process: avoid redundant effort to reap orphan processes (#3743)

tokio/src/process/unix/driver.rs

@@ -3,11 +3,8 @@
 //! Process driver
 
 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, SignalKind};
-use crate::sync::watch;
+use crate::signal::unix::driver::{Driver as SignalDriver, Handle as SignalHandle};
 
 use std::io;
 use std::time::Duration;
@@ -16,51 +13,20 @@ use std::time::Duration;
 #[derive(Debug)]
 pub(crate) struct Driver {
     park: SignalDriver,
-    inner: CoreDriver<watch::Receiver<()>, GlobalOrphanQueue>,
-}
-
-#[derive(Debug)]
-struct CoreDriver<S, Q> {
-    sigchild: S,
-    orphan_queue: Q,
-}
-
-trait HasChanged {
-    fn has_changed(&mut self) -> bool;
-}
-
-impl<T> HasChanged for watch::Receiver<T> {
-    fn has_changed(&mut self) -> bool {
-        self.try_has_changed().and_then(Result::ok).is_some()
-    }
-}
-
-// ===== impl CoreDriver =====
-
-impl<S, Q> CoreDriver<S, Q>
-where
-    S: HasChanged,
-    Q: ReapOrphanQueue,
-{
-    fn process(&mut self) {
-        if self.sigchild.has_changed() {
-            self.orphan_queue.reap_orphans();
-        }
-    }
+    signal_handle: SignalHandle,
 }
 
 // ===== impl Driver =====
 
 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,
-        };
+    pub(crate) fn new(park: SignalDriver) -> Self {
+        let signal_handle = park.handle();
 
-        Ok(Self { park, inner })
+        Self {
+            park,
+            signal_handle,
+        }
     }
 }
 
@@ -76,57 +42,17 @@ impl Park for Driver {
 
     fn park(&mut self) -> Result<(), Self::Error> {
         self.park.park()?;
-        self.inner.process();
+        GlobalOrphanQueue::reap_orphans(&self.signal_handle);
         Ok(())
     }
 
     fn park_timeout(&mut self, duration: Duration) -> Result<(), Self::Error> {
         self.park.park_timeout(duration)?;
-        self.inner.process();
+        GlobalOrphanQueue::reap_orphans(&self.signal_handle);
         Ok(())
     }
 
     fn shutdown(&mut self) {
         self.park.shutdown()
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    use crate::process::unix::orphan::test::MockQueue;
-
-    struct MockStream {
-        total_try_recv: usize,
-        values: Vec<Option<()>>,
-    }
-
-    impl MockStream {
-        fn new(values: Vec<Option<()>>) -> Self {
-            Self {
-                total_try_recv: 0,
-                values,
-            }
-        }
-    }
-
-    impl HasChanged for MockStream {
-        fn has_changed(&mut self) -> bool {
-            self.total_try_recv += 1;
-            self.values.remove(0).is_some()
-        }
-    }
-
-    #[test]
-    fn no_reap_if_no_signal() {
-        let mut driver = CoreDriver {
-            sigchild: MockStream::new(vec![None]),
-            orphan_queue: MockQueue::<()>::new(),
-        };
-
-        driver.process();
-
-        assert_eq!(1, driver.sigchild.total_try_recv);
-        assert_eq!(0, driver.orphan_queue.total_reaps.get());
-    }
-}

tokio/src/process/unix/mod.rs

@@ -24,14 +24,15 @@
 pub(crate) mod driver;
 
 pub(crate) mod orphan;
-use orphan::{OrphanQueue, OrphanQueueImpl, ReapOrphanQueue, Wait};
+use orphan::{OrphanQueue, OrphanQueueImpl, Wait};
 
 mod reap;
 use reap::Reaper;
 
 use crate::io::PollEvented;
 use crate::process::kill::Kill;
 use crate::process::SpawnedChild;
+use crate::signal::unix::driver::Handle as SignalHandle;
 use crate::signal::unix::{signal, Signal, SignalKind};
 
 use mio::event::Source;
@@ -73,9 +74,9 @@ impl fmt::Debug for GlobalOrphanQueue {
     }
 }
 
-impl ReapOrphanQueue for GlobalOrphanQueue {
-    fn reap_orphans(&self) {
-        ORPHAN_QUEUE.reap_orphans()
+impl GlobalOrphanQueue {
+    fn reap_orphans(handle: &SignalHandle) {
+        ORPHAN_QUEUE.reap_orphans(handle)
     }
 }