support system variable wait_timeout. (#8245)

server/conn.go

@@ -215,6 +215,18 @@ func (cc *clientConn) writePacket(data []byte) error {
 	return cc.pkt.writePacket(data)
 }
 
+// getSessionVarsWaitTimeout get session variable wait_timeout
+func (cc *clientConn) getSessionVarsWaitTimeout() uint64 {
+	valStr, _ := cc.ctx.GetSessionVars().GetSystemVar(variable.WaitTimeout)
+	waitTimeout, err := strconv.ParseUint(valStr, 10, 64)
+	if err != nil {
+		log.Errorf("con:%d get sysval wait_timeout error, use default value.", cc.connectionID)
+		// if get waitTimeout error, use default value
+		waitTimeout, _ = strconv.ParseUint(variable.WaitTimeoutDefaultValue, 10, 64)
+	}
+	return waitTimeout
+}
+
 type handshakeResponse41 struct {
 	Capability uint32
 	Collation  uint8
@@ -449,13 +461,22 @@ func (cc *clientConn) Run() {
 		}
 
 		cc.alloc.Reset()
+		// close connection when idle time is more than wait_timout
+		waitTimeout := cc.getSessionVarsWaitTimeout()
+		cc.pkt.setReadTimeout(time.Duration(waitTimeout) * time.Second)
+		start := time.Now()
 		data, err := cc.readPacket()
 		if err != nil {
 			if terror.ErrorNotEqual(err, io.EOF) {
-				errStack := errors.ErrorStack(err)
-				if !strings.Contains(errStack, "use of closed network connection") {
-					log.Errorf("con:%d read packet error, close this connection %s",
-						cc.connectionID, errStack)
+				if netErr, isNetErr := errors.Cause(err).(net.Error); isNetErr && netErr.Timeout() {
+					idleTime := time.Now().Sub(start)
+					log.Infof("con:%d read packet timeout, close this connection, idle: %v, wait_timeout: %v", cc.connectionID, idleTime, waitTimeout)
+				} else {
+					errStack := errors.ErrorStack(err)
+					if !strings.Contains(errStack, "use of closed network connection") {
+						log.Errorf("con:%d read packet error, close this connection %s",
+							cc.connectionID, errStack)
+					}
 				}
 			}
 			return

server/conn_test.go

@@ -20,9 +20,16 @@ import (
 
 	. "github.com/pingcap/check"
 	"github.com/pingcap/parser/mysql"
+	"github.com/pingcap/tidb/domain"
+	"github.com/pingcap/tidb/kv"
+	"github.com/pingcap/tidb/session"
+	"github.com/pingcap/tidb/store/mockstore"
 )
 
-type ConnTestSuite struct{}
+type ConnTestSuite struct {
+	dom   *domain.Domain
+	store kv.Storage
+}
 
 var _ = Suite(ConnTestSuite{})
 
@@ -149,6 +156,29 @@ func (ts ConnTestSuite) TestInitialHandshake(c *C) {
 	c.Assert(outBuffer.Bytes()[4:], DeepEquals, expected.Bytes())
 }
 
+func (ts ConnTestSuite) testGetSessionVarsWaitTimeout(c *C) {
+	c.Parallel()
+	var err error
+	ts.store, err = mockstore.NewMockTikvStore()
+	c.Assert(err, IsNil)
+	ts.dom, err = session.BootstrapSession(ts.store)
+	c.Assert(err, IsNil)
+	se, err := session.CreateSession4Test(ts.store)
+	c.Assert(err, IsNil)
+	tc := &TiDBContext{
+		session: se,
+		stmts:   make(map[int]*TiDBStatement),
+	}
+	cc := &clientConn{
+		connectionID: 1,
+		server: &Server{
+			capability: defaultCapability,
+		},
+		ctx: tc,
+	}
+	c.Assert(cc.getSessionVarsWaitTimeout(), Equals, 28800)
+}
+
 func mapIdentical(m1, m2 map[string]string) bool {
 	return mapBelong(m1, m2) && mapBelong(m2, m1)
 }

server/packetio.go

@@ -37,6 +37,7 @@ package server
 import (
 	"bufio"
 	"io"
+	"time"
 
 	"github.com/pingcap/errors"
 	"github.com/pingcap/parser/mysql"
@@ -50,6 +51,7 @@ type packetIO struct {
 	bufReadConn *bufferedReadConn
 	bufWriter   *bufio.Writer
 	sequence    uint8
+	readTimeout time.Duration
 }
 
 func newPacketIO(bufReadConn *bufferedReadConn) *packetIO {
@@ -63,9 +65,17 @@ func (p *packetIO) setBufferedReadConn(bufReadConn *bufferedReadConn) {
 	p.bufWriter = bufio.NewWriterSize(bufReadConn, defaultWriterSize)
 }
 
+func (p *packetIO) setReadTimeout(timeout time.Duration) {
+	p.readTimeout = timeout
+}
+
 func (p *packetIO) readOnePacket() ([]byte, error) {
 	var header [4]byte
-
+	if p.readTimeout > 0 {
+		if err := p.bufReadConn.SetReadDeadline(time.Now().Add(p.readTimeout)); err != nil {
+			return nil, err
+		}
+	}
 	if _, err := io.ReadFull(p.bufReadConn, header[:]); err != nil {
 		return nil, errors.Trace(err)
 	}
@@ -80,6 +90,11 @@ func (p *packetIO) readOnePacket() ([]byte, error) {
 	length := int(uint32(header[0]) | uint32(header[1])<<8 | uint32(header[2])<<16)
 
 	data := make([]byte, length)
+	if p.readTimeout > 0 {
+		if err := p.bufReadConn.SetReadDeadline(time.Now().Add(p.readTimeout)); err != nil {
+			return nil, err
+		}
+	}
 	if _, err := io.ReadFull(p.bufReadConn, data); err != nil {
 		return nil, errors.Trace(err)
 	}

session/session.go

@@ -1373,6 +1373,7 @@ const loadCommonGlobalVarsSQL = "select HIGH_PRIORITY * from mysql.global_variab
 	variable.MaxAllowedPacket + quoteCommaQuote +
 	variable.TimeZone + quoteCommaQuote +
 	variable.BlockEncryptionMode + quoteCommaQuote +
+	variable.WaitTimeout + quoteCommaQuote +
 	/* TiDB specific global variables: */
 	variable.TiDBSkipUTF8Check + quoteCommaQuote +
 	variable.TiDBIndexJoinBatchSize + quoteCommaQuote +

sessionctx/variable/sysvar.go

@@ -535,7 +535,7 @@ var defaultSysVars = []*SysVar{
 	{ScopeGlobal, "innodb_buffer_pool_size", "134217728"},
 	{ScopeGlobal, "innodb_adaptive_flushing", "ON"},
 	{ScopeNone, "datadir", "/usr/local/mysql/data/"},
-	{ScopeGlobal | ScopeSession, "wait_timeout", "28800"},
+	{ScopeGlobal | ScopeSession, WaitTimeout, WaitTimeoutDefaultValue},
 	{ScopeGlobal, "innodb_monitor_enable", ""},
 	{ScopeNone, "date_format", "%Y-%m-%d"},
 	{ScopeGlobal, "innodb_buffer_pool_filename", "ib_buffer_pool"},
@@ -774,6 +774,10 @@ const (
 	SyncBinlog = "sync_binlog"
 	// BlockEncryptionMode is the name for 'block_encryption_mode' system variable.
 	BlockEncryptionMode = "block_encryption_mode"
+	// WaitTimeout is the name for 'wait_timeout' system variable.
+	WaitTimeout = "wait_timeout"
+	// WaitTimeoutDefaultValue is the default value of 'wait_timeout' system variable.
+	WaitTimeoutDefaultValue = "28800"
 )
 
 // GlobalVarAccessor is the interface for accessing global scope system and status variables.

sessionctx/variable/varsutil.go

@@ -280,6 +280,8 @@ func ValidateSetSystemVar(vars *SessionVars, name string, value string) (string,
 		return checkUInt64SystemVar(name, value, 400, 524288, vars)
 	case TmpTableSize:
 		return checkUInt64SystemVar(name, value, 1024, math.MaxUint64, vars)
+	case WaitTimeout:
+		return checkUInt64SystemVar(name, value, 1, 31536000, vars)
 	case TimeZone:
 		if strings.EqualFold(value, "SYSTEM") {
 			return "SYSTEM", nil