From 6a95994098348a27b4c2a2f1ccaee67e2bd60127 Mon Sep 17 00:00:00 2001
From: pfreixes <pfreixes@gmail.com>
Date: Tue, 21 Jun 2016 22:15:52 +0200
Subject: [PATCH] POC fix for #732

---
 redis/sentinel.py | 40 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/redis/sentinel.py b/redis/sentinel.py
index 518fec582f..a99d2e69a1 100644
--- a/redis/sentinel.py
+++ b/redis/sentinel.py
@@ -2,6 +2,10 @@
 import random
 import weakref
 
+from threading import Lock
+from itertools import chain
+from copy import copy
+
 from redis.client import StrictRedis
 from redis.connection import ConnectionPool, Connection
 from redis.exceptions import (ConnectionError, ResponseError, ReadOnlyError,
@@ -65,6 +69,25 @@ def read_response(self):
                 raise ConnectionError('The previous master is now a slave')
             raise
 
+    def shutdown_socket(self):
+        """
+        Thread safe function to reset the soket belonging to the connection.
+        The connection will end up cleaning the socket and its dependencies
+        in a safe way
+        """
+        try:
+            self._sock.shutdown(socket.SHUT_RDWR)
+        except AttributeError:
+            # either _sock attribute does not exist or
+            # connection removed it.
+            pass
+        except OSError as e:
+            if e.errno == 107:
+                # Transport endpoint is not connected
+                pass
+            else:
+                raise 
+
 
 class SentinelConnectionPool(ConnectionPool):
     """
@@ -83,6 +106,7 @@ def __init__(self, service_name, sentinel_manager, **kwargs):
         self.connection_kwargs['connection_pool'] = weakref.proxy(self)
         self.service_name = service_name
         self.sentinel_manager = sentinel_manager
+        self._lock_get_master_address = Lock()
 
     def __repr__(self):
         return "%s<service=%s(%s)" % (
@@ -99,12 +123,17 @@ def reset(self):
     def get_master_address(self):
         master_address = self.sentinel_manager.discover_master(
             self.service_name)
+
         if self.is_master:
-            if self.master_address is None:
-                self.master_address = master_address
-            elif master_address != self.master_address:
-                # Master address changed, disconnect all clients in this pool
-                self.disconnect()
+            with self._lock_get_master_address:
+                if master_address != self.master_address:
+                    # Master address changed, disconnect all clients in this pool
+                    all_conns = chain(copy(self._available_connections),
+                                      copy(self._in_use_connections))
+                    for connection in all_conns:
+                        connection.shutdown_socket()
+                else:
+                    self.master_address = master_address
         return master_address
 
     def rotate_slaves(self):
@@ -125,6 +154,7 @@ def rotate_slaves(self):
             pass
         raise SlaveNotFoundError('No slave found for %r' % (self.service_name))
 
+
     def _checkpid(self):
         if self.pid != os.getpid():
             self.disconnect()