Some of the available glance stores like file, cinder etc has capability to reuse already initiated driver (DRIVER_REUSABLE = 0b01000000). In Caracal we have added a feature to sort image locations based on store weight. As RBD driver of glance does not have this reuse capability, during image list API call it initializes the RBD driver for each of the available image which is causing noticable delay in list call.

To avoid this, introducing new interface in glance_store which will directly get the weight of the store from memory and return it back to user.