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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)
}
}