refactor(client): use some api instead of manual implementaion

Author: tottoto

src/client/legacy/client.rs

@@ -916,7 +916,7 @@ fn set_scheme(uri: &mut Uri, scheme: Scheme) {
         uri.scheme().is_none(),
         "set_scheme expects no existing scheme"
     );
-    let old = std::mem::replace(uri, Uri::default());
+    let old = std::mem::take(uri);
     let mut parts: ::http::uri::Parts = old.into();
     parts.scheme = Some(scheme);
     parts.path_and_query = Some("/".parse().expect("slash is a valid path"));

src/client/legacy/connect/http.rs

@@ -606,9 +606,7 @@ struct ConnectingTcpRemote {
 
 impl ConnectingTcpRemote {
     fn new(addrs: dns::SocketAddrs, connect_timeout: Option<Duration>) -> Self {
-        let connect_timeout = connect_timeout
-            .map(|t| t.checked_div(addrs.len() as u32))
-            .flatten();
+        let connect_timeout = connect_timeout.and_then(|t| t.checked_div(addrs.len() as u32));
 
         Self {
             addrs,

src/client/legacy/pool.rs

@@ -380,7 +380,7 @@ impl<T: Poolable, K: Key> PoolInner<T, K> {
             Some(value) => {
                 // borrow-check scope...
                 {
-                    let idle_list = self.idle.entry(key.clone()).or_insert_with(Vec::new);
+                    let idle_list = self.idle.entry(key.clone()).or_default();
                     if self.max_idle_per_host <= idle_list.len() {
                         trace!("max idle per host for {:?}, dropping connection", key);
                         return;