How to use the persistent.PickleCache function in persistent

def _resetCache(self):
        """Creates a new cache, discarding the old one.

        See the docstring for the resetCaches() function.
        """
        self._reset_counter = global_reset_counter
        self._invalidated.clear()
        cache_size = self._cache.cache_size
        self._cache = cache = PickleCache(self, cache_size)

cache, measured in objects.
          - `cache_deactivate_after`: deprecated, ignored
          - `mvcc`: boolean indicating whether MVCC is enabled
          - `txn_mgr`: transaction manager to use.  None means
             used the default transaction manager.
          - `synch`: boolean indicating whether Connection should
             register for afterCompletion() calls.
        """

        self._log = logging.getLogger("ZODB.Connection")
        self._storage = None
        self._debug_info = ()
        self._opened = None # time.time() when DB.open() opened us

        self._version = version
        self._cache = cache = PickleCache(self, cache_size)
        if version:
            # Caches for versions end up empty if the version
            # is not used for a while. Non-version caches
            # keep their content indefinitely.

            # XXX Why do we want version caches to behave this way?

            self._cache.cache_drain_resistance = 100
        self._committed = []
        self._added = {}
        self._added_during_commit = None
        self._reset_counter = global_reset_counter
        self._load_count = 0   # Number of objects unghosted
        self._store_count = 0  # Number of objects stored

        # List of oids of modified objects (to be invalidated on an abort).