Revert parallel close_blocking

Author: ryanfowler

src/pool.rs

@@ -197,9 +197,9 @@ impl Pool {
     /// After this method returns, all calls to `self::conn()` or
     /// `self::conn_mut()` will return an [`Error::Closed`] error.
     pub async fn close(&self) -> Result<(), Error> {
-        for client in self.state.clients.iter() {
-            client.close().await?;
-        }
+        let closes = self.state.clients.iter().map(|client| client.close());
+        let res = join_all(closes).await;
+        res.into_iter().collect::<Result<Vec<_>, Error>>()?;
         Ok(())
     }
 

tests/tests.rs

@@ -84,6 +84,7 @@ async_test!(test_journal_mode);
 async_test!(test_concurrency);
 async_test!(test_pool);
 async_test!(test_pool_conn_for_each);
+async_test!(test_pool_close_concurrent);
 
 async fn test_journal_mode() {
     let tmp_dir = tempfile::tempdir().unwrap();
@@ -227,3 +228,24 @@ async fn test_pool_conn_for_each() {
     // cleanup
     pool.close().await.expect("closing client conn");
 }
+
+async fn test_pool_close_concurrent() {
+    let tmp_dir = tempfile::tempdir().unwrap();
+    let pool = PoolBuilder::new()
+        .path(tmp_dir.path().join("sqlite.db"))
+        .num_conns(2)
+        .open()
+        .await
+        .expect("pool unable to be opened");
+
+    let c1 = pool.close();
+    let c2 = pool.close();
+    futures_util::future::join_all([c1, c2])
+        .await
+        .into_iter()
+        .collect::<Result<Vec<_>, Error>>()
+        .expect("closing concurrently");
+
+    let res = pool.conn(|c| c.execute("SELECT 1", ())).await;
+    assert!(matches!(res, Err(Error::Closed)));
+}