From bf757a2f4dad519fac1b4a458376de3a040f5ca8 Mon Sep 17 00:00:00 2001
From: Michael Manfre <mmanfre@gmail.com>
Date: Mon, 23 Sep 2013 12:40:19 -0400
Subject: [PATCH] Fixed #21147 -- Avoided time.time precision issue with cache
backends.
The precision of time.time() is OS specific and it is possible for the
resolution to be low enough to allow reading a cache key previously set
with a timeout of 0.
---
django/core/cache/backends/base.py | 13 +++++++++++++
django/core/cache/backends/db.py | 7 +++----
django/core/cache/backends/filebased.py | 5 +----
django/core/cache/backends/locmem.py | 5 +----
django/core/cache/backends/memcached.py | 18 +++++++++++++-----
docs/internals/deprecation.txt | 4 ++++
docs/releases/1.7.txt | 6 ++++++
7 files changed, 41 insertions(+), 17 deletions(-)
diff --git a/django/core/cache/backends/base.py b/django/core/cache/backends/base.py
index db76192354..13c34ea697 100644
--- a/django/core/cache/backends/base.py
+++ b/django/core/cache/backends/base.py
@@ -1,6 +1,7 @@
"Base Cache class."
from __future__ import unicode_literals
+import time
import warnings
from django.core.exceptions import ImproperlyConfigured, DjangoRuntimeWarning
@@ -74,6 +75,18 @@ class BaseCache(object):
self.version = params.get('VERSION', 1)
self.key_func = get_key_func(params.get('KEY_FUNCTION', None))
+ def get_backend_timeout(self, timeout=DEFAULT_TIMEOUT):
+ """
+ Returns the timeout value usable by this backend based upon the provided
+ timeout.
+ """
+ if timeout == DEFAULT_TIMEOUT:
+ timeout = self.default_timeout
+ elif timeout == 0:
+ # ticket 21147 - avoid time.time() related precision issues
+ timeout = -1
+ return None if timeout is None else time.time() + timeout
+
def make_key(self, key, version=None):
"""Constructs the key used by all other methods. By default it
uses the key_func to generate a key (which, by default,
diff --git a/django/core/cache/backends/db.py b/django/core/cache/backends/db.py
index 8844bc8f61..40d1320e37 100644
--- a/django/core/cache/backends/db.py
+++ b/django/core/cache/backends/db.py
@@ -92,8 +92,7 @@ class DatabaseCache(BaseDatabaseCache):
return self._base_set('add', key, value, timeout)
def _base_set(self, mode, key, value, timeout=DEFAULT_TIMEOUT):
- if timeout == DEFAULT_TIMEOUT:
- timeout = self.default_timeout
+ timeout = self.get_backend_timeout(timeout)
db = router.db_for_write(self.cache_model_class)
table = connections[db].ops.quote_name(self._table)
cursor = connections[db].cursor()
@@ -105,9 +104,9 @@ class DatabaseCache(BaseDatabaseCache):
if timeout is None:
exp = datetime.max
elif settings.USE_TZ:
- exp = datetime.utcfromtimestamp(time.time() + timeout)
+ exp = datetime.utcfromtimestamp(timeout)
else:
- exp = datetime.fromtimestamp(time.time() + timeout)
+ exp = datetime.fromtimestamp(timeout)
exp = exp.replace(microsecond=0)
if num > self._max_entries:
self._cull(db, cursor, now)
diff --git a/django/core/cache/backends/filebased.py b/django/core/cache/backends/filebased.py
index d19eed4a95..83ded57034 100644
--- a/django/core/cache/backends/filebased.py
+++ b/django/core/cache/backends/filebased.py
@@ -51,9 +51,6 @@ class FileBasedCache(BaseCache):
fname = self._key_to_file(key)
dirname = os.path.dirname(fname)
- if timeout == DEFAULT_TIMEOUT:
- timeout = self.default_timeout
-
self._cull()
try:
@@ -61,7 +58,7 @@ class FileBasedCache(BaseCache):
os.makedirs(dirname)
with open(fname, 'wb') as f:
- expiry = None if timeout is None else time.time() + timeout
+ expiry = self.get_backend_timeout(timeout)
pickle.dump(expiry, f, pickle.HIGHEST_PROTOCOL)
pickle.dump(value, f, pickle.HIGHEST_PROTOCOL)
except (IOError, OSError):
diff --git a/django/core/cache/backends/locmem.py b/django/core/cache/backends/locmem.py
index 44d7db62c3..cab690bb0c 100644
--- a/django/core/cache/backends/locmem.py
+++ b/django/core/cache/backends/locmem.py
@@ -63,11 +63,8 @@ class LocMemCache(BaseCache):
def _set(self, key, value, timeout=DEFAULT_TIMEOUT):
if len(self._cache) >= self._max_entries:
self._cull()
- if timeout == DEFAULT_TIMEOUT:
- timeout = self.default_timeout
- expiry = None if timeout is None else time.time() + timeout
self._cache[key] = value
- self._expire_info[key] = expiry
+ self._expire_info[key] = self.get_backend_timeout(timeout)
def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
key = self.make_key(key, version=version)
diff --git a/django/core/cache/backends/memcached.py b/django/core/cache/backends/memcached.py
index 19e8b02f74..edb756c365 100644
--- a/django/core/cache/backends/memcached.py
+++ b/django/core/cache/backends/memcached.py
@@ -7,9 +7,17 @@ from threading import local
from django.core.cache.backends.base import BaseCache, DEFAULT_TIMEOUT
from django.utils import six
+from django.utils.deprecation import RenameMethodsBase
from django.utils.encoding import force_str
-class BaseMemcachedCache(BaseCache):
+
+class BaseMemcachedCacheMethods(RenameMethodsBase):
+ renamed_methods = (
+ ('_get_memcache_timeout', 'get_backend_timeout', PendingDeprecationWarning),
+ )
+
+
+class BaseMemcachedCache(six.with_metaclass(BaseMemcachedCacheMethods, BaseCache)):
def __init__(self, server, params, library, value_not_found_exception):
super(BaseMemcachedCache, self).__init__(params)
if isinstance(server, six.string_types):
@@ -36,7 +44,7 @@ class BaseMemcachedCache(BaseCache):
return self._client
- def _get_memcache_timeout(self, timeout=DEFAULT_TIMEOUT):
+ def get_backend_timeout(self, timeout=DEFAULT_TIMEOUT):
"""
Memcached deals with long (> 30 days) timeouts in a special
way. Call this function to obtain a safe value for your timeout.
@@ -68,7 +76,7 @@ class BaseMemcachedCache(BaseCache):
def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
key = self.make_key(key, version=version)
- return self._cache.add(key, value, self._get_memcache_timeout(timeout))
+ return self._cache.add(key, value, self.get_backend_timeout(timeout))
def get(self, key, default=None, version=None):
key = self.make_key(key, version=version)
@@ -79,7 +87,7 @@ class BaseMemcachedCache(BaseCache):
def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
key = self.make_key(key, version=version)
- self._cache.set(key, value, self._get_memcache_timeout(timeout))
+ self._cache.set(key, value, self.get_backend_timeout(timeout))
def delete(self, key, version=None):
key = self.make_key(key, version=version)
@@ -140,7 +148,7 @@ class BaseMemcachedCache(BaseCache):
for key, value in data.items():
key = self.make_key(key, version=version)
safe_data[key] = value
- self._cache.set_multi(safe_data, self._get_memcache_timeout(timeout))
+ self._cache.set_multi(safe_data, self.get_backend_timeout(timeout))
def delete_many(self, keys, version=None):
l = lambda x: self.make_key(x, version=version)
diff --git a/docs/internals/deprecation.txt b/docs/internals/deprecation.txt
index 5c1b1cab6f..498f303daf 100644
--- a/docs/internals/deprecation.txt
+++ b/docs/internals/deprecation.txt
@@ -457,6 +457,10 @@ these changes.
* ``ModelAdmin.get_formsets`` will be removed.
+* Remove the backward compatible shims introduced to rename the
+ ``BaseMemcachedCache._get_memcache_timeout()`` method to
+ ``get_backend_timeout()``.
+
2.0
---
diff --git a/docs/releases/1.7.txt b/docs/releases/1.7.txt
index 74fc74947c..a978bb8ac1 100644
--- a/docs/releases/1.7.txt
+++ b/docs/releases/1.7.txt
@@ -552,3 +552,9 @@ The :class:`django.db.models.IPAddressField` and
:class:`django.db.models.GenericIPAddressField` and
:class:`django.forms.GenericIPAddressField`.
+``BaseMemcachedCache._get_memcache_timeout`` method
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``BaseMemcachedCache._get_memcache_timeout()`` method has been renamed to
+``get_backend_timeout()``. Despite being a private API, it will go through the
+normal deprecation.