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//! //! [Under construction](https://github.com/rayon-rs/rayon/issues/231) //! //! ## 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. #![doc(html_root_url = "https://docs.rs/rayon-core/1.4")] #![deny(missing_debug_implementations)] #![deny(missing_docs)] #![cfg_attr(test, feature(conservative_impl_trait))] use std::any::Any; use std::env; use std::io; use std::error::Error; use std::marker::PhantomData; use std::str::FromStr; use std::fmt; extern crate crossbeam_deque; #[macro_use] extern crate lazy_static; extern crate libc; extern crate num_cpus; extern crate rand; #[macro_use] mod log; mod latch; mod join; mod job; mod registry; mod scope; mod sleep; mod spawn; mod test; mod thread_pool; mod unwind; mod util; #[cfg(rayon_unstable)] pub mod internal; pub use thread_pool::ThreadPool; pub use thread_pool::current_thread_index; pub use thread_pool::current_thread_has_pending_tasks; pub use join::{join, join_context}; pub use scope::{scope, Scope}; pub use spawn::spawn; /// 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 { ::registry::Registry::current_num_threads() } /// Error when initializing a thread pool. #[derive(Debug)] pub struct ThreadPoolBuildError { kind: ErrorKind, } #[derive(Debug)] enum ErrorKind { GlobalPoolAlreadyInitialized, 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 #[derive(Default)] pub struct ThreadPoolBuilder { /// 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, /// 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<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>>, /// 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 = Fn(Box<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 = 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 = Fn(usize) + Send + Sync; impl ThreadPoolBuilder { /// Creates and returns a valid rayon thread pool builder, but does not initialize it. pub fn new() -> ThreadPoolBuilder { ThreadPoolBuilder::default() } /// Create a new `ThreadPool` initialized using this configuration. pub fn build(self) -> Result<ThreadPool, ThreadPoolBuildError> { thread_pool::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 = try!(registry::init_global_registry(self)); registry.wait_until_primed(); Ok(()) } /// 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 { match env::var("RAYON_NUM_THREADS").ok().and_then(|s| usize::from_str(&s).ok()) { Some(x) if x > 0 => return x, Some(x) if x == 0 => return num_cpus::get(), _ => {}, } // 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) if x > 0 => x, _ => num_cpus::get(), } } } /// Get the thread name for the thread with the given index. fn get_thread_name(&mut self, index: usize) -> Option<String> { self.get_thread_name.as_mut().map(|c| c(index)) } /// Set 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 } /// Set 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 the [`num_cpus` /// crate](https://crates.io/crates/num_cpus) 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 prefered. pub fn num_threads(mut self, num_threads: usize) -> ThreadPoolBuilder { self.num_threads = num_threads; 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) -> ThreadPoolBuilder where H: Fn(Box<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 } /// Set the stack size of the worker threads pub fn stack_size(mut self, stack_size: usize) -> Self { self.stack_size = Some(stack_size); self } /// 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 worker's 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. 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() } /// Set 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) -> ThreadPoolBuilder 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() } /// Set 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) -> ThreadPoolBuilder 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<Error + 'static>> { self.builder.build().map_err(|e| e.into()) } /// 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<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: kind } } } impl Error for ThreadPoolBuildError { fn description(&self) -> &str { match self.kind { ErrorKind::GlobalPoolAlreadyInitialized => "The global thread pool has already been initialized.", ErrorKind::IOError(ref e) => e.description(), } } } impl fmt::Display for ThreadPoolBuildError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self.kind { ErrorKind::IOError(ref e) => e.fmt(f), _ => self.description().fmt(f), } } } /// Deprecated in favor of `ThreadPoolBuilder::build_global`. #[deprecated(note = "use `ThreadPoolBuilder::build_global`")] #[allow(deprecated)] pub fn initialize(config: Configuration) -> Result<(), Box<Error>> { config.into_builder().build_global().map_err(|e| e.into()) } impl fmt::Debug for ThreadPoolBuilder { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { let ThreadPoolBuilder { ref num_threads, ref get_thread_name, ref panic_handler, ref stack_size, ref start_handler, ref exit_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("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: 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 } }