tracker: make UpdateOnEntrieSend errorless

The method will not be used in states other than StateProbe or
StateReplicate, so there is little sense in having the error path in it.

Signed-off-by: Pavel Kalinnikov <[email protected]>

raft.go

@@ -627,10 +627,6 @@ func (r *raft) maybeSendAppend(to uint64, sendIfEmpty bool) bool {
 	}
 
 	// Send the actual MsgApp otherwise, and update the progress accordingly.
-	if err := pr.UpdateOnEntriesSend(len(ents), uint64(payloadsSize(ents))); err != nil {
-		r.logger.Panicf("%x: %v", r.id, err)
-	}
-	// NB: pr has been updated, but we make sure to only use its old values below.
 	r.send(pb.Message{
 		To:      to,
 		Type:    pb.MsgApp,
@@ -639,6 +635,7 @@ func (r *raft) maybeSendAppend(to uint64, sendIfEmpty bool) bool {
 		Entries: ents,
 		Commit:  r.raftLog.committed,
 	})
+	pr.UpdateOnEntriesSend(len(ents), uint64(payloadsSize(ents)))
 	return true
 }
 

tracker/progress.go

@@ -152,7 +152,9 @@ func (pr *Progress) BecomeSnapshot(snapshoti uint64) {
 // UpdateOnEntriesSend updates the progress on the given number of consecutive
 // entries being sent in a MsgApp, with the given total bytes size, appended at
 // log indices >= pr.Next.
-func (pr *Progress) UpdateOnEntriesSend(entries int, bytes uint64) error {
+//
+// Must be used with StateProbe or StateReplicate.
+func (pr *Progress) UpdateOnEntriesSend(entries int, bytes uint64) {
 	switch pr.State {
 	case StateReplicate:
 		if entries > 0 {
@@ -170,9 +172,8 @@ func (pr *Progress) UpdateOnEntriesSend(entries int, bytes uint64) error {
 			pr.MsgAppFlowPaused = true
 		}
 	default:
-		return fmt.Errorf("sending append in unhandled state %s", pr.State)
+		panic(fmt.Sprintf("sending append in unhandled state %s", pr.State))
 	}
-	return nil
 }
 
 // MaybeUpdate is called when an MsgAppResp arrives from the follower, with the