MUSIC: Multi-Site Critical Sections over Geo-Distributed State

A crucial requirement for many multi-site production services operating at global scale is the need for exclusive access to latest state. Here, a novel approach to address these requirements through the abstraction of a critical section over geo-distributed state is proposed. This abstraction is realized in a key-value store called MUSIC, which provides critical sections with novel semantics suitable for geo-distributed state referred to as entry consistency under failures (ECF). The semantics of ECF in MUSIC, its formal verification, and its implementation are presented, along with details of how MUSIC has been used to realize various fundamental geo-distributed structuring paradigms. MUSIC has been deployed in production geo-distributed services at AT&T as part of the Open Network Automation Platform (ONAP). Our evaluation of MUSIC shows that, despite providing additional properties, MUSIC has higher throughput (~1.4-17.17 times) than Zookeeper for larger critical section sizes and outperforms (~2-4 times) similar structures in which state updates use Paxos or CockroachDB transactions.