mirror of
https://github.com/reddit-archive/reddit.git
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154 lines
4.8 KiB
Python
154 lines
4.8 KiB
Python
# The contents of this file are subject to the Common Public Attribution
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# License Version 1.0. (the "License"); you may not use this file except in
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# compliance with the License. You may obtain a copy of the License at
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# http://code.reddit.com/LICENSE. The License is based on the Mozilla Public
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# License Version 1.1, but Sections 14 and 15 have been added to cover use of
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# software over a computer network and provide for limited attribution for the
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# Original Developer. In addition, Exhibit A has been modified to be consistent
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# with Exhibit B.
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#
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# Software distributed under the License is distributed on an "AS IS" basis,
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# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License for
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# the specific language governing rights and limitations under the License.
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#
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# The Original Code is Reddit.
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#
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# The Original Developer is the Initial Developer. The Initial Developer of the
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# Original Code is CondeNet, Inc.
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#
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# All portions of the code written by CondeNet are Copyright (c) 2006-2009
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# CondeNet, Inc. All Rights Reserved.
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################################################################################
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from __future__ import with_statement
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import cPickle as pickle
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import os, shutil, time
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from utils import Storage
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from datetime import datetime, timedelta
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class LoggedSlots(object):
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def __init__(self, logfile, **kw):
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for k, v in kw.iteritems():
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super(LoggedSlots, self).__setattr__(k, v)
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self.__logfile = logfile
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self.load_slots()
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def __setattr__(self, k, v):
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super(LoggedSlots, self).__setattr__(k, v)
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if k in self.__slots__:
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self.dump_slots()
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def load_slots(self):
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d = self._get_slots(self.__logfile)
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for k, v in d.iteritems():
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super(LoggedSlots, self).__setattr__(k, v)
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def dump_slots(self):
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if self.__logfile:
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with WithWriteLock(self.__logfile) as handle:
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d = {}
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for s in self.__slots__:
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try:
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d[s] = getattr(self, s)
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except AttributeError:
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continue
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pickle.dump(d, handle)
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@classmethod
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def _get_slots(self, file):
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if os.path.exists(file):
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with open(file) as handle:
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return Storage(pickle.load(handle))
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return Storage()
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class WriteLockExistsException(): pass
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class WithWriteLock():
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def __init__(self, file_name, mode = 'w', force = False, age = 60):
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self.fname = file_name
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self.lock_file = file_name + ".write_lock"
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self.time = datetime.now()
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self.handle = None
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self.created = True
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if self.exists():
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if force:
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self.destroy()
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elif not self.try_expire(age):
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raise WriteLockExistsException
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# back up the file to be written to
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if os.path.exists(self.fname):
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shutil.copyfile(self.fname, self.backup_file)
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# write out a lock file
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with open(self.lock_file, 'w') as handle:
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pickle.dump(self.time, handle)
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# lastly, open the file!
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self.handle = open(file_name, mode)
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def write(self, *a, **kw):
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self.handle.write(*a, **kw)
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@property
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def backup_file(self):
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return "%s-%s.bak" % (self.fname,
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time.mktime(self.time.timetuple()))
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def exists(self):
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return os.path.exists(self.lock_file)
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def try_expire(self, age):
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'''destroys an existing lock file if it is more than age seconds old'''
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with open(self.lock_file, 'r') as handle:
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time = pickle.load(handle)
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if self.time - time > timedelta(0, age):
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self.destroy()
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return True
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return False
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def destroy(self):
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# close any open handles
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if self.handle:
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self.handle.close()
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self.handle = None
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# wipe the lock file and the back-up
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if self.created:
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self.created = False
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if self.exists():
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os.unlink(self.lock_file)
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if os.path.exists(self.backup_file):
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os.unlink(self.backup_file)
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def close(self):
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self.destroy()
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def rollback(self):
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# close any open handles
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if self.handle:
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self.handle.close()
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self.handle = None
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if self.created:
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# clobber any changes to the file with our archive
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if os.path.exists(self.backup_file):
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shutil.copyfile(self.backup_file, self.fname)
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#destroy as usual
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self.destroy()
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def __enter__(self):
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return self
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def __exit__(self, type, value, tb):
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if tb is None:
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self.close()
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else:
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self.rollback()
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