raft: separate MaxCommittedSizePerReady config from MaxSizePerMsg

raft/log.go

@@ -39,7 +39,9 @@ type raftLog struct {
 
 	logger Logger
 
-	maxMsgSize uint64
+	// maxNextEntsSize is the maximum number aggregate byte size of the messages
+	// returned from calls to nextEnts.
+	maxNextEntsSize uint64
 }
 
 // newLog returns log using the given storage and default options. It
@@ -51,14 +53,14 @@ func newLog(storage Storage, logger Logger) *raftLog {
 
 // newLogWithSize returns a log using the given storage and max
 // message size.
-func newLogWithSize(storage Storage, logger Logger, maxMsgSize uint64) *raftLog {
+func newLogWithSize(storage Storage, logger Logger, maxNextEntsSize uint64) *raftLog {
 	if storage == nil {
 		log.Panic("storage must not be nil")
 	}
 	log := &raftLog{
-		storage:    storage,
-		logger:     logger,
-		maxMsgSize: maxMsgSize,
+		storage:         storage,
+		logger:          logger,
+		maxNextEntsSize: maxNextEntsSize,
 	}
 	firstIndex, err := storage.FirstIndex()
 	if err != nil {
@@ -149,7 +151,7 @@ func (l *raftLog) unstableEntries() []pb.Entry {
 func (l *raftLog) nextEnts() (ents []pb.Entry) {
 	off := max(l.applied+1, l.firstIndex())
 	if l.committed+1 > off {
-		ents, err := l.slice(off, l.committed+1, l.maxMsgSize)
+		ents, err := l.slice(off, l.committed+1, l.maxNextEntsSize)
 		if err != nil {
 			l.logger.Panicf("unexpected error when getting unapplied entries (%v)", err)
 		}

raft/node_test.go

@@ -894,7 +894,7 @@ func TestAppendPagination(t *testing.T) {
 func TestCommitPagination(t *testing.T) {
 	s := NewMemoryStorage()
 	cfg := newTestConfig(1, []uint64{1}, 10, 1, s)
-	cfg.MaxSizePerMsg = 2048
+	cfg.MaxCommittedSizePerReady = 2048
 	r := newRaft(cfg)
 	n := newNode()
 	go n.run(r)

raft/raft.go

@@ -154,6 +154,9 @@ type Config struct {
 	// throughput during normal replication. Note: math.MaxUint64 for unlimited,
 	// 0 for at most one entry per message.
 	MaxSizePerMsg uint64
+	// MaxCommittedSizePerReady limits the size of the committed entries which
+	// can be applied.
+	MaxCommittedSizePerReady uint64
 	// MaxUncommittedEntriesSize limits the aggregate byte size of the
 	// uncommitted entries that may be appended to a leader's log. Once this
 	// limit is exceeded, proposals will begin to return ErrProposalDropped
@@ -224,6 +227,12 @@ func (c *Config) validate() error {
 		c.MaxUncommittedEntriesSize = noLimit
 	}
 
+	// default MaxCommittedSizePerReady to MaxSizePerMsg because they were
+	// previously the same parameter.
+	if c.MaxCommittedSizePerReady == 0 {
+		c.MaxCommittedSizePerReady = c.MaxSizePerMsg
+	}
+
 	if c.MaxInflightMsgs <= 0 {
 		return errors.New("max inflight messages must be greater than 0")
 	}
@@ -316,7 +325,7 @@ func newRaft(c *Config) *raft {
 	if err := c.validate(); err != nil {
 		panic(err.Error())
 	}
-	raftlog := newLogWithSize(c.Storage, c.Logger, c.MaxSizePerMsg)
+	raftlog := newLogWithSize(c.Storage, c.Logger, c.MaxCommittedSizePerReady)
 	hs, cs, err := c.Storage.InitialState()
 	if err != nil {
 		panic(err) // TODO(bdarnell)