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chain.go
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chain.go
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/*
Copyright IBM Corp. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package etcdraft
import (
"context"
"sync"
"sync/atomic"
"time"
"github.com/hyperledger/fabric/common/flogging"
"github.com/hyperledger/fabric/orderer/consensus"
"github.com/hyperledger/fabric/protos/common"
"github.com/hyperledger/fabric/protos/orderer"
"github.com/hyperledger/fabric/protos/utils"
"code.cloudfoundry.org/clock"
"github.com/coreos/etcd/raft"
"github.com/coreos/etcd/raft/raftpb"
"github.com/pkg/errors"
)
// Storage is currently backed by etcd/raft.MemoryStorage. This interface is
// defined to expose dependencies of fsm so that it may be swapped in the
// future. TODO(jay) Add other necessary methods to this interface once we need
// them in implementation, e.g. ApplySnapshot.
type Storage interface {
raft.Storage
Append(entries []raftpb.Entry) error
}
// Options contains all the configurations relevant to the chain.
type Options struct {
RaftID uint64
Clock clock.Clock
Storage Storage
Logger *flogging.FabricLogger
TickInterval time.Duration
ElectionTick int
HeartbeatTick int
MaxSizePerMsg uint64
MaxInflightMsgs int
Peers []raft.Peer
}
// Chain implements consensus.Chain interface.
type Chain struct {
raftID uint64
submitC chan *orderer.SubmitRequest
commitC chan *common.Block
observeC chan<- uint64 // Notifies external observer on leader change
haltC chan struct{}
doneC chan struct{}
clock clock.Clock
support consensus.ConsenterSupport
leaderLock sync.RWMutex
leader uint64
appliedIndex uint64
node raft.Node
storage Storage
opts Options
logger *flogging.FabricLogger
}
// NewChain returns a new chain.
func NewChain(support consensus.ConsenterSupport, opts Options, observe chan<- uint64) (*Chain, error) {
return &Chain{
raftID: opts.RaftID,
submitC: make(chan *orderer.SubmitRequest),
commitC: make(chan *common.Block),
haltC: make(chan struct{}),
doneC: make(chan struct{}),
observeC: observe,
support: support,
clock: opts.Clock,
logger: opts.Logger.With("channel", support.ChainID()),
storage: opts.Storage,
opts: opts,
}, nil
}
// Start instructs the orderer to begin serving the chain and keep it current.
func (c *Chain) Start() {
config := &raft.Config{
ID: c.raftID,
ElectionTick: c.opts.ElectionTick,
HeartbeatTick: c.opts.HeartbeatTick,
MaxSizePerMsg: c.opts.MaxSizePerMsg,
MaxInflightMsgs: c.opts.MaxInflightMsgs,
Logger: c.logger,
Storage: c.opts.Storage,
}
c.node = raft.StartNode(config, c.opts.Peers)
go c.serveRaft()
go c.serveRequest()
}
// Order submits normal type transactions for ordering.
func (c *Chain) Order(env *common.Envelope, configSeq uint64) error {
return c.Submit(&orderer.SubmitRequest{LastValidationSeq: configSeq, Content: env}, 0)
}
// Configure submits config type transactions for ordering.
func (c *Chain) Configure(env *common.Envelope, configSeq uint64) error {
c.logger.Panicf("Configure not implemented yet")
return nil
}
// WaitReady is currently a no-op.
func (c *Chain) WaitReady() error {
return nil
}
// Errored returns a channel that closes when the chain stops.
func (c *Chain) Errored() <-chan struct{} {
return c.doneC
}
// Halt stops the chain.
func (c *Chain) Halt() {
select {
case c.haltC <- struct{}{}:
case <-c.doneC:
return
}
<-c.doneC
}
// Submit forwards the incoming request to:
// - the local serveRequest goroutine if this is leader
// - the actual leader via the transport mechanism
// The call fails if there's no leader elected yet.
func (c *Chain) Submit(req *orderer.SubmitRequest, sender uint64) error {
c.leaderLock.RLock()
defer c.leaderLock.RUnlock()
if c.leader == raft.None {
return errors.Errorf("no raft leader")
}
if c.leader == c.raftID {
select {
case c.submitC <- req:
return nil
case <-c.doneC:
return errors.Errorf("chain is stopped")
}
}
// TODO forward request to actual leader when we implement multi-node raft
return errors.Errorf("only single raft node is currently supported")
}
func (c *Chain) serveRequest() {
ticking := false
timer := c.clock.NewTimer(time.Second)
// we need a stopped timer rather than nil,
// because we will be select waiting on timer.C()
if !timer.Stop() {
<-timer.C()
}
// if timer is already started, this is a no-op
start := func() {
if !ticking {
ticking = true
timer.Reset(c.support.SharedConfig().BatchTimeout())
}
}
stop := func() {
if !timer.Stop() && ticking {
// we only need to drain the channel if the timer expired (not explicitly stopped)
<-timer.C()
}
ticking = false
}
for {
seq := c.support.Sequence()
select {
case msg := <-c.submitC:
if c.isConfig(msg.Content) {
c.logger.Panicf("Processing config envelope is not implemented yet")
}
if msg.LastValidationSeq < seq {
if _, err := c.support.ProcessNormalMsg(msg.Content); err != nil {
c.logger.Warningf("Discarding bad normal message: %s", err)
continue
}
}
batches, _ := c.support.BlockCutter().Ordered(msg.Content)
if len(batches) == 0 {
start()
continue
}
stop()
if err := c.commitBatches(batches...); err != nil {
c.logger.Errorf("Failed to commit block: %s", err)
}
case <-timer.C():
ticking = false
batch := c.support.BlockCutter().Cut()
if len(batch) == 0 {
c.logger.Warningf("Batch timer expired with no pending requests, this might indicate a bug")
continue
}
c.logger.Debugf("Batch timer expired, creating block")
if err := c.commitBatches(batch); err != nil {
c.logger.Errorf("Failed to commit block: %s", err)
}
case <-c.doneC:
c.logger.Infof("Stop serving requests")
return
}
}
}
func (c *Chain) commitBatches(batches ...[]*common.Envelope) error {
for _, batch := range batches {
b := c.support.CreateNextBlock(batch)
data := utils.MarshalOrPanic(b)
if err := c.node.Propose(context.TODO(), data); err != nil {
return errors.Errorf("failed to propose data to raft: %s", err)
}
select {
case block := <-c.commitC:
if utils.IsConfigBlock(block) {
c.logger.Panicf("Config block is not supported yet")
}
c.support.WriteBlock(block, nil)
case <-c.doneC:
return nil
}
}
return nil
}
func (c *Chain) serveRaft() {
ticker := c.clock.NewTicker(c.opts.TickInterval)
for {
select {
case <-ticker.C():
c.node.Tick()
case rd := <-c.node.Ready():
c.storage.Append(rd.Entries)
// TODO send messages to other peers when we implement multi-node raft
c.apply(c.entriesToApply(rd.CommittedEntries))
c.node.Advance()
if rd.SoftState != nil {
c.leaderLock.Lock()
newLead := atomic.LoadUint64(&rd.SoftState.Lead)
if newLead != c.leader {
c.logger.Infof("Raft leader changed on node %x: %x -> %x", c.raftID, c.leader, newLead)
c.leader = newLead
// notify external observer
select {
case c.observeC <- newLead:
default:
}
}
c.leaderLock.Unlock()
}
case <-c.haltC:
close(c.doneC)
ticker.Stop()
c.node.Stop()
c.logger.Infof("Raft node %x stopped", c.raftID)
return
}
}
}
func (c *Chain) apply(ents []raftpb.Entry) {
for i := range ents {
switch ents[i].Type {
case raftpb.EntryNormal:
if len(ents[i].Data) == 0 {
break
}
c.commitC <- utils.UnmarshalBlockOrPanic(ents[i].Data)
case raftpb.EntryConfChange:
var cc raftpb.ConfChange
if err := cc.Unmarshal(ents[i].Data); err != nil {
c.logger.Warnf("Failed to unmarshal ConfChange data: %s", err)
continue
}
c.node.ApplyConfChange(cc)
}
c.appliedIndex = ents[i].Index
}
}
// this is taken from coreos/contrib/raftexample/raft.go
func (c *Chain) entriesToApply(ents []raftpb.Entry) (nents []raftpb.Entry) {
if len(ents) == 0 {
return
}
firstIdx := ents[0].Index
if firstIdx > c.appliedIndex+1 {
c.logger.Panicf("first index of committed entry[%d] should <= progress.appliedIndex[%d]+1", firstIdx, c.appliedIndex)
}
// If we do have unapplied entries in nents.
// | applied | unapplied |
// |----------------|----------------------|
// firstIdx appliedIndex last
if c.appliedIndex-firstIdx+1 < uint64(len(ents)) {
nents = ents[c.appliedIndex-firstIdx+1:]
}
return nents
}
func (c *Chain) isConfig(env *common.Envelope) bool {
h, err := utils.ChannelHeader(env)
if err != nil {
c.logger.Panicf("programming error: failed to extract channel header from envelope")
}
return h.Type == int32(common.HeaderType_CONFIG) || h.Type == int32(common.HeaderType_ORDERER_TRANSACTION)
}