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72 lines
1.9 KiB
72 lines
1.9 KiB
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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#-----------------------
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# Name: cache_engine.py
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# Python Library
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# Author: Raymond Wagner
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# Purpose: Base cache engine class for collecting registered engines
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#-----------------------
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import time
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from weakref import ref
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class Engines( object ):
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def __init__(self):
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self._engines = {}
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def register(self, engine):
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self._engines[engine.__name__] = engine
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self._engines[engine.name] = engine
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def __getitem__(self, key):
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return self._engines[key]
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def __contains__(self, key):
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return self._engines.__contains__(key)
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Engines = Engines()
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class CacheEngineType( type ):
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"""
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Cache Engine Metaclass that registers new engines against the cache
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for named selection and use.
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"""
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def __init__(mcs, name, bases, attrs):
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super(CacheEngineType, mcs).__init__(name, bases, attrs)
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if name != 'CacheEngine':
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# skip base class
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Engines.register(mcs)
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class CacheEngine( object ):
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__metaclass__ = CacheEngineType
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name = 'unspecified'
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def __init__(self, parent):
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self.parent = ref(parent)
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def configure(self):
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raise RuntimeError
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def get(self, date):
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raise RuntimeError
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def put(self, key, value, lifetime):
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raise RuntimeError
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def expire(self, key):
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raise RuntimeError
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class CacheObject( object ):
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"""
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Cache object class, containing one stored record.
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"""
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def __init__(self, key, data, lifetime=0, creation=None):
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self.key = key
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self.data = data
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self.lifetime = lifetime
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self.creation = creation if creation is not None else time.time()
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def __len__(self):
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return len(self.data)
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@property
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def expired(self):
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return (self.remaining == 0)
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@property
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def remaining(self):
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return max((self.creation + self.lifetime) - time.time(), 0)
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