From bc1e228980d68c4fbdfce58090486fe803b27a73 Mon Sep 17 00:00:00 2001
From: Lily Tsai <tslilyai@mit.edu>
Date: Tue, 23 Feb 2021 12:07:54 -0800
Subject: [PATCH] update

---
 src/raft/config.go | 19 ++++++++++++++++---
 1 file changed, 16 insertions(+), 3 deletions(-)

diff --git a/src/raft/config.go b/src/raft/config.go
index 6ff73cc..73b34c5 100644
--- a/src/raft/config.go
+++ b/src/raft/config.go
@@ -127,8 +127,9 @@ func (cfg *config) crash1(i int) {
 
 	if cfg.saved[i] != nil {
 		raftlog := cfg.saved[i].ReadRaftState()
+		snapshot := cfg.saved[i].ReadSnapshot()
 		cfg.saved[i] = &Persister{}
-		cfg.saved[i].SaveRaftState(raftlog)
+		cfg.saved[i].SaveStateAndSnapshot(raftlog, snapshot)
 	}
 }
 
@@ -178,8 +179,11 @@ const SnapShotInterval = 10
 
 // periodically snapshot raft state
 func (cfg *config) applierSnap(i int, applyCh chan ApplyMsg) {
+	lastApplied := 0
 	for m := range applyCh {
 		if m.SnapshotValid {
+			//DPrintf("Installsnapshot %v %v\n", m.SnapshotIndex, lastApplied)
+			cfg.mu.Lock()
 			if cfg.rafts[i].CondInstallSnapshot(m.SnapshotTerm,
 				m.SnapshotIndex, m.Snapshot) {
 				cfg.logs[i] = make(map[int]interface{})
@@ -190,8 +194,11 @@ func (cfg *config) applierSnap(i int, applyCh chan ApplyMsg) {
 					log.Fatalf("decode error\n")
 				}
 				cfg.logs[i][m.SnapshotIndex] = v
+				lastApplied = m.SnapshotIndex
 			}
-		} else if m.CommandValid {
+			cfg.mu.Unlock()
+		} else if m.CommandValid && m.CommandIndex > lastApplied {
+			//DPrintf("apply %v lastApplied %v\n", m.CommandIndex, lastApplied)
 			cfg.mu.Lock()
 			err_msg, prevok := cfg.checkLogs(i, m)
 			cfg.mu.Unlock()
@@ -204,6 +211,7 @@ func (cfg *config) applierSnap(i int, applyCh chan ApplyMsg) {
 				// keep reading after error so that Raft doesn't block
 				// holding locks...
 			}
+			lastApplied = m.CommandIndex
 			if (m.CommandIndex+1)%SnapShotInterval == 0 {
 				w := new(bytes.Buffer)
 				e := labgob.NewEncoder(w)
@@ -212,7 +220,12 @@ func (cfg *config) applierSnap(i int, applyCh chan ApplyMsg) {
 				cfg.rafts[i].Snapshot(m.CommandIndex, w.Bytes())
 			}
 		} else {
-			// ignore other types of ApplyMsg
+			// Ignore other types of ApplyMsg or old
+			// commands. Old command may never happen,
+			// depending on the Raft implementation, but
+			// just in case.
+			// DPrintf("Ignore: Index %v lastApplied %v\n", m.CommandIndex, lastApplied)
+
 		}
 	}
 }