Crate openraft

source · [−]
Expand description

openraft

Advanced Raft using the Tokio framework. Please ⭐ on github!

CI

License


Raft is not yet good enough. This project intends to improve raft as the next generation consensus protocol for distributed data storage systems (SQL, NoSQL, KV, Streaming, Graph … or maybe something more exotic).

The guide is the best place to get started.

Openraft is derived from async-raft with several bugs fixed: Fixed bugs.

A full list of changes/fixes can be found in change-log

Features

  • It is fully reactive and embraces the async ecosystem. It is driven by actual Raft events taking place in the system as opposed to being driven by a tick operation. Batching of messages during replication is still used whenever possible for maximum throughput.

  • Storage and network integration is well defined via two traits RaftStorage & RaftNetwork. This provides applications maximum flexibility in being able to choose their storage and networking mediums.

  • All interaction with the Raft node is well defined via a single public Raft type, which is used to spawn the Raft async task, and to interact with that task. The API for this system is clear and concise.

  • Log replication is fully pipelined and batched for optimal performance. Log replication also uses a congestion control mechanism to help keep nodes up-to-date as efficiently as possible.

  • It fully supports dynamic cluster membership changes with joint config. The buggy single-step membership change algo is not considered. See the dynamic membership chapter in the guide.

  • Details on initial cluster formation, and how to effectively do so from an application’s perspective, are discussed in the cluster formation chapter in the guide.

  • Automatic log compaction with snapshots, as well as snapshot streaming from the leader node to follower nodes is fully supported and configurable.

  • The entire code base is instrumented with tracing. This can be used for standard logging, or for distributed tracing, and the verbosity can be statically configured at compile time to completely remove all instrumentation below the configured level.

Contributing

Check out the CONTRIBUTING.md guide for more details on getting started with contributing to this project.

License

Openraft is licensed under the terms of the MIT License or the Apache License 2.0, at your choosing.

Feature flags

  • bt: Enable backtrace: generate backtrace for errors. This requires a unstable feature backtrace thus it can not be used with stable rust, unless explicity allowing using unstable features in stable rust with RUSTC_BOOTSTRAP=1.

Re-exports

pub use anyerror;
pub use async_trait;
pub use crate::config::Config;
pub use crate::config::SnapshotPolicy;
pub use crate::error::ChangeMembershipError;
pub use crate::error::ClientWriteError;
pub use crate::error::ConfigError;
pub use crate::error::InitializeError;
pub use crate::error::RaftError;
pub use crate::error::ReplicationError;
pub use crate::metrics::RaftMetrics;
pub use crate::raft::Raft;
pub use crate::types::v065::AppData;
pub use crate::types::v065::AppDataResponse;
pub use crate::types::v065::AppendEntriesRequest;
pub use crate::types::v065::AppendEntriesResponse;
pub use crate::types::v065::DefensiveError;
pub use crate::types::v065::EffectiveMembership;
pub use crate::types::v065::Entry;
pub use crate::types::v065::EntryPayload;
pub use crate::types::v065::ErrorSubject;
pub use crate::types::v065::ErrorVerb;
pub use crate::types::v065::HardState;
pub use crate::types::v065::InitialState;
pub use crate::types::v065::LogId;
pub use crate::types::v065::Membership;
pub use crate::types::v065::NodeId;
pub use crate::types::v065::RaftNetwork;
pub use crate::types::v065::RaftStorage;
pub use crate::types::v065::RaftStorageDebug;
pub use crate::types::v065::Snapshot;
pub use crate::types::v065::SnapshotId;
pub use crate::types::v065::SnapshotMeta;
pub use crate::types::v065::SnapshotSegmentId;
pub use crate::types::v065::StateMachineChanges;
pub use crate::types::v065::StorageError;
pub use crate::types::v065::StorageIOError;
pub use crate::types::v065::Violation;

Modules

config

Raft runtime configuration.

error

Error types exposed by this crate.

metrics

Raft metrics for observability.

network
raft

Public Raft interface and data types.

storage
types

Structs

AnyError

AnyError is a serializable wrapper Error.

ReplicationMetrics
StoreExt

Extended store backed by another impl.

Enums

State

All possible states of a Raft node.

Update

Traits

DefensiveCheck

Defines methods of defensive checks for RaftStorage.

MessageSummary
Wrapper

A wrapper extends the APIs of a base RaftStore.