tracker: remove unused OptimisticUpdate method

Signed-off-by: Pavel Kalinnikov <pavel@cockroachlabs.com>

Author: pav-kv

raft_test.go

@@ -2901,7 +2901,7 @@ func TestRecvMsgUnreachable(t *testing.T) {
 	// set node 2 to state replicate
 	r.trk.Progress[2].Match = 3
 	r.trk.Progress[2].BecomeReplicate()
-	r.trk.Progress[2].OptimisticUpdate(5)
+	r.trk.Progress[2].Next = 6
 
 	r.Step(pb.Message{From: 2, To: 1, Type: pb.MsgUnreachable})
 

tracker/progress.go

@@ -190,10 +190,6 @@ func (pr *Progress) MaybeUpdate(n uint64) bool {
 	return updated
 }
 
-// OptimisticUpdate signals that appends all the way up to and including index n
-// are in-flight. As a result, Next is increased to n+1.
-func (pr *Progress) OptimisticUpdate(n uint64) { pr.Next = n + 1 }
-
 // MaybeDecrTo adjusts the Progress to the receipt of a MsgApp rejection. The
 // arguments are the index of the append message rejected by the follower, and
 // the hint that we want to decrease to.