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//! Ping to the event loop
//!
//! This is an event source that just produces `()` events whevener the associated
//! [`Ping::ping`](Ping#method.ping) method is called. If the event source is pinged multiple times
//! between a single dispatching, it'll only generate one event.
//!
//! This event source is a simple way of waking up the event loop from an other part of your program
//! (and is what backs the [`LoopSignal`](crate::LoopSignal)). It can also be used as a building
//! block to construct event sources whose source of event is not file descriptor, but rather an
//! userspace source (like an other thread).
// The ping source has platform-dependent implementations provided by modules
// under this one. These modules should expose:
// - a make_ping() function
// - a Ping type
// - a PingSource type
//
// See eg. the pipe implementation for these items' specific requirements.
#[cfg(target_os = "linux")]
mod eventfd;
#[cfg(target_os = "linux")]
use eventfd as platform;
#[cfg(windows)]
mod iocp;
#[cfg(windows)]
use iocp as platform;
#[cfg(not(any(target_os = "linux", windows)))]
mod pipe;
#[cfg(not(any(target_os = "linux", windows)))]
use pipe as platform;
/// Create a new ping event source
///
/// you are given a [`Ping`] instance, which can be cloned and used to ping the
/// event loop, and a [`PingSource`], which you can insert in your event loop to
/// receive the pings.
pub fn make_ping() -> std::io::Result<(Ping, PingSource)> {
platform::make_ping()
}
/// The ping event source
///
/// You can insert it in your event loop to receive pings.
///
/// If you use it directly, it will automatically remove itself from the event loop
/// once all [`Ping`] instances are dropped.
pub type Ping = platform::Ping;
/// The Ping handle
///
/// This handle can be cloned and sent accross threads. It can be used to
/// send pings to the `PingSource`.
pub type PingSource = platform::PingSource;
/// An error arising from processing events for a ping.
#[derive(thiserror::Error, Debug)]
#[error(transparent)]
pub struct PingError(Box<dyn std::error::Error + Sync + Send>);
#[cfg(test)]
mod tests {
use crate::transient::TransientSource;
use std::time::Duration;
use super::*;
#[test]
fn ping() {
let mut event_loop = crate::EventLoop::<bool>::try_new().unwrap();
let (ping, source) = make_ping().unwrap();
event_loop
.handle()
.insert_source(source, |(), &mut (), dispatched| *dispatched = true)
.unwrap();
ping.ping();
let mut dispatched = false;
event_loop
.dispatch(std::time::Duration::ZERO, &mut dispatched)
.unwrap();
assert!(dispatched);
// Ping has been drained an no longer generates events
let mut dispatched = false;
event_loop
.dispatch(std::time::Duration::ZERO, &mut dispatched)
.unwrap();
assert!(!dispatched);
}
#[test]
fn ping_closed() {
let mut event_loop = crate::EventLoop::<bool>::try_new().unwrap();
let (_, source) = make_ping().unwrap();
event_loop
.handle()
.insert_source(source, |(), &mut (), dispatched| *dispatched = true)
.unwrap();
let mut dispatched = false;
// If the sender is closed from the start, the ping should first trigger
// once, disabling itself but not invoking the callback
event_loop
.dispatch(std::time::Duration::ZERO, &mut dispatched)
.unwrap();
assert!(!dispatched);
// Then it should not trigger any more, so this dispatch should wait the whole 100ms
let now = std::time::Instant::now();
event_loop
.dispatch(std::time::Duration::from_millis(100), &mut dispatched)
.unwrap();
assert!(now.elapsed() >= std::time::Duration::from_millis(100));
}
#[test]
fn ping_removed() {
// This keeps track of whether the event fired.
let mut dispatched = false;
let mut event_loop = crate::EventLoop::<bool>::try_new().unwrap();
let (sender, source) = make_ping().unwrap();
let wrapper = TransientSource::from(source);
// Check that the source starts off in the wrapper.
assert!(!wrapper.is_none());
// Put the source in the loop.
let dispatcher =
crate::Dispatcher::new(wrapper, |(), &mut (), dispatched| *dispatched = true);
let token = event_loop
.handle()
.register_dispatcher(dispatcher.clone())
.unwrap();
// Drop the sender and check that it's actually removed.
drop(sender);
// There should be no event, but the loop still needs to wake up to
// process the close event (just like in the ping_closed() test).
event_loop
.dispatch(Duration::ZERO, &mut dispatched)
.unwrap();
assert!(!dispatched);
// Pull the source wrapper out.
event_loop.handle().remove(token);
let wrapper = dispatcher.into_source_inner();
// Check that the inner source is now gone.
assert!(wrapper.is_none());
}
#[test]
fn ping_fired_and_removed() {
// This is like ping_removed() with the single difference that we fire a
// ping and drop it between two successive dispatches of the loop.
// This keeps track of whether the event fired.
let mut dispatched = false;
let mut event_loop = crate::EventLoop::<bool>::try_new().unwrap();
let (sender, source) = make_ping().unwrap();
let wrapper = TransientSource::from(source);
// Check that the source starts off in the wrapper.
assert!(!wrapper.is_none());
// Put the source in the loop.
let dispatcher =
crate::Dispatcher::new(wrapper, |(), &mut (), dispatched| *dispatched = true);
let token = event_loop
.handle()
.register_dispatcher(dispatcher.clone())
.unwrap();
// Send a ping AND drop the sender and check that it's actually removed.
sender.ping();
drop(sender);
// There should be an event, but the source should be removed from the
// loop immediately after.
event_loop
.dispatch(Duration::ZERO, &mut dispatched)
.unwrap();
assert!(dispatched);
// Pull the source wrapper out.
event_loop.handle().remove(token);
let wrapper = dispatcher.into_source_inner();
// Check that the inner source is now gone.
assert!(wrapper.is_none());
}
#[test]
fn ping_multiple_senders() {
// This is like ping_removed() but for testing the behaviour of multiple
// senders.
// This keeps track of whether the event fired.
let mut dispatched = false;
let mut event_loop = crate::EventLoop::<bool>::try_new().unwrap();
let (sender0, source) = make_ping().unwrap();
let wrapper = TransientSource::from(source);
let sender1 = sender0.clone();
let sender2 = sender1.clone();
// Check that the source starts off in the wrapper.
assert!(!wrapper.is_none());
// Put the source in the loop.
let dispatcher =
crate::Dispatcher::new(wrapper, |(), &mut (), dispatched| *dispatched = true);
let token = event_loop
.handle()
.register_dispatcher(dispatcher.clone())
.unwrap();
// Send a ping AND drop the sender and check that it's actually removed.
sender0.ping();
drop(sender0);
// There should be an event, and the source should remain in the loop.
event_loop
.dispatch(Duration::ZERO, &mut dispatched)
.unwrap();
assert!(dispatched);
// Now test that the clones still work. Drop after the dispatch loop
// instead of before, this time.
dispatched = false;
sender1.ping();
event_loop
.dispatch(Duration::ZERO, &mut dispatched)
.unwrap();
assert!(dispatched);
// Finally, drop all of them without sending anything.
dispatched = false;
drop(sender1);
drop(sender2);
event_loop
.dispatch(Duration::ZERO, &mut dispatched)
.unwrap();
assert!(!dispatched);
// Pull the source wrapper out.
event_loop.handle().remove(token);
let wrapper = dispatcher.into_source_inner();
// Check that the inner source is now gone.
assert!(wrapper.is_none());
}
}