From 326714a0772e75858c2539242fd935cd6dd9569c Mon Sep 17 00:00:00 2001
From: Minghao Li <castermode@gmail.com>
Date: Tue, 7 Jun 2022 14:35:20 +0800
Subject: [PATCH] fix(sync): snapshot maybe change when sending

---
 source/libs/sync/inc/syncSnapshot.h           | 16 +++++++++-------
 source/libs/sync/src/syncAppendEntriesReply.c | 13 +++++--------
 source/libs/sync/src/syncSnapshot.c           |  4 ++--
 3 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/source/libs/sync/inc/syncSnapshot.h b/source/libs/sync/inc/syncSnapshot.h
index c028e732b8..f9f890aa8a 100644
--- a/source/libs/sync/inc/syncSnapshot.h
+++ b/source/libs/sync/inc/syncSnapshot.h
@@ -39,8 +39,8 @@ typedef struct SSyncSnapshotSender {
   bool       start;
   int32_t    seq;
   int32_t    ack;
-  void *     pReader;
-  void *     pCurrentBlock;
+  void      *pReader;
+  void      *pCurrentBlock;
   int32_t    blockLen;
   SSnapshot  snapshot;
   int64_t    sendingMS;
@@ -50,20 +50,22 @@ typedef struct SSyncSnapshotSender {
   bool       finish;
 } SSyncSnapshotSender;
 
+void snapshotSenderDoStart(SSyncSnapshotSender *pSender);
+
 SSyncSnapshotSender *snapshotSenderCreate(SSyncNode *pSyncNode, int32_t replicaIndex);
 void                 snapshotSenderDestroy(SSyncSnapshotSender *pSender);
 void                 snapshotSenderStart(SSyncSnapshotSender *pSender);
 void                 snapshotSenderStop(SSyncSnapshotSender *pSender);
 int32_t              snapshotSend(SSyncSnapshotSender *pSender);
 int32_t              snapshotReSend(SSyncSnapshotSender *pSender);
-cJSON *              snapshotSender2Json(SSyncSnapshotSender *pSender);
-char *               snapshotSender2Str(SSyncSnapshotSender *pSender);
+cJSON               *snapshotSender2Json(SSyncSnapshotSender *pSender);
+char                *snapshotSender2Str(SSyncSnapshotSender *pSender);
 
 typedef struct SSyncSnapshotReceiver {
   bool start;
 
   int32_t  ack;
-  void *   pWriter;
+  void    *pWriter;
   SyncTerm term;
 
   SSyncNode *pSyncNode;
@@ -74,8 +76,8 @@ SSyncSnapshotReceiver *snapshotReceiverCreate(SSyncNode *pSyncNode, int32_t repl
 void                   snapshotReceiverDestroy(SSyncSnapshotReceiver *pReceiver);
 void                   snapshotReceiverStart(SSyncSnapshotReceiver *pReceiver);
 void                   snapshotReceiverStop(SSyncSnapshotReceiver *pReceiver);
-cJSON *                snapshotReceiver2Json(SSyncSnapshotReceiver *pReceiver);
-char *                 snapshotReceiver2Str(SSyncSnapshotReceiver *pReceiver);
+cJSON                 *snapshotReceiver2Json(SSyncSnapshotReceiver *pReceiver);
+char                  *snapshotReceiver2Str(SSyncSnapshotReceiver *pReceiver);
 
 int32_t syncNodeOnSnapshotSendCb(SSyncNode *ths, SyncSnapshotSend *pMsg);
 int32_t syncNodeOnSnapshotRspCb(SSyncNode *ths, SyncSnapshotRsp *pMsg);
diff --git a/source/libs/sync/src/syncAppendEntriesReply.c b/source/libs/sync/src/syncAppendEntriesReply.c
index 82b462eacd..47e76dab4c 100644
--- a/source/libs/sync/src/syncAppendEntriesReply.c
+++ b/source/libs/sync/src/syncAppendEntriesReply.c
@@ -174,18 +174,15 @@ int32_t syncNodeOnAppendEntriesReplySnapshotCb(SSyncNode* ths, SyncAppendEntries
         }
         ASSERT(pSender != NULL);
 
-        // calculate sentryIndex
         SyncIndex sentryIndex;
-        if (pSender->start) {
+        if (pSender->start && pSender->term == ths->pRaftStore->currentTerm) {
+          // already start
           sentryIndex = pSender->snapshot.lastApplyIndex;
 
         } else {
-          // start send snapshot
-          if (!(pSender->term == ths->pRaftStore->currentTerm && pSender->finish == true)) {
-            snapshotSenderStart(pSender);
-          } else {
-            sInfo("snapshot send finish, send_term:%lu, current_term:%lu", pSender->term, ths->pRaftStore->currentTerm);
-          }
+          // start send snapshot, first time
+          snapshotSenderDoStart(pSender);
+          pSender->start = true;
           sentryIndex = pSender->snapshot.lastApplyIndex;
         }
 
diff --git a/source/libs/sync/src/syncSnapshot.c b/source/libs/sync/src/syncSnapshot.c
index 36388e6d6a..4df955083b 100644
--- a/source/libs/sync/src/syncSnapshot.c
+++ b/source/libs/sync/src/syncSnapshot.c
@@ -19,7 +19,7 @@
 #include "syncUtil.h"
 #include "wal.h"
 
-static void snapshotSenderDoStart(SSyncSnapshotSender *pSender);
+// static void snapshotSenderDoStart(SSyncSnapshotSender *pSender);
 static void snapshotReceiverDoStart(SSyncSnapshotReceiver *pReceiver);
 
 SSyncSnapshotSender *snapshotSenderCreate(SSyncNode *pSyncNode, int32_t replicaIndex) {
@@ -59,7 +59,7 @@ void snapshotSenderDestroy(SSyncSnapshotSender *pSender) {
 }
 
 // begin send snapshot (current term, seq begin)
-static void snapshotSenderDoStart(SSyncSnapshotSender *pSender) {
+void snapshotSenderDoStart(SSyncSnapshotSender *pSender) {
   pSender->term = pSender->pSyncNode->pRaftStore->currentTerm;
   pSender->seq = SYNC_SNAPSHOT_SEQ_BEGIN;
   pSender->ack = SYNC_SNAPSHOT_SEQ_INVALID;