Resurrect on_release support from #89 by spawning

bb8/src/api.rs

@@ -273,13 +273,18 @@ pub trait CustomizeConnection<C: Send + 'static, E: 'static>:
     /// Called with connections immediately after they are returned from
     /// `ManageConnection::connect`.
     ///
-    /// The default implementation simply returns `Ok(())`.
-    ///
-    /// # Errors
+    /// The default implementation simply returns `Ok(())`. Any errors will be forwarded to the
+    /// configured error sink.
+    async fn on_acquire(&self, _connection: &mut C) -> Result<(), E> {
+        Ok(())
+    }
+
+    /// Called with connections before they're returned to the connection pool.
     ///
-    /// If this method returns an error, the connection will be discarded.
+    /// The default implementation simply returns `Ok(())`. Any errors will be forwarded to the
+    /// configured error sink.
     #[allow(unused_variables)]
-    async fn on_acquire(&self, connection: &mut C) -> Result<(), E> {
+    async fn on_release(&'_ self, _connection: &'_ mut C) -> Result<(), E> {
         Ok(())
     }
 }
@@ -304,8 +309,8 @@ where
         }
     }
 
-    pub(crate) fn drop_invalid(mut self) {
-        let _ = self.conn.take();
+    pub(crate) fn extract(mut self) -> Conn<M::Connection> {
+        self.conn.take().unwrap()
     }
 }
 

bb8/src/inner.rs

@@ -102,7 +102,9 @@ where
             match self.inner.manager.is_valid(&mut conn).await {
                 Ok(()) => return Ok(conn),
                 Err(_) => {
-                    conn.drop_invalid();
+                    self.on_release_connection(conn.extract());
+                    // Once we've extracted the connection, the `Drop` impl for `PooledConnection`
+                    // will call `put_back(None)`, so we don't need to do anything else here.
                     continue;
                 }
             }
@@ -133,6 +135,7 @@ where
             if !self.inner.manager.has_broken(&mut conn.conn) {
                 Some(conn)
             } else {
+                self.on_release_connection(conn);
                 None
             }
         });
@@ -147,6 +150,25 @@ where
         }
     }
 
+    fn on_release_connection(&self, mut conn: Conn<M::Connection>) {
+        if self.inner.statics.connection_customizer.is_none() {
+            return;
+        }
+
+        let pool = self.inner.clone();
+        spawn(async move {
+            let customizer = match pool.statics.connection_customizer.as_ref() {
+                Some(customizer) => customizer,
+                None => return,
+            };
+
+            let future = customizer.on_release(&mut conn.conn);
+            if let Err(e) = future.await {
+                pool.statics.error_sink.sink(e);
+            }
+        });
+    }
+
     /// Returns information about the current state of the pool.
     pub(crate) fn state(&self) -> State {
         self.inner.internals.lock().state()

bb8/src/internals.rs

@@ -168,12 +168,12 @@ where
 }
 
 pub(crate) struct InternalsGuard<M: ManageConnection> {
-    conn: Option<Conn<M::Connection>>,
-    pool: Arc<SharedPool<M>>,
+    pub(crate) conn: Option<Conn<M::Connection>>,
+    pub(crate) pool: Arc<SharedPool<M>>,
 }
 
 impl<M: ManageConnection> InternalsGuard<M> {
-    fn new(conn: Conn<M::Connection>, pool: Arc<SharedPool<M>>) -> Self {
+    pub(crate) fn new(conn: Conn<M::Connection>, pool: Arc<SharedPool<M>>) -> Self {
         Self {
             conn: Some(conn),
             pool,

bb8/tests/test.rs

@@ -5,7 +5,7 @@ use std::iter::FromIterator;
 use std::marker::PhantomData;
 use std::pin::Pin;
 use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
-use std::sync::Mutex;
+use std::sync::{Arc, Mutex};
 use std::task::Poll;
 use std::time::Duration;
 use std::{error, fmt, mem};
@@ -14,7 +14,7 @@ use async_trait::async_trait;
 use futures_channel::oneshot;
 use futures_util::future::{err, lazy, ok, pending, ready, try_join_all, FutureExt};
 use futures_util::stream::{FuturesUnordered, TryStreamExt};
-use tokio::time::timeout;
+use tokio::time::{sleep, timeout};
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct Error;
@@ -786,3 +786,121 @@ async fn test_customize_connection_acquire() {
     let connection_1_or_2 = pool.get().await.unwrap();
     assert!(connection_1_or_2.custom_field == 1 || connection_1_or_2.custom_field == 2);
 }
+
+#[tokio::test]
+async fn test_customize_connection_release() {
+    #[derive(Debug)]
+    struct CountingCustomizer {
+        num_conn_released: Arc<AtomicUsize>,
+    }
+
+    impl CountingCustomizer {
+        fn new(num_conn_released: Arc<AtomicUsize>) -> Self {
+            Self { num_conn_released }
+        }
+    }
+
+    #[async_trait]
+    impl<E: 'static> CustomizeConnection<FakeConnection, E> for CountingCustomizer {
+        async fn on_release(&self, _connection: &mut FakeConnection) -> Result<(), E> {
+            self.num_conn_released.fetch_add(1, Ordering::SeqCst);
+            Ok(())
+        }
+    }
+
+    #[derive(Debug)]
+    struct BreakableManager<C> {
+        _c: PhantomData<C>,
+        valid: Arc<AtomicBool>,
+        broken: Arc<AtomicBool>,
+    };
+
+    impl<C> BreakableManager<C> {
+        fn new(valid: Arc<AtomicBool>, broken: Arc<AtomicBool>) -> Self {
+            Self {
+                valid,
+                broken,
+                _c: PhantomData,
+            }
+        }
+    }
+
+    #[async_trait]
+    impl<C> ManageConnection for BreakableManager<C>
+    where
+        C: Default + Send + Sync + 'static,
+    {
+        type Connection = C;
+        type Error = Error;
+
+        async fn connect(&self) -> Result<Self::Connection, Self::Error> {
+            Ok(Default::default())
+        }
+
+        async fn is_valid(
+            &self,
+            _conn: &mut PooledConnection<'_, Self>,
+        ) -> Result<(), Self::Error> {
+            if self.valid.load(Ordering::SeqCst) {
+                Ok(())
+            } else {
+                Err(Error)
+            }
+        }
+
+        fn has_broken(&self, _: &mut Self::Connection) -> bool {
+            self.broken.load(Ordering::SeqCst)
+        }
+    }
+
+    let valid = Arc::new(AtomicBool::new(true));
+    let broken = Arc::new(AtomicBool::new(false));
+    let manager = BreakableManager::<FakeConnection>::new(valid.clone(), broken.clone());
+
+    let num_conn_released = Arc::new(AtomicUsize::new(0));
+    let customizer = CountingCustomizer::new(num_conn_released.clone());
+
+    let pool = Pool::builder()
+        .max_size(2)
+        .connection_customizer(Box::new(customizer))
+        .build(manager)
+        .await
+        .unwrap();
+
+    // Connections go in and out of the pool without being released
+    {
+        {
+            let _connection_1 = pool.get().await.unwrap();
+            let _connection_2 = pool.get().await.unwrap();
+            assert_eq!(num_conn_released.load(Ordering::SeqCst), 0);
+        }
+        {
+            let _connection_1 = pool.get().await.unwrap();
+            let _connection_2 = pool.get().await.unwrap();
+            assert_eq!(num_conn_released.load(Ordering::SeqCst), 0);
+        }
+    }
+
+    // Invalid connections get released
+    {
+        valid.store(false, Ordering::SeqCst);
+        let _connection_1 = pool.get().await.unwrap();
+        assert_eq!(num_conn_released.load(Ordering::SeqCst), 2);
+        let _connection_2 = pool.get().await.unwrap();
+        assert_eq!(num_conn_released.load(Ordering::SeqCst), 2);
+        valid.store(true, Ordering::SeqCst);
+    }
+
+    // Broken connections get released
+    {
+        num_conn_released.store(0, Ordering::SeqCst);
+        broken.store(true, Ordering::SeqCst);
+        {
+            let _connection_1 = pool.get().await.unwrap();
+            let _connection_2 = pool.get().await.unwrap();
+            assert_eq!(num_conn_released.load(Ordering::SeqCst), 0);
+        }
+        sleep(Duration::from_millis(100)).await;
+        assert_eq!(num_conn_released.load(Ordering::SeqCst), 2);
+    }
+}