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Fixed #12399 -- Added handling for memcache timeouts longer than 30 d…

…ays. Thanks to houdinihound for the report, and gciotta for the patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12408 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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commit 75ab212d12058494eaf171acfc762206d8a62d47 1 parent be57541
@freakboy3742 freakboy3742 authored
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24 django/core/cache/backends/memcached.py
@@ -1,5 +1,7 @@
"Memcached cache backend"
+import time
+
from django.core.cache.backends.base import BaseCache, InvalidCacheBackendError
from django.utils.encoding import smart_unicode, smart_str
@@ -16,10 +18,26 @@ def __init__(self, server, params):
BaseCache.__init__(self, params)
self._cache = memcache.Client(server.split(';'))
+ def _get_memcache_timeout(self, timeout):
+ """
+ Memcached deals with long (> 30 days) timeouts in a special
+ way. Call this function to obtain a safe value for your timeout.
+ """
+ timeout = timeout or self.default_timeout
+ if timeout > 2592000: # 60*60*24*30, 30 days
+ # See http://code.google.com/p/memcached/wiki/FAQ
+ # "You can set expire times up to 30 days in the future. After that
+ # memcached interprets it as a date, and will expire the item after
+ # said date. This is a simple (but obscure) mechanic."
+ #
+ # This means that we have to switch to absolute timestamps.
+ timeout += int(time.time())
+ return timeout
+
def add(self, key, value, timeout=0):
if isinstance(value, unicode):
value = value.encode('utf-8')
- return self._cache.add(smart_str(key), value, timeout or self.default_timeout)
+ return self._cache.add(smart_str(key), value, self._get_memcache_timeout(timeout))
def get(self, key, default=None):
val = self._cache.get(smart_str(key))
@@ -34,7 +52,7 @@ def get(self, key, default=None):
def set(self, key, value, timeout=0):
if isinstance(value, unicode):
value = value.encode('utf-8')
- self._cache.set(smart_str(key), value, timeout or self.default_timeout)
+ self._cache.set(smart_str(key), value, self._get_memcache_timeout(timeout))
def delete(self, key):
self._cache.delete(smart_str(key))
@@ -78,7 +96,7 @@ def set_many(self, data, timeout=0):
if isinstance(value, unicode):
value = value.encode('utf-8')
safe_data[smart_str(key)] = value
- self._cache.set_multi(safe_data, timeout or self.default_timeout)
+ self._cache.set_multi(safe_data, self._get_memcache_timeout(timeout))
def delete_many(self, keys):
self._cache.delete_multi(map(smart_str, keys))
View
16 tests/regressiontests/cache/tests.py
@@ -324,6 +324,22 @@ def test_clear(self):
self.assertEqual(self.cache.get("key1"), None)
self.assertEqual(self.cache.get("key2"), None)
+ def test_long_timeout(self):
+ '''
+ Using a timeout greater than 30 days makes memcached think
+ it is an absolute expiration timestamp instead of a relative
+ offset. Test that we honour this convention. Refs #12399.
+ '''
+ self.cache.set('key1', 'eggs', 60*60*24*30 + 1) #30 days + 1 second
+ self.assertEqual(self.cache.get('key1'), 'eggs')
+
+ self.cache.add('key2', 'ham', 60*60*24*30 + 1)
+ self.assertEqual(self.cache.get('key2'), 'ham')
+
+ self.cache.set_many({'key3': 'sausage', 'key4': 'lobster bisque'}, 60*60*24*30 + 1)
+ self.assertEqual(self.cache.get('key3'), 'sausage')
+ self.assertEqual(self.cache.get('key4'), 'lobster bisque')
+
class DBCacheTests(unittest.TestCase, BaseCacheTests):
def setUp(self):
management.call_command('createcachetable', 'test_cache_table', verbosity=0, interactive=False)
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