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96 lines
2.5 KiB
96 lines
2.5 KiB
5 years ago
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"""
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Proxy Backends
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------------------
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Provides a utility and a decorator class that allow for modifying the behavior
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of different backends without altering the class itself or having to extend the
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base backend.
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.. versionadded:: 0.5.0 Added support for the :class:`.ProxyBackend` class.
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"""
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from .api import CacheBackend
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class ProxyBackend(CacheBackend):
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"""A decorator class for altering the functionality of backends.
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Basic usage::
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from dogpile.cache import make_region
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from dogpile.cache.proxy import ProxyBackend
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class MyFirstProxy(ProxyBackend):
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def get(self, key):
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# ... custom code goes here ...
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return self.proxied.get(key)
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def set(self, key, value):
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# ... custom code goes here ...
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self.proxied.set(key)
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class MySecondProxy(ProxyBackend):
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def get(self, key):
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# ... custom code goes here ...
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return self.proxied.get(key)
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region = make_region().configure(
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'dogpile.cache.dbm',
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expiration_time = 3600,
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arguments = {
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"filename":"/path/to/cachefile.dbm"
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},
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wrap = [ MyFirstProxy, MySecondProxy ]
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)
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Classes that extend :class:`.ProxyBackend` can be stacked
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together. The ``.proxied`` property will always
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point to either the concrete backend instance or
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the next proxy in the chain that a method can be
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delegated towards.
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.. versionadded:: 0.5.0
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"""
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def __init__(self, *args, **kwargs):
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self.proxied = None
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def wrap(self, backend):
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''' Take a backend as an argument and setup the self.proxied property.
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Return an object that be used as a backend by a :class:`.CacheRegion`
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object.
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'''
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assert(
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isinstance(backend, CacheBackend) or
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isinstance(backend, ProxyBackend))
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self.proxied = backend
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return self
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#
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# Delegate any functions that are not already overridden to
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# the proxies backend
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#
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def get(self, key):
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return self.proxied.get(key)
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def set(self, key, value):
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self.proxied.set(key, value)
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def delete(self, key):
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self.proxied.delete(key)
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def get_multi(self, keys):
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return self.proxied.get_multi(keys)
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def set_multi(self, mapping):
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self.proxied.set_multi(mapping)
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def delete_multi(self, keys):
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self.proxied.delete_multi(keys)
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def get_mutex(self, key):
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return self.proxied.get_mutex(key)
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