braft is an embeddable C++ library that implements the Raft consensus algorithm, providing a distributed consensus engine for building fault-tolerant, replicated state machines. At its core, it manages leader election, log replication, cluster membership changes, and state machine synchronization across a cluster of nodes, ensuring strong consistency and data durability even in the face of node failures.
The library distinguishes itself through a comprehensive set of mechanisms for reliable distributed coordination. It uses a randomized timeout-based leader election process with term management to ensure a single leader coordinates the cluster, and employs heartbeat-driven failure detection to trigger automatic leader failover when a node becomes unresponsive. Cluster membership changes are handled through a joint consensus protocol that prevents split-brain scenarios during dynamic node additions or removals, while quorum-based log replication guarantees that entries are committed only after reaching a majority of followers.
braft supports a replicated state machine model where each node applies the same sequence of committed log entries deterministically, ensuring identical state across the cluster. It includes snapshot-based log compaction to prevent unbounded log growth, and provides leader-routed service access for reading and writing to the replicated state machine. The library is designed for embedding directly into applications, handling automatic leader election, failover, and consistent log replication across cluster nodes.