sink(ticdc): store checkpointTs by flushedResolvedTsMap in mysql sink

close pingcap#5107

cdc/sink/common/common.go

@@ -111,39 +111,46 @@ func (c *UnresolvedTxnCache) Append(filter *filter.Filter, rows ...*model.RowCha
 func (c *UnresolvedTxnCache) Resolved(resolvedTsMap *sync.Map) (map[model.TableID]uint64, map[model.TableID][]*model.SingleTableTxn) {
 	c.unresolvedTxnsMu.Lock()
 	defer c.unresolvedTxnsMu.Unlock()
-	if len(c.unresolvedTxns) == 0 {
-		return nil, nil
-	}
 
 	return splitResolvedTxn(resolvedTsMap, c.unresolvedTxns)
 }
 
 func splitResolvedTxn(
 	resolvedTsMap *sync.Map, unresolvedTxns map[model.TableID][]*txnsWithTheSameCommitTs,
-) (flushedResolvedTsMap map[model.TableID]uint64, resolvedRowsMap map[model.TableID][]*model.SingleTableTxn) {
+) (checkpointTsMap map[model.TableID]uint64, resolvedRowsMap map[model.TableID][]*model.SingleTableTxn) {
+	var (
+		ok                              bool
+		txnsLength                      int
+		txns                            []*txnsWithTheSameCommitTs
+		resolvedTxnsWithTheSameCommitTs []*txnsWithTheSameCommitTs
+	)
+
+	checkpointTsMap = make(map[model.TableID]uint64, len(unresolvedTxns))
+	resolvedTsMap.Range(func(k, v interface{}) bool {
+		tableID := k.(model.TableID)
+		resolvedTs := v.(model.Ts)
+		checkpointTsMap[tableID] = resolvedTs
+		return true
+	})
+
 	resolvedRowsMap = make(map[model.TableID][]*model.SingleTableTxn, len(unresolvedTxns))
-	flushedResolvedTsMap = make(map[model.TableID]uint64, len(unresolvedTxns))
-	for tableID, txns := range unresolvedTxns {
-		v, ok := resolvedTsMap.Load(tableID)
-		if !ok {
+	for tableID, resolvedTs := range checkpointTsMap {
+		if txns, ok = unresolvedTxns[tableID]; !ok {
 			continue
 		}
-		resolvedTs := v.(uint64)
 		i := sort.Search(len(txns), func(i int) bool {
 			return txns[i].commitTs > resolvedTs
 		})
 		if i == 0 {
 			continue
 		}
-		var resolvedTxnsWithTheSameCommitTs []*txnsWithTheSameCommitTs
 		if i == len(txns) {
 			resolvedTxnsWithTheSameCommitTs = txns
 			delete(unresolvedTxns, tableID)
 		} else {
 			resolvedTxnsWithTheSameCommitTs = txns[:i]
 			unresolvedTxns[tableID] = txns[i:]
 		}
-		var txnsLength int
 		for _, txns := range resolvedTxnsWithTheSameCommitTs {
 			txnsLength += len(txns.txns)
 		}
@@ -154,7 +161,6 @@ func splitResolvedTxn(
 			}
 		}
 		resolvedRowsMap[tableID] = resolvedTxns
-		flushedResolvedTsMap[tableID] = resolvedTs
 	}
 	return
 }