def connectionLostForKey(self, key):
        """
        Remove lost connection from cache.

        @param key: key of connection that was lost
        @type key: L{tuple} of L{IAddress} and C{extraHash}
        """
        if key in self.cachedConnections:
            del self.cachedConnections[key]
        if self._shuttingDown and self._shuttingDown.get(key):
            d, self._shuttingDown[key] = self._shuttingDown[key], None
            d.callback(None)