enh: save a copy of snapshot info in syncNodeOnSnapshotPrepRsp

source/libs/sync/src/syncSnapshot.c

@@ -121,6 +121,11 @@ void snapshotSenderDestroy(SSyncSnapshotSender *pSender) {
   if (pSender->pSndBuf) {
     syncSnapBufferDestroy(&pSender->pSndBuf);
   }
+
+  if (pSender->snapshotParam.data) {
+    taosMemoryFree(pSender->snapshotParam.data);
+    pSender->snapshotParam.data = NULL;
+  }
   // free sender
   taosMemoryFree(pSender);
 }
@@ -344,9 +349,6 @@ _out:;
   return code;
 }
 
-// return 0, start ok
-// return 1, last snapshot finish ok
-// return -1, error
 int32_t syncNodeStartSnapshot(SSyncNode *pSyncNode, SRaftId *pDestId) {
   SSyncSnapshotSender *pSender = syncNodeGetSnapshotSender(pSyncNode, pDestId);
   if (pSender == NULL) {
@@ -377,6 +379,7 @@ int32_t syncNodeStartSnapshot(SSyncNode *pSyncNode, SRaftId *pDestId) {
   return 0;
 }
 
+// receiver
 SSyncSnapshotReceiver *snapshotReceiverCreate(SSyncNode *pSyncNode, SRaftId fromId) {
   bool condition = (pSyncNode->pFsm->FpSnapshotStartWrite != NULL) && (pSyncNode->pFsm->FpSnapshotStopWrite != NULL) &&
                    (pSyncNode->pFsm->FpSnapshotDoWrite != NULL);
@@ -506,8 +509,6 @@ void snapshotReceiverStart(SSyncSnapshotReceiver *pReceiver, SyncSnapshotSend *p
   sRInfo(pReceiver, "snapshot receiver start, from dnode:%d.", DID(&pReceiver->fromId));
 }
 
-// just set start = false
-// FpSnapshotStopWrite should not be called
 void snapshotReceiverStop(SSyncSnapshotReceiver *pReceiver) {
   sRDebug(pReceiver, "snapshot receiver stop, not apply, writer:%p", pReceiver->pWriter);
 
@@ -528,7 +529,6 @@ void snapshotReceiverStop(SSyncSnapshotReceiver *pReceiver) {
   syncSnapBufferReset(pReceiver->pRcvBuf);
 }
 
-// when recv last snapshot block, apply data into snapshot
 static int32_t snapshotReceiverFinish(SSyncSnapshotReceiver *pReceiver, SyncSnapshotSend *pMsg) {
   int32_t code = 0;
   if (pReceiver->pWriter != NULL) {
@@ -587,8 +587,6 @@ static int32_t snapshotReceiverFinish(SSyncSnapshotReceiver *pReceiver, SyncSnap
   return 0;
 }
 
-// apply data block
-// update progress
 static int32_t snapshotReceiverGotData(SSyncSnapshotReceiver *pReceiver, SyncSnapshotSend *pMsg) {
   if (pMsg->seq != pReceiver->ack + 1) {
     sRError(pReceiver, "snapshot receiver invalid seq, ack:%d seq:%d", pReceiver->ack, pMsg->seq);
@@ -641,8 +639,8 @@ SyncIndex syncNodeGetSnapBeginIndex(SSyncNode *ths) {
   return snapStart;
 }
 
-static int32_t syncNodeExchangeSnapInfo(SSyncNode *pSyncNode, SSyncSnapshotReceiver *pReceiver, SyncSnapshotSend *pMsg,
+static int32_t syncSnapReceiverExchgSnapInfo(SSyncNode *pSyncNode, SSyncSnapshotReceiver *pReceiver,
-                                        SSnapshot *pInfo) {
+                                             SyncSnapshotSend *pMsg, SSnapshot *pInfo) {
   ASSERT(pMsg->payloadType == TDMT_SYNC_PREP_SNAPSHOT);
   int32_t code = 0;
 
@@ -734,7 +732,7 @@ _SEND_REPLY:;
   SSnapshot snapInfo = {.type = TDMT_SYNC_PREP_SNAPSHOT_REPLY};
   int32_t   dataLen = 0;
   if (pMsg->payloadType == TDMT_SYNC_PREP_SNAPSHOT) {
-    if (syncNodeExchangeSnapInfo(pSyncNode, pReceiver, pMsg, &snapInfo) != 0) {
+    if (syncSnapReceiverExchgSnapInfo(pSyncNode, pReceiver, pMsg, &snapInfo) != 0) {
       goto _out;
     }
     SSyncTLV *datHead = snapInfo.data;
@@ -949,26 +947,6 @@ _SEND_REPLY:;
   return code;
 }
 
-// receiver on message
-//
-// condition 1, recv SYNC_SNAPSHOT_SEQ_PREP
-//              if receiver already start
-//                    if sender.start-time > receiver.start-time, restart receiver(reply snapshot start)
-//                    if sender.start-time = receiver.start-time, maybe duplicate msg
-//                    if sender.start-time < receiver.start-time, ignore
-//              else
-//                    waiting for clock match
-//                    start receiver(reply snapshot start)
-//
-// condition 2, recv SYNC_SNAPSHOT_SEQ_BEGIN
-//              a. create writer with <begin, end>
-//
-// condition 3, recv SYNC_SNAPSHOT_SEQ_END, finish receiver(apply snapshot data, update commit index, maybe reconfig)
-//
-// condition 4, recv SYNC_SNAPSHOT_SEQ_FORCE_CLOSE, force close
-//
-// condition 5, got data, update ack
-//
 int32_t syncNodeOnSnapshot(SSyncNode *pSyncNode, SRpcMsg *pRpcMsg) {
   SyncSnapshotSend **ppMsg = (SyncSnapshotSend **)&pRpcMsg->pCont;
   SyncSnapshotSend      *pMsg = ppMsg[0];
@@ -1052,6 +1030,32 @@ _out:;
   return code;
 }
 
+static int32_t syncSnapSenderExchgSnapInfo(SSyncNode *pSyncNode, SSyncSnapshotSender *pSender, SyncSnapshotRsp *pMsg) {
+  ASSERT(pMsg->payloadType == TDMT_SYNC_PREP_SNAPSHOT_REPLY);
+
+  SSyncTLV *datHead = (void *)pMsg->data;
+  if (datHead->typ != pMsg->payloadType) {
+    sSError(pSender, "unexpected data type in data of SyncSnapshotRsp. typ: %d", datHead->typ);
+    terrno = TSDB_CODE_INVALID_DATA_FMT;
+    return -1;
+  }
+  int32_t dataLen = sizeof(SSyncTLV) + datHead->len;
+
+  SSnapshotParam *pParam = &pSender->snapshotParam;
+  void           *data = taosMemoryRealloc(pParam->data, dataLen);
+  if (data == NULL) {
+    terrno = TSDB_CODE_OUT_OF_MEMORY;
+    return -1;
+  }
+  memcpy(data, pMsg->data, dataLen);
+
+  pParam->data = data;
+  data = NULL;
+  sSInfo(pSender, "data of snapshot param. len: %d", datHead->len);
+  return 0;
+}
+
+// sender
 static int32_t syncNodeOnSnapshotPrepRsp(SSyncNode *pSyncNode, SSyncSnapshotSender *pSender, SyncSnapshotRsp *pMsg) {
   SSnapshot snapshot = {0};
   pSyncNode->pFsm->FpGetSnapshotInfo(pSyncNode->pFsm, &snapshot);
@@ -1068,14 +1072,9 @@ static int32_t syncNodeOnSnapshotPrepRsp(SSyncNode *pSyncNode, SSyncSnapshotSend
 
   // start reader
   if (pMsg->payloadType == TDMT_SYNC_PREP_SNAPSHOT_REPLY) {
-    SSyncTLV *datHead = (void *)pMsg->data;
+    if (syncSnapSenderExchgSnapInfo(pSyncNode, pSender, pMsg) != 0) {
-    if (datHead->typ != pMsg->payloadType) {
-      sSError(pSender, "unexpected data type in data of SyncSnapshotRsp. typ: %d", datHead->typ);
-      terrno = TSDB_CODE_INVALID_DATA_FMT;
       return -1;
     }
-    pSender->snapshotParam.data = (void *)pMsg->data;
-    sSInfo(pSender, "data of snapshot param. len: %d", datHead->len);
   }
 
   int32_t code = pSyncNode->pFsm->FpSnapshotStartRead(pSyncNode->pFsm, &pSender->snapshotParam, &pSender->pReader);
@@ -1160,12 +1159,6 @@ _out:
   return code;
 }
 
-// sender on message
-//
-// condition 1 sender receives SYNC_SNAPSHOT_SEQ_END, close sender
-// condition 2 sender receives ack, set seq = ack + 1, send msg from seq
-// condition 3 sender receives error msg, just print error log
-//
 int32_t syncNodeOnSnapshotRsp(SSyncNode *pSyncNode, SRpcMsg *pRpcMsg) {
   SyncSnapshotRsp **ppMsg = (SyncSnapshotRsp **)&pRpcMsg->pCont;
   SyncSnapshotRsp  *pMsg = ppMsg[0];