From 4c2e9d987aaef85882c8c2af266742ea82a197c9 Mon Sep 17 00:00:00 2001
From: AhaanKanaujia <kanaujia.ahaan@gmail.com>
Date: Sun, 13 Apr 2025 19:22:41 -0500
Subject: [PATCH] added optimization
---
raft/raft.go | 52 +++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 49 insertions(+), 3 deletions(-)
diff --git a/raft/raft.go b/raft/raft.go
index 3299033..c110a38 100644
--- a/raft/raft.go
+++ b/raft/raft.go
@@ -240,6 +240,9 @@ type AppendEntriesArgs struct {
type AppendEntriesReply struct {
Term int // current term (for leader to update itself)
Success bool // true if follower contained entry matching prevLogIndex and prevLogTerm
+
+ ConflictTerm int // term of conflicting entry
+ ConflictIndex int // index of first entry in log that conflicts with new entries
}
// AppendEntries RPC handler
@@ -252,7 +255,11 @@ func (rf *Raft) AppendEntries(args *AppendEntriesArgs, reply *AppendEntriesReply
defer rf.mu.Unlock()
rf.resetElectionTimer()
+
+ reply.Term = rf.currentTerm
reply.Success = false
+ reply.ConflictTerm = -1
+ reply.ConflictIndex = -1
// candidate term is less than current term
if args.Term < rf.currentTerm {
@@ -274,6 +281,23 @@ func (rf *Raft) AppendEntries(args *AppendEntriesArgs, reply *AppendEntriesReply
return
}
+ // check if log contains entry within log
+ if args.PrevLogIndex >= len(rf.log) {
+ reply.ConflictIndex = len(rf.log)
+ return
+ }
+
+ // check if log entry at precLogIndex does not match prevLogTerm
+ if rf.log[args.PrevLogIndex].Term != args.PrevLogTerm {
+ reply.ConflictTerm = rf.log[args.PrevLogIndex].Term
+ conflictIndex := args.PrevLogIndex
+ for conflictIndex >= 0 && rf.log[conflictIndex].Term == reply.ConflictTerm {
+ conflictIndex--
+ }
+ reply.ConflictIndex = conflictIndex + 1
+ return
+ }
+
// // check if existing entry conflicts with new entries
// // delete any conflicting entries
// for j, entry := range args.Entries {
@@ -318,7 +342,6 @@ func (rf *Raft) AppendEntries(args *AppendEntriesArgs, reply *AppendEntriesReply
}
}
- reply.Term = rf.currentTerm
reply.Success = true
// fmt.Println(rf.me, rf.log)
@@ -425,8 +448,31 @@ func (rf *Raft) sendHeartbeats() {
rf.matchIndex[server] = newMatchIndex
rf.nextIndex[server] = newMatchIndex + 1
} else {
- if rf.nextIndex[server] > 1 {
- rf.nextIndex[server]--
+ // if rf.nextIndex[server] > 1 {
+ // rf.nextIndex[server]--
+ // }
+
+ // optimized nextIndex calculation
+ if reply.ConflictTerm != -1 {
+ conflictTerm := reply.ConflictTerm
+ lastIndexOfTerm := -1
+ for i := len(rf.log) - 1; i >= 0; i-- {
+ if rf.log[i].Term == conflictTerm {
+ lastIndexOfTerm = i
+ break
+ }
+ }
+ if lastIndexOfTerm >= 0 {
+ rf.nextIndex[server] = lastIndexOfTerm + 1
+ } else {
+ rf.nextIndex[server] = reply.ConflictIndex
+ }
+ } else {
+ rf.nextIndex[server] = reply.ConflictIndex
+ }
+
+ if rf.nextIndex[server] < 1 {
+ rf.nextIndex[server] = 1
}
}
--
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