bug: reset all sequences when mastership is lost

go/vt/vttablet/endtoend/main_test.go

@@ -139,6 +139,9 @@ create table vitess_bool(auto int auto_increment, bval tinyint(1) default 0, sva
 create table vitess_seq(id int default 0, next_id bigint default null, cache bigint default null, increment bigint default null, primary key(id)) comment 'vitess_sequence';
 insert into vitess_seq(id, next_id, cache) values(0, 1, 3);
 
+create table vitess_reset_seq(id int default 0, next_id bigint default null, cache bigint default null, increment bigint default null, primary key(id)) comment 'vitess_sequence';
+insert into vitess_reset_seq(id, next_id, cache) values(0, 1, 3);
+
 create table vitess_part(id int, data varchar(16), primary key(id));
 alter table vitess_part partition by range (id) (partition p0 values less than (10), partition p1 values less than (maxvalue));
 
@@ -200,6 +203,13 @@ var tableACLConfig = `{
       "writers": ["dev"],
       "admins": ["dev"]
     },
+    {
+      "name": "vitess_reset_seq",
+      "table_names_or_prefixes": ["vitess_reset_seq"],
+      "readers": ["dev"],
+      "writers": ["dev"],
+      "admins": ["dev"]
+    },
     {
       "name": "vitess_message",
       "table_names_or_prefixes": ["vitess_message"],

go/vt/vttablet/endtoend/sequence_test.go

@@ -24,6 +24,7 @@ import (
 	"github.com/youtube/vitess/go/vt/vttablet/endtoend/framework"
 
 	querypb "github.com/youtube/vitess/go/vt/proto/query"
+	topodatapb "github.com/youtube/vitess/go/vt/proto/topodata"
 )
 
 func TestSequence(t *testing.T) {
@@ -41,8 +42,7 @@ func TestSequence(t *testing.T) {
 		want.Rows[0][0] = sqltypes.NewInt64(wantval)
 		qr, err := framework.NewClient().Execute("select next 2 values from vitess_seq", nil)
 		if err != nil {
-			t.Error(err)
-			return
+			t.Fatal(err)
 		}
 		if !reflect.DeepEqual(*qr, want) {
 			t.Errorf("Execute: \n%#v, want \n%#v", *qr, want)
@@ -58,11 +58,51 @@ func TestSequence(t *testing.T) {
 	}
 	qr, err := framework.NewClient().Execute("select next_id, cache from vitess_seq", nil)
 	if err != nil {
-		t.Error(err)
-		return
+		t.Fatal(err)
 	}
 	qr.Fields = nil
 	if !reflect.DeepEqual(*qr, want) {
 		t.Errorf("Execute: \n%#v, want \n%#v", *qr, want)
 	}
 }
+
+func TestResetSequence(t *testing.T) {
+	client := framework.NewClient()
+	want := sqltypes.Result{
+		Fields: []*querypb.Field{{
+			Name: "nextval",
+			Type: sqltypes.Int64,
+		}},
+		RowsAffected: 1,
+		Rows: [][]sqltypes.Value{{
+			sqltypes.NewInt64(1),
+		}},
+	}
+	qr, err := client.Execute("select next value from vitess_reset_seq", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(*qr, want) {
+		t.Errorf("Execute: \n%#v, want \n%#v", *qr, want)
+	}
+
+	// Reset mastership
+	err = client.SetServingType(topodatapb.TabletType_REPLICA)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = client.SetServingType(topodatapb.TabletType_MASTER)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Ensure the next value skips previously cached values.
+	want.Rows[0][0] = sqltypes.NewInt64(4)
+	qr, err = client.Execute("select next value from vitess_reset_seq", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(*qr, want) {
+		t.Errorf("Execute: \n%#v, want \n%#v", *qr, want)
+	}
+}

go/vt/vttablet/tabletserver/schema/engine.go

@@ -189,6 +189,22 @@ func (se *Engine) Close() {
 	se.isOpen = false
 }
 
+// MakeNonMaster clears the sequence caches to make sure that
+// they don't get accidentally reused after losing mastership.
+func (se *Engine) MakeNonMaster() {
+	// This function is tested through endtoend test.
+	se.mu.Lock()
+	defer se.mu.Unlock()
+	for _, t := range se.tables {
+		if t.SequenceInfo != nil {
+			t.SequenceInfo.Lock()
+			t.SequenceInfo.NextVal = 0
+			t.SequenceInfo.LastVal = 0
+			t.SequenceInfo.Unlock()
+		}
+	}
+}
+
 // Reload reloads the schema info from the db.
 // Any tables that have changed since the last load are updated.
 // This is a no-op if the Engine is closed.

go/vt/vttablet/tabletserver/tabletserver.go

@@ -466,6 +466,9 @@ func (tsv *TabletServer) serveNewType() (err error) {
 		tsv.te.Close(true)
 		tsv.watcher.Open(tsv.dbconfigs, tsv.mysqld)
 		tsv.txThrottler.Close()
+
+		// Reset the sequences.
+		tsv.se.MakeNonMaster()
 	}
 	tsv.transition(StateServing)
 	return nil