From 246b91edd49a7b86cd592cab3c636ba1ff855f0d Mon Sep 17 00:00:00 2001
From: Maxwell <passagesfall@gmail.com>
Date: Wed, 27 Nov 2019 12:57:07 +0800
Subject: [PATCH] meta: refine error code for package `meta` (#13654)

---
 domain/domain_test.go |  2 +-
 meta/meta.go          | 32 ++++++++++++--------------------
 meta/meta_test.go     |  5 +++++
 3 files changed, 18 insertions(+), 21 deletions(-)

diff --git a/domain/domain_test.go b/domain/domain_test.go
index 9890cf6f72456..9e6e6d9fddace 100644
--- a/domain/domain_test.go
+++ b/domain/domain_test.go
@@ -268,7 +268,7 @@ func (*testSuite) TestT(c *C) {
 	m, err := dom.GetSnapshotMeta(snapTS)
 	c.Assert(err, IsNil)
 	tblInfo1, err := m.GetTable(dbInfo.ID, tbl.Meta().ID)
-	c.Assert(err.Error(), Equals, meta.ErrDBNotExists.Error())
+	c.Assert(meta.ErrDBNotExists.Equal(err), IsTrue)
 	c.Assert(tblInfo1, IsNil)
 	m, err = dom.GetSnapshotMeta(currSnapTS)
 	c.Assert(err, IsNil)
diff --git a/meta/meta.go b/meta/meta.go
index 289be03042c60..4c10e30cff46a 100644
--- a/meta/meta.go
+++ b/meta/meta.go
@@ -68,13 +68,13 @@ var (
 
 var (
 	// ErrDBExists is the error for db exists.
-	ErrDBExists = terror.ClassMeta.New(codeDatabaseExists, "database already exists")
+	ErrDBExists = terror.ClassMeta.New(mysql.ErrDBCreateExists, mysql.MySQLErrName[mysql.ErrDBCreateExists])
 	// ErrDBNotExists is the error for db not exists.
-	ErrDBNotExists = terror.ClassMeta.New(codeDatabaseNotExists, "database doesn't exist")
+	ErrDBNotExists = terror.ClassMeta.New(mysql.ErrBadDB, mysql.MySQLErrName[mysql.ErrBadDB])
 	// ErrTableExists is the error for table exists.
-	ErrTableExists = terror.ClassMeta.New(codeTableExists, "table already exists")
+	ErrTableExists = terror.ClassMeta.New(mysql.ErrTableExists, mysql.MySQLErrName[mysql.ErrTableExists])
 	// ErrTableNotExists is the error for table not exists.
-	ErrTableNotExists = terror.ClassMeta.New(codeTableNotExists, "table doesn't exist")
+	ErrTableNotExists = terror.ClassMeta.New(mysql.ErrNoSuchTable, mysql.MySQLErrName[mysql.ErrNoSuchTable])
 )
 
 // Meta is for handling meta information in a transaction.
@@ -194,7 +194,7 @@ func (m *Meta) GenSchemaVersion() (int64, error) {
 func (m *Meta) checkDBExists(dbKey []byte) error {
 	v, err := m.txn.HGet(mDBs, dbKey)
 	if err == nil && v == nil {
-		err = ErrDBNotExists
+		err = ErrDBNotExists.GenWithStack("database doesn't exist")
 	}
 	return errors.Trace(err)
 }
@@ -202,7 +202,7 @@ func (m *Meta) checkDBExists(dbKey []byte) error {
 func (m *Meta) checkDBNotExists(dbKey []byte) error {
 	v, err := m.txn.HGet(mDBs, dbKey)
 	if err == nil && v != nil {
-		err = ErrDBExists
+		err = ErrDBExists.GenWithStack("database already exists")
 	}
 	return errors.Trace(err)
 }
@@ -210,7 +210,7 @@ func (m *Meta) checkDBNotExists(dbKey []byte) error {
 func (m *Meta) checkTableExists(dbKey []byte, tableKey []byte) error {
 	v, err := m.txn.HGet(dbKey, tableKey)
 	if err == nil && v == nil {
-		err = ErrTableNotExists
+		err = ErrTableNotExists.GenWithStack("table doesn't exist")
 	}
 	return errors.Trace(err)
 }
@@ -218,7 +218,7 @@ func (m *Meta) checkTableExists(dbKey []byte, tableKey []byte) error {
 func (m *Meta) checkTableNotExists(dbKey []byte, tableKey []byte) error {
 	v, err := m.txn.HGet(dbKey, tableKey)
 	if err == nil && v != nil {
-		err = ErrTableExists
+		err = ErrTableExists.GenWithStack("table already exists")
 	}
 	return errors.Trace(err)
 }
@@ -817,20 +817,12 @@ func (m *Meta) SetSchemaDiff(diff *model.SchemaDiff) error {
 	return errors.Trace(err)
 }
 
-// meta error codes.
-const (
-	codeDatabaseExists    terror.ErrCode = 1007
-	codeDatabaseNotExists terror.ErrCode = 1049
-	codeTableExists       terror.ErrCode = 1050
-	codeTableNotExists    terror.ErrCode = 1146
-)
-
 func init() {
 	metaMySQLErrCodes := map[terror.ErrCode]uint16{
-		codeDatabaseExists:    mysql.ErrDBCreateExists,
-		codeDatabaseNotExists: mysql.ErrBadDB,
-		codeTableNotExists:    mysql.ErrNoSuchTable,
-		codeTableExists:       mysql.ErrTableExists,
+		mysql.ErrDBCreateExists: mysql.ErrDBCreateExists,
+		mysql.ErrBadDB:          mysql.ErrBadDB,
+		mysql.ErrNoSuchTable:    mysql.ErrNoSuchTable,
+		mysql.ErrTableExists:    mysql.ErrTableExists,
 	}
 	terror.ErrClassToMySQLCodes[terror.ClassMeta] = metaMySQLErrCodes
 }
diff --git a/meta/meta_test.go b/meta/meta_test.go
index c130580292edb..8c8c23f0e0b57 100644
--- a/meta/meta_test.go
+++ b/meta/meta_test.go
@@ -97,6 +97,7 @@ func (s *testSuite) TestMeta(c *C) {
 
 	err = t.CreateDatabase(dbInfo)
 	c.Assert(err, NotNil)
+	c.Assert(meta.ErrDBExists.Equal(err), IsTrue)
 
 	v, err := t.GetDatabase(1)
 	c.Assert(err, IsNil)
@@ -131,6 +132,7 @@ func (s *testSuite) TestMeta(c *C) {
 
 	err = t.CreateTableOrView(1, tbInfo)
 	c.Assert(err, NotNil)
+	c.Assert(meta.ErrTableExists.Equal(err), IsTrue)
 
 	tbInfo.Name = model.NewCIStr("tt")
 	err = t.UpdateTable(1, tbInfo)
@@ -193,11 +195,13 @@ func (s *testSuite) TestMeta(c *C) {
 	nonExistentID := int64(1234)
 	_, err = t.GenAutoTableID(currentDBID, nonExistentID, 10)
 	c.Assert(err, NotNil)
+	c.Assert(meta.ErrTableNotExists.Equal(err), IsTrue)
 	// Fail to update auto ID.
 	// The current database ID doesn't exist.
 	currentDBID = nonExistentID
 	_, err = t.GenAutoTableID(currentDBID, tid, 10)
 	c.Assert(err, NotNil)
+	c.Assert(meta.ErrDBNotExists.Equal(err), IsTrue)
 	// Test case for CreateTableAndSetAutoID.
 	tbInfo3 := &model.TableInfo{
 		ID:   3,
@@ -290,6 +294,7 @@ func (s *testSuite) TestSnapshot(c *C) {
 	c.Assert(n, Equals, int64(1))
 	_, err = snapMeta.GenGlobalID()
 	c.Assert(err, NotNil)
+	c.Assert(err.Error(), Equals, "[structure:5]write on snapshot")
 }
 
 func (s *testSuite) TestDDL(c *C) {