/
timers.go
255 lines (211 loc) · 7.5 KB
/
timers.go
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package main
/*
@Author: Bhaskar S
@Blog: https://www.polarsparc.com
@Date: 22 Aug 2020
*/
import (
"fmt"
"time"
)
// Goroutine - Executed by all the nodes
func StartRaftTimer(node *RaftNode) {
fmt.Printf("++ [%s] Election timer duration %d\n", node.Addr, node.Duration)
_ = node.Log.Open() // Initialize the replication log
// Election timer
ed := time.Duration(node.Duration) * time.Millisecond
et := time.NewTimer(ed)
go func() {
fmt.Printf("++ [%s] Election timer started @ %v\n", node.Addr, time.Now())
for {
select {
case <-et.C: // Election timer event
//fmt.Printf("++ [%s] ***** Election timer triggered @ %v\n", node.Addr, time.Now())
HandleElectionTimeout(node)
// Reset should always be invoked on stopped or expired channels
et.Reset(ed)
case msg := <-node.PeerC: // Handle peer events
flag := false
switch msg.(type) {
case RequestVote: // From a Candidate peer
//fmt.Printf("++ [%s] ***** Received RequestVote @ %v\n", node.Addr, time.Now())
HandleRequestVote(node, msg.(RequestVote))
flag = true
case GrantVote: // From a Follower peer
//fmt.Printf("++ [%s] ***** Received GrantVote @ %v\n", node.Addr, time.Now())
HandleGrantVote(node, msg.(GrantVote))
flag = true
case Heartbeat: // From a Leader peer
//fmt.Printf("++ [%s] ***** Received Heartbeat @ %v\n", node.Addr, time.Now())
HandleHeartbeat(node, msg.(Heartbeat))
flag = true
case AppendEntries: // From a Leader peer
//fmt.Printf("++ [%s] ***** Received AppendEntries @ %v\n", node.Addr, time.Now())
HandleAppendEntries(node, msg.(AppendEntries))
flag = true
case CommitAck: // From a Follower peer
//fmt.Printf("++ [%s] ***** Received CommitAck @ %v\n", node.Addr, time.Now())
HandleCommitAck(node, msg.(CommitAck))
flag = true
default:
flag = false
}
//fmt.Printf("++ [%s] Reset flag - %v @ %v\n", node.Addr, flag, time.Now())
if flag {
//fmt.Printf("++ [%s] ----- Resetting Election timer @ %v\n", node.Addr, time.Now())
// Stop the current et and re-initialize a new et
if !et.Stop() {
<-et.C
}
et = time.NewTimer(ed)
}
case msg := <-node.LeaderC: // Handle client events
switch msg.(type) {
case ClientUpdate: // From a client
//fmt.Printf("++ [%s] ***** Received ClientUpdate @ %v\n", node.Addr, time.Now())
HandleClientUpdate(node, msg.(ClientUpdate))
default:
fmt.Printf("++ [%s] ***** Received Unknown Event @ %v\n", node.Addr, time.Now())
}
}
}
}()
}
// Goroutine - Only started on the Leader peer
func StartHeartbeatTimer(node *RaftNode) {
fmt.Printf("++ [%s] Heartbeat timer duration %d\n", node.Addr, HeartbeatDuration)
// Heartbeat timer
hd := time.Duration(HeartbeatDuration) * time.Millisecond
ht := time.NewTimer(hd)
go func() {
for {
<-ht.C
if node.IsLeader() {
fmt.Printf("++ [%s] Heartbeat timer - {Term: %d, Index: %d, Committed: %d}\n",
node.Addr, node.CurrentTerm, node.CurrentIndex, node.CommittedIndex)
if !sendHeartbeat(node) {
ht.Stop()
break
}
} else {
fmt.Printf("-- [%s] Heartbeat timer - NOT Leader, terminating Heartbeat timer @ %v\n",
node.Addr, time.Now())
ht.Stop()
nodeStateReset(false, node)
break
}
// Reset should always be invoked on stopped or expired channels
ht.Reset(hd)
}
}()
}
func HandleElectionTimeout(node *RaftNode) {
fmt.Printf("++ [%s] Election timeout - {Type: %s, IsLeaderOk: %v, GrantedVote: %v, LastHB: %v}\n",
node.Addr, node.GetType(), node.isLeaderOk(), node.GrantedVote, node.LastHB)
// No leader yet ???
if node.IsFollower() && !node.isLeaderOk() && !node.GrantedVote {
fmt.Printf("++ [%s] Election timeout - Follower ready to start Leader election\n", node.Addr)
nodeStateReset(false, node)
node.ToCandidate()
node.VotesAck.IncrementYes(node.Addr, node.Addr) // Self vote YES
rv := NewRequestVote(node.CurrentTerm+1, node.CurrentIndex, node.Addr)
b := Serialize(*node, rv)
if len(b) > 0 {
count := 1 // Self count
for _, addr := range node.PeerAddr {
if SendToPeer(*node, addr, b) {
count++
}
}
// No Quorum of Peers ???
if count < node.QuorumCount() {
fmt.Printf("-- [%s] Election timeout - No QUORUM of Peer connections, RESET back to Follower\n",
node.Addr)
node.SetCurrentTerm(rv.Term)
nodeStateReset(false, node)
}
}
} else if node.IsCandidate() {
yes := 1 // Self Ack YES
no := 0
for _, addr := range node.PeerAddr {
yes += node.VotesAck.GetYes(addr, node.Addr)
no += node.VotesAck.GetNo(addr, node.Addr)
}
fmt.Printf("++ [%s] Election timeout - Candidate {Votes: [YES: %d, NO: %d], Quorum: %d}\n",
node.Addr, yes, no, node.QuorumCount())
if yes >= node.QuorumCount() {
fmt.Printf("++ [%s] Election timeout - Candidate PROMOTED to Leader\n", node.Addr)
node.SetCurrentTerm(node.CurrentTerm + 1)
node.SetLeaderAddr(node.Addr)
nodeStateReset(true, node)
sendHeartbeat(node)
StartHeartbeatTimer(node)
} else {
if node.VotesCycles >= MaxWaitCycles {
fmt.Printf("-- [%s] Election timeout - Maxed wait cycles - Election FAILED, " +
"Candidate RESET to Follower\n", node.Addr)
node.IncrDuration()
nodeStateReset(false, node)
} else {
node.IncrVoteCycles()
}
}
} else if node.IsLeader() && node.CurrentIndex != node.CommittedIndex {
clients := node.ClientC.Clients()
//fmt.Printf("++ [%s] Election timeout - Leader {Clients: %v}\n", node.Addr, clients)
for _, addr := range clients {
yes := 1 // Self Ack YES
no := 0
for _, peer := range node.PeerAddr {
yes += node.CommitAck.GetYes(addr, peer)
no += node.CommitAck.GetNo(addr, peer)
}
fmt.Printf("++ [%s] Election timeout - Leader {Client: [%s], Votes: [YES: %d, NO: %d], Quorum: %d}\n",
node.Addr, addr, yes, no, node.QuorumCount())
if yes >= node.QuorumCount() {
fmt.Printf("++ [%s] Election timeout - Leader ACCEPTED update {Client: [%s], Index: %d}\n",
node.Addr, addr, node.CurrentIndex)
ua := NewUpdateAck(true, addr, node.Addr)
node.ClientC[addr] <-ua
commitAckReset(node, addr)
node.SetCommittedIndex(node.CurrentIndex)
} else {
if node.CommitCycles.Count(addr) >= MaxWaitCycles {
fmt.Printf("-- [%s] Election timeout - Maxed wait cycles, Leader REJECTED "+
"update {Client: [%s], Index: %d, Committed: %d}\n",
node.Addr, addr, node.CurrentIndex, node.CommittedIndex)
ua := NewUpdateAck(false, addr, node.Addr)
node.ClientC[addr] <-ua
commitAckReset(node, addr)
} else {
node.CommitCycles.Increment(addr)
}
}
}
} else {
if node.GrantedVote {
nodeStateReset(false, node)
}
}
}
// To be executed by the Follower nodes
func HandleHeartbeat(node *RaftNode, msg Heartbeat) {
fmt.Printf("++ [%s] Heartbeat event - {Term: %d, Index: %d, Leader: [%s]} => " +
"{Term: %d, Index: %d, From: [%s]}\n", node.Addr, node.CurrentTerm, node.CurrentIndex, node.LeaderAddr,
msg.Term, msg.Index, msg.From)
if node.CurrentTerm <= msg.Term {
if node.IsFollower() || node.IsCandidate() {
node.SetLastHB(time.Now())
if node.LeaderAddr != msg.From {
node.SetCurrentTerm(msg.Term)
node.SetLeaderAddr(msg.From)
nodeStateReset(false, node)
}
if node.CurrentIndex < msg.Index {
fmt.Printf("-- [%s] Heartbeat timeout - Node index BEHIND from [%s]\n", node.Addr, msg.From)
sendCommitAck(node, false, true, msg.Term, node.CurrentIndex, msg.From)
}
}
}
}