*: Support sleep function (pingcap#1457)

* *: support sleep function

* evaluator: add SQL mode judgement

evaluator/builtin.go

@@ -121,6 +121,8 @@ var Funcs = map[string]Func{
 	"nullif": {builtinNullIf, 2, 2},
 
 	// miscellaneous functions
+	"sleep": {builtinSleep, 1, 1},
+
 	// get_lock() and release_lock() is parsed but do nothing.
 	// It is used for preventing error in Ruby's activerecord migrations.
 	"get_lock":     {builtinLock, 2, 2},

evaluator/builtin_other.go

@@ -16,6 +16,7 @@ package evaluator
 import (
 	"regexp"
 	"strings"
+	"time"
 
 	"github.com/juju/errors"
 	"github.com/pingcap/tidb/context"
@@ -25,6 +26,42 @@ import (
 	"github.com/pingcap/tidb/util/types"
 )
 
+// See http://dev.mysql.com/doc/refman/5.7/en/miscellaneous-functions.html#function_sleep
+func builtinSleep(args []types.Datum, ctx context.Context) (d types.Datum, err error) {
+	if ctx == nil {
+		return d, errors.Errorf("Missing context when evalue builtin")
+	}
+
+	sessVars := variable.GetSessionVars(ctx)
+	if args[0].IsNull() {
+		if sessVars.StrictSQLMode {
+			return d, errors.New("Incorrect arguments to sleep.")
+		}
+		d.SetInt64(0)
+		return
+	}
+	// processing argument is negative
+	zero := types.NewIntDatum(0)
+	ret, err := args[0].CompareDatum(zero)
+	if err != nil {
+		return d, errors.Trace(err)
+	}
+	if ret == -1 {
+		if sessVars.StrictSQLMode {
+			return d, errors.New("Incorrect arguments to sleep.")
+		}
+		d.SetInt64(0)
+		return
+	}
+
+	// TODO: consider it's interrupted using KILL QUERY from other session, or
+	// interrupted by time out.
+	duration := time.Duration(args[0].GetFloat64() * float64(time.Second.Nanoseconds()))
+	time.Sleep(duration)
+	d.SetInt64(0)
+	return
+}
+
 func builtinAndAnd(args []types.Datum, _ context.Context) (d types.Datum, err error) {
 	leftDatum := args[0]
 	rightDatum := args[1]

evaluator/evaluator_test.go

@@ -78,6 +78,44 @@ func (s *testEvaluatorSuite) TestBetween(c *C) {
 	s.runTests(c, cases)
 }
 
+func (s *testEvaluatorSuite) TestSleep(c *C) {
+	defer testleak.AfterTest(c)()
+	ctx := mock.NewContext()
+	variable.BindSessionVars(ctx)
+	sessVars := variable.GetSessionVars(ctx)
+
+	// non-strict model
+	sessVars.StrictSQLMode = false
+	d := make([]types.Datum, 1)
+	_, err := builtinSleep(d, nil)
+	c.Assert(err, NotNil)
+	ret, err := builtinSleep(d, ctx)
+	c.Assert(err, IsNil)
+	c.Assert(ret, DeepEquals, types.NewIntDatum(0))
+	d[0].SetInt64(-1)
+	ret, err = builtinSleep(d, ctx)
+	c.Assert(err, IsNil)
+	c.Assert(ret, DeepEquals, types.NewIntDatum(0))
+
+	// for error case under the strict model
+	sessVars.StrictSQLMode = true
+	d[0].SetNull()
+	_, err = builtinSleep(d, ctx)
+	c.Assert(err, NotNil)
+	d[0].SetFloat64(-2.5)
+	_, err = builtinSleep(d, ctx)
+	c.Assert(err, NotNil)
+
+	// strict model
+	d[0].SetFloat64(0.5)
+	start := time.Now()
+	ret, err = builtinSleep(d, ctx)
+	c.Assert(err, IsNil)
+	c.Assert(ret, DeepEquals, types.NewIntDatum(0))
+	sub := time.Now().Sub(start)
+	c.Assert(sub.Nanoseconds(), GreaterEqual, int64(0.5*1e9))
+}
+
 func (s *testEvaluatorSuite) TestBinopComparison(c *C) {
 	defer testleak.AfterTest(c)()
 	ctx := mock.NewContext()

parser/parser.y

@@ -270,6 +270,7 @@ import (
 	set		"SET"
 	share		"SHARE"
 	show		"SHOW"
+	sleep		"SLEEP"
 	signed		"SIGNED"
 	some 		"SOME"
 	space 		"SPACE"
@@ -1964,11 +1965,12 @@ UnReservedKeyword:
 
 NotKeywordToken:
 	"ABS" | "ADDDATE" | "ADMIN" | "COALESCE" | "CONCAT" | "CONCAT_WS" | "CONNECTION_ID" | "CUR_TIME"| "COUNT" | "DAY"
-|	"DATE_ADD" | "DATE_FORMAT" | "DATE_SUB" | "DAYNAME" | "DAYOFMONTH" | "DAYOFWEEK" | "DAYOFYEAR" | "FOUND_ROWS" | "GROUP_CONCAT"| "HOUR"
-|	"IFNULL" | "ISNULL" | "LAST_INSERT_ID" | "LCASE" | "LENGTH" | "LOCATE" | "LOWER" | "LTRIM" | "MAX" | "MICROSECOND" | "MIN"
-|	"MINUTE" | "NULLIF" | "MONTH" | "MONTHNAME" | "NOW" | "POW" | "POWER" | "RAND" | "SECOND" | "SQL_CALC_FOUND_ROWS" | "SUBDATE"
-|	"SUBSTRING" %prec lowerThanLeftParen | "SUBSTRING_INDEX" | "SUM" | "TRIM" | "RTRIM" | "UCASE" | "UPPER" | "VERSION"
-|	"WEEKDAY" | "WEEKOFYEAR" | "YEARWEEK" | "ROUND" | "STATS_PERSISTENT" | "GET_LOCK" | "RELEASE_LOCK"
+|	"DATE_ADD" | "DATE_FORMAT" | "DATE_SUB" | "DAYNAME" | "DAYOFMONTH" | "DAYOFWEEK" | "DAYOFYEAR" | "FOUND_ROWS"
+|	"GROUP_CONCAT"| "HOUR" | "IFNULL" | "ISNULL" | "LAST_INSERT_ID" | "LCASE" | "LENGTH" | "LOCATE" | "LOWER" | "LTRIM"
+|	"MAX" | "MICROSECOND" | "MIN" |	"MINUTE" | "NULLIF" | "MONTH" | "MONTHNAME" | "NOW" | "POW" | "POWER" | "RAND"
+|	"SECOND" | "SLEEP" | "SQL_CALC_FOUND_ROWS" | "SUBDATE" | "SUBSTRING" %prec lowerThanLeftParen | "SUBSTRING_INDEX"
+|	"SUM" | "TRIM" | "RTRIM" | "UCASE" | "UPPER" | "VERSION" | "WEEKDAY" | "WEEKOFYEAR" | "YEARWEEK" | "ROUND"
+|	"STATS_PERSISTENT" | "GET_LOCK" | "RELEASE_LOCK"
 
 /************************************************************************************
  *
@@ -2653,6 +2655,10 @@ FunctionCallNonKeyword:
 	{
 		$$ = &ast.FuncCallExpr{FnName: model.NewCIStr($1.(string)), Args: []ast.ExprNode{$3.(ast.ExprNode)}}
 	}
+|	"SLEEP" '(' Expression ')'
+	{
+		$$ = &ast.FuncCallExpr{FnName: model.NewCIStr($1.(string)), Args: []ast.ExprNode{$3.(ast.ExprNode)}}
+	}
 |	"SPACE" '(' Expression ')'
 	{
 		$$ = &ast.FuncCallExpr{FnName: model.NewCIStr($1.(string)), Args: []ast.ExprNode{$3.(ast.ExprNode)}}

parser/parser_test.go

@@ -48,7 +48,7 @@ func (s *testParserSuite) TestSimple(c *C) {
 		"delay_key_write", "isolation", "repeatable", "committed", "uncommitted", "only", "serializable", "level",
 		"curtime", "variables", "dayname", "version", "btree", "hash", "row_format", "dynamic", "fixed", "compressed",
 		"compact", "redundant", "sql_no_cache sql_no_cache", "sql_cache sql_cache", "action", "round",
-		"enable", "disable", "reverse", "space", "privileges", "get_lock", "release_lock",
+		"enable", "disable", "reverse", "space", "privileges", "get_lock", "release_lock", "sleep",
 	}
 	for _, kw := range unreservedKws {
 		src := fmt.Sprintf("SELECT %s FROM tbl;", kw)
@@ -526,6 +526,9 @@ func (s *testParserSuite) TestBuiltin(c *C) {
 		// Repeat
 		{`SELECT REPEAT("a", 10);`, true},
 
+		// Sleep
+		{`SELECT SLEEP(10);`, true},
+
 		// For date_add
 		{`select date_add("2011-11-11 10:10:10.123456", interval 10 microsecond)`, true},
 		{`select date_add("2011-11-11 10:10:10.123456", interval 10 second)`, true},

parser/scanner.l

@@ -472,6 +472,7 @@ session		{s}{e}{s}{s}{i}{o}{n}
 set		{s}{e}{t}
 share		{s}{h}{a}{r}{e}
 show		{s}{h}{o}{w}
+sleep		{s}{l}{e}{e}{p}
 some		{s}{o}{m}{e}
 space		{s}{p}{a}{c}{e}
 start		{s}{t}{a}{r}{t}
@@ -1026,6 +1027,8 @@ redundant		lval.item = string(l.val)
 {set}			return set
 {share}			return share
 {show}			return show
+{sleep}			lval.item = string(l.val)
+			return sleep
 {subdate}		lval.item = string(l.val)
 			return subDate
 {strcmp}		lval.item = string(l.val)

session_test.go

@@ -1975,6 +1975,24 @@ func (s *testSessionSuite) TestRetryPreparedStmt(c *C) {
 	c.Assert(err, IsNil)
 }
 
+func (s *testSessionSuite) TestSleep(c *C) {
+	defer testleak.AfterTest(c)()
+	store := newStore(c, s.dbName)
+	se := newSession(c, store, s.dbName)
+
+	mustExecSQL(c, se, "select sleep(0.01);")
+	mustExecSQL(c, se, "drop table if exists t;")
+	mustExecSQL(c, se, "create table t (a int);")
+	mustExecSQL(c, se, "insert t values (sleep(0.02));")
+	r := mustExecSQL(c, se, "select * from t;")
+	row, err := r.Next()
+	c.Assert(err, IsNil)
+	match(c, row.Data, 0)
+
+	err = store.Close()
+	c.Assert(err, IsNil)
+}
+
 func (s *testSessionSuite) TestIssue893(c *C) {
 	defer testleak.AfterTest(c)()
 	store := newStore(c, s.dbName)