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