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Android: avoid deadlocks while handling UserEvent #2343

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Merged
msiglreith merged 3 commits into from
Jul 20, 2022
Merged

Android: avoid deadlocks while handling UserEvent #2343

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6a29433
android: avoid deadlocks while handling UserEvent
Rodrigodd Jun 20, 2022
5d87712
android: replace `Arc<Mutex<VecDeque<T>>` by `mpsc`
Rodrigodd Jun 21, 2022
59f8725
android: use field init shorthand in `EventLoop::new`
Rodrigodd Jun 22, 2022
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24 changes: 15 additions & 9 deletions src/platform_impl/android/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

use std::{
collections::VecDeque,
sync::{Arc, Mutex, RwLock},
sync::{mpsc, RwLock},
time::{Duration, Instant},
};

Expand Down Expand Up @@ -234,7 +234,8 @@ fn poll(poll: Poll) -> Option<EventSource> {

pub struct EventLoop<T: 'static> {
window_target: event_loop::EventLoopWindowTarget<T>,
user_queue: Arc<Mutex<VecDeque<T>>>,
user_events_sender: mpsc::Sender<T>,
user_events_receiver: mpsc::Receiver<T>,
first_event: Option<EventSource>,
start_cause: event::StartCause,
looper: ThreadLooper,
Expand All @@ -256,14 +257,16 @@ macro_rules! call_event_handler {

impl<T: 'static> EventLoop<T> {
pub(crate) fn new(_: &PlatformSpecificEventLoopAttributes) -> Self {
let (user_events_sender, user_events_receiver) = mpsc::channel();
Self {
window_target: event_loop::EventLoopWindowTarget {
p: EventLoopWindowTarget {
_marker: std::marker::PhantomData,
},
_marker: std::marker::PhantomData,
},
user_queue: Default::default(),
user_events_sender,
user_events_receiver,
first_event: None,
start_cause: event::StartCause::Init,
looper: ThreadLooper::for_thread().unwrap(),
Expand Down Expand Up @@ -470,8 +473,9 @@ impl<T: 'static> EventLoop<T> {
}
}
Some(EventSource::User) => {
let mut user_queue = self.user_queue.lock().unwrap();
while let Some(event) = user_queue.pop_front() {
// try_recv only errors when empty (expected) or disconnect. But because Self
// contains a Sender it will never disconnect, so no error handling need.
while let Ok(event) = self.user_events_receiver.try_recv() {
call_event_handler!(
event_handler,
self.window_target(),
Expand Down Expand Up @@ -572,20 +576,22 @@ impl<T: 'static> EventLoop<T> {

pub fn create_proxy(&self) -> EventLoopProxy<T> {
EventLoopProxy {
queue: self.user_queue.clone(),
user_events_sender: self.user_events_sender.clone(),
looper: ForeignLooper::for_thread().expect("called from event loop thread"),
}
}
}

pub struct EventLoopProxy<T: 'static> {
queue: Arc<Mutex<VecDeque<T>>>,
user_events_sender: mpsc::Sender<T>,
looper: ForeignLooper,
}

impl<T> EventLoopProxy<T> {
pub fn send_event(&self, event: T) -> Result<(), event_loop::EventLoopClosed<T>> {
self.queue.lock().unwrap().push_back(event);
self.user_events_sender
.send(event)
.map_err(|mpsc::SendError(x)| event_loop::EventLoopClosed(x))?;
self.looper.wake();
Ok(())
}
Expand All @@ -594,7 +600,7 @@ impl<T> EventLoopProxy<T> {
impl<T> Clone for EventLoopProxy<T> {
fn clone(&self) -> Self {
EventLoopProxy {
queue: self.queue.clone(),
user_events_sender: self.user_events_sender.clone(),
looper: self.looper.clone(),
}
}
Expand Down