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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 logic 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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−from google.appengine.api import memcache
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−from google.appengine.ext import db
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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(model, filter, order):
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−  """Returns the memcache key for this query.
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−  """
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−
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−  new_filter = {}
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−
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−  for filter_key, value in filter.iteritems():
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−    new_value = value.key().name() if isinstance(value, db.Model) else value
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−    new_filter[filter_key] = new_value
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−
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−  return 'query_for_%(kind)s_%(filter)s_%(order)s' % {
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−      'kind': repr(model.kind()),
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−      'filter': repr(new_filter),
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−      'order': repr(order),
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−      }
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−
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−
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−def get(model, filter, order, *args, **kwargs):
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−  """Retrieves the data for the specified query from the memcache.
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−  """
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−
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−  memcache_key = key(model, filter, order)
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−  return memcache.get(memcache_key), memcache_key
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−
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−
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−def put(data, memcache_key, *args, **kwargs):
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−  """Sets the data for the specified query in the memcache.
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−
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−  Args:
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−    data: the data to be cached
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−  """
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−
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−  # Store data for fifteen minutes to force a refresh every so often
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−  retention = 15*60
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−  memcache.add(memcache_key, data, retention)
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−
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−
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−def flush(model, filter):
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−  """Removes the data for the current user from the memcache.
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−  """
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−
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−  memcache_key = key(model, filter)
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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)