raft

Documentation

Index

• Constants
• func DPrintf(format string, a ...interface{}) (n int, err error)
• type AppendEntriesArgs
• type AppendEntriesReply
• type ApplyMsg
• type InstallSnapArgs
• type InstallSnapReply
• type Log
• type Persister
  • func MakePersister() *Persister
  • func (ps *Persister) Copy() *Persister
  • func (ps *Persister) RaftStateSize() int
  • func (ps *Persister) ReadRaftState() []byte
  • func (ps *Persister) ReadSnapshot() []byte
  • func (ps *Persister) SaveRaftState(state []byte)
  • func (ps *Persister) SaveStateAndSnapshot(state []byte, snapshot []byte)
  • func (ps *Persister) SnapshotSize() int
• type Raft
  • func Make(peers []*labrpc.ClientEnd, me int, persister *Persister, applyCh chan ApplyMsg) *Raft
  • func (rf *Raft) AppendEntries(args AppendEntriesArgs, reply *AppendEntriesReply)
  • func (rf *Raft) GetState() (int, bool)
  • func (rf *Raft) Kill()
  • func (rf *Raft) RequestVote(args RequestVoteArgs, reply *RequestVoteReply)
  • func (rf *Raft) Start(command interface{}) (int, int, bool)
• type RequestVoteArgs
• type RequestVoteReply

Constants

const (
	LEADER = iota
	CANDIDATE
	FOLLOWER
)

const Debug = 0

Debugging

Functions

func DPrintf

func DPrintf(format string, a ...interface{}) (n int, err error)

Types

type AppendEntriesArgs

type AppendEntriesArgs struct {
	Term         int
	LeadID       int
	PrevLogIndex int
	PrevLogTerm  int
	Entries      []Log
	LeaderCommit int
}

type AppendEntriesReply

type AppendEntriesReply struct {
	Term         int
	Success      bool
	NextLogIndex int
}

type ApplyMsg

type ApplyMsg struct {
	CommandIndex int
	Command      interface{}
	CommandValid bool
	UseSnapshot  bool   // ignore for lab2; only used in lab3
	Snapshot     []byte // ignore for lab2; only used in lab3
}

as each Raft peer becomes aware that successive log entries are committed, the peer should send an ApplyMsg to the service (or tester) on the same server, via the applyCh passed to Make().

type InstallSnapArgs

type InstallSnapArgs struct {
	Term              int
	LeaderId          int
	LastIncludedIndex int
	LastIncludedTerm  int
	Offset            int
	Data              []byte
	Done              bool
}

type InstallSnapReply

type InstallSnapReply struct {
	Term int
}

type Log

type Log struct {
	Term    int
	Index   int
	Command interface{}
}

type Persister

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

func MakePersister

func MakePersister() *Persister

func (*Persister) Copy

func (ps *Persister) Copy() *Persister

func (*Persister) RaftStateSize

func (ps *Persister) RaftStateSize() int

func (*Persister) ReadRaftState

func (ps *Persister) ReadRaftState() []byte

func (*Persister) ReadSnapshot

func (ps *Persister) ReadSnapshot() []byte

func (*Persister) SaveRaftState

func (ps *Persister) SaveRaftState(state []byte)

func (*Persister) SaveStateAndSnapshot

func (ps *Persister) SaveStateAndSnapshot(state []byte, snapshot []byte)

Save both Raft state and K/V snapshot as a single atomic action, to help avoid them getting out of sync.

func (*Persister) SnapshotSize

func (ps *Persister) SnapshotSize() int

type Raft

type Raft struct {
	State       int
	VoteCount   int
	CurrentTerm int
	VotedFor    int
	Entry       []Log
	CommitIndex int
	LastApplied int

	NextIndex  []int
	MatchIndex []int

	Heartbeatchan chan bool
	IsLeaderchan  chan bool
	VotedForchan  chan bool
	GrantVotechan chan bool
	CommitLogchan chan bool
	// contains filtered or unexported fields
}

A Go object implementing a single Raft peer.

func Make

func Make(peers []*labrpc.ClientEnd, me int,
	persister *Persister, applyCh chan ApplyMsg) *Raft

the service or tester wants to create a Raft server. the ports of all the Raft servers (including this one) are in peers[]. this server's port is peers[me]. all the servers' peers[] arrays have the same order. persister is a place for this server to save its persistent state, and also initially holds the most recent saved state, if any. applyCh is a channel on which the tester or service expects Raft to send ApplyMsg messages. Make() must return quickly, so it should start goroutines for any long-running work.

func (*Raft) AppendEntries

func (rf *Raft) AppendEntries(args AppendEntriesArgs, reply *AppendEntriesReply)

func (*Raft) GetState

func (rf *Raft) GetState() (int, bool)

return currentTerm and whether this server believes it is the leader.

func (*Raft) Kill

func (rf *Raft) Kill()

the tester calls Kill() when a Raft instance won't be needed again. you are not required to do anything in Kill(), but it might be convenient to (for example) turn off debug output from this instance.

func (*Raft) RequestVote

func (rf *Raft) RequestVote(args RequestVoteArgs, reply *RequestVoteReply)

example RequestVote RPC handler.

func (*Raft) Start

func (rf *Raft) Start(command interface{}) (int, int, bool)

the service using Raft (e.g. a k/v server) wants to start agreement on the next command to be appended to Raft's log. if this server isn't the leader, returns false. otherwise start the agreement and return immediately. there is no guarantee that this command will ever be committed to the Raft log, since the leader may fail or lose an election.

the first return value is the index that the command will appear at if it's ever committed. the second return value is the current term. the third return value is true if this server believes it is the leader.

type RequestVoteArgs

type RequestVoteArgs struct {
	// Your data here.
	Term         int
	CandidateID  int
	LastLogIndex int
	LastLogTerm  int
}

example RequestVote RPC arguments structure. field names must start with capital letters!

type RequestVoteReply

type RequestVoteReply struct {
	// Your data here (2A).
	Term        int
	VoteGranted bool
}

example RequestVote RPC reply structure. field names must start with capital letters!