From 9780bf703f9f3791b7a1987ad3427ac201e3db1d Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Wed, 28 Oct 2015 22:19:00 +0900
Subject: [PATCH] close_async check connection is closed already

---
 tornado_mysql/connections.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tornado_mysql/connections.py b/tornado_mysql/connections.py
index c266ed1..2a14f4e 100644
--- a/tornado_mysql/connections.py
+++ b/tornado_mysql/connections.py
@@ -624,6 +624,9 @@ def close(self):
     @gen.coroutine
     def close_async(self):
         """Send the quit message and close the socket"""
+        if self._stream is None or self._stream.closed():
+            self._stream = None
+            return
         send_data = struct.pack('<i', 1) + int2byte(COMMAND.COM_QUIT)
         yield self._stream.write(send_data)
         self.close()