*: make SET TRANSACTION ISOLATION LEVEL READ COMMITTED take effect

it is equivalent to setting "tx_isolation" variable. if the value is READ-COMMITTED, set the transaction isolation level option.
pingcap · Jul 4, 2017 · e38a2fc · e38a2fc
1 parent 4023bb8
commit e38a2fc
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Showing 6 changed files with 103 additions and 4 deletions.
diff --git a/ast/misc.go b/ast/misc.go
@@ -46,6 +46,13 @@ var (
 	_ Node = &VariableAssignment{}
 )
 
+const (
+	ReadCommitted   = "READ-COMMITTED"
+	ReadUncommitted = "READ-UNCOMMITTED"
+	Serializable    = "SERIALIZABLE "
+	RepeatableRead  = "REPEATABLE-READ"
+)
+
 // TypeOpt is used for parsing data type option from SQL.
 type TypeOpt struct {
 	IsUnsigned bool

diff --git a/executor/set_test.go b/executor/set_test.go
@@ -123,6 +123,16 @@ func (s *testSuite) TestSetVar(c *C) {
 	c.Assert(vars.SkipConstraintCheck, IsTrue)
 	tk.MustExec("set @@tidb_skip_constraint_check = '0'")
 	c.Assert(vars.SkipConstraintCheck, IsFalse)
+
+	// Test set transaction isolation level, which is equivalent to setting variable "tx_isolation".
+	tk.MustExec("SET GLOBAL TRANSACTION ISOLATION LEVEL SERIALIZABLE")
+	tk.MustQuery("select @@global.tx_isolation").Check(testkit.Rows("SERIALIZABLE"))
+
+	tk.MustExec("SET SESSION TRANSACTION ISOLATION LEVEL READ UNCOMMITTED")
+	tk.MustQuery("select @@session.tx_isolation").Check(testkit.Rows("READ-UNCOMMITTED"))
+
+	tk.MustExec("SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED")
+	tk.MustQuery("select @@session.tx_isolation").Check(testkit.Rows("READ-COMMITTED"))
 }
 
 func (s *testSuite) TestSetCharset(c *C) {

diff --git a/parser/parser.y b/parser/parser.y
@@ -757,6 +757,8 @@ import (
 	TableOptionListOpt	"create table option list opt"
 	TableRef 		"table reference"
 	TableRefs 		"table references"
+	TransactionChar		"Transaction characteristic"
+	TransactionChars	"Transaction characteristic list"
 	TrimDirection		"Trim string direction"
 	TruncateTableStmt	"TRANSACTION TABLE statement"
 	UnionOpt		"Union Option(empty/ALL/DISTINCT)"
@@ -835,8 +837,6 @@ import (
 	OuterOpt		"optional OUTER clause"
 	CrossOpt		"Cross join option"
 	TablesTerminalSym 	"{TABLE|TABLES}"
-	TransactionChar		"Transaction characteristic"
-	TransactionChars	"Transaction characteristic list"
 	IsolationLevel		"Isolation level"
 	ShowIndexKwd		"Show index/indexs/key keyword"
 	FromOrIn		"From or In"
@@ -4836,27 +4836,72 @@ SetStmt:
 	}
 |	"SET" "GLOBAL" "TRANSACTION" TransactionChars
 	{
-		// Parsed but ignored
+		vars := $4.([]*ast.VariableAssignment)
+		for _, v := range vars {
+			v.IsGlobal = true
+		}
+		$$ = &ast.SetStmt{Variables: vars}
 	}
 |	"SET" "SESSION" "TRANSACTION" TransactionChars
 	{
-		// Parsed but ignored
+		$$ = &ast.SetStmt{Variables: $4.([]*ast.VariableAssignment)}
 	}
 
 TransactionChars:
 	TransactionChar
+	{
+		if $1 != nil {
+			$$ = []*ast.VariableAssignment{$1.(*ast.VariableAssignment)}
+		} else {
+			$$ = []*ast.VariableAssignment{}
+		}
+	}
 |	TransactionChars ',' TransactionChar
+	{
+		if $3 != nil {
+			$$ = append($1.([]*ast.VariableAssignment), $3.(*ast.VariableAssignment))
+		} else {
+			$$ = $1
+		}
+	}
 
 TransactionChar:
 	"ISOLATION" "LEVEL" IsolationLevel
+	{
+		tp := types.NewFieldType(mysql.TypeString)
+		tp.Charset, tp.Collate = parser.charset, parser.collation
+		expr := ast.NewValueExpr($3)
+		expr.SetType(tp)
+		$$ = &ast.VariableAssignment{Name: "tx_isolation", Value: expr, IsSystem: true}
+	}
 |	"READ" "WRITE"
+	{
+		// Parsed but ignored
+		$$ = nil
+	}
 |	"READ" "ONLY"
+	{
+		// Parsed but ignored
+		$$ = nil
+	}
 
 IsolationLevel:
 	"REPEATABLE" "READ"
+	{
+		$$ = ast.RepeatableRead
+	}
 |	"READ"	"COMMITTED"
+	{
+		$$ = ast.ReadCommitted
+	}
 |	"READ"	"UNCOMMITTED"
+	{
+		$$ = ast.ReadUncommitted
+	}
 |	"SERIALIZABLE"
+	{
+		$$ = ast.Serializable
+	}
 
 VariableAssignment:
 	Identifier eq Expression

diff --git a/parser/parser_test.go b/parser/parser_test.go
@@ -1761,3 +1761,36 @@ func (s *testParserSuite) TestGeneratedColumn(c *C) {
 	}
 
 }
+
+func (s *testParserSuite) TestSetTransaction(c *C) {
+	defer testleak.AfterTest(c)()
+	// Set transaction is equivalent to setting the global or session value of tx_isolation.
+	// For example:
+	// SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED
+	// SET SESSION tx_isolation='READ-COMMITTED'
+	tests := []struct {
+		input    string
+		isGlobal bool
+		value    string
+	}{
+		{
+			"SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED",
+			false, "READ-COMMITTED",
+		},
+		{
+			"SET GLOBAL TRANSACTION ISOLATION LEVEL REPEATABLE READ",
+			true, "REPEATABLE-READ",
+		},
+	}
+	parser := New()
+	for _, t := range tests {
+		stmt1, err := parser.ParseOneStmt(t.input, "", "")
+		c.Assert(err, IsNil)
+		setStmt := stmt1.(*ast.SetStmt)
+		vars := setStmt.Variables[0]
+		c.Assert(vars.Name, Equals, "tx_isolation")
+		c.Assert(vars.IsGlobal, Equals, t.isGlobal)
+		c.Assert(vars.IsSystem, Equals, true)
+		c.Assert(vars.Value.GetValue(), Equals, t.value)
+	}
+}
diff --git a/session.go b/session.go
@@ -1130,6 +1130,9 @@ func (s *session) ActivePendingTxn() error {
 	if err != nil {
 		return errors.Trace(err)
 	}
+	if s.sessionVars.Systems[variable.TxnIsolation] == ast.ReadCommitted {
+		txn.SetOption(kv.IsolationLevel, kv.RC)
+	}
 	return nil
 }
 

diff --git a/sessionctx/variable/session.go b/sessionctx/variable/session.go
@@ -304,6 +304,7 @@ const (
 	CharacterSetResults = "character_set_results"
 	MaxAllowedPacket    = "max_allowed_packet"
 	TimeZone            = "time_zone"
+	TxnIsolation        = "tx_isolation"
 )
 
 // TableDelta stands for the changed count for one table.