Crate openraft

Openraft

API status

Openraft API is currently unstable. Incompatibilities may arise in upgrades prior to 1.0.0. Refer to our Change-Log for details. Upgrade Guides explains how to upgrade.

Each commit message begins with a keyword indicating the type of change:

• DataChange: Changes to on-disk data types, possibly requiring manual upgrade.
• Change: Introduces incompatible API changes.
• Feature: Adds compatible, non-breaking new features.
• Fix: Addresses bug fixes.

Openraft Document

If you’re starting to build an application with Openraft, check out

• getting_started.
• faq,

To maintain an Openraft cluster, e.g., add or remove nodes, refer to

• cluster_control :
  • cluster_formation describes how to form a cluster;
  • dynamic membership describes how to add or remove nodes without downtime;
  • node lifecycle describes the transition of a node’s state;

When upgrading an Openraft application, consult:

• upgrade_guide :
  • v0.6-to-v0.7;
  • v0.7-to-v0.8;
  • v0.8.3-to-v0.8.4;
  • v0.8-to-v0.9;

To learn about the data structures used in Openraft and the commit protocol, see

• feature_flags;
• data :
  • Vote is the core in a distributed system;
  • Log pointers shows how Openraft tracks entries in the log;
  • Leader lease explains leader lease for a Leader and a Follower;
  • Extended membership explains how members are organized in Openraft;
  • Effective membership explains when membership config takes effect;
• components explains the components in Openraft;
  • RaftStateMachine is the core API for managing the state machine and snapshot functionalities;
• protocol :
  • replication;
    • leader_lease;
    • log_replication;
    • snapshot_replication;

Contributors who want to understand the internals of Openraft can find relevant information in

• internal :
  • Architecture shows the overall architecture of Openraft;
  • Threading describes the threading model of Openraft;

Finally, the archived and discarded documents:

• obsolete describes obsolete design documents and why they are discarded;
  • blank-log-heartbeeat;
  • fast-commit;

Re-exports

• pub extern crate openraft_macros;
• pub use crate::async_runtime::AsyncRuntime;
• pub use crate::async_runtime::TokioRuntime;
• pub use crate::entry::Entry;
• pub use crate::entry::EntryPayload;
• pub use crate::instant::Instant;
• pub use crate::instant::TokioInstant;
• pub use crate::log_id::LogId;
• pub use crate::log_id::LogIdOptionExt;
• pub use crate::log_id::LogIndexOptionExt;
• pub use crate::log_id::RaftLogId;
• pub use crate::metrics::RaftMetrics;
• pub use crate::network::RPCTypes;
• pub use crate::network::RaftNetwork;
• pub use crate::network::RaftNetworkFactory;
• pub use crate::raft::Raft;
• pub use crate::storage::LogState;
• pub use crate::storage::RaftLogReader;
• pub use crate::storage::RaftSnapshotBuilder;
• pub use crate::storage::Snapshot;
• pub use crate::storage::SnapshotMeta;
• pub use crate::storage::StorageHelper;
• pub use anyerror;

Modules

• async_runtime
  async runtime interface.
• compat
  This mod is a upgrade helper that provides functionalities for a newer openraft application to read data written by an older application.
• docs
  Openraft Document
• entry
  The default log entry type that implements RaftEntry.
• error
  Error types exposed by this crate.
• impls
  Collection of implementations of usually used traits defined by Openraft
• instant
  A trait for time instants.
• log_id
  This mod defines the identity of a raft log and provides supporting utilities to work with log id related types.
• metrics
  Raft metrics for observability.
• network
  The Raft network interface.
• raft
  Public Raft interface and data types.
• storage
  The Raft storage interface and data types.
• testing
  Testing utilities for OpenRaft.

Macros

• declare_raft_types
  Define types for a Raft type configuration.

Structs

• AnyError
  AnyError is a serializable wrapper Error.
• BasicNode
  An implementation of trait Node that contains minimal node information.
• Config
  The runtime configuration for a Raft node.
• DefensiveError
  An error that occurs when the RaftStore impl runs defensive check of input or output. E.g. re-applying an log entry is a violation that may be a potential bug.
• EffectiveMembership
  The currently active membership config.
• EmptyNode
  EmptyNode is an implementation of trait Node that contains nothing.
• LeaderId
  LeaderId is identifier of a leader.
• Membership
  The membership configuration of the cluster.
• MembershipState
  The state of membership configs a raft node needs to know.
• RaftState
  A struct used to represent the raft state which a Raft node needs.
• SnapshotSegmentId
  The identity of a segment of a snapshot.
• StorageIOError
  Error that occurs when operating the store.
• StoredMembership
  This struct represents information about a membership config that has already been stored in the raft logs.
• Vote
  Vote represent the privilege of a node.

Enums

• ChangeMembers
  Defines various actions to change the membership, including adding or removing learners or voters.
• ConfigError
  Error variants related to configuration.
• ErrorSubject
• ErrorVerb
  What it is doing when an error occurs.
• ServerState
  All possible states of a Raft node.
• SnapshotPolicy
  Log compaction and snapshot policy.
• StorageError
  A storage error could be either a defensive check error or an error occurred when doing the actual io operation.
• Violation
  Violations a store would return when running defensive check.

Traits

• AppData
  A trait defining application specific data.
• AppDataResponse
  A trait defining application specific response data.
• MessageSummary
• Node
  A Raft Node, this trait holds all relevant node information.
• NodeId
  A Raft node’s ID.
• OptionalSend
• OptionalSync
• RaftTypeConfig
  Configuration of types used by the Raft core engine.
• ToStorageResult
  Convert error to StorageError::IO();
• TryAsRef
  Similar to AsRef<T>, it does a cheap reference to reference conversion, but with the ability to return None if it is unable to perform the conversion to &T.

Type Aliases

• CommittedLeaderId
  The unique identifier of a leader that is already granted by a quorum in phase-1(voting).
• SnapshotId
  Id of a snapshot stream.

Attribute Macros

• add_async_trait
  This proc macro attribute optionally adds Send bounds to a trait.