From b118c02aa86af407357b34ebcd3e17e2dc33e8e1 Mon Sep 17 00:00:00 2001
From: Ti Chi Robot <ti-community-prow-bot@tidb.io>
Date: Thu, 18 Jan 2024 16:55:47 +0800
Subject: [PATCH] puller(ticdc):  fix resolvedTs get stuck when region split
 and merge (#10488) (#10494)

ref pingcap/tiflow#10157
---
 cdc/puller/frontier/frontier.go      |  3 ++-
 cdc/puller/frontier/frontier_test.go | 19 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/cdc/puller/frontier/frontier.go b/cdc/puller/frontier/frontier.go
index 46a18e547f1..983808ad598 100644
--- a/cdc/puller/frontier/frontier.go
+++ b/cdc/puller/frontier/frontier.go
@@ -84,7 +84,7 @@ func (s *spanFrontier) Frontier() uint64 {
 func (s *spanFrontier) Forward(regionID uint64, span regionspan.ComparableSpan, ts uint64) {
 	// it's the fast part to detect if the region is split or merged,
 	// if not we can update the minTsHeap with use new ts directly
-	if n, ok := s.cachedRegions[regionID]; ok && n.regionID != fakeRegionID && n.end != nil {
+	if n, ok := s.cachedRegions[regionID]; ok && n.regionID == regionID && n.end != nil {
 		if bytes.Equal(n.Key(), span.Start) && bytes.Equal(n.End(), span.End) {
 			s.minTsHeap.UpdateKey(n.Value(), ts)
 			return
@@ -106,6 +106,7 @@ func (s *spanFrontier) insert(regionID uint64, span regionspan.ComparableSpan, t
 	if next != nil {
 		if bytes.Equal(seekRes.Node().Key(), span.Start) && bytes.Equal(next.Key(), span.End) {
 			s.minTsHeap.UpdateKey(seekRes.Node().Value(), ts)
+			delete(s.cachedRegions, seekRes.Node().regionID)
 			if regionID != fakeRegionID {
 				s.cachedRegions[regionID] = seekRes.Node()
 				s.cachedRegions[regionID].regionID = regionID
diff --git a/cdc/puller/frontier/frontier_test.go b/cdc/puller/frontier/frontier_test.go
index ca1daefb377..d621f463b50 100644
--- a/cdc/puller/frontier/frontier_test.go
+++ b/cdc/puller/frontier/frontier_test.go
@@ -15,6 +15,7 @@ package frontier
 
 import (
 	"bytes"
+	"fmt"
 	"math"
 	"math/rand"
 	"sort"
@@ -437,3 +438,21 @@ func TestFrontierEntries(t *testing.T) {
 	require.Equal(t, []byte("a"), slowestRange.Start)
 	require.Equal(t, []byte("b"), slowestRange.End)
 }
+
+func TestMergeSpitWithDifferentRegionID(t *testing.T) {
+	frontier := NewFrontier(100, c, regionspan.ComparableSpan{Start: []byte("a"), End: []byte("c")})
+	frontier.Forward(1, regionspan.ComparableSpan{Start: []byte("a"), End: []byte("b")}, 1222)
+	frontier.Forward(2, regionspan.ComparableSpan{Start: []byte("b"), End: []byte("c")}, 102)
+	frontier.Forward(4, regionspan.ComparableSpan{Start: []byte("b"), End: []byte("c")}, 103)
+	frontier.Forward(1, regionspan.ComparableSpan{Start: []byte("a"), End: []byte("c")}, 104)
+	frontier.Forward(1, regionspan.ComparableSpan{Start: []byte("a"), End: []byte("b")}, 1223)
+	frontier.Forward(3, regionspan.ComparableSpan{Start: []byte("b"), End: []byte("c")}, 105)
+	frontier.Forward(2, regionspan.ComparableSpan{Start: []byte("b"), End: []byte("c")}, 107)
+	frontier.(*spanFrontier).spanList.Entries(func(node *skipListNode) bool {
+		fmt.Printf("%d:[%s: %s) %d\n", node.regionID,
+			string(node.Key()),
+			string(node.End()), node.value.key)
+		return true
+	})
+	require.Equal(t, uint64(107), frontier.Frontier())
+}