fix: handle database switch correctly

pkg/boot/discovery.go

@@ -268,10 +268,8 @@ func (fp *discovery) ListNodes(ctx context.Context, tenant, cluster, group strin
 		return nil, nil
 	}
 
-	var nodes []string
-	for i := range bingo.Nodes {
-		nodes = append(nodes, bingo.Nodes[i])
-	}
+	nodes := make([]string, len(bingo.Nodes))
+	copy(nodes, bingo.Nodes)
 
 	return nodes, nil
 }

pkg/constants/mysql/constants.go

@@ -589,8 +589,7 @@ const (
 	// SSNoDatabaseSelected is ER_NO_DB
 	SSNoDatabaseSelected = "3D000"
 
-	// SSSPNotExist is ER_SP_DOES_NOT_EXIST
-	SSSPNotExist = "42000"
+	SS42000 = "42000"
 )
 
 // Status flags. They are returned by the server in a few cases.

pkg/executor/redirect.go

@@ -20,6 +20,7 @@ package executor
 import (
 	"bytes"
 	stdErrors "errors"
+	"fmt"
 	"strings"
 	"sync"
 	"time"
@@ -32,6 +33,8 @@ import (
 	pMysql "github.com/arana-db/parser/mysql"
 
 	"github.com/pkg/errors"
+
+	"golang.org/x/exp/slices"
 )
 
 import (
@@ -77,7 +80,7 @@ func IsErrMissingTx(err error) bool {
 }
 
 type RedirectExecutor struct {
-	localTransactionMap sync.Map // map[uint32]proto.Tx, (ConnectionID,Tx)
+	localTransactionMap sync.Map // map[uint32]proto.Tx, (connectionID,Tx)
 }
 
 func NewRedirectExecutor() *RedirectExecutor {
@@ -89,30 +92,35 @@ func (executor *RedirectExecutor) ProcessDistributedTransaction() bool {
 }
 
 func (executor *RedirectExecutor) InLocalTransaction(ctx *proto.Context) bool {
-	_, ok := executor.localTransactionMap.Load(ctx.ConnectionID)
+	_, ok := executor.localTransactionMap.Load(ctx.C.ID())
 	return ok
 }
 
 func (executor *RedirectExecutor) InGlobalTransaction(ctx *proto.Context) bool {
 	return false
 }
 
-func (executor *RedirectExecutor) ExecuteUseDB(ctx *proto.Context) error {
-	// TODO: check permission, target database should belong to same tenant.
-	// TODO: process transactions when database switched?
+func (executor *RedirectExecutor) ExecuteUseDB(ctx *proto.Context, db string) error {
+	if ctx.C.Schema() == db {
+		return nil
+	}
+
+	clusters := security.DefaultTenantManager().GetClusters(ctx.C.Tenant())
+	if !slices.Contains(clusters, db) {
+		return mysqlErrors.NewSQLError(mConstants.ERBadDb, mConstants.SS42000, fmt.Sprintf("Unknown database '%s'", db))
+	}
+
+	if hasTx := executor.InLocalTransaction(ctx); hasTx {
+		// TODO: should commit existing TX when DB switched
+		log.Debugf("commit tx when db switched: conn=%s", ctx.C)
+	}
+
+	// bind schema
+	ctx.C.SetSchema(db)
+
+	// reset transient variables
+	ctx.C.SetTransientVariables(make(map[string]proto.Value))
 
-	// do nothing.
-	//resourcePool := resource.GetDataSourceManager().GetMasterResourcePool(executor.dataSources[0].Master.Name)
-	//r, err := resourcePool.Get(ctx)
-	//defer func() {
-	//	resourcePool.Put(r)
-	//}()
-	//if err != nil {
-	//	return err
-	//}
-	//backendConn := r.(*mysql.BackendConnection)
-	//db := string(ctx.Data[1:])
-	//return backendConn.WriteComInitDB(db)
 	return nil
 }
 
@@ -121,7 +129,7 @@ func (executor *RedirectExecutor) ExecuteFieldList(ctx *proto.Context) ([]proto.
 	table := string(ctx.Data[1:index])
 	wildcard := string(ctx.Data[index+1:])
 
-	rt, err := runtime.Load(ctx.Schema)
+	rt, err := runtime.Load(ctx.C.Schema())
 	if err != nil {
 		return nil, errors.WithStack(err)
 	}
@@ -141,6 +149,15 @@ func (executor *RedirectExecutor) ExecuteFieldList(ctx *proto.Context) ([]proto.
 }
 
 func (executor *RedirectExecutor) doExecutorComQuery(ctx *proto.Context, act ast.StmtNode) (proto.Result, uint16, error) {
+	// switch DB
+	switch u := act.(type) {
+	case *ast.UseStmt:
+		if err := executor.ExecuteUseDB(ctx, u.DBName); err != nil {
+			return nil, 0, err
+		}
+		return resultx.New(), 0, nil
+	}
+
 	var (
 		start      = time.Now()
 		schemaless bool // true if schema is not specified
@@ -158,23 +175,23 @@ func (executor *RedirectExecutor) doExecutorComQuery(ctx *proto.Context, act ast
 	trace.Extract(ctx, hints)
 	metrics.ParserDuration.Observe(time.Since(start).Seconds())
 
-	if len(ctx.Schema) < 1 {
+	if len(ctx.C.Schema()) < 1 {
 		// TODO: handle multiple clusters
-		clusters := security.DefaultTenantManager().GetClusters(ctx.Tenant)
+		clusters := security.DefaultTenantManager().GetClusters(ctx.C.Tenant())
 		if len(clusters) != 1 {
 			// reject if no schema specified
 			return nil, 0, mysqlErrors.NewSQLError(mConstants.ERNoDb, mConstants.SSNoDatabaseSelected, "No database selected")
 		}
 		schemaless = true
-		ctx.Schema = security.DefaultTenantManager().GetClusters(ctx.Tenant)[0]
+		ctx.C.SetSchema(security.DefaultTenantManager().GetClusters(ctx.C.Tenant())[0])
 	}
 
 	ctx.Stmt = &proto.Stmt{
 		Hints:    hints,
 		StmtNode: act,
 	}
 
-	rt, err := runtime.Load(ctx.Schema)
+	rt, err := runtime.Load(ctx.C.Schema())
 	if err != nil {
 		return nil, 0, err
 	}
@@ -285,7 +302,7 @@ func (executor *RedirectExecutor) ExecutorComQuery(ctx *proto.Context, h func(re
 	query := ctx.GetQuery()
 	log.Debugf("ComQuery: %s", query)
 
-	charset, collation := getCharsetCollation(ctx.CharacterSet)
+	charset, collation := getCharsetCollation(ctx.C.CharacterSet())
 
 	switch strings.IndexByte(query, ';') {
 	case -1: // no ';' exists
@@ -352,7 +369,7 @@ func (executor *RedirectExecutor) ExecutorComStmtExecute(ctx *proto.Context) (pr
 		executable = tx
 	} else {
 		var rt runtime.Runtime
-		if rt, err = runtime.Load(ctx.Schema); err != nil {
+		if rt, err = runtime.Load(ctx.C.Schema()); err != nil {
 			return nil, 0, err
 		}
 		executable = rt
@@ -380,7 +397,7 @@ func (executor *RedirectExecutor) ConnectionClose(ctx *proto.Context) {
 	}
 
 	//resourcePool := resource.GetDataSourceManager().GetMasterResourcePool(executor.dataSources[0].Master.Name)
-	//r, ok := executor.localTransactionMap[ctx.ConnectionID]
+	//r, ok := executor.localTransactionMap[ctx.connectionID]
 	//if ok {
 	//	defer func() {
 	//		resourcePool.Put(r)
@@ -394,19 +411,19 @@ func (executor *RedirectExecutor) ConnectionClose(ctx *proto.Context) {
 }
 
 func (executor *RedirectExecutor) putTx(ctx *proto.Context, tx proto.Tx) {
-	executor.localTransactionMap.Store(ctx.ConnectionID, tx)
+	executor.localTransactionMap.Store(ctx.C.ID(), tx)
 }
 
 func (executor *RedirectExecutor) removeTx(ctx *proto.Context) (proto.Tx, bool) {
-	exist, ok := executor.localTransactionMap.LoadAndDelete(ctx.ConnectionID)
+	exist, ok := executor.localTransactionMap.LoadAndDelete(ctx.C.ID())
 	if !ok {
 		return nil, false
 	}
 	return exist.(proto.Tx), true
 }
 
 func (executor *RedirectExecutor) getTx(ctx *proto.Context) (proto.Tx, bool) {
-	exist, ok := executor.localTransactionMap.Load(ctx.ConnectionID)
+	exist, ok := executor.localTransactionMap.Load(ctx.C.ID())
 	if !ok {
 		return nil, false
 	}

pkg/executor/redirect_test.go

@@ -22,13 +22,16 @@ import (
 )
 
 import (
+	"github.com/golang/mock/gomock"
+
 	"github.com/pkg/errors"
 
 	"github.com/stretchr/testify/assert"
 )
 
 import (
 	"github.com/arana-db/arana/pkg/proto"
+	"github.com/arana-db/arana/testdata"
 )
 
 func TestIsErrMissingTx(t *testing.T) {
@@ -42,21 +45,33 @@ func TestProcessDistributedTransaction(t *testing.T) {
 }
 
 func TestInGlobalTransaction(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	c := testdata.NewMockFrontConn(ctrl)
+	c.EXPECT().ID().Return(uint32(0)).AnyTimes()
+
 	redirect := NewRedirectExecutor()
-	assert.False(t, redirect.InGlobalTransaction(createContext()))
+	assert.False(t, redirect.InGlobalTransaction(createContext(c)))
 }
 
 func TestInLocalTransaction(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	c := testdata.NewMockFrontConn(ctrl)
+	c.EXPECT().ID().Return(uint32(0)).Times(1)
+
 	redirect := NewRedirectExecutor()
-	result := redirect.InLocalTransaction(createContext())
+	result := redirect.InLocalTransaction(createContext(c))
 	assert.False(t, result)
 }
 
-func createContext() *proto.Context {
+func createContext(c proto.FrontConn) *proto.Context {
 	result := &proto.Context{
-		ConnectionID: 0,
-		Data:         make([]byte, 0),
-		Stmt:         nil,
+		C:    c,
+		Data: make([]byte, 0),
+		Stmt: nil,
 	}
 	return result
 }

pkg/mysql/client.go

@@ -501,7 +501,7 @@ func (c *Connector) NewBackendConnection(ctx context.Context) (*BackendConnectio
 //                 \                   /
 //                      >>> SYNC <<<
 func (conn *BackendConnection) SyncVariables(vars map[string]proto.Value) error {
-	transient := conn.c.TransientVariables
+	transient := conn.c.TransientVariables()
 
 	if len(vars) < 1 && len(transient) < 1 {
 		return nil
@@ -799,7 +799,7 @@ func (conn *BackendConnection) parseInitialHandshakePacket(data []byte) (uint32,
 	}
 
 	// Read the connection id.
-	conn.c.ConnectionID, pos, ok = readUint32(data, pos)
+	conn.c.connectionID, pos, ok = readUint32(data, pos)
 	if !ok {
 		return 0, nil, "", err2.NewSQLError(mysql.CRMalformedPacket, mysql.SSUnknownSQLState, "parseInitialHandshakePacket: packet has no connection id")
 	}

pkg/mysql/conn.go

@@ -91,21 +91,21 @@ type Conn struct {
 	// If there are any ongoing reads or writes, they may get interrupted.
 	conn net.Conn
 
-	// Schema is the current database name.
-	Schema string
+	// schema is the current database name.
+	schema string
 
-	// Tenant is the current tenant login.
-	Tenant string
+	// tenant is the current tenant login.
+	tenant string
 
-	// ConnectionID is set:
+	// connectionID is set:
 	// - at Connect() time for clients, with the value returned by
 	// the server.
 	// - at accept time for the server.
-	ConnectionID uint32
+	connectionID uint32
 
-	// TransientVariables represents local transient variables.
+	// transientVariables represents local transient variables.
 	// These variables will always keep sync with backend mysql conns.
-	TransientVariables map[string]proto.Value
+	transientVariables map[string]proto.Value
 
 	// closed is set to true when Close() is called on the connection.
 	closed *atomic.Bool
@@ -149,7 +149,9 @@ type Conn struct {
 	// connection.
 	// It is set during the initial handshake.
 	// See the values in constants.go.
-	CharacterSet uint8
+	characterSet uint8
+
+	serverVersion string
 }
 
 // newConn is an internal method to create a Conn. Used by client and server
@@ -159,10 +161,42 @@ func newConn(conn net.Conn) *Conn {
 		conn:               conn,
 		closed:             atomic.NewBool(false),
 		bufferedReader:     bufio.NewReaderSize(conn, connBufferSize),
-		TransientVariables: make(map[string]proto.Value),
+		transientVariables: make(map[string]proto.Value),
 	}
 }
 
+func (c *Conn) ServerVersion() string {
+	return c.serverVersion
+}
+
+func (c *Conn) CharacterSet() uint8 {
+	return c.characterSet
+}
+
+func (c *Conn) Schema() string {
+	return c.schema
+}
+
+func (c *Conn) SetSchema(schema string) {
+	c.schema = schema
+}
+
+func (c *Conn) Tenant() string {
+	return c.tenant
+}
+
+func (c *Conn) SetTenant(t string) {
+	c.tenant = t
+}
+
+func (c *Conn) TransientVariables() map[string]proto.Value {
+	return c.transientVariables
+}
+
+func (c *Conn) SetTransientVariables(v map[string]proto.Value) {
+	c.transientVariables = v
+}
+
 // startWriterBuffering starts using buffered writes. This should
 // be terminated by a call to endWriteBuffering.
 func (c *Conn) startWriterBuffering() {
@@ -631,13 +665,13 @@ func (c *Conn) RemoteAddr() net.Addr {
 }
 
 // ID returns the MySQL connection ID for this connection.
-func (c *Conn) ID() int64 {
-	return int64(c.ConnectionID)
+func (c *Conn) ID() uint32 {
+	return c.connectionID
 }
 
 // Ident returns a useful identification string for error logging
 func (c *Conn) String() string {
-	return fmt.Sprintf("client %v (%s)", c.ConnectionID, c.RemoteAddr().String())
+	return fmt.Sprintf("client %v (%s)", c.ID(), c.RemoteAddr().String())
 }
 
 // Close closes the connection. It can be called from a different go
@@ -708,7 +742,7 @@ func (c *Conn) fixErrNoSuchTable(errorMessage string) string {
 		var sb strings.Builder
 		sb.Grow(len(errorMessage))
 		sb.WriteString("Table '")
-		sb.WriteString(c.Schema)
+		sb.WriteString(c.Schema())
 		sb.WriteByte('.')
 		sb.WriteString(matches[2])
 		sb.WriteString("' doesn't exist")