To maximize performance, many modern blockchain systems rely on eventually-synchronous, Byzantine fault-tolerant (BFT) consensus protocols. Two protocol designs have emerged in this space: protocols that minimize latency using a leader that drives both data dissemination and consensus, and protocols that maximize throughput using a separate, asynchronous data dissemination layer. Recent protocols such as Partially-Synchronous Bullshark and Sailfish combine elements of both approaches by using a DAG to enable parallel data dissemination and a leader that paces DAG formation. This improves latency while achieving state-of-the-art throughput. However, the DAG-formation process of those protocols imposes overheads that prevent matching the latency possible with a leader-based protocol. We present Angelfish, a hybrid protocol that adapts smoothly across this design space, from leader-based to DAG-based consensus. Angelfish lets a dynamically-adjusted subset of parties use best-effort broadcast to issue lightweight votes instead of using a costlier reliably broadcast to create DAG vertices. This reduces communication, tolerates more lagging nodes, and lowers latency in practice compared to prior DAG-based protocols. Our empirical evaluation shows that Angelfish attains state-of-the-art peak throughput while matching the latency of leader-based protocols under moderate throughput, delivering the best of both worlds. The implementation is open-sourced and publicly available.

翻译：为了最大化性能，许多现代区块链系统依赖于最终同步的拜占庭容错（BFT）共识协议。该领域已出现两种协议设计：一种通过领导者同时驱动数据传播与共识以最小化延迟，另一种通过独立的异步数据传播层以最大化吞吐量。近期协议如部分同步的Bullshark和Sailfish融合了两种方法的要素，它们利用有向无环图（DAG）实现并行数据传播，并由领导者协调DAG的构建。这能在实现顶尖吞吐量的同时改善延迟。然而，这些协议的DAG构建过程会引入额外开销，使其无法达到基于领导者的协议所能实现的最低延迟。本文提出天使鱼（Angelfish），一种能在从基于领导者到基于DAG的共识这一设计空间中平滑过渡的混合协议。天使鱼允许动态调整的参与方子集使用尽力而为广播来发布轻量级投票，而非依赖成本更高的可靠广播来创建DAG顶点。与先前的基于DAG的协议相比，这减少了通信开销，能容忍更多滞后节点，并在实践中降低了延迟。我们的实证评估表明，天使鱼在实现顶尖峰值吞吐量的同时，能在中等吞吐量下匹配基于领导者协议的延迟，从而兼得两者优势。该实现已开源并公开可用。