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process: add ProcessDriver to handle orphan reaping (#2907)
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Original file line number | Diff line number | Diff line change |
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//! Process driver | ||
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use crate::park::Park; | ||
use crate::process::unix::orphan::ReapOrphanQueue; | ||
use crate::process::unix::GlobalOrphanQueue; | ||
use crate::signal::unix::driver::Driver as SignalDriver; | ||
use crate::signal::unix::{signal_with_handle, InternalStream, Signal, SignalKind}; | ||
use crate::sync::mpsc::error::TryRecvError; | ||
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use std::io; | ||
use std::time::Duration; | ||
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/// Responsible for cleaning up orphaned child processes on Unix platforms. | ||
#[derive(Debug)] | ||
pub(crate) struct Driver { | ||
park: SignalDriver, | ||
inner: CoreDriver<Signal, GlobalOrphanQueue>, | ||
} | ||
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#[derive(Debug)] | ||
struct CoreDriver<S, Q> { | ||
sigchild: S, | ||
orphan_queue: Q, | ||
} | ||
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// ===== impl CoreDriver ===== | ||
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impl<S, Q> CoreDriver<S, Q> | ||
where | ||
S: InternalStream, | ||
Q: ReapOrphanQueue, | ||
{ | ||
fn got_signal(&mut self) -> bool { | ||
match self.sigchild.try_recv() { | ||
Ok(()) => true, | ||
Err(TryRecvError::Empty) => false, | ||
Err(TryRecvError::Closed) => panic!("signal was deregistered"), | ||
} | ||
} | ||
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fn process(&mut self) { | ||
if self.got_signal() { | ||
// Drain all notifications which may have been buffered | ||
// so we can try to reap all orphans in one batch | ||
while self.got_signal() {} | ||
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self.orphan_queue.reap_orphans(); | ||
} | ||
} | ||
} | ||
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// ===== impl Driver ===== | ||
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impl Driver { | ||
/// Creates a new signal `Driver` instance that delegates wakeups to `park`. | ||
pub(crate) fn new(park: SignalDriver) -> io::Result<Self> { | ||
let sigchild = signal_with_handle(SignalKind::child(), park.handle())?; | ||
let inner = CoreDriver { | ||
sigchild, | ||
orphan_queue: GlobalOrphanQueue, | ||
}; | ||
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Ok(Self { park, inner }) | ||
} | ||
} | ||
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// ===== impl Park for Driver ===== | ||
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impl Park for Driver { | ||
type Unpark = <SignalDriver as Park>::Unpark; | ||
type Error = io::Error; | ||
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fn unpark(&self) -> Self::Unpark { | ||
self.park.unpark() | ||
} | ||
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fn park(&mut self) -> Result<(), Self::Error> { | ||
self.park.park()?; | ||
self.inner.process(); | ||
Ok(()) | ||
} | ||
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fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> { | ||
self.park.park_timeout(duration)?; | ||
self.inner.process(); | ||
Ok(()) | ||
} | ||
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fn shutdown(&mut self) { | ||
self.park.shutdown() | ||
} | ||
} | ||
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#[cfg(test)] | ||
mod test { | ||
use super::*; | ||
use crate::process::unix::orphan::test::MockQueue; | ||
use crate::sync::mpsc::error::TryRecvError; | ||
use std::task::{Context, Poll}; | ||
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struct MockStream { | ||
total_try_recv: usize, | ||
values: Vec<Option<()>>, | ||
} | ||
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impl MockStream { | ||
fn new(values: Vec<Option<()>>) -> Self { | ||
Self { | ||
total_try_recv: 0, | ||
values, | ||
} | ||
} | ||
} | ||
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impl InternalStream for MockStream { | ||
fn poll_recv(&mut self, _cx: &mut Context<'_>) -> Poll<Option<()>> { | ||
unimplemented!(); | ||
} | ||
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fn try_recv(&mut self) -> Result<(), TryRecvError> { | ||
self.total_try_recv += 1; | ||
match self.values.remove(0) { | ||
Some(()) => Ok(()), | ||
None => Err(TryRecvError::Empty), | ||
} | ||
} | ||
} | ||
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#[test] | ||
fn no_reap_if_no_signal() { | ||
let mut driver = CoreDriver { | ||
sigchild: MockStream::new(vec![None]), | ||
orphan_queue: MockQueue::<()>::new(), | ||
}; | ||
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driver.process(); | ||
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assert_eq!(1, driver.sigchild.total_try_recv); | ||
assert_eq!(0, driver.orphan_queue.total_reaps.get()); | ||
} | ||
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#[test] | ||
fn coalesce_signals_before_reaping() { | ||
let mut driver = CoreDriver { | ||
sigchild: MockStream::new(vec![Some(()), Some(()), None]), | ||
orphan_queue: MockQueue::<()>::new(), | ||
}; | ||
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driver.process(); | ||
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assert_eq!(3, driver.sigchild.total_try_recv); | ||
assert_eq!(1, driver.orphan_queue.total_reaps.get()); | ||
} | ||
} |
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