93 lines
2.5 KiB
Python
93 lines
2.5 KiB
Python
#!/usr/bin/env python
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__author__ = "Abhinav Sarkar <abhinav@abhinavsarkar.net>"
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__version__ = "0.2"
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__license__ = "GNU Lesser General Public License"
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import md5
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import os
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import tempfile
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class _FileCacheError(Exception):
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'''Base exception class for FileCache related errors'''
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class FileCache(object):
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DEPTH = 3
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def __init__(self,root_directory=None):
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self._InitializeRootDirectory(root_directory)
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def Get(self,key):
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path = self._GetPath(key)
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if os.path.exists(path):
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return open(path).read()
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else:
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return None
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def Set(self,key,data):
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path = self._GetPath(key)
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directory = os.path.dirname(path)
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if not os.path.exists(directory):
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os.makedirs(directory)
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if not os.path.isdir(directory):
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raise _FileCacheError('%s exists but is not a directory' % directory)
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temp_fd, temp_path = tempfile.mkstemp()
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temp_fp = os.fdopen(temp_fd, 'w')
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temp_fp.write(data)
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temp_fp.close()
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if not path.startswith(self._root_directory):
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raise _FileCacheError('%s does not appear to live under %s' %
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(path, self._root_directory))
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if os.path.exists(path):
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os.remove(path)
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os.rename(temp_path, path)
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def Remove(self,key):
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path = self._GetPath(key)
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if not path.startswith(self._root_directory):
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raise _FileCacheError('%s does not appear to live under %s' %
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(path, self._root_directory ))
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if os.path.exists(path):
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os.remove(path)
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def GetCachedTime(self,key):
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path = self._GetPath(key)
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if os.path.exists(path):
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return os.path.getmtime(path)
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else:
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return None
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def _GetUsername(self):
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'''Attempt to find the username in a cross-platform fashion.'''
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return os.getenv('USER') or \
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os.getenv('LOGNAME') or \
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os.getenv('USERNAME') or \
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os.getlogin() or \
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'nobody'
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def _GetTmpCachePath(self):
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username = self._GetUsername()
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cache_directory = 'python.cache_' + username
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return os.path.join(tempfile.gettempdir(), cache_directory)
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def _InitializeRootDirectory(self, root_directory):
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if not root_directory:
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root_directory = self._GetTmpCachePath()
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root_directory = os.path.abspath(root_directory)
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if not os.path.exists(root_directory):
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os.mkdir(root_directory)
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if not os.path.isdir(root_directory):
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raise _FileCacheError('%s exists but is not a directory' %
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root_directory)
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self._root_directory = root_directory
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def _GetPath(self,key):
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hashed_key = md5.new(key).hexdigest()
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return os.path.join(self._root_directory,
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self._GetPrefix(hashed_key),
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hashed_key)
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def _GetPrefix(self,hashed_key):
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return os.path.sep.join(hashed_key[0:FileCache.DEPTH])
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