PREP-UC: A Practical Replicated Persistent Universal Construction

The process of designing and implementing correct concurrent data structures is non-trivial and often error prone. The recent commercial availability of non-volatile memory has prompted many researchers to also consider designing concurrent data structures that persist shared state allowing the data structure to be recovered following a power failure. These so called persistent concurrent data structures further complicate the process of achieving correct and efficient implementations. Universal constructions (UCs) which produce a concurrent object given a sequential object, have been studied extensively in the space of volatile shared memory as a means of more easily implementing correct concurrent data structures. In contrast, there are only a handful of persistent universal constructions (PUCs) which beyond producing a concurrent object from a sequential object, guarantees that the object can be recovered following a crash. Existing PUCs satisfy the correctness condition of durable linearizability which requires that operations are persisted before they complete. Satisfying the weaker correctness condition of buffered durable linearizability allows for improved performance at the cost of failing to recover some completed operations following a crash. In this work we design and implement both a buffered durable linearizable and a durable linearizable PUC based on the node replication UC. We demonstrate that we can achieve significantly better performance satisfying buffered durable linearizability while also restricting the maximum number of operations that can be lost after a crash.