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−#!/usr/bin/python2.5
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−#
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−# Copyright 2009 the Melange authors.
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−#
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−# Licensed under the Apache License, Version 2.0 (the "License");
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−# you may not use this file except in compliance with the License.
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−# You may obtain a copy of the License at
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−#
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−#   http://www.apache.org/licenses/LICENSE-2.0
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−#
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−# Unless required by applicable law or agreed to in writing, software
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−# distributed under the License is distributed on an "AS IS" BASIS,
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−# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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−# See the License for the specific language governing permissions and
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−# limitations under the License.
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−
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−"""Module contains homepage memcaching functions.
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−"""
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−
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−__authors__ = [
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−    '"Sverre Rabbelier" <sverre@rabbelier.nl>',
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−  ]
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−
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−
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−import logging
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−
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−from google.appengine.api import memcache
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−
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−from soc.logic import accounts
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−from soc.logic import system
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−
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−import soc.cache.base
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−
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−
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−def key(entity):
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−  """Returns the memcache key for an entities homepage.
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−  """
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−
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−  host = system.getHostname()
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−  version = system.getAppVersion()
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−  kind = entity.kind()
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−  key = entity.key().id_or_name()
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−
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−  return 'homepage_for_%s_%s_%s_%s' % (host, version, kind, key)
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−
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−
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−def get(self, *args, **kwargs):
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−  """Retrieves the homepage for the specified entity from the memcache.
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−  """
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−
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−  # only cache the page for non-logged-in users
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−  # TODO: figure out how to cache everything but the sidebar
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−  # also, no need to normalize as we don't use it anyway
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−  if accounts.getCurrentAccount(normalize=False):
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−    return (None, None)
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−
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−  entity = self._logic.getFromKeyFields(kwargs)
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−
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−  # if we can't retrieve the entity, leave it to the actual method
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−  if not entity:
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−    return (None, None)
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−
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−  memcache_key = key(entity)
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−  logging.info("Retrieving %s" % memcache_key)
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−  # pylint: disable-msg=E1101
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−  return memcache.get(memcache_key), memcache_key
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−
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−def put(result, memcache_key, *args, **kwargs):
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−  """Sets the homepage for the specified entity in the memcache.
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−
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−  Args:
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−    result: the homepage to be cached
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−  """
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−
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−  # no sense in storing anything if we won't query it later on
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−  # also, no need to normalize as we don't use it anyway
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−  if accounts.getCurrentAccount(normalize=False):
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−    return
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−
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−  # Store homepage for just ten minutes to force a refresh every so often
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−  retention = 10*60
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−
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−  logging.info("Setting %s" % memcache_key)
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−  # pylint: disable-msg=E1101
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−  memcache.add(memcache_key, result, retention)
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−
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−
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−def flush(entity):
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−  """Removes the homepage for the current entity from the memcache.
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−
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−  Also calls soc.cache.rights.flush for the specified user.
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−
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−  Args:
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−    id: defaults to the current account if not set
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−  """
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−
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−  memcache_key = key(entity)
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−  logging.info("Flushing %s" % memcache_key)
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−  # pylint: disable-msg=E1101
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−  memcache.delete(memcache_key)
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−
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−
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−# define the cache function
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−cache = soc.cache.base.getCacher(get, put)