Sui Lutris: A Blockchain Combining Broadcast and Consensus

TL;DR

A novel reconfiguration protocol is developed, the first to provably show the safe and efficient reconfiguration of a consensusless blockchain and underpins the Sui smart-contract platform.

Abstract

Sui Lutris is the first smart-contract platform to sustainably achieve sub-second finality. It achieves this significant decrease by employing consensusless agreement not only for simple payments but for a large variety of transactions. Unlike prior work, Sui Lutris neither compromises expressiveness nor throughput and can run perpetually without restarts. Sui Lutris achieves this by safely integrating consensuless agreement with a high-throughput consensus protocol that is invoked out of the critical finality path but ensures that when a transaction is at risk of inconsistent concurrent accesses, its settlement is delayed until the total ordering is resolved. Building such a hybrid architecture is especially delicate during reconfiguration events, where the system needs to preserve the safety of the consensusless path without compromising the long-term liveness of potentially misconfigured clients. We thus develop a novel reconfiguration protocol, the first to provably show the safe and efficient reconfiguration of a consensusless blockchain. Sui Lutris is currently running in production and underpins the Sui smart-contract platform. Combined with the use of Objects instead of accounts it enables the safe execution of smart contracts that expose objects as a first-class resource. In our experiments Sui Lutris achieves latency lower than 0.5 seconds for throughput up to 5,000 certificates per second (150k ops/s with transaction blocks), compared to the state-of-the-art real-world consensus latencies of 3 seconds. Furthermore, it gracefully handles validators crash-recovery and does not suffer visible performance degradation during reconfiguration.

Figures (8)

• Figure 1: Owned object contract for inventory management.
• Figure 2: Shared object contract for an atomic swap.
• Figure 3: Overview and transaction life cycle. The Byzantine agreement protocol is only executed for transactions containing shared objects and is not necessary for transactions involving only single-owner objects.
• Figure 4: Sui Lutris and Bullshark WAN latency-throughput with 10, 50, and 100 validators (no faults).
• Figure 5: Sui Lutris latency-throughput with bundles of 100 transactions per programmable transaction block (PTB); 100 validators, no faults.

Theorems & Definitions (22)

• Lemma 1: Owned-Object Execution Set
• Lemma 2: Shared-Object Execution Set
• Lemma 3: BCB Consistency
• Lemma 4: Shared-Locks Consistency
• Lemma 5: Owned Objects Sequential Execution
• Lemma 6: Shared Objects Sequential Execution
• Lemma 7: Objects Identifiers Uniqueness
• Lemma 8: Deterministic Execution
• Theorem 1: Sui Lutris Safety
• Theorem 2: Client-Perceived Safety