async: Close listener fd after server shutdown

The listener fd is not closed when server.shutdown(), this will make a
residual fd if a process start and close different servers for many
times.

Signed-off-by: Abel Feng <[email protected]>

Author: abel-von

src/asynchronous/server.rs

@@ -231,6 +231,11 @@ impl Server {
         self.stop_listen().await;
         self.disconnect().await;
 
+        while let Some(fd) = self.listeners.pop() {
+            unistd::close(fd).unwrap_or_else(|e| {
+                warn!("failed to close listener fd: {}", e);
+            });
+        }
         Ok(())
     }