config: fix the panic caused by zero RegionSplitSizeMB (#8324) (#8329)

close #8323

Bypass the case that `RegionSplitSizeMB` might be zero in `(*StoreConfig) CheckRegionSize`.

Signed-off-by: ti-chi-bot <[email protected]>
Signed-off-by: JmPotato <[email protected]>

Co-authored-by: JmPotato <[email protected]>

pkg/typeutil/size_test.go

@@ -17,6 +17,7 @@ package typeutil
 import (
 	"encoding/json"
 
+	"github.com/docker/go-units"
 	. "github.com/pingcap/check"
 )
 
@@ -41,23 +42,31 @@ func (s *testSizeSuite) TestJSON(c *C) {
 }
 
 func (s *testSizeSuite) TestParseMbFromText(c *C) {
+	const defaultValue = 2
+
 	testdata := []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 * 1024),
+		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 _, t := range testdata {
 		for _, b := range t.body {
-			c.Assert(int(ParseMBFromText(b, 1)), Equals, int(t.size))
+			c.Assert(ParseMBFromText(b, defaultValue), Equals, t.size)
 		}
 	}
 }

server/config/store_config.go

@@ -129,9 +129,14 @@ 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")

server/config/store_config_test.go

@@ -147,4 +147,8 @@ func (t *testTiKVConfigSuite) TestMergeCheck(c *C) {
 			c.Assert(config.CheckRegionKeys(v.keys, v.mergeKeys), NotNil)
 		}
 	}
+	// Test CheckRegionSize when the region split size is 0.
+	config.RegionSplitSize = "100KiB"
+	c.Assert(config.GetRegionSplitSize(), Equals, uint64(0))
+	c.Assert(config.CheckRegionSize(defaultRegionMaxSize, 50), IsNil)
 }