blob: e4b30896364adbd5e86990b2c6e1fd8b028441fc [file] [log] [blame]
A pytz version that runs smoothly on Google App Engine.
Based on
To use, add pytz to your path normally, but import it from the gae module:
from pytz.gae import pytz
Applied patches:
- The zoneinfo dir is removed from pytz, as this module includes a ziped
version of it.
- pytz is monkey patched to load zoneinfos from a zipfile.
- pytz is patched to not check all zoneinfo files when loaded. This is
sad, I wish that was lazy, so it could be monkey patched. As it is,
the zipfile patch doesn't work and it'll spend resources checking
hundreds of files that we know aren't there.
pytz caches loaded zoneinfos, and this module will additionally cache them
in memcache to avoid unzipping constantly. The cache key includes the
OLSON_VERSION so it is invalidated when pytz is updated.
import os
import logging
import pytz
import zipfile
from cStringIO import StringIO
from google.appengine.api import memcache
except ImportError:
# This means that we're not running under the SDK, likely a script
class memcache(object):
def add(*args, **kwargs):
def get(*args, **kwargs):
return None
zoneinfo = None
zoneinfo_path = os.path.abspath(os.path.join(os.path.dirname(__file__),
def get_zoneinfo():
"""Cache the opened zipfile in the module."""
global zoneinfo
if zoneinfo is None:
zoneinfo = zipfile.ZipFile(zoneinfo_path)
return zoneinfo
class TimezoneLoader(object):
"""A loader that that reads timezones using ZipFile."""
def __init__(self):
self.available = {}
def open_resource(self, name):
"""Opens a resource from the zoneinfo subdir for reading."""
name_parts = name.lstrip('/').split('/')
if os.path.pardir in name_parts:
raise ValueError('Bad path segment: %r' % os.path.pardir)
cache_key = 'pytz.zoneinfo.%s.%s' % (pytz.OLSON_VERSION, name)
zonedata = memcache.get(cache_key)
if zonedata is None:
zonedata = get_zoneinfo().read('zoneinfo/' + '/'.join(name_parts))
memcache.add(cache_key, zonedata)'Added timezone to memcache: %s' % cache_key)
else:'Loaded timezone from memcache: %s' % cache_key)
return StringIO(zonedata)
def resource_exists(self, name):
"""Return true if the given resource exists"""
if name not in self.available:
get_zoneinfo().getinfo('zoneinfo/' + name)
self.available[name] = True
except KeyError:
self.available[name] = False
return self.available[name]
pytz.loader = TimezoneLoader()