From 6287b24f431afc219caa916cd878fce21ba5f962 Mon Sep 17 00:00:00 2001
From: H <huhao0715@gmail.com>
Date: Thu, 2 Aug 2018 12:57:06 +0800
Subject: [PATCH] expression: handle max_allowed_packet warnings for space
 function. (#7210)

---
 expression/builtin_string.go      | 19 +++++++++++++++----
 expression/builtin_string_test.go | 27 +++++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/expression/builtin_string.go b/expression/builtin_string.go
index c21ecae092aeb..22a6bbd28448d 100644
--- a/expression/builtin_string.go
+++ b/expression/builtin_string.go
@@ -708,17 +708,24 @@ func (c *spaceFunctionClass) getFunction(ctx sessionctx.Context, args []Expressi
 	}
 	bf := newBaseBuiltinFuncWithTp(ctx, args, types.ETString, types.ETInt)
 	bf.tp.Flen = mysql.MaxBlobWidth
-	sig := &builtinSpaceSig{bf}
+	valStr, _ := ctx.GetSessionVars().GetSystemVar(variable.MaxAllowedPacket)
+	maxAllowedPacket, err := strconv.ParseUint(valStr, 10, 64)
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
+	sig := &builtinSpaceSig{bf, maxAllowedPacket}
 	return sig, nil
 }
 
 type builtinSpaceSig struct {
 	baseBuiltinFunc
+	maxAllowedPacket uint64
 }
 
 func (b *builtinSpaceSig) Clone() builtinFunc {
 	newSig := &builtinSpaceSig{}
 	newSig.cloneFrom(&b.baseBuiltinFunc)
+	newSig.maxAllowedPacket = b.maxAllowedPacket
 	return newSig
 }
 
@@ -731,12 +738,16 @@ func (b *builtinSpaceSig) evalString(row chunk.Row) (d string, isNull bool, err
 	if isNull || err != nil {
 		return d, isNull, errors.Trace(err)
 	}
-	if x > mysql.MaxBlobWidth {
-		return d, true, nil
-	}
 	if x < 0 {
 		x = 0
 	}
+	if uint64(x) > b.maxAllowedPacket {
+		b.ctx.GetSessionVars().StmtCtx.AppendWarning(errWarnAllowedPacketOverflowed.GenByArgs("space", b.maxAllowedPacket))
+		return d, true, nil
+	}
+	if x > mysql.MaxBlobWidth {
+		return d, true, nil
+	}
 	return strings.Repeat(" ", int(x)), false, nil
 }
 
diff --git a/expression/builtin_string_test.go b/expression/builtin_string_test.go
index 46dde9237fa0d..5425996080143 100644
--- a/expression/builtin_string_test.go
+++ b/expression/builtin_string_test.go
@@ -761,6 +761,33 @@ func (s *testEvaluatorSuite) TestSpace(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *testEvaluatorSuite) TestSpaceSig(c *C) {
+	colTypes := []*types.FieldType{
+		{Tp: mysql.TypeLonglong},
+	}
+	resultType := &types.FieldType{Tp: mysql.TypeVarchar, Flen: 1000}
+	args := []Expression{
+		&Column{Index: 0, RetType: colTypes[0]},
+	}
+	base := baseBuiltinFunc{args: args, ctx: s.ctx, tp: resultType}
+	space := &builtinSpaceSig{base, 1000}
+	input := chunk.NewChunkWithCapacity(colTypes, 10)
+	input.AppendInt64(0, 6)
+	input.AppendInt64(0, 1001)
+	res, isNull, err := space.evalString(input.GetRow(0))
+	c.Assert(res, Equals, "      ")
+	c.Assert(isNull, IsFalse)
+	c.Assert(err, IsNil)
+	res, isNull, err = space.evalString(input.GetRow(1))
+	c.Assert(res, Equals, "")
+	c.Assert(isNull, IsTrue)
+	c.Assert(err, IsNil)
+	warnings := s.ctx.GetSessionVars().StmtCtx.GetWarnings()
+	c.Assert(len(warnings), Equals, 1)
+	lastWarn := warnings[len(warnings)-1]
+	c.Assert(terror.ErrorEqual(errWarnAllowedPacketOverflowed, lastWarn.Err), IsTrue)
+}
+
 func (s *testEvaluatorSuite) TestLocate(c *C) {
 	// 1. Test LOCATE without binary input.
 	defer testleak.AfterTest(c)()