MASTER_WRITE_ONLY option

docs/advanced_configuration.rst

@@ -129,6 +129,7 @@ read/write server and secondary servers as read-only.
             'OPTIONS': {
                 'PASSWORD': 'yadayada',
                 'MASTER_CACHE': '127.0.0.1:6379',
+                'MASTER_WRITE_ONLY': False,
                 ...
             },
             ...

redis_cache/backends/base.py

@@ -162,7 +162,7 @@ def get_master_client(self):
         """
         cache = self.options.get('MASTER_CACHE', None)
         if cache is None:
-            return next(iter(self.client_list))
+            return next(iter(self.clients.values()))
 
         kwargs = parse_connection_kwargs(cache, db=self.db)
         return self.clients[(

redis_cache/backends/single.py

@@ -21,13 +21,17 @@ def __init__(self, server, params):
             client = self.create_client(server)
             self.clients[client.connection_pool.connection_identifier] = client
 
-        self.client_list = self.clients.values()
-        self.master_client = self.get_master_client()
+        self.master_client = master = self.get_master_client()
+        master_write_only = self.options.get('MASTER_WRITE_ONLY', False)
+        self.client_list = [
+            client for client in self.clients.values()
+            if not (master_write_only and client is master)
+        ]
 
     def get_client(self, key, write=False):
         if write and self.master_client is not None:
             return self.master_client
-        return random.choice(list(self.client_list))
+        return random.choice(self.client_list)
 
     ####################
     # Django cache api #

tests/testapp/tests/master_slave_tests.py

@@ -28,6 +28,18 @@
             'MASTER_CACHE': MASTER_LOCATION,
         },
     },
+    'master_write_only': {
+        'BACKEND': 'redis_cache.RedisCache',
+        'LOCATION': LOCATIONS,
+        'OPTIONS': {
+            'DB': 1,
+            'PASSWORD': 'yadayada',
+            'PARSER_CLASS': 'redis.connection.HiredisParser',
+            'PICKLE_VERSION': -1,
+            'MASTER_CACHE': MASTER_LOCATION,
+            'MASTER_WRITE_ONLY': True,
+        },
+    },
 })
 class MasterSlaveTestCase(SetupMixin, TestCase):
 
@@ -93,3 +105,13 @@ def test_clear(self):
         time.sleep(.2)
         for client in self.cache.clients.values():
             self.assertEqual(len(client.keys('*')), 0)
+
+    def test_master_in_client_list_by_default(self):
+        cache = self.get_cache()
+        master = cache.get_master_client()
+        self.assertIn(master, cache.client_list)
+
+    def test_master_not_in_client_list_if_master_write_only(self):
+        cache = self.get_cache('master_write_only')
+        master = cache.get_master_client()
+        self.assertNotIn(master, cache.client_list)