Hide GetConn

This makes the future implementation private. This is a braking
change, but:

* It is unlikely anyone was using GetConn directly instead of just
  awaiting it.

* This opens the way for replacing the manual implementation with an
  async fn.

src/conn/pool/futures/get_conn.rs

@@ -58,20 +58,25 @@ impl fmt::Debug for GetConnInner {
 /// This future will take connection from a pool and resolve to [`Conn`].
 #[derive(Debug)]
 #[must_use = "futures do nothing unless you `.await` or poll them"]
-pub struct GetConn {
-    pub(crate) queue_id: QueueId,
-    pub(crate) pool: Option<Pool>,
-    pub(crate) inner: GetConnInner,
+struct GetConn {
+    queue_id: QueueId,
+    pool: Option<Pool>,
+    inner: GetConnInner,
     reset_upon_returning_to_a_pool: bool,
     #[cfg(feature = "tracing")]
     span: Arc<Span>,
 }
 
+pub(crate) async fn get_conn(pool: Pool) -> Result<Conn> {
+    let reset_connection = pool.opts.pool_opts().reset_connection();
+    GetConn::new(pool, reset_connection).await
+}
+
 impl GetConn {
-    pub(crate) fn new(pool: &Pool, reset_upon_returning_to_a_pool: bool) -> GetConn {
+    fn new(pool: Pool, reset_upon_returning_to_a_pool: bool) -> GetConn {
         GetConn {
             queue_id: QueueId::next(),
-            pool: Some(pool.clone()),
+            pool: Some(pool),
             inner: GetConnInner::New,
             reset_upon_returning_to_a_pool,
             #[cfg(feature = "tracing")]

src/conn/pool/futures/mod.rs

@@ -6,8 +6,8 @@
 // option. All files in the project carrying such notice may not be copied,
 // modified, or distributed except according to those terms.
 
+pub use self::disconnect_pool::DisconnectPool;
+pub(crate) use self::get_conn::get_conn;
 pub(super) use self::get_conn::GetConnInner;
-pub use self::{disconnect_pool::DisconnectPool, get_conn::GetConn};
-
 mod disconnect_pool;
 mod get_conn;

src/conn/pool/mod.rs

@@ -15,6 +15,7 @@ use std::{
     cmp::Reverse,
     collections::VecDeque,
     convert::TryFrom,
+    future::Future,
     hash::{Hash, Hasher},
     str::FromStr,
     sync::{atomic, Arc, Mutex},
@@ -239,9 +240,8 @@ impl Pool {
     }
 
     /// Async function that resolves to `Conn`.
-    pub fn get_conn(&self) -> GetConn {
-        let reset_connection = self.opts.pool_opts().reset_connection();
-        GetConn::new(self, reset_connection)
+    pub fn get_conn(&self) -> impl Future<Output = Result<Conn>> {
+        get_conn(self.clone())
     }
 
     /// Starts a new transaction.
@@ -253,7 +253,7 @@ impl Pool {
     /// Async function that disconnects this pool from the server and resolves to `()`.
     ///
     /// **Note:** This Future won't resolve until all active connections, taken from it,
-    /// are dropped or disonnected. Also all pending and new `GetConn`'s will resolve to error.
+    /// are dropped or disonnected. Also all pending and new `get_conn()`'s will resolve to error.
     pub fn disconnect(self) -> DisconnectPool {
         DisconnectPool::new(self)
     }

src/lib.rs

@@ -542,7 +542,7 @@ pub use self::queryable::stmt::Statement;
 
 /// Futures used in this crate
 pub mod futures {
-    pub use crate::conn::pool::futures::{DisconnectPool, GetConn};
+    pub use crate::conn::pool::futures::DisconnectPool;
 }
 
 /// Traits used in this crate

tests/exports.rs

@@ -1,7 +1,7 @@
 #[allow(unused_imports)]
 use mysql_async::{
     consts, from_row, from_row_opt, from_value, from_value_opt,
-    futures::{DisconnectPool, GetConn},
+    futures::DisconnectPool,
     params,
     prelude::{
         BatchQuery, FromRow, FromValue, GlobalHandler, Protocol, Query, Queryable, StatementLike,