From b5f6ef6ab76b8cb024788e7d0aaa0bad510259da Mon Sep 17 00:00:00 2001
From: JmPotato <ghzpotato@gmail.com>
Date: Tue, 25 Jun 2024 17:52:21 +0800
Subject: [PATCH] This is an automated cherry-pick of #8324

close tikv/pd#8323

Signed-off-by: ti-chi-bot <ti-community-prow-bot@tidb.io>
---
 pkg/schedule/config/store_config_test.go | 75 ++++++++++++++++++++++++
 pkg/utils/typeutil/size_test.go          | 19 ++++--
 server/config/store_config.go            |  9 ++-
 3 files changed, 97 insertions(+), 6 deletions(-)
 create mode 100644 pkg/schedule/config/store_config_test.go

diff --git a/pkg/schedule/config/store_config_test.go b/pkg/schedule/config/store_config_test.go
new file mode 100644
index 00000000000..3f4789a74c9
--- /dev/null
+++ b/pkg/schedule/config/store_config_test.go
@@ -0,0 +1,75 @@
+// Copyright 2022 TiKV Project Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMergeCheck(t *testing.T) {
+	re := require.New(t)
+	testdata := []struct {
+		size      uint64
+		mergeSize uint64
+		keys      uint64
+		mergeKeys uint64
+		pass      bool
+	}{{
+		// case 1: the merged region size is smaller than the max region size
+		size:      96 + 20,
+		mergeSize: 20,
+		keys:      1440000 + 200000,
+		mergeKeys: 200000,
+		pass:      true,
+	}, {
+		// case 2: the smallest region is 68MiB, it can't be merged again.
+		size:      144 + 20,
+		mergeSize: 20,
+		keys:      1440000 + 200000,
+		mergeKeys: 200000,
+		pass:      true,
+	}, {
+		// case 3: the smallest region is 50MiB, it can be merged again.
+		size:      144 + 2,
+		mergeSize: 50,
+		keys:      1440000 + 20000,
+		mergeKeys: 500000,
+		pass:      false,
+	}, {
+		// case4: the smallest region is 51MiB, it can't be merged again.
+		size:      144 + 3,
+		mergeSize: 50,
+		keys:      1440000 + 30000,
+		mergeKeys: 500000,
+		pass:      true,
+	}}
+	config := &StoreConfig{}
+	for _, v := range testdata {
+		if v.pass {
+			re.NoError(config.CheckRegionSize(v.size, v.mergeSize))
+			re.NoError(config.CheckRegionKeys(v.keys, v.mergeKeys))
+		} else {
+			re.Error(config.CheckRegionSize(v.size, v.mergeSize))
+			re.Error(config.CheckRegionKeys(v.keys, v.mergeKeys))
+		}
+	}
+	// Test CheckRegionSize when the region split size is 0.
+	config.RegionSplitSize = "100KiB"
+	config.Adjust()
+	re.Empty(config.GetRegionSplitSize())
+	re.NoError(config.CheckRegionSize(defaultRegionMaxSize, 50))
+}
diff --git a/pkg/utils/typeutil/size_test.go b/pkg/utils/typeutil/size_test.go
index 57c246953e4..1c2aa2b217a 100644
--- a/pkg/utils/typeutil/size_test.go
+++ b/pkg/utils/typeutil/size_test.go
@@ -40,25 +40,36 @@ func TestSizeJSON(t *testing.T) {
 }
 
 func TestParseMbFromText(t *testing.T) {
+<<<<<<< HEAD
 	t.Parallel()
+=======
+	const defaultValue = 2
+
+>>>>>>> 6fbe73796 (config: fix the panic caused by zero RegionSplitSizeMB (#8324))
 	re := require.New(t)
 	testCases := []struct {
 		body []string
 		size uint64
 	}{{
 		body: []string{"10Mib", "10MiB", "10M", "10MB"},
-		size: uint64(10),
+		size: 10,
 	}, {
 		body: []string{"10GiB", "10Gib", "10G", "10GB"},
-		size: uint64(10 * units.GiB / units.MiB),
+		size: 10 * units.GiB / units.MiB,
+	}, {
+		body: []string{"1024KiB", "1048576"},
+		size: 1,
+	}, {
+		body: []string{"100KiB", "1023KiB", "1048575", "0"},
+		size: 0,
 	}, {
 		body: []string{"10yiB", "10aib"},
-		size: uint64(1),
+		size: defaultValue,
 	}}
 
 	for _, testCase := range testCases {
 		for _, b := range testCase.body {
-			re.Equal(int(testCase.size), int(ParseMBFromText(b, 1)))
+			re.Equal(testCase.size, ParseMBFromText(b, defaultValue))
 		}
 	}
 }
diff --git a/server/config/store_config.go b/server/config/store_config.go
index 8f4baa91522..b7ad34a6b51 100644
--- a/server/config/store_config.go
+++ b/server/config/store_config.go
@@ -164,9 +164,14 @@ func (c *StoreConfig) CheckRegionSize(size, mergeSize uint64) error {
 	if size < c.GetRegionMaxSize() {
 		return nil
 	}
-
+	// This could happen when the region split size is set to a value less than 1MiB,
+	// which is a very extreme case, we just pass the check here to prevent panic.
+	regionSplitSize := c.GetRegionSplitSize()
+	if regionSplitSize == 0 {
+		return nil
+	}
 	// the smallest of the split regions can not be merge again, so it's size should less merge size.
-	if smallSize := size % c.GetRegionSplitSize(); smallSize <= mergeSize && smallSize != 0 {
+	if smallSize := size % regionSplitSize; smallSize <= mergeSize && smallSize != 0 {
 		log.Debug("region size is too small", zap.Uint64("size", size), zap.Uint64("merge-size", mergeSize), zap.Uint64("small-size", smallSize))
 		return errs.ErrCheckerMergeAgain.FastGenByArgs("the smallest region of the split regions is less than max-merge-region-size, " +
 			"it will be merged again")