I'm picturing the same, but my guess is that it's using a time-synced serializability graph or MVCC in some way. However, even a "basic" distributed lock syste

I'm picturing the same, but my guess is that it's using a time-synced serializability graph or MVCC in some way. However, even a "basic" distributed lock system (like a consistently-hashed in-memory DB, sharded across reliable servers) might provide both the scale and single source of truth that's needed. The difficulty arises when one of those servers has a hiccup. It'd be a delicious irony if it was based on hardware like an old-school mainframe or something like that.