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Rewrite/reorganize docs for stack size/thread names for spawned threads. #43848

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55 changes: 45 additions & 10 deletions src/libstd/thread/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,29 @@
//! will want to make use of some form of **interior mutability** through the
//! [`Cell`] or [`RefCell`] types.
//!
//! ## Naming threads
//!
//! Threads are able to have associated names for identification purposes. By default, spawned
//! threads are unnamed. To specify a name for a thread, build the thread with [`Builder`] and pass
//! the desired thread name to [`Builder::name`]. To retrieve the thread name from within the
//! thread, use [`Thread::name`]. A couple examples of where the name of a thread gets used:
//!
//! * If a panic occurs in a named thread, the thread name will be printed in the panic message.
//! * The thread name is provided to the OS where applicable (e.g. `pthread_setname_np` in
//! unix-like platforms).
//!
//! ## Stack size
//!
//! The default stack size for spawned threads is 2 MiB, though this particular stack size is
//! subject to change in the future. There are two ways to manually specify the stack size for
//! spawned threads:
//!
//! * Build the thread with [`Builder`] and pass the desired stack size to [`Builder::stack_size`].
//! * Set the `RUST_MIN_STACK` environment variable to an integer representing the desired stack
//! size (in bytes). Note that setting [`Builder::stack_size`] will override this.
//!
//! Note that the stack size of the main thread is *not* determined by Rust.
//!
//! [channels]: ../../std/sync/mpsc/index.html
//! [`Arc`]: ../../std/sync/struct.Arc.html
//! [`spawn`]: ../../std/thread/fn.spawn.html
Expand All @@ -123,11 +146,14 @@
//! [`Err`]: ../../std/result/enum.Result.html#variant.Err
//! [`panic!`]: ../../std/macro.panic.html
//! [`Builder`]: ../../std/thread/struct.Builder.html
//! [`Builder::stack_size`]: ../../std/thread/struct.Builder.html#method.stack_size
//! [`Builder::name`]: ../../std/thread/struct.Builder.html#method.name
//! [`thread::current`]: ../../std/thread/fn.current.html
//! [`thread::Result`]: ../../std/thread/type.Result.html
//! [`Thread`]: ../../std/thread/struct.Thread.html
//! [`park`]: ../../std/thread/fn.park.html
//! [`unpark`]: ../../std/thread/struct.Thread.html#method.unpark
//! [`Thread::name`]: ../../std/thread/struct.Thread.html#method.name
//! [`thread::park_timeout`]: ../../std/thread/fn.park_timeout.html
//! [`Cell`]: ../cell/struct.Cell.html
//! [`RefCell`]: ../cell/struct.RefCell.html
Expand Down Expand Up @@ -187,16 +213,8 @@ pub use self::local::{LocalKey, LocalKeyState, AccessError};
///
/// The two configurations available are:
///
/// - [`name`]: allows to give a name to the thread which is currently
/// only used in `panic` messages.
/// - [`stack_size`]: specifies the desired stack size. Note that this can
/// be overridden by the OS.
///
/// If the [`stack_size`] field is not specified, the stack size
/// will be the `RUST_MIN_STACK` environment variable. If it is
/// not specified either, a sensible default will be set.
///
/// If the [`name`] field is not specified, the thread will not be named.
/// - [`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 create an
/// [`io::Result`] to the thread handle with the given configuration.
Expand Down Expand Up @@ -228,6 +246,8 @@ pub use self::local::{LocalKey, LocalKeyState, AccessError};
/// [`spawn`]: ../../std/thread/struct.Builder.html#method.spawn
/// [`io::Result`]: ../../std/io/type.Result.html
/// [`unwrap`]: ../../std/result/enum.Result.html#method.unwrap
/// [naming-threads]: ./index.html#naming-threads
/// [stack-size]: ./index.html#stack-size
#[stable(feature = "rust1", since = "1.0.0")]
#[derive(Debug)]
pub struct Builder {
Expand Down Expand Up @@ -267,6 +287,9 @@ impl Builder {
/// Names the thread-to-be. Currently the name is used for identification
/// only in panic messages.
///
/// For more information about named threads, see
/// [this module-level documentation][naming-threads].
///
/// # Examples
///
/// ```
Expand All @@ -281,6 +304,8 @@ impl Builder {
///
/// handler.join().unwrap();
/// ```
///
/// [naming-threads]: ./index.html#naming-threads
#[stable(feature = "rust1", since = "1.0.0")]
pub fn name(mut self, name: String) -> Builder {
self.name = Some(name);
Expand All @@ -292,13 +317,18 @@ impl Builder {
/// The actual stack size may be greater than this value if
/// the platform specifies minimal stack size.
///
/// For more information about the stack size for threads, see
/// [this module-level documentation][stack-size].
///
/// # Examples
///
/// ```
/// use std::thread;
///
/// let builder = thread::Builder::new().stack_size(32 * 1024);
/// ```
///
/// [stack-size]: ./index.html#stack-size
#[stable(feature = "rust1", since = "1.0.0")]
pub fn stack_size(mut self, size: usize) -> Builder {
self.stack_size = Some(size);
Expand Down Expand Up @@ -987,6 +1017,9 @@ impl Thread {

/// Gets the thread's name.
///
/// For more information about named threads, see
/// [this module-level documentation][naming-threads].
///
/// # Examples
///
/// Threads by default have no name specified:
Expand Down Expand Up @@ -1017,6 +1050,8 @@ impl Thread {
///
/// handler.join().unwrap();
/// ```
///
/// [naming-threads]: ./index.html#naming-threads
#[stable(feature = "rust1", since = "1.0.0")]
pub fn name(&self) -> Option<&str> {
self.cname().map(|s| unsafe { str::from_utf8_unchecked(s.to_bytes()) } )
Expand Down