bump(github.com/benbjohnson/go-raft): d46748244f1f1830a002b8f645342426c5d73e81
This commit is contained in:
Brandon Philips
271
third_party/github.com/benbjohnson/go-raft/peer.go
vendored
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271
third_party/github.com/benbjohnson/go-raft/peer.go
vendored
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package raft
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import (
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"sync"
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"time"
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)
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//------------------------------------------------------------------------------
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//
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// Typedefs
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//
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//------------------------------------------------------------------------------
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// A peer is a reference to another server involved in the consensus protocol.
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type Peer struct {
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server *Server
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name string
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prevLogIndex uint64
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mutex sync.RWMutex
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stopChan chan bool
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heartbeatTimeout time.Duration
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}
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//------------------------------------------------------------------------------
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//
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// Constructor
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//
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//------------------------------------------------------------------------------
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// Creates a new peer.
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func newPeer(server *Server, name string, heartbeatTimeout time.Duration) *Peer {
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return &Peer{
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server: server,
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name: name,
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heartbeatTimeout: heartbeatTimeout,
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}
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}
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//------------------------------------------------------------------------------
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//
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// Accessors
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//
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//------------------------------------------------------------------------------
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// Retrieves the name of the peer.
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func (p *Peer) Name() string {
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return p.name
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}
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// Sets the heartbeat timeout.
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func (p *Peer) setHeartbeatTimeout(duration time.Duration) {
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p.heartbeatTimeout = duration
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}
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//--------------------------------------
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// Prev log index
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//--------------------------------------
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// Retrieves the previous log index.
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func (p *Peer) getPrevLogIndex() uint64 {
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p.mutex.RLock()
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defer p.mutex.RUnlock()
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return p.prevLogIndex
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}
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// Sets the previous log index.
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func (p *Peer) setPrevLogIndex(value uint64) {
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p.mutex.Lock()
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defer p.mutex.Unlock()
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p.prevLogIndex = value
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}
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//------------------------------------------------------------------------------
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//
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// Methods
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//
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//------------------------------------------------------------------------------
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//--------------------------------------
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// Heartbeat
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//--------------------------------------
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// Starts the peer heartbeat.
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func (p *Peer) startHeartbeat() {
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p.stopChan = make(chan bool, 1)
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c := make(chan bool)
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go p.heartbeat(c)
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<-c
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}
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// Stops the peer heartbeat.
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func (p *Peer) stopHeartbeat() {
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// here is a problem
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// the previous stop is no buffer leader may get blocked
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// when heartbeat returns at line 132
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// I make the channel with 1 buffer
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// and try to panic here
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select {
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case p.stopChan <- true:
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default:
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panic("[" + p.server.Name() + "] cannot stop [" + p.Name() + "] heartbeat")
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}
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}
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//--------------------------------------
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// Copying
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//--------------------------------------
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// Clones the state of the peer. The clone is not attached to a server and
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// the heartbeat timer will not exist.
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func (p *Peer) clone() *Peer {
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p.mutex.Lock()
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defer p.mutex.Unlock()
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return &Peer{
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name: p.name,
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prevLogIndex: p.prevLogIndex,
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}
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}
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//--------------------------------------
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// Heartbeat
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//--------------------------------------
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// Listens to the heartbeat timeout and flushes an AppendEntries RPC.
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func (p *Peer) heartbeat(c chan bool) {
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stopChan := p.stopChan
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c <- true
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debugln("peer.heartbeat: ", p.Name(), p.heartbeatTimeout)
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for {
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select {
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case <-stopChan:
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debugln("peer.heartbeat.stop: ", p.Name())
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return
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case <-time.After(p.heartbeatTimeout):
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debugln("peer.heartbeat.run: ", p.Name())
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prevLogIndex := p.getPrevLogIndex()
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entries, prevLogTerm := p.server.log.getEntriesAfter(prevLogIndex, p.server.maxLogEntriesPerRequest)
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if p.server.State() != Leader {
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return
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}
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if entries != nil {
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p.sendAppendEntriesRequest(newAppendEntriesRequest(p.server.currentTerm, prevLogIndex, prevLogTerm, p.server.log.CommitIndex(), p.server.name, entries))
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} else {
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p.sendSnapshotRequest(newSnapshotRequest(p.server.name, p.server.lastSnapshot))
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}
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}
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}
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}
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//--------------------------------------
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// Append Entries
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//--------------------------------------
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// Sends an AppendEntries request to the peer through the transport.
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func (p *Peer) sendAppendEntriesRequest(req *AppendEntriesRequest) {
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traceln("peer.flush.send: ", p.server.Name(), "->", p.Name(), " ", len(req.Entries))
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resp := p.server.Transporter().SendAppendEntriesRequest(p.server, p, req)
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if resp == nil {
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debugln("peer.flush.timeout: ", p.server.Name(), "->", p.Name())
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return
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}
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traceln("peer.flush.recv: ", p.Name())
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// If successful then update the previous log index.
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p.mutex.Lock()
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if resp.Success {
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if len(req.Entries) > 0 {
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p.prevLogIndex = req.Entries[len(req.Entries)-1].Index
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// if peer append a log entry from the current term
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// we set append to true
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if req.Entries[len(req.Entries)-1].Term == p.server.currentTerm {
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resp.append = true
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}
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}
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traceln("peer.flush.success: ", p.server.Name(), "->", p.Name(), "; idx =", p.prevLogIndex)
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// If it was unsuccessful then decrement the previous log index and
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// we'll try again next time.
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} else {
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if resp.CommitIndex >= p.prevLogIndex {
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// we may miss a response from peer
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// so maybe the peer has commited the logs we sent
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// but we did not receive the success reply and did not increase
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// the prevLogIndex
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p.prevLogIndex = resp.CommitIndex
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debugln("peer.flush.commitIndex: ", p.server.Name(), "->", p.Name(), " idx =", p.prevLogIndex)
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} else if p.prevLogIndex > 0 {
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// Decrement the previous log index down until we find a match. Don't
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// let it go below where the peer's commit index is though. That's a
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// problem.
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p.prevLogIndex--
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// if it not enough, we directly decrease to the index of the
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if p.prevLogIndex > resp.Index {
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p.prevLogIndex = resp.Index
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}
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debugln("peer.flush.decrement: ", p.server.Name(), "->", p.Name(), " idx =", p.prevLogIndex)
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}
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}
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p.mutex.Unlock()
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// Attach the peer to resp, thus server can know where it comes from
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resp.peer = p.Name()
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// Send response to server for processing.
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p.server.send(resp)
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}
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// Sends an Snapshot request to the peer through the transport.
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func (p *Peer) sendSnapshotRequest(req *SnapshotRequest) {
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debugln("peer.snap.send: ", p.name)
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resp := p.server.Transporter().SendSnapshotRequest(p.server, p, req)
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if resp == nil {
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debugln("peer.snap.timeout: ", p.name)
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return
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}
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debugln("peer.snap.recv: ", p.name)
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// If successful, the peer should have been to snapshot state
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// Send it the snapshot!
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if resp.Success {
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p.sendSnapshotRecoveryRequest()
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} else {
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debugln("peer.snap.failed: ", p.name)
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return
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}
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}
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// Sends an Snapshot Recovery request to the peer through the transport.
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func (p *Peer) sendSnapshotRecoveryRequest() {
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req := newSnapshotRecoveryRequest(p.server.name, p.server.lastSnapshot)
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debugln("peer.snap.recovery.send: ", p.name)
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resp := p.server.Transporter().SendSnapshotRecoveryRequest(p.server, p, req)
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if resp.Success {
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p.prevLogIndex = req.LastIndex
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} else {
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debugln("peer.snap.recovery.failed: ", p.name)
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return
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}
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// Send response to server for processing.
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p.server.send(&AppendEntriesResponse{Term: resp.Term, Success: resp.Success, append: (resp.Term == p.server.currentTerm)})
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}
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//--------------------------------------
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// Vote Requests
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//--------------------------------------
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// send VoteRequest Request
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func (p *Peer) sendVoteRequest(req *RequestVoteRequest, c chan *RequestVoteResponse) {
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debugln("peer.vote: ", p.server.Name(), "->", p.Name())
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req.peer = p
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if resp := p.server.Transporter().SendVoteRequest(p.server, p, req); resp != nil {
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debugln("peer.vote: recv", p.server.Name(), "<-", p.Name())
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resp.peer = p
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c <- resp
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}
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}
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