use crate::job::*; use crate::registry::Registry; use crate::unwind; use std::mem; use std::sync::Arc; /// Fires off a task into the Rayon threadpool in the "static" or /// "global" scope. Just like a standard thread, this task is not /// tied to the current stack frame, and hence it cannot hold any /// references other than those with `'static` lifetime. If you want /// to spawn a task that references stack data, use [the `scope()` /// function][scope] to create a scope. /// /// [scope]: fn.scope.html /// /// Since tasks spawned with this function cannot hold references into /// the enclosing stack frame, you almost certainly want to use a /// `move` closure as their argument (otherwise, the closure will /// typically hold references to any variables from the enclosing /// function that you happen to use). /// /// This API assumes that the closure is executed purely for its /// side-effects (i.e., it might send messages, modify data protected /// by a mutex, or some such thing). /// /// There is no guaranteed order of execution for spawns, given that /// other threads may steal tasks at any time. However, they are /// generally prioritized in a LIFO order on the thread from which /// they were spawned. Other threads always steal from the other end of /// the deque, like FIFO order. The idea is that "recent" tasks are /// most likely to be fresh in the local CPU's cache, while other /// threads can steal older "stale" tasks. For an alternate approach, /// consider [`spawn_fifo()`] instead. /// /// [`spawn_fifo()`]: fn.spawn_fifo.html /// /// # Panic handling /// /// If this closure should panic, the resulting panic will be /// propagated to the panic handler registered in the `ThreadPoolBuilder`, /// if any. See [`ThreadPoolBuilder::panic_handler()`][ph] for more /// details. /// /// [ph]: struct.ThreadPoolBuilder.html#method.panic_handler /// /// # Examples /// /// This code creates a Rayon task that increments a global counter. /// /// ```rust /// # use rayon_core as rayon; /// use std::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT}; /// /// static GLOBAL_COUNTER: AtomicUsize = ATOMIC_USIZE_INIT; /// /// rayon::spawn(move || { /// GLOBAL_COUNTER.fetch_add(1, Ordering::SeqCst); /// }); /// ``` pub fn spawn(func: F) where F: FnOnce() + Send + 'static, { // We assert that current registry has not terminated. unsafe { spawn_in(func, &Registry::current()) } } /// Spawns an asynchronous job in `registry.` /// /// Unsafe because `registry` must not yet have terminated. pub(super) unsafe fn spawn_in(func: F, registry: &Arc) where F: FnOnce() + Send + 'static, { // We assert that this does not hold any references (we know // this because of the `'static` bound in the inferface); // moreover, we assert that the code below is not supposed to // be able to panic, and hence the data won't leak but will be // enqueued into some deque for later execution. let abort_guard = unwind::AbortIfPanic; // just in case we are wrong, and code CAN panic let job_ref = spawn_job(func, registry); registry.inject_or_push(job_ref); mem::forget(abort_guard); } unsafe fn spawn_job(func: F, registry: &Arc) -> JobRef where F: FnOnce() + Send + 'static, { // Ensure that registry cannot terminate until this job has // executed. This ref is decremented at the (*) below. registry.increment_terminate_count(); Box::new(HeapJob::new({ let registry = registry.clone(); move || { match unwind::halt_unwinding(func) { Ok(()) => {} Err(err) => { registry.handle_panic(err); } } registry.terminate(); // (*) permit registry to terminate now } })) .as_job_ref() } /// Fires off a task into the Rayon threadpool in the "static" or /// "global" scope. Just like a standard thread, this task is not /// tied to the current stack frame, and hence it cannot hold any /// references other than those with `'static` lifetime. If you want /// to spawn a task that references stack data, use [the `scope_fifo()` /// function](fn.scope_fifo.html) to create a scope. /// /// The behavior is essentially the same as [the `spawn` /// function](fn.spawn.html), except that calls from the same thread /// will be prioritized in FIFO order. This is similar to the now- /// deprecated [`breadth_first`] option, except the effect is isolated /// to relative `spawn_fifo` calls, not all threadpool tasks. /// /// For more details on this design, see Rayon [RFC #1]. /// /// [`breadth_first`]: struct.ThreadPoolBuilder.html#method.breadth_first /// [RFC #1]: https://github.com/rayon-rs/rfcs/blob/master/accepted/rfc0001-scope-scheduling.md /// /// # Panic handling /// /// If this closure should panic, the resulting panic will be /// propagated to the panic handler registered in the `ThreadPoolBuilder`, /// if any. See [`ThreadPoolBuilder::panic_handler()`][ph] for more /// details. /// /// [ph]: struct.ThreadPoolBuilder.html#method.panic_handler pub fn spawn_fifo(func: F) where F: FnOnce() + Send + 'static, { // We assert that current registry has not terminated. unsafe { spawn_fifo_in(func, &Registry::current()) } } /// Spawns an asynchronous FIFO job in `registry.` /// /// Unsafe because `registry` must not yet have terminated. pub(super) unsafe fn spawn_fifo_in(func: F, registry: &Arc) where F: FnOnce() + Send + 'static, { // We assert that this does not hold any references (we know // this because of the `'static` bound in the inferface); // moreover, we assert that the code below is not supposed to // be able to panic, and hence the data won't leak but will be // enqueued into some deque for later execution. let abort_guard = unwind::AbortIfPanic; // just in case we are wrong, and code CAN panic let job_ref = spawn_job(func, registry); // If we're in the pool, use our thread's private fifo for this thread to execute // in a locally-FIFO order. Otherwise, just use the pool's global injector. match registry.current_thread() { Some(worker) => worker.push_fifo(job_ref), None => registry.inject(&[job_ref]), } mem::forget(abort_guard); } #[cfg(test)] mod test;