Make sure a new connection is established upon retry, before marking dead, to avoid reusing a stale socket.

Author: Ricardo Alves

memcache.py

@@ -1048,7 +1048,7 @@ def _unsafe_set():
         except _ConnectionDeadError:
             # retry once
             try:
-                if server._get_socket():
+                if server._get_socket(reconnect=True):
                     return _unsafe_set()
             except (_ConnectionDeadError, socket.error) as msg:
                 server.mark_dead(msg)
@@ -1101,7 +1101,7 @@ def _unsafe_get():
         except _ConnectionDeadError:
             # retry once
             try:
-                if server.connect():
+                if server._get_socket(reconnect=True):
                     return _unsafe_get()
                 return None
             except (_ConnectionDeadError, socket.error) as msg:
@@ -1386,10 +1386,10 @@ def mark_dead(self, reason):
             self.flush_on_next_connect = 1
         self.close_socket()
 
-    def _get_socket(self):
+    def _get_socket(self, reconnect=False):
         if self._check_dead():
             return None
-        if self.socket:
+        if self.socket and not reconnect:
             return self.socket
         s = socket.socket(self.family, socket.SOCK_STREAM)
         if hasattr(s, 'settimeout'):

tests/test_memcache.py

@@ -1,5 +1,6 @@
 from __future__ import print_function
 
+import socket
 import unittest
 
 import six
@@ -167,5 +168,52 @@ def test_disconnect_all_delete_multi(self):
         self.assertEqual(ret, 1)
 
 
+class TestMemcacheMarkDead(unittest.TestCase):
+
+    def setUp(self):
+        self.status = locals()
+        self.address = ("127.0.0.1", 11213)
+        self._start_stub_server()
+        self.client = Client(["127.0.0.1:11213"], debug=1)
+
+    def tearDown(self):
+        self._stop_stub_server()
+
+    def _start_stub_server(self):
+        # setup stub server
+        stub_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        stub_socket.bind(self.address)
+        stub_socket.listen(1)
+        self.stub_socket = stub_socket
+
+    def _stop_stub_server(self):
+        self.stub_socket.close()
+
+    def test_mark_server_dead(self):
+        mc_host = self.client._get_server('foo')[0]
+        client_socket = mc_host._get_socket()
+
+        # make sure the server is not marked dead
+        self.assertEqual(0, mc_host._check_dead())
+
+        # stop the stub server
+        self._stop_stub_server()
+
+        # host is not yet marked as dead
+        self.assertEqual(0, mc_host._check_dead())
+
+        # create a new stub socket again
+        self._start_stub_server()
+
+        # The client will try to re-use the old socket and if it fails
+        # then should re-establish a new connection
+        # so the socket must be a new one
+        new_client_socket = mc_host._get_socket(reconnect=True)
+        self.assertNotEquals(new_client_socket, client_socket)
+
+        # server is not marked dead, because connection succeeded
+        self.assertEqual(0, mc_host._check_dead())
+
+
 if __name__ == '__main__':
     unittest.main()