Merge pull request gusdan#8 from uncovertruth/feature/ignore_cluster_info_error

Feature/ignore cluster info error

Author: Surgo

README.rst

@@ -48,7 +48,11 @@ Your cache backend should look something like this::
     CACHES = {
         'default': {
             'BACKEND': 'django_elastipymemcache.memcached.ElastiPyMemCache',
-            'LOCATION': '[configuration endpoint].com:11211',
+            'LOCATION': '[configuration endpoint]:11211',
+            'OPTIONS': {
+              'cluster_timeout': 1, # its used when get cluster info
+              'ignore_exc': True, # pymemcache Client params
+            }
         }
     }
 

django_elastipymemcache/cluster_utils.py

@@ -3,6 +3,7 @@
 """
 import re
 from distutils.version import StrictVersion
+import socket
 from telnetlib import Telnet
 
 from django.utils.encoding import smart_text
@@ -18,7 +19,7 @@ def __init__(self, cmd, response):
             'Unexpected response {} for command {}'.format(response, cmd))
 
 
-def get_cluster_info(host, port, ignore_cluster_errors=False):
+def get_cluster_info(host, port, timeout=socket._GLOBAL_DEFAULT_TIMEOUT):
     """
     return dict with info about nodes in cluster and current version
     {
@@ -29,7 +30,7 @@ def get_cluster_info(host, port, ignore_cluster_errors=False):
         'version': '1.4.4'
     }
     """
-    client = Telnet(host, int(port))
+    client = Telnet(host, int(port), timeout=timeout)
     client.write(b'version\n')
     res = client.read_until(b'\r\n').strip()
     version_list = res.split(b' ')
@@ -47,14 +48,6 @@ def get_cluster_info(host, port, ignore_cluster_errors=False):
     ])
     client.close()
 
-    if res == b'ERROR\r\n' and ignore_cluster_errors:
-        return {
-            'version': version,
-            'nodes': [
-                (smart_text(host), int(port))
-            ]
-        }
-
     ls = list(filter(None, re.compile(br'\r?\n').split(res)))
     if len(ls) != 4:
         raise WrongProtocolData(cmd, res)

django_elastipymemcache/memcached.py

@@ -1,6 +1,7 @@
 """
 Backend for django cache
 """
+import logging
 import socket
 from functools import wraps
 
@@ -11,6 +12,9 @@
 from .cluster_utils import get_cluster_info
 
 
+logger = logging.getLogger(__name__)
+
+
 def invalidate_cache_after_error(f):
     """
     catch any exception and invalidate internal cache with list of nodes
@@ -46,8 +50,8 @@ def __init__(self, server, params):
 
         # Patch for django<1.11
         self._options = self._options or dict()
-        self._ignore_cluster_errors = self._options.get(
-            'ignore_exc', False)
+        self._cluster_timeout = self._options.get(
+                'cluster_timeout', socket._GLOBAL_DEFAULT_TIMEOUT)
 
     def clear_cluster_nodes_cache(self):
         """clear internal cache with list of nodes in cluster"""
@@ -63,18 +67,28 @@ def get_cluster_nodes(self):
             return get_cluster_info(
                 server,
                 port,
-                self._ignore_cluster_errors
+                self._cluster_timeout
             )['nodes']
-        except (socket.gaierror, socket.timeout) as err:
-            raise Exception('Cannot connect to cluster {} ({})'.format(
-                self._servers[0], err
-            ))
+        except (OSError, socket.gaierror, socket.timeout) as err:
+            logger.debug(
+                'Cannot connect to cluster %s, err: %s',
+                self._servers[0],
+                err
+            )
+            return []
 
     @property
     def _cache(self):
+
         if getattr(self, '_client', None) is None:
+
+            options = self._options
+            options.setdefault('ignore_exc', True)
+            options.pop('cluster_timeout', None)
+
             self._client = self._lib.Client(
-                self.get_cluster_nodes(), **self._options)
+                self.get_cluster_nodes(), **options)
+
         return self._client
 
     @invalidate_cache_after_error

tests/test_backend.py

@@ -1,3 +1,4 @@
+import socket
 import sys
 
 from django.conf import global_settings, settings
@@ -25,8 +26,9 @@ def test_split_servers(get_cluster_info):
     }
     backend._lib.Client = Mock()
     assert backend._cache
-    get_cluster_info.assert_called_once_with('h', '0', False)
-    backend._lib.Client.assert_called_once_with(servers)
+    get_cluster_info.assert_called_once_with(
+            'h', '0', socket._GLOBAL_DEFAULT_TIMEOUT)
+    backend._lib.Client.assert_called_once_with(servers, ignore_exc=True)
 
 
 @patch('django.conf.settings', global_settings)
@@ -44,11 +46,12 @@ def test_node_info_cache(get_cluster_info):
     backend.get('key1')
     backend.set('key2', 'val')
     backend.get('key2')
-    backend._lib.Client.assert_called_once_with(servers)
+    backend._lib.Client.assert_called_once_with(servers, ignore_exc=True)
     eq_(backend._cache.get.call_count, 2)
     eq_(backend._cache.set.call_count, 2)
 
-    get_cluster_info.assert_called_once_with('h', '0', False)
+    get_cluster_info.assert_called_once_with(
+            'h', '0', socket._GLOBAL_DEFAULT_TIMEOUT)
 
 
 @patch('django.conf.settings', global_settings)

tests/test_protocol.py

@@ -103,27 +103,13 @@ def test_ubuntu_protocol(Telnet):
     ])
 
 
-@patch('django_elastipymemcache.cluster_utils.Telnet')
-def test_no_configuration_protocol_support_with_errors_ignored(Telnet):
-    client = Telnet.return_value
-    client.read_until.side_effect = TEST_PROTOCOL_4_READ_UNTIL
-    client.expect.side_effect = TEST_PROTOCOL_4_EXPECT
-    info = get_cluster_info('test', 0, ignore_cluster_errors=True)
-    client.write.assert_has_calls([
-        call(b'version\n'),
-        call(b'config get cluster\n'),
-    ])
-    eq_(info['version'], b'1.4.34')
-    eq_(info['nodes'], [('test', 0)])
-
-
 @raises(WrongProtocolData)
 @patch('django_elastipymemcache.cluster_utils.Telnet')
 def test_no_configuration_protocol_support_with_errors(Telnet):
     client = Telnet.return_value
     client.read_until.side_effect = TEST_PROTOCOL_4_READ_UNTIL
     client.expect.side_effect = TEST_PROTOCOL_4_EXPECT
-    get_cluster_info('test', 0, ignore_cluster_errors=False)
+    get_cluster_info('test', 0)
     client.write.assert_has_calls([
         call(b'version\n'),
         call(b'config get cluster\n'),