pool: fix panic when using callbacks

add regression test

sqlx-core/src/pool/connection.rs

@@ -325,8 +325,10 @@ impl<DB: Database> Floating<DB, Idle<DB>> {
         let now = Instant::now();
 
         PoolConnectionMetadata {
-            age: self.created_at.duration_since(now),
-            idle_for: self.idle_since.duration_since(now),
+            // NOTE: the receiver is the later `Instant` and the arg is the earlier
+            // https://github.com/launchbadge/sqlx/issues/1912
+            age: now.saturating_duration_since(self.created_at),
+            idle_for: now.saturating_duration_since(self.idle_since),
         }
     }
 }

tests/any/pool.rs

@@ -1,4 +1,6 @@
 use sqlx::any::AnyPoolOptions;
+use sqlx::Executor;
+use std::sync::atomic::AtomicI32;
 use std::sync::{
     atomic::{AtomicUsize, Ordering},
     Arc,
@@ -64,3 +66,133 @@ async fn pool_should_be_returned_failed_transactions() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[sqlx_macros::test]
+async fn test_pool_callbacks() -> anyhow::Result<()> {
+    sqlx_test::setup_if_needed();
+
+    #[derive(sqlx::FromRow, Debug, PartialEq, Eq)]
+    struct ConnStats {
+        id: i32,
+        before_acquire_calls: i32,
+        after_release_calls: i32,
+    }
+
+    let current_id = AtomicI32::new(0);
+
+    let pool = AnyPoolOptions::new()
+        .max_connections(1)
+        .acquire_timeout(Duration::from_secs(5))
+        .after_connect(move |conn, meta| {
+            assert_eq!(meta.age, Duration::ZERO);
+            assert_eq!(meta.idle_for, Duration::ZERO);
+
+            let id = current_id.fetch_add(1, Ordering::AcqRel);
+
+            Box::pin(async move {
+                let statement = format!(
+                    // language=SQL
+                    r#"
+                    CREATE TEMPORARY TABLE conn_stats(
+                        id int primary key,
+                        before_acquire_calls int default 0,
+                        after_release_calls int default 0 
+                    );
+                    INSERT INTO conn_stats(id) VALUES ({});
+                    "#,
+                    // Until we have generalized bind parameters
+                    id
+                );
+
+                conn.execute(&statement[..]).await?;
+                Ok(())
+            })
+        })
+        .before_acquire(|conn, meta| {
+            // `age` and `idle_for` should both be nonzero
+            assert_ne!(meta.age, Duration::ZERO);
+            assert_ne!(meta.idle_for, Duration::ZERO);
+
+            Box::pin(async move {
+                // MySQL and MariaDB don't support UPDATE ... RETURNING
+                sqlx::query(
+                    r#"
+                        UPDATE conn_stats 
+                        SET before_acquire_calls = before_acquire_calls + 1
+                    "#,
+                )
+                .execute(&mut *conn)
+                .await?;
+
+                let stats: ConnStats = sqlx::query_as("SELECT * FROM conn_stats")
+                    .fetch_one(conn)
+                    .await?;
+
+                // For even IDs, cap by the number of before_acquire calls.
+                // Ignore the check for odd IDs.
+                Ok((stats.id & 1) == 1 || stats.before_acquire_calls < 3)
+            })
+        })
+        .after_release(|conn, meta| {
+            // `age` should be nonzero but `idle_for` should be zero.
+            assert_ne!(meta.age, Duration::ZERO);
+            assert_eq!(meta.idle_for, Duration::ZERO);
+
+            Box::pin(async move {
+                sqlx::query(
+                    r#"
+                        UPDATE conn_stats 
+                        SET after_release_calls = after_release_calls + 1
+                    "#,
+                )
+                .execute(&mut *conn)
+                .await?;
+
+                let stats: ConnStats = sqlx::query_as("SELECT * FROM conn_stats")
+                    .fetch_one(conn)
+                    .await?;
+
+                // For odd IDs, cap by the number of before_release calls.
+                // Ignore the check for even IDs.
+                Ok((stats.id & 1) == 0 || stats.after_release_calls < 4)
+            })
+        })
+        // Don't establish a connection yet.
+        .connect_lazy(&dotenv::var("DATABASE_URL")?)?;
+
+    // Expected pattern of (id, before_acquire_calls, after_release_calls)
+    let pattern = [
+        // The connection pool starts empty.
+        (0, 0, 0),
+        (0, 1, 1),
+        (0, 2, 2),
+        (1, 0, 0),
+        (1, 1, 1),
+        (1, 2, 2),
+        // We should expect one more `acquire` because the ID is odd
+        (1, 3, 3),
+        (2, 0, 0),
+        (2, 1, 1),
+        (2, 2, 2),
+        (3, 0, 0),
+    ];
+
+    for (id, before_acquire_calls, after_release_calls) in pattern {
+        let conn_stats: ConnStats = sqlx::query_as("SELECT * FROM conn_stats")
+            .fetch_one(&pool)
+            .await?;
+
+        assert_eq!(
+            conn_stats,
+            ConnStats {
+                id,
+                before_acquire_calls,
+                after_release_calls
+            }
+        );
+    }
+
+    pool.close().await;
+
+    Ok(())
+}