| use super::plumbing::*; |
| use super::*; |
| use std::sync::atomic::{AtomicBool, Ordering}; |
| use std::thread; |
| |
| /// `PanicFuse` is an adaptor that wraps an iterator with a fuse in case |
| /// of panics, to halt all threads as soon as possible. |
| /// |
| /// This struct is created by the [`panic_fuse()`] method on [`ParallelIterator`] |
| /// |
| /// [`panic_fuse()`]: trait.ParallelIterator.html#method.panic_fuse |
| /// [`ParallelIterator`]: trait.ParallelIterator.html |
| #[must_use = "iterator adaptors are lazy and do nothing unless consumed"] |
| #[derive(Debug, Clone)] |
| pub struct PanicFuse<I: ParallelIterator> { |
| base: I, |
| } |
| |
| /// Helper that sets a bool to `true` if dropped while unwinding. |
| #[derive(Clone)] |
| struct Fuse<'a>(&'a AtomicBool); |
| |
| impl<'a> Drop for Fuse<'a> { |
| #[inline] |
| fn drop(&mut self) { |
| if thread::panicking() { |
| self.0.store(true, Ordering::Relaxed); |
| } |
| } |
| } |
| |
| impl<'a> Fuse<'a> { |
| #[inline] |
| fn panicked(&self) -> bool { |
| self.0.load(Ordering::Relaxed) |
| } |
| } |
| |
| impl<I> PanicFuse<I> |
| where |
| I: ParallelIterator, |
| { |
| /// Creates a new `PanicFuse` iterator. |
| pub(super) fn new(base: I) -> PanicFuse<I> { |
| PanicFuse { base } |
| } |
| } |
| |
| impl<I> ParallelIterator for PanicFuse<I> |
| where |
| I: ParallelIterator, |
| { |
| type Item = I::Item; |
| |
| fn drive_unindexed<C>(self, consumer: C) -> C::Result |
| where |
| C: UnindexedConsumer<Self::Item>, |
| { |
| let panicked = AtomicBool::new(false); |
| let consumer1 = PanicFuseConsumer { |
| base: consumer, |
| fuse: Fuse(&panicked), |
| }; |
| self.base.drive_unindexed(consumer1) |
| } |
| |
| fn opt_len(&self) -> Option<usize> { |
| self.base.opt_len() |
| } |
| } |
| |
| impl<I> IndexedParallelIterator for PanicFuse<I> |
| where |
| I: IndexedParallelIterator, |
| { |
| fn drive<C>(self, consumer: C) -> C::Result |
| where |
| C: Consumer<Self::Item>, |
| { |
| let panicked = AtomicBool::new(false); |
| let consumer1 = PanicFuseConsumer { |
| base: consumer, |
| fuse: Fuse(&panicked), |
| }; |
| self.base.drive(consumer1) |
| } |
| |
| fn len(&self) -> usize { |
| self.base.len() |
| } |
| |
| fn with_producer<CB>(self, callback: CB) -> CB::Output |
| where |
| CB: ProducerCallback<Self::Item>, |
| { |
| return self.base.with_producer(Callback { callback }); |
| |
| struct Callback<CB> { |
| callback: CB, |
| } |
| |
| impl<T, CB> ProducerCallback<T> for Callback<CB> |
| where |
| CB: ProducerCallback<T>, |
| { |
| type Output = CB::Output; |
| |
| fn callback<P>(self, base: P) -> CB::Output |
| where |
| P: Producer<Item = T>, |
| { |
| let panicked = AtomicBool::new(false); |
| let producer = PanicFuseProducer { |
| base, |
| fuse: Fuse(&panicked), |
| }; |
| self.callback.callback(producer) |
| } |
| } |
| } |
| } |
| |
| /// //////////////////////////////////////////////////////////////////////// |
| /// Producer implementation |
| |
| struct PanicFuseProducer<'a, P> { |
| base: P, |
| fuse: Fuse<'a>, |
| } |
| |
| impl<'a, P> Producer for PanicFuseProducer<'a, P> |
| where |
| P: Producer, |
| { |
| type Item = P::Item; |
| type IntoIter = PanicFuseIter<'a, P::IntoIter>; |
| |
| fn into_iter(self) -> Self::IntoIter { |
| PanicFuseIter { |
| base: self.base.into_iter(), |
| fuse: self.fuse, |
| } |
| } |
| |
| fn min_len(&self) -> usize { |
| self.base.min_len() |
| } |
| fn max_len(&self) -> usize { |
| self.base.max_len() |
| } |
| |
| fn split_at(self, index: usize) -> (Self, Self) { |
| let (left, right) = self.base.split_at(index); |
| ( |
| PanicFuseProducer { |
| base: left, |
| fuse: self.fuse.clone(), |
| }, |
| PanicFuseProducer { |
| base: right, |
| fuse: self.fuse, |
| }, |
| ) |
| } |
| |
| fn fold_with<G>(self, folder: G) -> G |
| where |
| G: Folder<Self::Item>, |
| { |
| let folder1 = PanicFuseFolder { |
| base: folder, |
| fuse: self.fuse, |
| }; |
| self.base.fold_with(folder1).base |
| } |
| } |
| |
| struct PanicFuseIter<'a, I> { |
| base: I, |
| fuse: Fuse<'a>, |
| } |
| |
| impl<'a, I> Iterator for PanicFuseIter<'a, I> |
| where |
| I: Iterator, |
| { |
| type Item = I::Item; |
| |
| fn next(&mut self) -> Option<Self::Item> { |
| if self.fuse.panicked() { |
| None |
| } else { |
| self.base.next() |
| } |
| } |
| |
| fn size_hint(&self) -> (usize, Option<usize>) { |
| self.base.size_hint() |
| } |
| } |
| |
| impl<'a, I> DoubleEndedIterator for PanicFuseIter<'a, I> |
| where |
| I: DoubleEndedIterator, |
| { |
| fn next_back(&mut self) -> Option<Self::Item> { |
| if self.fuse.panicked() { |
| None |
| } else { |
| self.base.next_back() |
| } |
| } |
| } |
| |
| impl<'a, I> ExactSizeIterator for PanicFuseIter<'a, I> |
| where |
| I: ExactSizeIterator, |
| { |
| fn len(&self) -> usize { |
| self.base.len() |
| } |
| } |
| |
| /// //////////////////////////////////////////////////////////////////////// |
| /// Consumer implementation |
| |
| struct PanicFuseConsumer<'a, C> { |
| base: C, |
| fuse: Fuse<'a>, |
| } |
| |
| impl<'a, T, C> Consumer<T> for PanicFuseConsumer<'a, C> |
| where |
| C: Consumer<T>, |
| { |
| type Folder = PanicFuseFolder<'a, C::Folder>; |
| type Reducer = PanicFuseReducer<'a, C::Reducer>; |
| type Result = C::Result; |
| |
| fn split_at(self, index: usize) -> (Self, Self, Self::Reducer) { |
| let (left, right, reducer) = self.base.split_at(index); |
| ( |
| PanicFuseConsumer { |
| base: left, |
| fuse: self.fuse.clone(), |
| }, |
| PanicFuseConsumer { |
| base: right, |
| fuse: self.fuse.clone(), |
| }, |
| PanicFuseReducer { |
| base: reducer, |
| _fuse: self.fuse, |
| }, |
| ) |
| } |
| |
| fn into_folder(self) -> Self::Folder { |
| PanicFuseFolder { |
| base: self.base.into_folder(), |
| fuse: self.fuse, |
| } |
| } |
| |
| fn full(&self) -> bool { |
| self.fuse.panicked() || self.base.full() |
| } |
| } |
| |
| impl<'a, T, C> UnindexedConsumer<T> for PanicFuseConsumer<'a, C> |
| where |
| C: UnindexedConsumer<T>, |
| { |
| fn split_off_left(&self) -> Self { |
| PanicFuseConsumer { |
| base: self.base.split_off_left(), |
| fuse: self.fuse.clone(), |
| } |
| } |
| |
| fn to_reducer(&self) -> Self::Reducer { |
| PanicFuseReducer { |
| base: self.base.to_reducer(), |
| _fuse: self.fuse.clone(), |
| } |
| } |
| } |
| |
| struct PanicFuseFolder<'a, C> { |
| base: C, |
| fuse: Fuse<'a>, |
| } |
| |
| impl<'a, T, C> Folder<T> for PanicFuseFolder<'a, C> |
| where |
| C: Folder<T>, |
| { |
| type Result = C::Result; |
| |
| fn consume(mut self, item: T) -> Self { |
| self.base = self.base.consume(item); |
| self |
| } |
| |
| fn consume_iter<I>(mut self, iter: I) -> Self |
| where |
| I: IntoIterator<Item = T>, |
| { |
| fn cool<'a, T>(fuse: &'a Fuse<'_>) -> impl Fn(&T) -> bool + 'a { |
| move |_| !fuse.panicked() |
| } |
| |
| self.base = { |
| let fuse = &self.fuse; |
| let iter = iter.into_iter().take_while(cool(fuse)); |
| self.base.consume_iter(iter) |
| }; |
| self |
| } |
| |
| fn complete(self) -> C::Result { |
| self.base.complete() |
| } |
| |
| fn full(&self) -> bool { |
| self.fuse.panicked() || self.base.full() |
| } |
| } |
| |
| struct PanicFuseReducer<'a, C> { |
| base: C, |
| _fuse: Fuse<'a>, |
| } |
| |
| impl<'a, T, C> Reducer<T> for PanicFuseReducer<'a, C> |
| where |
| C: Reducer<T>, |
| { |
| fn reduce(self, left: T, right: T) -> T { |
| self.base.reduce(left, right) |
| } |
| } |