172 lines
3.8 KiB
Go
172 lines
3.8 KiB
Go
package raft
|
|
|
|
import (
|
|
"sync"
|
|
"sync/atomic"
|
|
)
|
|
|
|
// RaftState captures the state of a Raft node: Follower, Candidate, Leader,
|
|
// or Shutdown.
|
|
type RaftState uint32
|
|
|
|
const (
|
|
// Follower is the initial state of a Raft node.
|
|
Follower RaftState = iota
|
|
|
|
// Candidate is one of the valid states of a Raft node.
|
|
Candidate
|
|
|
|
// Leader is one of the valid states of a Raft node.
|
|
Leader
|
|
|
|
// Shutdown is the terminal state of a Raft node.
|
|
Shutdown
|
|
)
|
|
|
|
func (s RaftState) String() string {
|
|
switch s {
|
|
case Follower:
|
|
return "Follower"
|
|
case Candidate:
|
|
return "Candidate"
|
|
case Leader:
|
|
return "Leader"
|
|
case Shutdown:
|
|
return "Shutdown"
|
|
default:
|
|
return "Unknown"
|
|
}
|
|
}
|
|
|
|
// raftState is used to maintain various state variables
|
|
// and provides an interface to set/get the variables in a
|
|
// thread safe manner.
|
|
type raftState struct {
|
|
// currentTerm commitIndex, lastApplied, must be kept at the top of
|
|
// the struct so they're 64 bit aligned which is a requirement for
|
|
// atomic ops on 32 bit platforms.
|
|
|
|
// The current term, cache of StableStore
|
|
currentTerm uint64
|
|
|
|
// Highest committed log entry
|
|
commitIndex uint64
|
|
|
|
// Last applied log to the FSM
|
|
lastApplied uint64
|
|
|
|
// protects 4 next fields
|
|
lastLock sync.Mutex
|
|
|
|
// Cache the latest snapshot index/term
|
|
lastSnapshotIndex uint64
|
|
lastSnapshotTerm uint64
|
|
|
|
// Cache the latest log from LogStore
|
|
lastLogIndex uint64
|
|
lastLogTerm uint64
|
|
|
|
// Tracks running goroutines
|
|
routinesGroup sync.WaitGroup
|
|
|
|
// The current state
|
|
state RaftState
|
|
}
|
|
|
|
func (r *raftState) getState() RaftState {
|
|
stateAddr := (*uint32)(&r.state)
|
|
return RaftState(atomic.LoadUint32(stateAddr))
|
|
}
|
|
|
|
func (r *raftState) setState(s RaftState) {
|
|
stateAddr := (*uint32)(&r.state)
|
|
atomic.StoreUint32(stateAddr, uint32(s))
|
|
}
|
|
|
|
func (r *raftState) getCurrentTerm() uint64 {
|
|
return atomic.LoadUint64(&r.currentTerm)
|
|
}
|
|
|
|
func (r *raftState) setCurrentTerm(term uint64) {
|
|
atomic.StoreUint64(&r.currentTerm, term)
|
|
}
|
|
|
|
func (r *raftState) getLastLog() (index, term uint64) {
|
|
r.lastLock.Lock()
|
|
index = r.lastLogIndex
|
|
term = r.lastLogTerm
|
|
r.lastLock.Unlock()
|
|
return
|
|
}
|
|
|
|
func (r *raftState) setLastLog(index, term uint64) {
|
|
r.lastLock.Lock()
|
|
r.lastLogIndex = index
|
|
r.lastLogTerm = term
|
|
r.lastLock.Unlock()
|
|
}
|
|
|
|
func (r *raftState) getLastSnapshot() (index, term uint64) {
|
|
r.lastLock.Lock()
|
|
index = r.lastSnapshotIndex
|
|
term = r.lastSnapshotTerm
|
|
r.lastLock.Unlock()
|
|
return
|
|
}
|
|
|
|
func (r *raftState) setLastSnapshot(index, term uint64) {
|
|
r.lastLock.Lock()
|
|
r.lastSnapshotIndex = index
|
|
r.lastSnapshotTerm = term
|
|
r.lastLock.Unlock()
|
|
}
|
|
|
|
func (r *raftState) getCommitIndex() uint64 {
|
|
return atomic.LoadUint64(&r.commitIndex)
|
|
}
|
|
|
|
func (r *raftState) setCommitIndex(index uint64) {
|
|
atomic.StoreUint64(&r.commitIndex, index)
|
|
}
|
|
|
|
func (r *raftState) getLastApplied() uint64 {
|
|
return atomic.LoadUint64(&r.lastApplied)
|
|
}
|
|
|
|
func (r *raftState) setLastApplied(index uint64) {
|
|
atomic.StoreUint64(&r.lastApplied, index)
|
|
}
|
|
|
|
// Start a goroutine and properly handle the race between a routine
|
|
// starting and incrementing, and exiting and decrementing.
|
|
func (r *raftState) goFunc(f func()) {
|
|
r.routinesGroup.Add(1)
|
|
go func() {
|
|
defer r.routinesGroup.Done()
|
|
f()
|
|
}()
|
|
}
|
|
|
|
func (r *raftState) waitShutdown() {
|
|
r.routinesGroup.Wait()
|
|
}
|
|
|
|
// getLastIndex returns the last index in stable storage.
|
|
// Either from the last log or from the last snapshot.
|
|
func (r *raftState) getLastIndex() uint64 {
|
|
r.lastLock.Lock()
|
|
defer r.lastLock.Unlock()
|
|
return max(r.lastLogIndex, r.lastSnapshotIndex)
|
|
}
|
|
|
|
// getLastEntry returns the last index and term in stable storage.
|
|
// Either from the last log or from the last snapshot.
|
|
func (r *raftState) getLastEntry() (uint64, uint64) {
|
|
r.lastLock.Lock()
|
|
defer r.lastLock.Unlock()
|
|
if r.lastLogIndex >= r.lastSnapshotIndex {
|
|
return r.lastLogIndex, r.lastLogTerm
|
|
}
|
|
return r.lastSnapshotIndex, r.lastSnapshotTerm
|
|
}
|