Make Sleep check for cancelled context every second (#798)

Make Sleep check for cancelled context every second

Author: ajnavarro

server/context.go

@@ -24,7 +24,7 @@ func DefaultSessionBuilder(c *mysql.Conn, addr string) sql.Session {
 
 // SessionManager is in charge of creating new sessions for the given
 // connections and keep track of which sessions are in each connection, so
-// they can be cancelled is the connection is closed.
+// they can be cancelled if the connection is closed.
 type SessionManager struct {
 	addr     string
 	tracer   opentracing.Tracer

sql/expression/function/sleep.go

@@ -1,11 +1,11 @@
 package function
 
 import (
+	"context"
 	"fmt"
-	"time"
-
 	"github.com/src-d/go-mysql-server/sql"
 	"github.com/src-d/go-mysql-server/sql/expression"
+	"time"
 )
 
 // Sleep is a function that just waits for the specified number of seconds
@@ -37,8 +37,15 @@ func (s *Sleep) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 		return nil, err
 	}
 
-	time.Sleep(time.Duration(child.(float64)*1000) * time.Millisecond)
-	return 0, nil
+	t := time.NewTimer(time.Duration(child.(float64) * 1000) * time.Millisecond)
+	defer t.Stop()
+
+	select {
+	case <-ctx.Done():
+		return 0, context.Canceled
+	case <-t.C:
+		return 0, nil
+	}
 }
 
 // String implements the Stringer interface.