Shut down statement worker in Sqlite Connection::close (#1453)

* add explicit shutdown of sqlite statement worker in Connection::close()

Signed-off-by: Andrew Whitehead <cywolf@gmail.com>

* test sqlite database close method

Signed-off-by: Andrew Whitehead <cywolf@gmail.com>

* await worker shutdown after dropping SqliteConnection

Signed-off-by: Andrew Whitehead <cywolf@gmail.com>

* restore explicit drop

Signed-off-by: Andrew Whitehead <cywolf@gmail.com>

sqlx-core/src/sqlite/connection/mod.rs

@@ -62,9 +62,15 @@ impl Connection for SqliteConnection {
 
     type Options = SqliteConnectOptions;
 
-    fn close(self) -> BoxFuture<'static, Result<(), Error>> {
-        // nothing explicit to do; connection will close in drop
-        Box::pin(future::ok(()))
+    fn close(mut self) -> BoxFuture<'static, Result<(), Error>> {
+        Box::pin(async move {
+            let shutdown = self.worker.shutdown();
+            // Drop the statement worker and any outstanding statements, which should
+            // cover all references to the connection handle outside of the worker thread
+            drop(self);
+            // Ensure the worker thread has terminated
+            shutdown.await
+        })
     }
 
     fn ping(&mut self) -> BoxFuture<'_, Result<(), Error>> {

sqlx-core/src/sqlite/statement/worker.rs

@@ -30,6 +30,9 @@ enum StatementWorkerCommand {
         statement: Weak<StatementHandle>,
         tx: oneshot::Sender<()>,
     },
+    Shutdown {
+        tx: oneshot::Sender<()>,
+    },
 }
 
 impl StatementWorker {
@@ -72,6 +75,13 @@ impl StatementWorker {
                             let _ = tx.send(());
                         }
                     }
+                    StatementWorkerCommand::Shutdown { tx } => {
+                        // drop the connection reference before sending confirmation
+                        // and ending the command loop
+                        drop(conn);
+                        let _ = tx.send(());
+                        return;
+                    }
                 }
             }
 
@@ -127,4 +137,25 @@ impl StatementWorker {
             rx.await.map_err(|_| Error::WorkerCrashed)
         }
     }
+
+    /// Send a command to the worker to shut down the processing thread.
+    ///
+    /// A `WorkerCrashed` error may be returned if the thread has already stopped.
+    /// Subsequent calls to `step()`, `reset()`, or this method will fail with
+    /// `WorkerCrashed`. Ensure that any associated statements are dropped first.
+    pub(crate) fn shutdown(&mut self) -> impl Future<Output = Result<(), Error>> {
+        let (tx, rx) = oneshot::channel();
+
+        let send_res = self
+            .tx
+            .send(StatementWorkerCommand::Shutdown { tx })
+            .map_err(|_| Error::WorkerCrashed);
+
+        async move {
+            send_res?;
+
+            // wait for the response
+            rx.await.map_err(|_| Error::WorkerCrashed)
+        }
+    }
 }

tests/sqlite/sqlite.rs

@@ -206,7 +206,8 @@ async fn it_executes_with_pool() -> anyhow::Result<()> {
 async fn it_opens_in_memory() -> anyhow::Result<()> {
     // If the filename is ":memory:", then a private, temporary in-memory database
     // is created for the connection.
-    let _ = SqliteConnection::connect(":memory:").await?;
+    let conn = SqliteConnection::connect(":memory:").await?;
+    conn.close().await?;
 
     Ok(())
 }
@@ -215,7 +216,8 @@ async fn it_opens_in_memory() -> anyhow::Result<()> {
 async fn it_opens_temp_on_disk() -> anyhow::Result<()> {
     // If the filename is an empty string, then a private, temporary on-disk database will
     // be created.
-    let _ = SqliteConnection::connect("").await?;
+    let conn = SqliteConnection::connect("").await?;
+    conn.close().await?;
 
     Ok(())
 }