Edelweiss: Automatic Storage Reclamation for Distributed Programming

Event Log Exchange (ELE) is a common programming pattern based on immutable state and messaging. ELE sidesteps traditional challenges in distributed consistency, at the expense of introducing new challenges in designing space reclamation protocols to avoid consuming unbounded storage. We introduce Edelweiss, a sublanguage of Bloom that provides an ELE programming model, yet automatically reclaims space without programmer assistance. We describe techniques to analyze Edelweiss programs and automatically generate application-specific distributed space reclamation logic. We show how Edelweiss can be used to elegantly implement a variety of communication and distributed storage protocols; the storage reclamation code generated by Edelweiss effectively garbage-collects state and often matches hand-written protocols from the literature.