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//! Rayon-core houses the core stable APIs of Rayon.
//!
//! These APIs have been mirrored in the Rayon crate and it is recommended to use these from there.
//!
//! [`join`] is used to take two closures and potentially run them in parallel.
//! - It will run in parallel if task B gets stolen before task A can finish.
//! - It will run sequentially if task A finishes before task B is stolen and can continue on task B.
//!
//! [`scope`] creates a scope in which you can run any number of parallel tasks.
//! These tasks can spawn nested tasks and scopes, but given the nature of work stealing, the order of execution can not be guaranteed.
//! The scope will exist until all tasks spawned within the scope have been completed.
//!
//! [`spawn`] add a task into the 'static' or 'global' scope, or a local scope created by the [`scope()`] function.
//!
//! [`ThreadPool`] can be used to create your own thread pools (using [`ThreadPoolBuilder`]) or to customize the global one.
//! Tasks spawned within the pool (using [`install()`], [`join()`], etc.) will be added to a deque,
//! where it becomes available for work stealing from other threads in the local threadpool.
//!
//! [`join`]: fn.join.html
//! [`scope`]: fn.scope.html
//! [`scope()`]: fn.scope.html
//! [`spawn`]: fn.spawn.html
//! [`ThreadPool`]: struct.threadpool.html
//! [`install()`]: struct.ThreadPool.html#method.install
//! [`spawn()`]: struct.ThreadPool.html#method.spawn
//! [`join()`]: struct.ThreadPool.html#method.join
//! [`ThreadPoolBuilder`]: struct.ThreadPoolBuilder.html
//!
//! # Global fallback when threading is unsupported
//!
//! Rayon uses `std` APIs for threading, but some targets have incomplete implementations that
//! always return `Unsupported` errors. The WebAssembly `wasm32-unknown-unknown` and `wasm32-wasi`
//! targets are notable examples of this. Rather than panicking on the unsupported error when
//! creating the implicit global threadpool, Rayon configures a fallback mode instead.
//!
//! This fallback mode mostly functions as if it were using a single-threaded "pool", like setting
//! `RAYON_NUM_THREADS=1`. For example, `join` will execute its two closures sequentially, since
//! there is no other thread to share the work. However, since the pool is not running independent
//! of the main thread, non-blocking calls like `spawn` may not execute at all, unless a lower-
//! priority call like `broadcast` gives them an opening. The fallback mode does not try to emulate
//! anything like thread preemption or `async` task switching, but `yield_now` or `yield_local`
//! can also volunteer execution time.
//!
//! Explicit `ThreadPoolBuilder` methods always report their error without any fallback.
//!
//! # Restricting multiple versions
//!
//! In order to ensure proper coordination between threadpools, and especially
//! to make sure there's only one global threadpool, `rayon-core` is actively
//! restricted from building multiple versions of itself into a single target.
//! You may see a build error like this in violation:
//!
//! ```text
//! error: native library `rayon-core` is being linked to by more
//! than one package, and can only be linked to by one package
//! ```
//!
//! While we strive to keep `rayon-core` semver-compatible, it's still
//! possible to arrive at this situation if different crates have overly
//! restrictive tilde or inequality requirements for `rayon-core`. The
//! conflicting requirements will need to be resolved before the build will
//! succeed.
#![deny(missing_debug_implementations)]
#![deny(missing_docs)]
#![deny(unreachable_pub)]
#![warn(rust_2018_idioms)]
use std::any::Any;
use std::env;
use std::error::Error;
use std::fmt;
use std::io;
use std::marker::PhantomData;
use std::str::FromStr;
use std::thread;
#[macro_use]
mod private;
mod broadcast;
mod job;
mod join;
mod latch;
mod registry;
mod scope;
mod sleep;
mod spawn;
mod thread_pool;
mod unwind;
mod compile_fail;
mod test;
pub use self::broadcast::{broadcast, spawn_broadcast, BroadcastContext};
pub use self::join::{join, join_context};
pub use self::registry::ThreadBuilder;
pub use self::scope::{in_place_scope, scope, Scope};
pub use self::scope::{in_place_scope_fifo, scope_fifo, ScopeFifo};
pub use self::spawn::{spawn, spawn_fifo};
pub use self::thread_pool::current_thread_has_pending_tasks;
pub use self::thread_pool::current_thread_index;
pub use self::thread_pool::ThreadPool;
pub use self::thread_pool::{yield_local, yield_now, Yield};
use self::registry::{CustomSpawn, DefaultSpawn, ThreadSpawn};
/// Returns the maximum number of threads that Rayon supports in a single thread-pool.
///
/// If a higher thread count is requested by calling `ThreadPoolBuilder::num_threads` or by setting
/// the `RAYON_NUM_THREADS` environment variable, then it will be reduced to this maximum.
///
/// The value may vary between different targets, and is subject to change in new Rayon versions.
pub fn max_num_threads() -> usize {
// We are limited by the bits available in the sleep counter's `AtomicUsize`.
crate::sleep::THREADS_MAX
}
/// Returns the number of threads in the current registry. If this
/// code is executing within a Rayon thread-pool, then this will be
/// the number of threads for the thread-pool of the current
/// thread. Otherwise, it will be the number of threads for the global
/// thread-pool.
///
/// This can be useful when trying to judge how many times to split
/// parallel work (the parallel iterator traits use this value
/// internally for this purpose).
///
/// # Future compatibility note
///
/// Note that unless this thread-pool was created with a
/// builder that specifies the number of threads, then this
/// number may vary over time in future versions (see [the
/// `num_threads()` method for details][snt]).
///
/// [snt]: struct.ThreadPoolBuilder.html#method.num_threads
pub fn current_num_threads() -> usize {
crate::registry::Registry::current_num_threads()
}
/// Error when initializing a thread pool.
#[derive(Debug)]
pub struct ThreadPoolBuildError {
kind: ErrorKind,
}
#[derive(Debug)]
enum ErrorKind {
GlobalPoolAlreadyInitialized,
CurrentThreadAlreadyInPool,
IOError(io::Error),
}
/// Used to create a new [`ThreadPool`] or to configure the global rayon thread pool.
/// ## Creating a ThreadPool
/// The following creates a thread pool with 22 threads.
///
/// ```rust
/// # use rayon_core as rayon;
/// let pool = rayon::ThreadPoolBuilder::new().num_threads(22).build().unwrap();
/// ```
///
/// To instead configure the global thread pool, use [`build_global()`]:
///
/// ```rust
/// # use rayon_core as rayon;
/// rayon::ThreadPoolBuilder::new().num_threads(22).build_global().unwrap();
/// ```
///
/// [`ThreadPool`]: struct.ThreadPool.html
/// [`build_global()`]: struct.ThreadPoolBuilder.html#method.build_global
pub struct ThreadPoolBuilder<S = DefaultSpawn> {
/// The number of threads in the rayon thread pool.
/// If zero will use the RAYON_NUM_THREADS environment variable.
/// If RAYON_NUM_THREADS is invalid or zero will use the default.
num_threads: usize,
/// The thread we're building *from* will also be part of the pool.
use_current_thread: bool,
/// Custom closure, if any, to handle a panic that we cannot propagate
/// anywhere else.
panic_handler: Option<Box<PanicHandler>>,
/// Closure to compute the name of a thread.
get_thread_name: Option<Box<dyn FnMut(usize) -> String>>,
/// The stack size for the created worker threads
stack_size: Option<usize>,
/// Closure invoked on worker thread start.
start_handler: Option<Box<StartHandler>>,
/// Closure invoked on worker thread exit.
exit_handler: Option<Box<ExitHandler>>,
/// Closure invoked to spawn threads.
spawn_handler: S,
/// If false, worker threads will execute spawned jobs in a
/// "depth-first" fashion. If true, they will do a "breadth-first"
/// fashion. Depth-first is the default.
breadth_first: bool,
}
/// Contains the rayon thread pool configuration. Use [`ThreadPoolBuilder`] instead.
///
/// [`ThreadPoolBuilder`]: struct.ThreadPoolBuilder.html
#[deprecated(note = "Use `ThreadPoolBuilder`")]
#[derive(Default)]
pub struct Configuration {
builder: ThreadPoolBuilder,
}
/// The type for a panic handling closure. Note that this same closure
/// may be invoked multiple times in parallel.
type PanicHandler = dyn Fn(Box<dyn Any + Send>) + Send + Sync;
/// The type for a closure that gets invoked when a thread starts. The
/// closure is passed the index of the thread on which it is invoked.
/// Note that this same closure may be invoked multiple times in parallel.
type StartHandler = dyn Fn(usize) + Send + Sync;
/// The type for a closure that gets invoked when a thread exits. The
/// closure is passed the index of the thread on which is is invoked.
/// Note that this same closure may be invoked multiple times in parallel.
type ExitHandler = dyn Fn(usize) + Send + Sync;
// NB: We can't `#[derive(Default)]` because `S` is left ambiguous.
impl Default for ThreadPoolBuilder {
fn default() -> Self {
ThreadPoolBuilder {
num_threads: 0,
use_current_thread: false,
panic_handler: None,
get_thread_name: None,
stack_size: None,
start_handler: None,
exit_handler: None,
spawn_handler: DefaultSpawn,
breadth_first: false,
}
}
}
impl ThreadPoolBuilder {
/// Creates and returns a valid rayon thread pool builder, but does not initialize it.
pub fn new() -> Self {
Self::default()
}
}
/// Note: the `S: ThreadSpawn` constraint is an internal implementation detail for the
/// default spawn and those set by [`spawn_handler`](#method.spawn_handler).
impl<S> ThreadPoolBuilder<S>
where
S: ThreadSpawn,
{
/// Creates a new `ThreadPool` initialized using this configuration.
pub fn build(self) -> Result<ThreadPool, ThreadPoolBuildError> {
ThreadPool::build(self)
}
/// Initializes the global thread pool. This initialization is
/// **optional**. If you do not call this function, the thread pool
/// will be automatically initialized with the default
/// configuration. Calling `build_global` is not recommended, except
/// in two scenarios:
///
/// - You wish to change the default configuration.
/// - You are running a benchmark, in which case initializing may
/// yield slightly more consistent results, since the worker threads
/// will already be ready to go even in the first iteration. But
/// this cost is minimal.
///
/// Initialization of the global thread pool happens exactly
/// once. Once started, the configuration cannot be
/// changed. Therefore, if you call `build_global` a second time, it
/// will return an error. An `Ok` result indicates that this
/// is the first initialization of the thread pool.
pub fn build_global(self) -> Result<(), ThreadPoolBuildError> {
let registry = registry::init_global_registry(self)?;
registry.wait_until_primed();
Ok(())
}
}
impl ThreadPoolBuilder {
/// Creates a scoped `ThreadPool` initialized using this configuration.
///
/// This is a convenience function for building a pool using [`std::thread::scope`]
/// to spawn threads in a [`spawn_handler`](#method.spawn_handler).
/// The threads in this pool will start by calling `wrapper`, which should
/// do initialization and continue by calling `ThreadBuilder::run()`.
///
///
/// # Examples
///
/// A scoped pool may be useful in combination with scoped thread-local variables.
///
/// ```
/// # use rayon_core as rayon;
///
/// scoped_tls::scoped_thread_local!(static POOL_DATA: Vec<i32>);
///
/// fn main() -> Result<(), rayon::ThreadPoolBuildError> {
/// let pool_data = vec![1, 2, 3];
///
/// // We haven't assigned any TLS data yet.
/// assert!(!POOL_DATA.is_set());
///
/// rayon::ThreadPoolBuilder::new()
/// .build_scoped(
/// // Borrow `pool_data` in TLS for each thread.
/// |thread| POOL_DATA.set(&pool_data, || thread.run()),
/// // Do some work that needs the TLS data.
/// |pool| pool.install(|| assert!(POOL_DATA.is_set())),
/// )?;
///
/// // Once we've returned, `pool_data` is no longer borrowed.
/// drop(pool_data);
/// Ok(())
/// }
/// ```
pub fn build_scoped<W, F, R>(self, wrapper: W, with_pool: F) -> Result<R, ThreadPoolBuildError>
where
W: Fn(ThreadBuilder) + Sync, // expected to call `run()`
F: FnOnce(&ThreadPool) -> R,
{
std::thread::scope(|scope| {
let pool = self
.spawn_handler(|thread| {
let mut builder = std::thread::Builder::new();
if let Some(name) = thread.name() {
builder = builder.name(name.to_string());
}
if let Some(size) = thread.stack_size() {
builder = builder.stack_size(size);
}
builder.spawn_scoped(scope, || wrapper(thread))?;
Ok(())
})
.build()?;
Ok(with_pool(&pool))
})
}
}
impl<S> ThreadPoolBuilder<S> {
/// Sets a custom function for spawning threads.
///
/// Note that the threads will not exit until after the pool is dropped. It
/// is up to the caller to wait for thread termination if that is important
/// for any invariants. For instance, threads created in [`std::thread::scope`]
/// will be joined before that scope returns, and this will block indefinitely
/// if the pool is leaked. Furthermore, the global thread pool doesn't terminate
/// until the entire process exits!
///
/// # Examples
///
/// A minimal spawn handler just needs to call `run()` from an independent thread.
///
/// ```
/// # use rayon_core as rayon;
/// fn main() -> Result<(), rayon::ThreadPoolBuildError> {
/// let pool = rayon::ThreadPoolBuilder::new()
/// .spawn_handler(|thread| {
/// std::thread::spawn(|| thread.run());
/// Ok(())
/// })
/// .build()?;
///
/// pool.install(|| println!("Hello from my custom thread!"));
/// Ok(())
/// }
/// ```
///
/// The default spawn handler sets the name and stack size if given, and propagates
/// any errors from the thread builder.
///
/// ```
/// # use rayon_core as rayon;
/// fn main() -> Result<(), rayon::ThreadPoolBuildError> {
/// let pool = rayon::ThreadPoolBuilder::new()
/// .spawn_handler(|thread| {
/// let mut b = std::thread::Builder::new();
/// if let Some(name) = thread.name() {
/// b = b.name(name.to_owned());
/// }
/// if let Some(stack_size) = thread.stack_size() {
/// b = b.stack_size(stack_size);
/// }
/// b.spawn(|| thread.run())?;
/// Ok(())
/// })
/// .build()?;
///
/// pool.install(|| println!("Hello from my fully custom thread!"));
/// Ok(())
/// }
/// ```
///
/// This can also be used for a pool of scoped threads like [`crossbeam::scope`],
/// or [`std::thread::scope`] introduced in Rust 1.63, which is encapsulated in
/// [`build_scoped`](#method.build_scoped).
///
///
/// ```
/// # use rayon_core as rayon;
/// fn main() -> Result<(), rayon::ThreadPoolBuildError> {
/// std::thread::scope(|scope| {
/// let pool = rayon::ThreadPoolBuilder::new()
/// .spawn_handler(|thread| {
/// let mut builder = std::thread::Builder::new();
/// if let Some(name) = thread.name() {
/// builder = builder.name(name.to_string());
/// }
/// if let Some(size) = thread.stack_size() {
/// builder = builder.stack_size(size);
/// }
/// builder.spawn_scoped(scope, || {
/// // Add any scoped initialization here, then run!
/// thread.run()
/// })?;
/// Ok(())
/// })
/// .build()?;
///
/// pool.install(|| println!("Hello from my custom scoped thread!"));
/// Ok(())
/// })
/// }
/// ```
pub fn spawn_handler<F>(self, spawn: F) -> ThreadPoolBuilder<CustomSpawn<F>>
where
F: FnMut(ThreadBuilder) -> io::Result<()>,
{
ThreadPoolBuilder {
spawn_handler: CustomSpawn::new(spawn),
// ..self
num_threads: self.num_threads,
use_current_thread: self.use_current_thread,
panic_handler: self.panic_handler,
get_thread_name: self.get_thread_name,
stack_size: self.stack_size,
start_handler: self.start_handler,
exit_handler: self.exit_handler,
breadth_first: self.breadth_first,
}
}
/// Returns a reference to the current spawn handler.
fn get_spawn_handler(&mut self) -> &mut S {
&mut self.spawn_handler
}
/// Get the number of threads that will be used for the thread
/// pool. See `num_threads()` for more information.
fn get_num_threads(&self) -> usize {
if self.num_threads > 0 {
self.num_threads
} else {
let default = || {
thread::available_parallelism()
.map(|n| n.get())
.unwrap_or(1)
};
match env::var("RAYON_NUM_THREADS")
.ok()
.and_then(|s| usize::from_str(&s).ok())
{
Some(x @ 1..) => return x,
Some(0) => return default(),
_ => {}
}
// Support for deprecated `RAYON_RS_NUM_CPUS`.
match env::var("RAYON_RS_NUM_CPUS")
.ok()
.and_then(|s| usize::from_str(&s).ok())
{
Some(x @ 1..) => x,
_ => default(),
}
}
}
/// Get the thread name for the thread with the given index.
fn get_thread_name(&mut self, index: usize) -> Option<String> {
let f = self.get_thread_name.as_mut()?;
Some(f(index))
}
/// Sets a closure which takes a thread index and returns
/// the thread's name.
pub fn thread_name<F>(mut self, closure: F) -> Self
where
F: FnMut(usize) -> String + 'static,
{
self.get_thread_name = Some(Box::new(closure));
self
}
/// Sets the number of threads to be used in the rayon threadpool.
///
/// If you specify a non-zero number of threads using this
/// function, then the resulting thread-pools are guaranteed to
/// start at most this number of threads.
///
/// If `num_threads` is 0, or you do not call this function, then
/// the Rayon runtime will select the number of threads
/// automatically. At present, this is based on the
/// `RAYON_NUM_THREADS` environment variable (if set),
/// or the number of logical CPUs (otherwise).
/// In the future, however, the default behavior may
/// change to dynamically add or remove threads as needed.
///
/// **Future compatibility warning:** Given the default behavior
/// may change in the future, if you wish to rely on a fixed
/// number of threads, you should use this function to specify
/// that number. To reproduce the current default behavior, you
/// may wish to use [`std::thread::available_parallelism`]
/// to query the number of CPUs dynamically.
///
/// **Old environment variable:** `RAYON_NUM_THREADS` is a one-to-one
/// replacement of the now deprecated `RAYON_RS_NUM_CPUS` environment
/// variable. If both variables are specified, `RAYON_NUM_THREADS` will
/// be preferred.
pub fn num_threads(mut self, num_threads: usize) -> Self {
self.num_threads = num_threads;
self
}
/// Use the current thread as one of the threads in the pool.
///
/// The current thread is guaranteed to be at index 0, and since the thread is not managed by
/// rayon, the spawn and exit handlers do not run for that thread.
///
/// Note that the current thread won't run the main work-stealing loop, so jobs spawned into
/// the thread-pool will generally not be picked up automatically by this thread unless you
/// yield to rayon in some way, like via [`yield_now()`], [`yield_local()`], or [`scope()`].
///
/// # Local thread-pools
///
/// Using this in a local thread-pool means the registry will be leaked. In future versions
/// there might be a way of cleaning up the current-thread state.
pub fn use_current_thread(mut self) -> Self {
self.use_current_thread = true;
self
}
/// Returns a copy of the current panic handler.
fn take_panic_handler(&mut self) -> Option<Box<PanicHandler>> {
self.panic_handler.take()
}
/// Normally, whenever Rayon catches a panic, it tries to
/// propagate it to someplace sensible, to try and reflect the
/// semantics of sequential execution. But in some cases,
/// particularly with the `spawn()` APIs, there is no
/// obvious place where we should propagate the panic to.
/// In that case, this panic handler is invoked.
///
/// If no panic handler is set, the default is to abort the
/// process, under the principle that panics should not go
/// unobserved.
///
/// If the panic handler itself panics, this will abort the
/// process. To prevent this, wrap the body of your panic handler
/// in a call to `std::panic::catch_unwind()`.
pub fn panic_handler<H>(mut self, panic_handler: H) -> Self
where
H: Fn(Box<dyn Any + Send>) + Send + Sync + 'static,
{
self.panic_handler = Some(Box::new(panic_handler));
self
}
/// Get the stack size of the worker threads
fn get_stack_size(&self) -> Option<usize> {
self.stack_size
}
/// Sets the stack size of the worker threads
pub fn stack_size(mut self, stack_size: usize) -> Self {
self.stack_size = Some(stack_size);
self
}
/// **(DEPRECATED)** Suggest to worker threads that they execute
/// spawned jobs in a "breadth-first" fashion.
///
/// Typically, when a worker thread is idle or blocked, it will
/// attempt to execute the job from the *top* of its local deque of
/// work (i.e., the job most recently spawned). If this flag is set
/// to true, however, workers will prefer to execute in a
/// *breadth-first* fashion -- that is, they will search for jobs at
/// the *bottom* of their local deque. (At present, workers *always*
/// steal from the bottom of other workers' deques, regardless of
/// the setting of this flag.)
///
/// If you think of the tasks as a tree, where a parent task
/// spawns its children in the tree, then this flag loosely
/// corresponds to doing a breadth-first traversal of the tree,
/// whereas the default would be to do a depth-first traversal.
///
/// **Note that this is an "execution hint".** Rayon's task
/// execution is highly dynamic and the precise order in which
/// independent tasks are executed is not intended to be
/// guaranteed.
///
/// This `breadth_first()` method is now deprecated per [RFC #1],
/// and in the future its effect may be removed. Consider using
/// [`scope_fifo()`] for a similar effect.
///
/// [`scope_fifo()`]: fn.scope_fifo.html
#[deprecated(note = "use `scope_fifo` and `spawn_fifo` for similar effect")]
pub fn breadth_first(mut self) -> Self {
self.breadth_first = true;
self
}
fn get_breadth_first(&self) -> bool {
self.breadth_first
}
/// Takes the current thread start callback, leaving `None`.
fn take_start_handler(&mut self) -> Option<Box<StartHandler>> {
self.start_handler.take()
}
/// Sets a callback to be invoked on thread start.
///
/// The closure is passed the index of the thread on which it is invoked.
/// Note that this same closure may be invoked multiple times in parallel.
/// If this closure panics, the panic will be passed to the panic handler.
/// If that handler returns, then startup will continue normally.
pub fn start_handler<H>(mut self, start_handler: H) -> Self
where
H: Fn(usize) + Send + Sync + 'static,
{
self.start_handler = Some(Box::new(start_handler));
self
}
/// Returns a current thread exit callback, leaving `None`.
fn take_exit_handler(&mut self) -> Option<Box<ExitHandler>> {
self.exit_handler.take()
}
/// Sets a callback to be invoked on thread exit.
///
/// The closure is passed the index of the thread on which it is invoked.
/// Note that this same closure may be invoked multiple times in parallel.
/// If this closure panics, the panic will be passed to the panic handler.
/// If that handler returns, then the thread will exit normally.
pub fn exit_handler<H>(mut self, exit_handler: H) -> Self
where
H: Fn(usize) + Send + Sync + 'static,
{
self.exit_handler = Some(Box::new(exit_handler));
self
}
}
#[allow(deprecated)]
impl Configuration {
/// Creates and return a valid rayon thread pool configuration, but does not initialize it.
pub fn new() -> Configuration {
Configuration {
builder: ThreadPoolBuilder::new(),
}
}
/// Deprecated in favor of `ThreadPoolBuilder::build`.
pub fn build(self) -> Result<ThreadPool, Box<dyn Error + 'static>> {
self.builder.build().map_err(Box::from)
}
/// Deprecated in favor of `ThreadPoolBuilder::thread_name`.
pub fn thread_name<F>(mut self, closure: F) -> Self
where
F: FnMut(usize) -> String + 'static,
{
self.builder = self.builder.thread_name(closure);
self
}
/// Deprecated in favor of `ThreadPoolBuilder::num_threads`.
pub fn num_threads(mut self, num_threads: usize) -> Configuration {
self.builder = self.builder.num_threads(num_threads);
self
}
/// Deprecated in favor of `ThreadPoolBuilder::panic_handler`.
pub fn panic_handler<H>(mut self, panic_handler: H) -> Configuration
where
H: Fn(Box<dyn Any + Send>) + Send + Sync + 'static,
{
self.builder = self.builder.panic_handler(panic_handler);
self
}
/// Deprecated in favor of `ThreadPoolBuilder::stack_size`.
pub fn stack_size(mut self, stack_size: usize) -> Self {
self.builder = self.builder.stack_size(stack_size);
self
}
/// Deprecated in favor of `ThreadPoolBuilder::breadth_first`.
pub fn breadth_first(mut self) -> Self {
self.builder = self.builder.breadth_first();
self
}
/// Deprecated in favor of `ThreadPoolBuilder::start_handler`.
pub fn start_handler<H>(mut self, start_handler: H) -> Configuration
where
H: Fn(usize) + Send + Sync + 'static,
{
self.builder = self.builder.start_handler(start_handler);
self
}
/// Deprecated in favor of `ThreadPoolBuilder::exit_handler`.
pub fn exit_handler<H>(mut self, exit_handler: H) -> Configuration
where
H: Fn(usize) + Send + Sync + 'static,
{
self.builder = self.builder.exit_handler(exit_handler);
self
}
/// Returns a ThreadPoolBuilder with identical parameters.
fn into_builder(self) -> ThreadPoolBuilder {
self.builder
}
}
impl ThreadPoolBuildError {
fn new(kind: ErrorKind) -> ThreadPoolBuildError {
ThreadPoolBuildError { kind }
}
fn is_unsupported(&self) -> bool {
matches!(&self.kind, ErrorKind::IOError(e) if e.kind() == io::ErrorKind::Unsupported)
}
}
const GLOBAL_POOL_ALREADY_INITIALIZED: &str =
"The global thread pool has already been initialized.";
const CURRENT_THREAD_ALREADY_IN_POOL: &str =
"The current thread is already part of another thread pool.";
impl Error for ThreadPoolBuildError {
#[allow(deprecated)]
fn description(&self) -> &str {
match self.kind {
ErrorKind::GlobalPoolAlreadyInitialized => GLOBAL_POOL_ALREADY_INITIALIZED,
ErrorKind::CurrentThreadAlreadyInPool => CURRENT_THREAD_ALREADY_IN_POOL,
ErrorKind::IOError(ref e) => e.description(),
}
}
fn source(&self) -> Option<&(dyn Error + 'static)> {
match &self.kind {
ErrorKind::GlobalPoolAlreadyInitialized | ErrorKind::CurrentThreadAlreadyInPool => None,
ErrorKind::IOError(e) => Some(e),
}
}
}
impl fmt::Display for ThreadPoolBuildError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match &self.kind {
ErrorKind::CurrentThreadAlreadyInPool => CURRENT_THREAD_ALREADY_IN_POOL.fmt(f),
ErrorKind::GlobalPoolAlreadyInitialized => GLOBAL_POOL_ALREADY_INITIALIZED.fmt(f),
ErrorKind::IOError(e) => e.fmt(f),
}
}
}
/// Deprecated in favor of `ThreadPoolBuilder::build_global`.
#[deprecated(note = "use `ThreadPoolBuilder::build_global`")]
#[allow(deprecated)]
pub fn initialize(config: Configuration) -> Result<(), Box<dyn Error>> {
config.into_builder().build_global().map_err(Box::from)
}
impl<S> fmt::Debug for ThreadPoolBuilder<S> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let ThreadPoolBuilder {
ref num_threads,
ref use_current_thread,
ref get_thread_name,
ref panic_handler,
ref stack_size,
ref start_handler,
ref exit_handler,
spawn_handler: _,
ref breadth_first,
} = *self;
// Just print `Some(<closure>)` or `None` to the debug
// output.
struct ClosurePlaceholder;
impl fmt::Debug for ClosurePlaceholder {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("<closure>")
}
}
let get_thread_name = get_thread_name.as_ref().map(|_| ClosurePlaceholder);
let panic_handler = panic_handler.as_ref().map(|_| ClosurePlaceholder);
let start_handler = start_handler.as_ref().map(|_| ClosurePlaceholder);
let exit_handler = exit_handler.as_ref().map(|_| ClosurePlaceholder);
f.debug_struct("ThreadPoolBuilder")
.field("num_threads", num_threads)
.field("use_current_thread", use_current_thread)
.field("get_thread_name", &get_thread_name)
.field("panic_handler", &panic_handler)
.field("stack_size", &stack_size)
.field("start_handler", &start_handler)
.field("exit_handler", &exit_handler)
.field("breadth_first", &breadth_first)
.finish()
}
}
#[allow(deprecated)]
impl fmt::Debug for Configuration {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.builder.fmt(f)
}
}
/// Provides the calling context to a closure called by `join_context`.
#[derive(Debug)]
pub struct FnContext {
migrated: bool,
/// disable `Send` and `Sync`, just for a little future-proofing.
_marker: PhantomData<*mut ()>,
}
impl FnContext {
#[inline]
fn new(migrated: bool) -> Self {
FnContext {
migrated,
_marker: PhantomData,
}
}
}
impl FnContext {
/// Returns `true` if the closure was called from a different thread
/// than it was provided from.
#[inline]
pub fn migrated(&self) -> bool {
self.migrated
}
}