raft

package
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 Go to latest Published: Sep 7, 2020 License: Apache-2.0 Imports: 11 Imported by: 0

Documentation

Overview

Package raft is a distributed consensus package that implements the Raft protocol.

This package is internally used by Dragonboat, applications are not expected to import this package.

Index

Constants

View Source 
const (
	// NoLeader is the flag used to indcate that there is no leader or the leader
	// is unknown.
	NoLeader uint64 = 0
	// NoNode is the flag used to indicate that the node id field is not set.
	NoNode uint64 = 0
)

Variables

View Source 
var ErrCompacted = errors.New("entry compacted")

ErrCompacted is the error returned to indicate that the requested entries are no longer in the LogDB due to compaction.

View Source 
var ErrSnapshotOutOfDate = errors.New("snapshot out of date")

ErrSnapshotOutOfDate is the error returned to indicate that the concerned snapshot is considered as out of date.

View Source 
var ErrUnavailable = errors.New("entry unavailable")

ErrUnavailable is the error returned to indicate that requested entries are not available in LogDB.

Functions

func ClusterID 

func ClusterID(clusterID uint64) string

ClusterID returns a human friendly form of ClusterID for logging purposes.

func IsLocalMessageType 

func IsLocalMessageType(t pb.MessageType) bool

IsLocalMessageType returns a boolean value indicating whether the specified message type is a local message type.

func NodeID 

func NodeID(nodeID uint64) string

NodeID returns a human friendly form of NodeID for logging purposes.

Types

type ILogDB 

type ILogDB interface {
	// GetRange returns the range of the entries in LogDB.
	GetRange() (uint64, uint64)
	// SetRange updates the ILogDB to extend the entry range known to the ILogDB.
	SetRange(index uint64, length uint64)
	// NodeState returns the state of the node persistent in LogDB.
	NodeState() (pb.State, pb.Membership)
	// SetState sets the persistent state known to ILogDB.
	SetState(ps pb.State)
	// CreateSnapshot sets the snapshot known to ILogDB
	CreateSnapshot(ss pb.Snapshot) error
	// ApplySnapshot makes the snapshot known to ILogDB and also update the entry
	// range known to ILogDB.
	ApplySnapshot(ss pb.Snapshot) error
	// Term returns the entry term of the specified entry.
	Term(index uint64) (uint64, error)
	// Entries returns entries between [low, high) with total size of entries
	// limited to maxSize bytes.
	Entries(low uint64, high uint64, maxSize uint64) ([]pb.Entry, error)
	// Snapshot returns the metadata for the most recent snapshot known to the
	// LogDB.
	Snapshot() pb.Snapshot
	// Compact performs entry range compaction on ILogDB up to the entry
	// specified by index.
	Compact(index uint64) error
	// Append makes the given entries known to the ILogDB instance. This is
	// usually not how entries are persisted.
	Append(entries []pb.Entry) error
}

ILogDB is a read-only interface to the underlying persistent storage to allow the raft package to access raft state, entries, snapshots stored in the persistent storage. Entries stored in the persistent storage accessible via ILogDB is usually not required in normal cases.

type LogTestHelper 

type LogTestHelper struct {
	// contains filtered or unexported fields
}

LogTestHelper is a helper type used for testing logEntry.

func NewLog 

func NewLog(logdb ILogDB) *LogTestHelper

NewLog creates and returns a new LogTestHelper instance used for testing purpose.

func (*LogTestHelper) AllEntries 

func (l *LogTestHelper) AllEntries() []pb.Entry

AllEntries ...

func (*LogTestHelper) Append 

func (l *LogTestHelper) Append(ents []pb.Entry) error

Append ...

func (*LogTestHelper) AppliedTo 

func (l *LogTestHelper) AppliedTo(index uint64)

AppliedTo ...

func (*LogTestHelper) CheckBound 

func (l *LogTestHelper) CheckBound(low uint64, high uint64) error

CheckBound ...

func (*LogTestHelper) Entries 

func (l *LogTestHelper) Entries(start uint64,
	maxsize uint64) ([]pb.Entry, error)

Entries ...

func (*LogTestHelper) EntriesToApply 

func (l *LogTestHelper) EntriesToApply() []pb.Entry

EntriesToApply ...

func (*LogTestHelper) EntriesToSave 

func (l *LogTestHelper) EntriesToSave() []pb.Entry

EntriesToSave ...

func (*LogTestHelper) FirstIndex 

func (l *LogTestHelper) FirstIndex() uint64

FirstIndex ...

func (*LogTestHelper) GetCommitted 

func (l *LogTestHelper) GetCommitted() uint64

GetCommitted ...

func (*LogTestHelper) GetConflictIndex 

func (l *LogTestHelper) GetConflictIndex(ents []pb.Entry) uint64

GetConflictIndex ...

func (*LogTestHelper) GetEntries 

func (l *LogTestHelper) GetEntries(low uint64, high uint64,
	maxsize uint64) ([]pb.Entry, error)

GetEntries ...

func (*LogTestHelper) HasEntriesToApply 

func (l *LogTestHelper) HasEntriesToApply() bool

HasEntriesToApply ...

func (*LogTestHelper) LastIndex 

func (l *LogTestHelper) LastIndex() uint64

LastIndex ...

func (*LogTestHelper) MatchTerm 

func (l *LogTestHelper) MatchTerm(index uint64, term uint64) bool

MatchTerm ...

func (*LogTestHelper) SetCommitted 

func (l *LogTestHelper) SetCommitted(v uint64)

SetCommitted ...

func (*LogTestHelper) Term 

func (l *LogTestHelper) Term(index uint64) (uint64, error)

Term ...

func (*LogTestHelper) TryAppend 

func (l *LogTestHelper) TryAppend(index uint64, logTerm uint64,
	committed uint64, ents []pb.Entry) (uint64, bool)

TryAppend ...

func (*LogTestHelper) TryCommit 

func (l *LogTestHelper) TryCommit(index uint64, term uint64) bool

TryCommit ...

func (*LogTestHelper) UnstableOffset 

func (l *LogTestHelper) UnstableOffset() uint64

UnstableOffset ...

func (*LogTestHelper) UpToDate 

func (l *LogTestHelper) UpToDate(index uint64, term uint64) bool

UpToDate ...

type Peer 

type Peer struct {
	// contains filtered or unexported fields
}

Peer is the interface struct for interacting with the underlying Raft protocol implementation.

func Launch 

func Launch(config *config.Config,
	logdb ILogDB, events server.IRaftEventListener,
	addresses []PeerAddress, initial bool, newNode bool) *Peer

Launch starts or restarts a Raft node.

func (*Peer) ApplyConfigChange 

func (p *Peer) ApplyConfigChange(cc pb.ConfigChange)

ApplyConfigChange applies a raft membership change to the local raft node.

func (*Peer) Commit 

func (p *Peer) Commit(ud pb.Update)

Commit commits the Update state to mark it as processed.

func (*Peer) DumpRaftInfoToLog 

func (p *Peer) DumpRaftInfoToLog(addrMap map[uint64]string)

DumpRaftInfoToLog prints the raft state to log for debugging purposes.

func (*Peer) GetUpdate 

func (p *Peer) GetUpdate(moreToApply bool, lastApplied uint64) pb.Update

GetUpdate returns the current state of the Peer.

func (*Peer) Handle 

func (p *Peer) Handle(m pb.Message)

Handle processes the given message.

func (*Peer) HasEntryToApply 

func (p *Peer) HasEntryToApply() bool

HasEntryToApply returns a boolean flag indicating whether there are more entries ready to be applied.

func (*Peer) HasUpdate 

func (p *Peer) HasUpdate(moreEntriesToApply bool) bool

HasUpdate returns a boolean value indicating whether there is any Update ready to be processed.

func (*Peer) NotifyRaftLastApplied 

func (p *Peer) NotifyRaftLastApplied(lastApplied uint64)

NotifyRaftLastApplied passes on the lastApplied index confirmed by the RSM to the raft state machine.

func (*Peer) ProposeConfigChange 

func (p *Peer) ProposeConfigChange(configChange pb.ConfigChange, key uint64)

ProposeConfigChange proposes a raft membership change.

func (*Peer) ProposeEntries 

func (p *Peer) ProposeEntries(ents []pb.Entry)

ProposeEntries proposes specified entries in a batched mode using a single MTPropose message.

func (*Peer) QuiescedTick 

func (p *Peer) QuiescedTick()

QuiescedTick moves the logical clock forward by one tick in quiesced mode.

func (*Peer) RateLimited 

func (p *Peer) RateLimited() bool

RateLimited returns a boolean flag indicating whether the Raft node is rate limited.

func (*Peer) ReadIndex 

func (p *Peer) ReadIndex(ctx pb.SystemCtx)

ReadIndex starts a ReadIndex operation. The ReadIndex protocol is defined in the section 6.4 of the Raft thesis.

func (*Peer) RejectConfigChange 

func (p *Peer) RejectConfigChange()

RejectConfigChange rejects the currently pending raft membership change.

func (*Peer) ReportSnapshotStatus 

func (p *Peer) ReportSnapshotStatus(nodeID uint64, reject bool)

ReportSnapshotStatus reports the status of the snapshot to the local raft node.

func (*Peer) ReportUnreachableNode 

func (p *Peer) ReportUnreachableNode(nodeID uint64)

ReportUnreachableNode marks the specified node as not reachable.

func (*Peer) RequestLeaderTransfer 

func (p *Peer) RequestLeaderTransfer(target uint64)

RequestLeaderTransfer makes a request to transfer the leadership to the specified target node.

func (*Peer) RestoreRemotes 

func (p *Peer) RestoreRemotes(ss pb.Snapshot)

RestoreRemotes applies the remotes info obtained from the specified snapshot.

func (*Peer) Tick 

func (p *Peer) Tick()

Tick moves the logical clock forward by one tick.

type PeerAddress 

type PeerAddress struct {
	NodeID  uint64
	Address string
}

PeerAddress is the basic info for a peer in the Raft cluster.

type State 

type State uint64

State is the state of a raft node defined in the raft paper, possible states are leader, follower, candidate and observer. Observer is non-voting member node.

func (State) String 

func (st State) String() string

type Status 

type Status struct {
	NodeID    uint64
	ClusterID uint64
	Applied   uint64
	LeaderID  uint64
	NodeState State
	pb.State
}

Status is the struct that captures the status of a raft node.

func (*Status) IsFollower 

func (s *Status) IsFollower() bool

IsFollower returns a boolean value indicating whether the node is a follower.

func (*Status) IsLeader 

func (s *Status) IsLeader() bool

IsLeader returns a boolean value indicating whether the node is leader.

Source Files

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