infoschema/slow_query: fix token too long (#10328)

infoschema/slow_log.go

@@ -15,6 +15,8 @@ package infoschema
 
 import (
 	"bufio"
+	"context"
+	"io"
 	"os"
 	"strconv"
 	"strings"
@@ -28,7 +30,7 @@ import (
 	"github.com/pingcap/tidb/util/execdetails"
 	"github.com/pingcap/tidb/util/hack"
 	"github.com/pingcap/tidb/util/logutil"
-	log "github.com/sirupsen/logrus"
+	"go.uber.org/zap"
 )
 
 var slowQueryCols = []columnInfo{
@@ -71,22 +73,27 @@ func parseSlowLogFile(tz *time.Location, filePath string) ([][]types.Datum, erro
 	}
 	defer func() {
 		if err = file.Close(); err != nil {
-			log.Error(err)
+			logutil.Logger(context.Background()).Error("close slow log file failed.", zap.String("file", filePath), zap.Error(err))
 		}
 	}()
-
-	return ParseSlowLog(tz, bufio.NewScanner(file))
+	return ParseSlowLog(tz, bufio.NewReader(file))
 }
 
 // ParseSlowLog exports for testing.
 // TODO: optimize for parse huge log-file.
-func ParseSlowLog(tz *time.Location, scanner *bufio.Scanner) ([][]types.Datum, error) {
+func ParseSlowLog(tz *time.Location, reader *bufio.Reader) ([][]types.Datum, error) {
 	var rows [][]types.Datum
 	startFlag := false
 	var st *slowQueryTuple
-	var err error
-	for scanner.Scan() {
-		line := scanner.Text()
+	for {
+		lineByte, err := getOneLine(reader)
+		if err != nil {
+			if err == io.EOF {
+				return rows, nil
+			}
+			return rows, err
+		}
+		line := string(hack.String(lineByte))
 		// Check slow log entry start flag.
 		if !startFlag && strings.HasPrefix(line, variable.SlowLogStartPrefixStr) {
 			st = &slowQueryTuple{}
@@ -124,10 +131,27 @@ func ParseSlowLog(tz *time.Location, scanner *bufio.Scanner) ([][]types.Datum, e
 			}
 		}
 	}
-	if err := scanner.Err(); err != nil {
-		return nil, errors.AddStack(err)
+}
+
+func getOneLine(reader *bufio.Reader) ([]byte, error) {
+	lineByte, isPrefix, err := reader.ReadLine()
+	if err != nil {
+		return lineByte, err
+	}
+	var tempLine []byte
+	for isPrefix {
+		tempLine, isPrefix, err = reader.ReadLine()
+		lineByte = append(lineByte, tempLine...)
+
+		// Use the max value of max_allowed_packet to check the single line length.
+		if len(lineByte) > int(variable.MaxOfMaxAllowedPacket) {
+			return lineByte, errors.Errorf("single line length exceeds limit: %v", variable.MaxOfMaxAllowedPacket)
+		}
+		if err != nil {
+			return lineByte, err
+		}
 	}
-	return rows, nil
+	return lineByte, err
 }
 
 type slowQueryTuple struct {

infoschema/slow_log_test.go

@@ -16,10 +16,12 @@ package infoschema_test
 import (
 	"bufio"
 	"bytes"
+	"strings"
 	"time"
 
 	. "github.com/pingcap/check"
 	"github.com/pingcap/tidb/infoschema"
+	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/util/logutil"
 )
 
@@ -36,10 +38,10 @@ func (s *testSuite) TestParseSlowLogFile(c *C) {
 # Cop_wait_avg: 0.05 Cop_wait_p90: 0.6 Cop_wait_max: 0.8
 # Mem_max: 70724
 select * from t;`)
-	scanner := bufio.NewScanner(slowLog)
+	reader := bufio.NewReader(slowLog)
 	loc, err := time.LoadLocation("Asia/Shanghai")
 	c.Assert(err, IsNil)
-	rows, err := infoschema.ParseSlowLog(loc, scanner)
+	rows, err := infoschema.ParseSlowLog(loc, reader)
 	c.Assert(err, IsNil)
 	c.Assert(len(rows), Equals, 1)
 	recordString := ""
@@ -67,8 +69,8 @@ select a# from t;
 # Stats: t1:1,t2:2
 select * from t;
 `)
-	scanner = bufio.NewScanner(slowLog)
-	_, err = infoschema.ParseSlowLog(loc, scanner)
+	reader = bufio.NewReader(slowLog)
+	_, err = infoschema.ParseSlowLog(loc, reader)
 	c.Assert(err, IsNil)
 
 	// test for time format compatibility.
@@ -78,8 +80,8 @@ select * from t;
 # Time: 2019-04-24-19:41:21.716221 +0800
 select * from t;
 `)
-	scanner = bufio.NewScanner(slowLog)
-	rows, err = infoschema.ParseSlowLog(loc, scanner)
+	reader = bufio.NewReader(slowLog)
+	rows, err = infoschema.ParseSlowLog(loc, reader)
 	c.Assert(err, IsNil)
 	c.Assert(len(rows) == 2, IsTrue)
 	t0Str, err := rows[0][0].ToString()
@@ -88,6 +90,26 @@ select * from t;
 	t1Str, err := rows[1][0].ToString()
 	c.Assert(err, IsNil)
 	c.Assert(t1Str, Equals, "2019-04-24 19:41:21.716221")
+
+	// test for bufio.Scanner: token too long.
+	slowLog = bytes.NewBufferString(
+		`# Time: 2019-04-28T15:24:04.309074+08:00
+select * from t;
+# Time: 2019-04-24-19:41:21.716221 +0800
+`)
+	originValue := variable.MaxOfMaxAllowedPacket
+	variable.MaxOfMaxAllowedPacket = 65536
+	sql := strings.Repeat("x", int(variable.MaxOfMaxAllowedPacket+1))
+	slowLog.WriteString(sql)
+	reader = bufio.NewReader(slowLog)
+	_, err = infoschema.ParseSlowLog(loc, reader)
+	c.Assert(err, NotNil)
+	c.Assert(err.Error(), Equals, "single line length exceeds limit: 65536")
+
+	variable.MaxOfMaxAllowedPacket = originValue
+	reader = bufio.NewReader(slowLog)
+	_, err = infoschema.ParseSlowLog(loc, reader)
+	c.Assert(err, IsNil)
 }
 
 func (s *testSuite) TestSlowLogParseTime(c *C) {

sessionctx/variable/tidb_vars.go

@@ -267,9 +267,10 @@ var (
 	maxDDLReorgWorkerCount int32 = 128
 	ddlReorgBatchSize      int32 = DefTiDBDDLReorgBatchSize
 	// Export for testing.
-	MaxDDLReorgBatchSize int32  = 10240
-	MinDDLReorgBatchSize int32  = 32
-	DDLSlowOprThreshold  uint32 = 300 // DDLSlowOprThreshold is the threshold for ddl slow operations, uint is millisecond.
-	ForcePriority               = int32(DefTiDBForcePriority)
-	ServerHostname, _           = os.Hostname()
+	MaxDDLReorgBatchSize  int32  = 10240
+	MinDDLReorgBatchSize  int32  = 32
+	DDLSlowOprThreshold   uint32 = 300 // DDLSlowOprThreshold is the threshold for ddl slow operations, uint is millisecond.
+	ForcePriority                = int32(DefTiDBForcePriority)
+	ServerHostname, _            = os.Hostname()
+	MaxOfMaxAllowedPacket uint64 = 1073741824
 )

sessionctx/variable/varsutil.go

@@ -276,7 +276,7 @@ func ValidateSetSystemVar(vars *SessionVars, name string, value string) (string,
 		return checkUInt64SystemVar(name, value, 1, 1073741824, vars)
 	// See "https://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_max_allowed_packet"
 	case MaxAllowedPacket:
-		return checkUInt64SystemVar(name, value, 1024, 1073741824, vars)
+		return checkUInt64SystemVar(name, value, 1024, MaxOfMaxAllowedPacket, vars)
 	case MaxConnections:
 		return checkUInt64SystemVar(name, value, 1, 100000, vars)
 	case MaxConnectErrors: