session: make min start ts reporter aware of internal session from `g…

…et_lock()` (#38790) (#38828)

close #38706

session/advisory_locks.go

@@ -49,7 +49,7 @@ func (a *advisoryLock) DecrReferences() {
 	a.referenceCount--
 }
 
-// References returns the current reference count for the advisory lock.
+// ReferenceCount returns the current reference count for the advisory lock.
 func (a *advisoryLock) ReferenceCount() int {
 	return a.referenceCount
 }

session/session.go

@@ -65,6 +65,7 @@ import (
 	"github.com/pingcap/tidb/config"
 	"github.com/pingcap/tidb/ddl/placement"
 	"github.com/pingcap/tidb/domain"
+	"github.com/pingcap/tidb/domain/infosync"
 	"github.com/pingcap/tidb/errno"
 	"github.com/pingcap/tidb/executor"
 	"github.com/pingcap/tidb/infoschema"
@@ -1615,10 +1616,11 @@ func (s *session) GetAdvisoryLock(lockName string, timeout int64) error {
 		lock.IncrReferences()
 		return nil
 	}
-	sess, err := createSession(s.GetStore())
+	sess, err := createSession(s.store)
 	if err != nil {
 		return err
 	}
+	infosync.StoreInternalSession(sess)
 	lock := &advisoryLock{session: sess, ctx: context.TODO()}
 	err = lock.GetLock(lockName, timeout)
 	if err != nil {
@@ -1640,6 +1642,7 @@ func (s *session) ReleaseAdvisoryLock(lockName string) (released bool) {
 		if lock.ReferenceCount() <= 0 {
 			lock.Close()
 			delete(s.advisoryLocks, lockName)
+			infosync.DeleteInternalSession(lock.session)
 		}
 		return true
 	}
@@ -1656,6 +1659,7 @@ func (s *session) ReleaseAllAdvisoryLocks() int {
 		lock.Close()
 		count += lock.ReferenceCount()
 		delete(s.advisoryLocks, lockName)
+		infosync.DeleteInternalSession(lock.session)
 	}
 	return count
 }
@@ -2976,6 +2980,10 @@ func createSessions(store kv.Storage, cnt int) ([]*session, error) {
 	return ses, nil
 }
 
+// createSession creates a new session.
+// Please note that such a session is not tracked by the internal session list.
+// This means the min ts reporter is not aware of it and may report a wrong min start ts.
+// In most cases you should use a session pool in domain instead.
 func createSession(store kv.Storage) (*session, error) {
 	return createSessionWithOpt(store, nil)
 }