add special error for bad address and fix protocol realization

Author: gusdan

README.rst

@@ -4,7 +4,7 @@ Amazon ElastiCache backend for Django
 Simple Django cache backend for Amazon ElastiCache (memcached based). It uses
 `pylibmc <http://github.com/lericson/pylibmc>`_ and setup connection to each
 node in cluster using
-`Auto Discovery <http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/AutoDiscovery.html>`_
+`auto discovery <http://docs.aws.amazon.com/AmazonElastiCache/latest/UserGuide/AutoDiscovery.html>`_
 function.
 
 
@@ -35,25 +35,26 @@ Your cache backend should look something like this::
 
     CACHES = {
         'default': {
-            'BACKEND': 'django_elasticache.memcached.ElasctiCache',
+            'BACKEND': 'django_elasticache.memcached.ElastiCache',
             'LOCATION': 'cache-c.drtgf.cfg.use1.cache.amazonaws.com:11211',
         }
     }
 
-By the first call to cache it connect to cluster (using LOCATION),
-get list of all nodes and setup pylibmc client using full
-list of nodes. As result your cache will work with all nodes and
+By the first call to cache it connects to cluster (using LOCATION param),
+gets list of all nodes and setup pylibmc client using full
+list of nodes. As result your cache will work with all nodes in cluster and
 automatically detect new nodes in cluster. List of nodes are stored in class-level
-cached, so any changes in cluster take affect only after restart working process.
+cached, so any changes in cluster take affect only after restart of working process.
 But if you're using gunicorn or mod_wsgi you usually have max_request settings which
-restart process after some count of processed requests.
+restart process after some count of processed requests, so auto discovery will work
+fine.
 
-Django-elascticache changes default pylibmc params to increase performance.
+Django-elasticache changes default pylibmc params to increase performance.
 
 
 Testing
 -------
 
 Run the tests like this::
 
-    nosetest
+    nosetest

django_elasticache/cluster_utils.py

@@ -38,6 +38,7 @@ def get_cluster_info(host, port):
     else:
         cmd = 'get AmazonElastiCache:cluster\n'
     client.write(cmd)
+    client.read_until('\r\n')
     res = client.read_until('\r\n').strip()
     try:
         version = int(res)

django_elasticache/memcached.py

@@ -1,6 +1,7 @@
 """
 Backend for django cache
 """
+import socket
 from django.core.cache import InvalidCacheBackendError
 from django.core.cache.backends.memcached import PyLibMCCache
 from django.utils.functional import cached_property
@@ -45,7 +46,12 @@ def get_cluster_nodes(self):
         return list with all nodes in cluster
         """
         server, port = self._servers[0].split(':')
-        return get_cluster_info(server, port)['nodes']
+        try:
+            return get_cluster_info(server, port)['nodes']
+        except socket.gaierror, err:
+            raise Exception('Cannot connect to cluster {} ({})'.format(
+                self._servers[0], err
+            ))
 
     @property
     def _cache(self):

tests/test_protocol.py

@@ -5,12 +5,14 @@
 
 TEST_PROTOCOL_1 = [
     'VERSION 1.4.14',
+    '',
     '1',
     'hostname|ip-address|port hostname||port'
 ]
 
 TEST_PROTOCOL_2 = [
     'VERSION 1.4.13',
+    '',
     '1',
     'hostname|ip-address|port hostname||port'
 ]