dogpile.cache / dogpile / cache /

Proxy Backends

Provides a utility and a decorator class that allow for modifying the behavior
of different backends without altering the class itself or having to extend the
base backend.

.. versionadded:: 0.5.0  Added support for the :class:`.ProxyBackend` class.


from .api import CacheBackend

class ProxyBackend(CacheBackend):
    """A decorator class for altering the functionality of backends.

    Basic usage::

        from dogpile.cache import make_region
        from dogpile.cache.proxy import ProxyBackend

        class MyFirstProxy(ProxyBackend):
            def get(self, key):
                # ... custom code goes here ...
                return self.proxied.get(key)

            def set(self, key, value):
                # ... custom code goes here ...

        class MySecondProxy(ProxyBackend):
            def get(self, key):
                # ... custom code goes here ...
                return self.proxied.get(key)

        region = make_region().configure(
            expiration_time = 3600,
            arguments = {
            wrap = [ MyFirstProxy, MySecondProxy ]

    Classes that extend :class:`.ProxyBackend` can be stacked
    together.  The ``.proxied`` property will always
    point to either the concrete backend instance or
    the next proxy in the chain that a method can be
    delegated towards.

    .. versionadded:: 0.5.0


    def __init__(self, *args, **kwargs):
        self.proxied = None

    def wrap(self, backend):
        ''' Take a backend as an argument and setup the self.proxied property.
        Return an object that be used as a backend by a :class:`.CacheRegion`
        assert(isinstance(backend, CacheBackend) or isinstance(backend, ProxyBackend))
        self.proxied = backend
        return self

    # Delegate any functions that are not already overridden to
    # the proxies backend
    def get(self, key):
        return self.proxied.get(key)

    def set(self, key, value):
        self.proxied.set(key, value)

    def delete(self, key):

    def get_multi(self, keys):
        return self.proxied.get_multi(keys)

    def set_multi(self, keys):

    def delete_multi(self, keys):

    def get_mutex(self, key):
        return self.proxied.get_mutex(key)
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