如果已经把最新的log更新了，那就多等一会，反之，很快就广播AppendEntries(也就是心跳消息)
func (rf *Raft) LeaderState() {
time.Sleep(10 * time.Millisecond)
if rf.LastApplied == rf.CommitIndex {
time.Sleep(25 * time.Millisecond)
}
go rf.BroadcastAppendEntriesRPC()
}
原文：http://www.cnblogs.com/yanchengwang/p/5913777.html