics of this function are equivalent to [`park`][park] except
941 /// that the thread will be blocked for roughly no longer than `dur`. This
942 /// method should not be used for precise timing due to anomalies such as
943 /// preemption or platform differences that may not cause the maximum
944 /// amount of time waited to be precisely `dur` long.
946 /// See the [park documentation][park] for more details.
948 /// # Platform-specific behavior
950 /// Platforms which do not support nanosecond precision for sleeping will have
951 /// `dur` rounded up to the nearest granularity of time they can sleep for.
955 /// Waiting for the complete expiration of the timeout:
958 /// use std::thread::park_timeout;
959 /// use std::time::{Instant, Duration};
961 /// let timeout = Duration::from_secs(2);
962 /// let beginning_park = Instant::now();
964 /// let mut timeout_remaining = timeout;
966 /// park_timeout(timeout_remaining);
967 /// let elapsed = beginning_park.elapsed();
968 /// if elapsed >= timeout {
971 /// println!("restarting park_timeout after {:?}", elapsed);
972 /// timeout_remaining = timeout - elapsed;
976 /// [park]: fn.park.html
977 #[stable(feature = "park_timeout", since = "1.4.0")]
978 pub fn park_timeout(dur: Duration) {
979 let thread = current();
981 // Like `park` above we have a fast path for an already-notified thread, and
982 // afterwards we start coordinating for a sleep.
984 if thread.inner.state.compare_exchange(NOTIFIED, EMPTY, SeqCst, SeqCst).is_ok() {
987 let m = thread.inner.lock.lock().unwrap();
988 match thread.inner.state.compare_exchange(EMPTY, PARKED, SeqCst, SeqCst) {
991 // We must read again here, see `park`.
992 let old = thread.inner.state.swap(EMPTY, SeqCst);
993 assert_eq!(old, NOTIFIED, "park state changed unexpectedly");
995 } // should consume this notification, so prohibit spurious wakeups in next park.
996 Err(_) => panic!("inconsistent park_timeout state"),
999 // Wait with a timeout, and if we spuriously wake up or otherwise wake up
1000 // from a notification we just want to unconditionally set the state back to
1001 // empty, either consuming a notification or un-flagging ourselves as
1003 let (_m, _result) = thread.inner.cvar.wait_timeout(m, dur).unwrap();
1004 match thread.inner.state.swap(EMPTY, SeqCst) {
1005 NOTIFIED => {} // got a notification, hurray!
1006 PARKED => {} // no notification, alas
1007 n => panic!("inconsistent park_timeout state: {}", n),
1011 ////////////////////////////////////////////////////////////////////////////////
1013 ////////////////////////////////////////////////////////////////////////////////
1015 /// A unique identifier for a running thread.
1017 /// A `ThreadId` is an opaque object that has a unique value for each thread
1018 /// that creates one. `ThreadId`s are not guaranteed to correspond to a thread's
1019 /// system-designated identifier. A `ThreadId` can be retrieved from the [`id`]
1020 /// method on a [`Thread`].
1025 /// use std::thread;
1027 /// let other_thread = thread::spawn(|| {
1028 /// thread::current().id()
1031 /// let other_thread_id = other_thread.join().unwrap();
1032 /// assert!(thread::current().id() != other_thread_id);
1035 /// [`id`]: ../../std/thread/struct.Thread.html#method.id
1036 /// [`Thread`]: ../../std/thread/struct.Thread.html
1037 #[stable(feature = "thread_id", since = "1.19.0")]
1038 #[derive(Eq, PartialEq, Clone, Copy, Hash, Debug)]
1039 pub struct ThreadId(u64);
1042 // Generate a new unique thread ID.
1043 fn new() -> ThreadId {
1044 // We never call `GUARD.init()`, so it is UB to attempt to
1045 // acquire this mutex reentrantly!
1046 static GUARD: mutex::Mutex = mutex::Mutex::new();
1047 static mut COUNTER: u64 = 0;
1050 let _guard = GUARD.lock();
1052 // If we somehow use up all our bits, panic so that we're not
1053 // covering up subtle bugs of IDs being reused.
1054 if COUNTER == crate::u64::MAX {
1055 panic!("failed to generate unique thread ID: bitspace exhausted");
1066 ////////////////////////////////////////////////////////////////////////////////
1068 ////////////////////////////////////////////////////////////////////////////////
1070 /// The internal representation of a `Thread` handle
1072 name: Option<CString>, // Guaranteed to be UTF-8
1075 // state for thread park/unpark
1082 #[stable(feature = "rust1", since = "1.0.0")]
1083 /// A handle to a thread.
1085 /// Threads are represented via the `Thread` type, which you can get in one of
1088 /// * By spawning a new thread, e.g., using the [`thread::spawn`][`spawn`]
1089 /// function, and calling [`thread`][`JoinHandle::thread`] on the
1091 /// * By requesting the current thread, using the [`thread::current`] function.
1093 /// The [`thread::current`] function is available even for threads not spawned
1094 /// by the APIs of this module.
1096 /// There is usually no need to create a `Thread` struct yourself, one
1097 /// should instead use a function like `spawn` to create new threads, see the
1098 /// docs of [`Builder`] and [`spawn`] for more details.
1100 /// [`Builder`]: ../../std/thread/struct.Builder.html
1101 /// [`JoinHandle::thread`]: ../../std/thread/struct.JoinHandle.html#method.thread
1102 /// [`JoinHandle`]: ../../std/thread/struct.JoinHandle.html
1103 /// [`thread::current`]: ../../std/thread/fn.current.html
1104 /// [`spawn`]: ../../std/thread/fn.spawn.html
1111 // Used only internally to construct a thread object without spawning
1112 // Panics if the name contains nuls.
1113 pub(crate) fn new(name: Option<String>) -> Thread {
1114 let cname = name.map(|n| {
1115 CString::new(n).expect("thread name may not contain interior null bytes")
1118 inner: Arc::new(Inner {
1120 id: ThreadId::new(),
1121 state: AtomicUsize::new(EMPTY),
1122 lock: Mutex::new(()),
1123 cvar: Condvar::new(),
1128 /// Atomically makes the handle's token available if it is not already.
1130 /// Every thread is equipped with some basic low-level blocking support, via
1131 /// the [`park`][park] function and the `unpark()` method. These can be
1132 /// used as a more CPU-efficient implementation of a spinlock.
1134 /// See the [park documentation][park] for more details.
1139 /// use std::thread;
1140 /// use std::time::Duration;
1142 /// let parked_thread = thread::Builder::new()
1144 /// println!("Parking thread");
1146 /// println!("Thread unparked");
1150 /// // Let some time pass for the thread to be spawned.
1151 /// thread::sleep(Duration::from_millis(10));
1153 /// println!("Unpark the thread");
1154 /// parked_thread.thread().unpark();
1156 /// parked_thread.join().unwrap();
1159 /// [park]: fn.park.html
1160 #[stable(feature = "rust1", since = "1.0.0")]
1161 pub fn unpark(&self) {
1162 // To ensure the unparked thread will observe any writes we made
1163 // before this call, we must perform a release operation that `park`
1164 // can synchronize with. To do that we must write `NOTIFIED` even if
1165 // `state` is already `NOTIFIED`. That is why this must be a swap
1166 // rather than a compare-and-swap that returns if it reads `NOTIFIED`
1168 match self.inner.state.swap(NOTIFIED, SeqCst) {
1169 EMPTY => return, // no one was waiting
1170 NOTIFIED => return, // already unparked
1171 PARKED => {} // gotta go wake someone up
1172 _ => panic!("inconsistent state in unpark"),
1175 // There is a period between when the parked thread sets `state` to
1176 // `PARKED` (or last checked `state` in the case of a spurious wake
1177 // up) and when it actually waits on `cvar`. If we were to notify
1178 // during this period it would be ignored and then when the parked
1179 // thread went to sleep it would never wake up. Fortunately, it has
1180 // `lock` locked at this stage so we can acquire `lock` to wait until
1181 // it is ready to receive the notification.
1183 // Releasing `lock` before the call to `notify_one` means that when the
1184 // parked thread wakes it doesn't get woken only to have to wait for us
1185 // to release `lock`.
1186 drop(self.inner.lock.lock().unwrap());
1187 self.inner.cvar.notify_one()
1190 /// Gets the thread's unique identifier.
1195 /// use std::thread;
1197 /// let other_thread = thread::spawn(|| {
1198 /// thread::current().id()
1201 /// let other_thread_id = other_thread.join().unwrap();
1202 /// assert!(thread::current().id() != other_thread_id);
1204 #[stable(feature = "thread_id", since = "1.19.0")]
1205 pub fn id(&self) -> ThreadId {
1209 /// Gets the thread's name.
1211 /// For more information about named threads, see
1212 /// [this module-level documentation][naming-threads].
1216 /// Threads by default have no name specified:
1219 /// use std::thread;
1221 /// let builder = thread::Builder::new();
1223 /// let handler = builder.spawn(|| {
1224 /// assert!(thread::current().name().is_none());
1227 /// handler.join().unwrap();
1230 /// Thread with a specified name:
1233 /// use std::thread;
1235 /// let builder = thread::Builder::new()
1236 /// .name("foo".into());
1238 /// let handler = builder.spawn(|| {
1239 /// assert_eq!(thread::current().name(), Some("foo"))
1242 /// handler.join().unwrap();
1245 /// [naming-threads]: ./index.html#naming-threads
1246 #[stable(feature = "rust1", since = "1.0.0")]
1247 pub fn name(&self) -> Option<&str> {
1248 self.cname().map(|s| unsafe { str::from_utf8_unchecked(s.to_bytes()) } )
1251 fn cname(&self) -> Option<&CStr> {
1252 self.inner.name.as_ref().map(|s| &**s)
1256 #[stable(feature = "rust1", since = "1.0.0")]
1257 impl fmt::Debug for Thread {
1258 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1259 fmt::Debug::fmt(&self.name(), f)
1263 ////////////////////////////////////////////////////////////////////////////////
1265 ////////////////////////////////////////////////////////////////////////////////
1267 /// A specialized [`Result`] type for threads.
1269 /// Indicates the manner in which a thread exited.
1271 /// A thread that completes without panicking is considered to exit successfully.
1276 /// use std::thread;
1279 /// fn copy_in_thread() -> thread::Result<()> {
1280 /// thread::spawn(move || { fs::copy("foo.txt", "bar.txt").unwrap(); }).join()
1284 /// match copy_in_thread() {
1285 /// Ok(_) => println!("this is fine"),
1286 /// Err(_) => println!("thread panicked"),
1291 /// [`Result`]: ../../std/result/enum.Result.html
1292 #[stable(feature = "rust1", since = "1.0.0")]
1293 pub type Result<T> = crate::result::Result<T, Box<dyn Any + Send + 'static>>;
1295 // This packet is used to communicate the return value between the child thread
1296 // and the parent thread. Memory is shared through the `Arc` within and there's
1297 // no need for a mutex here because synchronization happens with `join()` (the
1298 // parent thread never reads this packet until the child has exited).
1300 // This packet itself is then stored into a `JoinInner` which in turns is placed
1301 // in `JoinHandle` and `JoinGuard`. Due to the usage of `UnsafeCell` we need to
1302 // manually worry about impls like Send and Sync. The type `T` should
1303 // already always be Send (otherwise the thread could not have been created) and
1304 // this type is inherently Sync because no methods take &self. Regardless,
1305 // however, we add inheriting impls for Send/Sync to this type to ensure it's
1306 // Send/Sync and that future modifications will still appropriately classify it.
1307 struct Packet<T>(Arc<UnsafeCell<Option<Result<T>>>>);
1309 unsafe impl<T: Send> Send for Packet<T> {}
1310 unsafe impl<T: Sync> Sync for Packet<T> {}
1312 /// Inner representation for JoinHandle
1313 struct JoinInner<T> {
1314 native: Option<imp::Thread>,
1319 impl<T> JoinInner<T> {
1320 fn join(&mut self) -> Result<T> {
1321 self.native.take().unwrap().join();
1323 (*self.packet.0.get()).take().unwrap()
1328 /// An owned permission to join on a thread (block on its termination).
1330 /// A `JoinHandle` *detaches* the associated thread when it is dropped, which
1331 /// means that there is no longer any handle to thread and no way to `join`
1334 /// Due to platform restrictions, it is not possible to [`Clone`] this
1335 /// handle: the ability to join a thread is a uniquely-owned permission.
1337 /// This `struct` is created by the [`thread::spawn`] function and the
1338 /// [`thread::Builder::spawn`] method.
1342 /// Creation from [`thread::spawn`]:
1345 /// use std::thread;
1347 /// let join_handle: thread::JoinHandle<_> = thread::spawn(|| {
1348 /// // some work here
1352 /// Creation from [`thread::Builder::spawn`]:
1355 /// use std::thread;
1357 /// let builder = thread::Builder::new();
1359 /// let join_handle: thread::JoinHandle<_> = builder.spawn(|| {
1360 /// // some work here
1364 /// Child being detached and outliving its parent:
1367 /// use std::thread;
1368 /// use std::time::Duration;
1370 /// let original_thread = thread::spawn(|| {
1371 /// let _detached_thread = thread::spawn(|| {
1372 /// // Here we sleep to make sure that the first thread returns before.
1373 /// thread::sleep(Duration::from_millis(10));
1374 /// // This will be called, even though the JoinHandle is dropped.
1375 /// println!("♫ Still alive ♫");
1379 /// original_thread.join().expect("The thread being joined has panicked");
1380 /// println!("Original thread is joined.");
1382 /// // We make sure that the new thread has time to run, before the main
1383 /// // thread returns.
1385 /// thread::sleep(Duration::from_millis(1000));
1388 /// [`Clone`]: ../../std/clone/trait.Clone.html
1389 /// [`thread::spawn`]: fn.spawn.html
1390 /// [`thread::Builder::spawn`]: struct.Builder.html#method.spawn
1391 #[stable(feature = "rust1", since = "1.0.0")]
1392 pub struct JoinHandle<T>(JoinInner<T>);
1394 #[stable(feature = "joinhandle_impl_send_sync", since = "1.29.0")]
1395 unsafe impl<T> Send for JoinHandle<T> {}
1396 #[stable(feature = "joinhandle_impl_send_sync", since = "1.29.0")]
1397 unsafe impl<T> Sync for JoinHandle<T> {}
1399 impl<T> JoinHandle<T> {
1400 /// Extracts a handle to the underlying thread.
1405 /// use std::thread;
1407 /// let builder = thread::Builder::new();
1409 /// let join_handle: thread::JoinHandle<_> = builder.spawn(|| {
1410 /// // some work here
1413 /// let thread = join_handle.thread();
1414 /// println!("thread id: {:?}", thread.id());
1416 #[stable(feature = "rust1", since = "1.0.0")]
1417 pub fn thread(&self) -> &Thread {
1421 /// Waits for the associated thread to finish.
1423 /// In terms of [atomic memory orderings], the completion of the associated
1424 /// thread synchronizes with this function returning. In other words, all
1425 /// operations performed by that thread are ordered before all
1426 /// operations that happen after `join` returns.
1428 /// If the child thread panics, [`Err`] is returned with the parameter given
1431 /// [`Err`]: ../../std/result/enum.Result.html#variant.Err
1432 /// [`panic`]: ../../std/macro.panic.html
1433 /// [atomic memory orderings]: ../../std/sync/atomic/index.html
1437 /// This function may panic on some platforms if a thread attempts to join
1438 /// itself or otherwise may create a deadlock with joining threads.
1443 /// use std::thread;
1445 /// let builder = thread::Builder::new();
1447 /// let join_handle: thread::JoinHandle<_> = builder.spawn(|| {
1448 /// // some work here
1450 /// join_handle.join().expect("Couldn't join on the associated thread");
1452 #[stable(feature = "rust1", since = "1.0.0")]
1453 pub fn join(mut self) -> Result<T> {
1458 impl<T> AsInner<imp::Thread> for JoinHandle<T> {
1459 fn as_inner(&self) -> &imp::Thread { self.0.native.as_ref().unwrap() }
1462 impl<T> IntoInner<imp::Thread> for JoinHandle<T> {
1463 fn into_inner(self) -> imp::Thread { self.0.native.unwrap() }
1466 #[stable(feature = "std_debug", since = "1.16.0")]
1467 impl<T> fmt::Debug for JoinHandle<T> {
1468 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1469 f.pad("JoinHandle { .. }")
1473 fn _assert_sync_and_send() {
1474 fn _assert_both<T: Send + Sync>() {}
1475 _assert_both::<JoinHandle<()>>();
1476 _assert_both::<Thread>();
1479 ////////////////////////////////////////////////////////////////////////////////
1481 ////////////////////////////////////////////////////////////////////////////////
1483 #[cfg(all(test, not(target_os = "emscripten")))]
1486 use crate::any::Any;
1487 use crate::sync::mpsc::{channel, Sender};
1490 use crate::time::Duration;
1493 // !!! These tests are dangerous. If something is buggy, they will hang, !!!
1494 // !!! instead of exiting cleanly. This might wedge the buildbots. !!!
1497 fn test_unnamed_thread() {
1498 thread::spawn(move|| {
1499 assert!(thread::current().name().is_none());
1500 }).join().ok().expect("thread panicked");
1504 fn test_named_thread() {
1505 Builder::new().name("ada lovelace".to_string()).spawn(move|| {
1506 assert!(thread::current().name().unwrap() == "ada lovelace".to_string());
1507 }).unwrap().join().unwrap();
1512 fn test_invalid_named_thread() {
1513 let _ = Builder::new().name("ada l\0velace".to_string()).spawn(|| {});
1517 fn test_run_basic() {
1518 let (tx, rx) = channel();
1519 thread::spawn(move|| {
1520 tx.send(()).unwrap();
1526 fn test_join_panic() {
1527 match thread::spawn(move|| {
1530 result::Result::Err(_) => (),
1531 result::Result::Ok(()) => panic!()
1536 fn test_spawn_sched() {
1537 let (tx, rx) = channel();
1539 fn f(i: i32, tx: Sender<()>) {
1540 let tx = tx.clone();
1541 thread::spawn(move|| {
1543 tx.send(()).unwrap();
1555 fn test_spawn_sched_childs_on_default_sched() {
1556 let (tx, rx) = channel();
1558 thread::spawn(move|| {
1559 thread::spawn(move|| {
1560 tx.send(()).unwrap();
1567 fn avoid_copying_the_body<F>(spawnfn: F) where F: FnOnce(Box<dyn Fn() + Send>) {
1568 let (tx, rx) = channel();
1570 let x: Box<_> = box 1;
1571 let x_in_parent = (&*x) as *const i32 as usize;
1573 spawnfn(Box::new(move|| {
1574 let x_in_child = (&*x) as *const i32 as usize;
1575 tx.send(x_in_child).unwrap();
1578 let x_in_child = rx.recv().unwrap();
1579 assert_eq!(x_in_parent, x_in_child);
1583 fn test_avoid_copying_the_body_spawn() {
1584 avoid_copying_the_body(|v| {
1585 thread::spawn(move || v());
1590 fn test_avoid_copying_the_body_thread_spawn() {
1591 avoid_copying_the_body(|f| {
1592 thread::spawn(move|| {
1599 fn test_avoid_copying_the_body_join() {
1600 avoid_copying_the_body(|f| {
1601 let _ = thread::spawn(move|| {
1608 fn test_child_doesnt_ref_parent() {
1609 // If the child refcounts the parent thread, this will stack overflow when
1610 // climbing the thread tree to dereference each ancestor. (See #1789)
1611 // (well, it would if the constant were 8000+ - I lowered it to be more
1612 // valgrind-friendly. try this at home, instead..!)
1613 const GENERATIONS: u32 = 16;
1614 fn child_no(x: u32) -> Box<dyn Fn() + Send> {
1615 return Box::new(move|| {
1616 if x < GENERATIONS {
1617 thread::spawn(move|| child_no(x+1)());
1621 thread::spawn(|| child_no(0)());
1625 fn test_simple_newsched_spawn() {
1626 thread::spawn(move || {});
1630 fn test_try_panic_message_static_str() {
1631 match thread::spawn(move|| {
1632 panic!("static string");
1635 type T = &'static str;
1636 assert!(e.is::<T>());
1637 assert_eq!(*e.downcast::<T>().unwrap(), "static string");
1644 fn test_try_panic_message_owned_str() {
1645 match thread::spawn(move|| {
1646 panic!("owned string".to_string());
1650 assert!(e.is::<T>());
1651 assert_eq!(*e.downcast::<T>().unwrap(), "owned string".to_string());
1658 fn test_try_panic_message_any() {
1659 match thread::spawn(move|| {
1660 panic!(box 413u16 as Box<dyn Any + Send>);
1663 type T = Box<dyn Any + Send>;
1664 assert!(e.is::<T>());
1665 let any = e.downcast::<T>().unwrap();
1666 assert!(any.is::<u16>());
1667 assert_eq!(*any.downcast::<u16>().unwrap(), 413);
1674 fn test_try_panic_message_unit_struct() {
1677 match thread::spawn(move|| {
1680 Err(ref e) if e.is::<Juju>() => {}
1681 Err(_) | Ok(()) => panic!()
1686 fn test_park_timeout_unpark_before() {
1688 thread::current().unpark();
1689 thread::park_timeout(Duration::from_millis(u32::MAX as u64));
1694 #[cfg_attr(target_env = "sgx", ignore)] // FIXME: https://github.com/fortanix/rust-sgx/issues/31
1695 fn test_park_timeout_unpark_not_called() {
1697 thread::park_timeout(Duration::from_millis(10));
1702 #[cfg_attr(target_env = "sgx", ignore)] // FIXME: https://github.com/fortanix/rust-sgx/issues/31
1703 fn test_park_timeout_unpark_called_other_thread() {
1705 let th = thread::current();
1707 let _guard = thread::spawn(move || {
1708 super::sleep(Duration::from_millis(50));
1712 thread::park_timeout(Duration::from_millis(u32::MAX as u64));
1717 #[cfg_attr(target_env = "sgx", ignore)] // FIXME: https://github.com/fortanix/rust-sgx/issues/31
1718 fn sleep_ms_smoke() {
1719 thread::sleep(Duration::from_millis(2));
1723 fn test_thread_id_equal() {
1724 assert!(thread::current().id() == thread::current().id());
1728 fn test_thread_id_not_equal() {
1729 let spawned_id = thread::spawn(|| thread::current().id()).join().unwrap();
1730 assert!(thread::current().id() != spawned_id);
1733 // NOTE: the corresponding test for stderr is in run-pass/thread-stderr, due
1734 // to the test harness apparently interfering with stderr configuration.