100 lines
3.3 KiB
Python
100 lines
3.3 KiB
Python
#!/usr/bin/env python3
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# This file is part of Cockpit.
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#
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# Copyright (C) 2015 Red Hat, Inc.
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#
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# Cockpit is free software; you can redistribute it and/or modify it
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# under the terms of the GNU Lesser General Public License as published by
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# the Free Software Foundation; either version 2.1 of the License, or
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# (at your option) any later version.
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#
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# Cockpit is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with Cockpit; If not, see <http://www.gnu.org/licenses/>.
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# Shared GitHub code. When run as a script, we print out info about
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# our GitHub interacition.
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import json
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import os
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import stat
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import tempfile
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import time
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import urllib.request, urllib.parse, urllib.error
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__all__ = (
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'Cache',
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)
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class Cache(object):
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def __init__(self, directory, lag=None):
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self.directory = directory
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self.pruned = False
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# Default to zero lag when command on command line
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if lag is None:
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if os.isatty(0):
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lag = 0
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else:
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lag = 60
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# The lag tells us how long to assume cached data is "current"
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self.lag = lag
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# The mark tells us that stuff before this time is not "current"
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self.marked = 0
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# Prune old expired data from the cache directory
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def prune(self):
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if not os.path.exists(self.directory):
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return
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now = time.time()
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try:
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for filename in os.listdir(self.directory):
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path = os.path.join(self.directory, filename)
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if os.path.isfile(path) and os.stat(path).st_mtime < now - 7 * 86400:
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os.remove(path)
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except OSError:
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pass
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# Read a resource from the cache or return None
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def read(self, resource):
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path = os.path.join(self.directory, urllib.parse.quote(resource, safe=''))
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try:
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with open(path, 'r') as fp:
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return json.load(fp)
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except (IOError, ValueError):
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return None
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# Write a resource to the cache in an atomic way
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def write(self, resource, contents):
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path = os.path.join(self.directory, urllib.parse.quote(resource, safe=''))
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os.makedirs(self.directory, exist_ok=True)
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(fd, temp) = tempfile.mkstemp(dir=self.directory)
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with os.fdopen(fd, 'w') as fp:
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json.dump(contents, fp)
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os.chmod(temp, stat.S_IRUSR | stat.S_IRGRP | stat.S_IROTH)
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os.rename(temp, path)
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if not self.pruned:
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self.pruned = True
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self.prune()
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# Tell the cache that stuff before this time is not "current"
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def mark(self, mtime=None):
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if not mtime:
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mtime = time.time()
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self.marked = mtime
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# Check if a given resource in the cache is "current" or not
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def current(self, resource):
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path = os.path.join(self.directory, urllib.parse.quote(resource, safe=''))
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try:
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mtime = os.path.getmtime(path)
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return mtime > self.marked and mtime > (time.time() - self.lag)
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except OSError:
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return False
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