reuse swift memcache instead of spawning one

reuse-swift-memcache.diff

diff --git i/keystone/middleware/auth_token.py w/keystone/middleware/auth_token.py
index 5c198e8..8f0ceb3 100644
--- i/keystone/middleware/auth_token.py
+++ w/keystone/middleware/auth_token.py
@@ -237,23 +237,13 @@ class AuthProtocol(object):
         # Token caching via memcache
         self._cache = None
         self._iso8601 = None
-        memcache_servers = self._conf_get('memcache_servers')
         # By default the token will be cached for 5 minutes
         self.token_cache_time = int(self._conf_get('token_cache_time'))
         self._token_revocation_list = None
         self._token_revocation_list_fetched_time = None
         cache_timeout = datetime.timedelta(seconds=0)
         self.token_revocation_list_cache_timeout = cache_timeout
-        if memcache_servers:
-            try:
-                import memcache
-                import iso8601
-                LOG.info('Using memcache for caching token')
-                self._cache = memcache.Client(memcache_servers.split(','))
-                self._iso8601 = iso8601
-            except ImportError as e:
-                LOG.warn('disabled caching due to missing libraries %s', e)
-
+        
     def _conf_get(self, name):
         # try config from paste-deploy first
         if name in self.conf:
@@ -268,6 +258,21 @@ class AuthProtocol(object):
         we can't authenticate.
 
         """
+        memcache_servers = self._conf_get('memcache_servers')
+        if memcache_servers:
+            try:
+                import memcache
+                import iso8601
+                LOG.info('Using memcache for caching token')
+                self._iso8601 = iso8601
+                self._cache = memcache.Client(memcache_servers.split(','))
+                self._cache_swift = False
+            except ImportError as e:
+                LOG.warn('disabled caching due to missing libraries %s', e)
+
+            if env.get('swift.cache'):
+                self._cache = env.get('swift.cache')
+                self._cache_swift = True
         LOG.debug('Authenticating user token')
         try:
             self._remove_auth_headers(env)
@@ -625,18 +630,24 @@ class AuthProtocol(object):
                 LOG.error('invalid token format')
                 return
             LOG.debug('Storing %s token in memcache', token)
-            self._cache.set(key,
-                            (data, expires),
-                            time=self.token_cache_time)
+            if self._cache_swift:
+                self._cache.set(key, (data, expires))
+            else:
+                self._cache.set(key,
+                                (data, expires),
+                                time=self.token_cache_time)
 
     def _cache_store_invalid(self, token):
         """Store invalid token in cache."""
         if self._cache:
             key = 'tokens/%s' % token
             LOG.debug('Marking token %s as unauthorized in memcache', token)
-            self._cache.set(key,
-                            'invalid',
-                            time=self.token_cache_time)
+            if self._cache_swift:
+                self._cache.set(key, 'invalid')
+            else:
+                self._cache.set(key,
+                                'invalid',
+                                time=self.token_cache_time)
 
     def cert_file_missing(self, called_proc_err, file_name):
         return (called_proc_err.output.find(file_name)