executor: fix data race at the ShowExec (#39817)

close #39816, close #40295

executor/BUILD.bazel

@@ -192,6 +192,7 @@ go_library(
  "//util/servermemorylimit",
  "//util/set",
  "//util/size",
+ "//util/slice",
  "//util/sqlexec",
  "//util/stmtsummary",
  "//util/stringutil",

executor/show.go

@@ -69,6 +69,7 @@ import (
  "github.com/pingcap/tidb/util/memory"
  "github.com/pingcap/tidb/util/sem"
  "github.com/pingcap/tidb/util/set"
+ "github.com/pingcap/tidb/util/slice"
  "github.com/pingcap/tidb/util/sqlexec"
  "github.com/pingcap/tidb/util/stringutil"
  "golang.org/x/exp/slices"
@@ -306,13 +307,14 @@ func (v *visibleChecker) Leave(in ast.Node) (out ast.Node, ok bool) {
 }
 
 func (e *ShowExec) fetchShowBind() error {
- var bindRecords []*bindinfo.BindRecord
+ var tmp []*bindinfo.BindRecord
  if !e.GlobalScope {
  handle := e.ctx.Value(bindinfo.SessionBindInfoKeyType).(*bindinfo.SessionHandle)
- bindRecords = handle.GetAllBindRecord()
+ tmp = handle.GetAllBindRecord()
  } else {
- bindRecords = domain.GetDomain(e.ctx).BindHandle().GetAllBindRecord()
+ tmp = domain.GetDomain(e.ctx).BindHandle().GetAllBindRecord()
  }
+ bindRecords := slice.Copy(tmp)
  // Remove the invalid bindRecord.
  ind := 0
  for _, bindData := range bindRecords {

util/slice/slice.go

@@ -39,3 +39,16 @@ func AllOf(s interface{}, p func(int) bool) bool {
  }
  return NoneOf(s, np)
 }
+
+// Copy is a deep copy of the slice.
+func Copy[T any](a []*T) []*T {
+ b := make([]*T, len(a))
+ for i, p := range a {
+ if p == nil {
+ continue
+ }
+ v := *p
+ b[i] = &v
+ }
+ return b
+}

util/slice/slice_test.go

@@ -43,3 +43,19 @@ func TestSlice(t *testing.T) {
  })
  }
 }
+
+func TestCopy(t *testing.T) {
+ type T int
+ v0, v1, v2, v3 := T(0), T(1), T(2), T(3)
+ s := []*T{&v0, &v1, &v2, &v3, nil}
+ e := Copy(s)
+ require.Equal(t, len(s), len(e))
+ for i := range s {
+ if s[i] == nil {
+ require.Nil(t, e[i])
+ } else {
+ require.Equal(t, *s[i], *e[i])
+ require.True(t, s[i] != e[i])
+ }
+ }
+}