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57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
from __future__ import absolute_import, division, print_function, unicode_literals
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import gzip
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import json
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import os
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_NONE = object()
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class FileCache(object):
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"""A two-level cache, which stores expensive results in memory and on disk.
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"""
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def __init__(self, cache_directory, creator, open=gzip.open, suffix='.gz'):
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self.cache_directory = cache_directory
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self.creator = creator
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self.open = open
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self.suffix = suffix
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self.cached_data = {}
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if not os.path.exists(self.cache_directory):
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os.makedirs(self.cache_directory)
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def get_file_data(self, name):
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if os.path.exists(filename):
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return json.load(self.open(filename))
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result = self.creator(name)
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return result
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def get_data(self, name, save_in_cache, can_create, default=None):
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name = str(name)
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result = self.cached_data.get(name, _NONE)
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if result is _NONE:
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filename = os.path.join(self.cache_directory, name) + self.suffix
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if os.path.exists(filename):
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result = json.load(self.open(filename)) or _NONE
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if result is _NONE and can_create:
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result = self.creator(name)
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if save_in_cache:
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json.dump(result, self.open(filename, 'w'))
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return default if result is _NONE else result
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def _files(self):
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return os.listdir(self.cache_directory)
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def cache_list(self):
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for f in self._files():
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if f.endswith(self.suffix):
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yield f[:-len(self.suffix)]
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def file_count(self):
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return len(self._files())
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def clear(self):
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"""Clears both local files and memory."""
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self.cached_data = {}
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for f in self._files():
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os.remove(os.path.join(self.cache_directory, f))
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