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# Copyright (c) 2012 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import base64
from appengine_wrappers import urlfetch
from future import Future
class _AsyncFetchDelegate(object):
def __init__(self, rpc):
self._rpc = rpc
def Get(self):
return self._rpc.get_result()
def _MakeHeaders(username, password):
headers = { 'Cache-Control': 'max-age=0' }
if username is not None and password is not None:
headers['Authorization'] = 'Basic %s' % base64.encodestring(
'%s:%s' % (username, password))
return headers
class AppEngineUrlFetcher(object):
"""A wrapper around the App Engine urlfetch module that allows for easy
async fetches.
"""
def __init__(self, base_path=None):
self._base_path = base_path
def Fetch(self, url, username=None, password=None):
"""Fetches a file synchronously.
"""
headers = _MakeHeaders(username, password)
if self._base_path is not None:
return urlfetch.fetch('%s/%s' % (self._base_path, url), headers=headers)
else:
return urlfetch.fetch(url, headers={ 'Cache-Control': 'max-age=0' })
def FetchAsync(self, url, username=None, password=None):
"""Fetches a file asynchronously, and returns a Future with the result.
"""
rpc = urlfetch.create_rpc()
headers = _MakeHeaders(username, password)
if self._base_path is not None:
urlfetch.make_fetch_call(rpc,
'%s/%s' % (self._base_path, url),
headers=headers)
else:
urlfetch.make_fetch_call(rpc, url, headers=headers)
return Future(delegate=_AsyncFetchDelegate(rpc))
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