| // Copyright 2016 Amanieu d'Antras |
| // |
| // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or |
| // http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or |
| // http://opensource.org/licenses/MIT>, at your option. This file may not be |
| // copied, modified, or distributed except according to those terms. |
| |
| //! A simple spin lock based thread parker. Used on platforms without better |
| //! parking facilities available. |
| |
| use core::sync::atomic::{spin_loop_hint, AtomicBool, Ordering}; |
| use instant::Instant; |
| use std::thread; |
| |
| // Helper type for putting a thread to sleep until some other thread wakes it up |
| pub struct ThreadParker { |
| parked: AtomicBool, |
| } |
| |
| impl super::ThreadParkerT for ThreadParker { |
| type UnparkHandle = UnparkHandle; |
| |
| const IS_CHEAP_TO_CONSTRUCT: bool = true; |
| |
| #[inline] |
| fn new() -> ThreadParker { |
| ThreadParker { |
| parked: AtomicBool::new(false), |
| } |
| } |
| |
| #[inline] |
| unsafe fn prepare_park(&self) { |
| self.parked.store(true, Ordering::Relaxed); |
| } |
| |
| #[inline] |
| unsafe fn timed_out(&self) -> bool { |
| self.parked.load(Ordering::Relaxed) != false |
| } |
| |
| #[inline] |
| unsafe fn park(&self) { |
| while self.parked.load(Ordering::Acquire) != false { |
| spin_loop_hint(); |
| } |
| } |
| |
| #[inline] |
| unsafe fn park_until(&self, timeout: Instant) -> bool { |
| while self.parked.load(Ordering::Acquire) != false { |
| if Instant::now() >= timeout { |
| return false; |
| } |
| spin_loop_hint(); |
| } |
| true |
| } |
| |
| #[inline] |
| unsafe fn unpark_lock(&self) -> UnparkHandle { |
| // We don't need to lock anything, just clear the state |
| self.parked.store(false, Ordering::Release); |
| UnparkHandle(()) |
| } |
| } |
| |
| pub struct UnparkHandle(()); |
| |
| impl super::UnparkHandleT for UnparkHandle { |
| #[inline] |
| unsafe fn unpark(self) {} |
| } |
| |
| #[inline] |
| pub fn thread_yield() { |
| thread::yield_now(); |
| } |