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import fcntl
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import logging
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import tempfile
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import threading
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from datetime import timedelta
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from django.utils.text import slugify
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from datetime import datetime
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import requests
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from pytz import utc
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from time import mktime, sleep
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import os
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import hashlib
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import os.path
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from django.core.files.storage import default_storage
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def truncate_unique(s, length):
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if len(s) < length:
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return s
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md5 = hashlib.md5(s.encode('ascii')).hexdigest()
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# we should be the first and last characters from the URL
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l = (length - len(md5)) / 2 - 2 # four additional characters
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assert l > 20
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return s[:l] + '...' + s[-l:] + '_' + md5
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def dt_to_timestamp(input_dt):
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return mktime(utc.localize(input_dt).utctimetuple())
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def load_federation_cache(url):
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logger = logging.getLogger(__name__)
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try:
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filename = truncate_unique(slugify(url), 250)
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path = os.path.join('metadata-cache', filename)
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unix_path = default_storage.path(path)
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if not os.path.exists('metadata-cache'):
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os.makedirs('metadata-cache')
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f = open(unix_path, 'w')
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try:
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fcntl.lockf(f, fcntl.LOCK_EX | fcntl.LOCK_NB)
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except IOError:
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return
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else:
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with tempfile.NamedTemporaryFile(dir=os.path.dirname(unix_path), delete=False) as temp:
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try:
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# increase modified time by one hour to prevent too many updates
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st = os.stat(unix_path)
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os.utime(unix_path, (st.st_atime, st.st_mtime + 3600))
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response = requests.get(url)
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response.raise_for_status()
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temp.write(response.content)
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temp.flush()
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os.rename(temp.name, unix_path)
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except:
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os.unlink(temp.name)
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finally:
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fcntl.lockf(f, fcntl.LOCK_UN)
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finally:
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f.close()
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except OSError:
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logger.exception(u"could create the intermediary 'metadata-cache' "
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"folder")
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return
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except:
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logger.exception(u'failed to load federation from %s', url)
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def get_federation_from_url(url, update_cache=False):
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logger = logging.getLogger(__name__)
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filename = truncate_unique(slugify(url), 250)
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path = os.path.join('metadata-cache', filename)
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if not default_storage.exists(path) or update_cache or \
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default_storage.created_time(path) < datetime.now() - timedelta(days=1):
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threading.Thread(target=load_federation_cache, args=(url,)).start()
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sleep(2)
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return default_storage.open(path).read()
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logger.warning('federation %s has not been loaded', url)
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return None
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