Feature/collect warnings

sql/parse/parse.go

@@ -10,7 +10,6 @@ import (
 	"strings"
 
 	opentracing "github.com/opentracing/opentracing-go"
-	"github.com/sirupsen/logrus"
 	"gopkg.in/src-d/go-errors.v1"
 	"gopkg.in/src-d/go-mysql-server.v0/sql"
 	"gopkg.in/src-d/go-mysql-server.v0/sql/expression"
@@ -58,8 +57,7 @@ func Parse(ctx *sql.Context, query string) (sql.Node, error) {
 	}
 
 	if s == "" {
-		logrus.WithField("query", query).
-			Infof("query became empty, so it will be ignored")
+		ctx.Warn(0, "query was empty after trimming comments, so it will be ignored")
 		return plan.Nothing, nil
 	}
 

sql/plan/create_index.go

@@ -201,10 +201,12 @@ func (c *CreateIndex) createIndex(
 			},
 		})
 
+		ctx.Error(0, "unable to save the index: %s", err)
 		logrus.WithField("err", err).Error("unable to save the index")
 
 		deleted, err := c.Catalog.DeleteIndex(index.Database(), index.ID(), true)
 		if err != nil {
+			ctx.Error(0, "unable to delete index: %s", err)
 			logrus.WithField("err", err).Error("unable to delete the index")
 		} else {
 			<-deleted

sql/plan/lock.go

@@ -3,7 +3,6 @@ package plan
 import (
 	"fmt"
 
-	"github.com/sirupsen/logrus"
 	errors "gopkg.in/src-d/go-errors.v1"
 	"gopkg.in/src-d/go-mysql-server.v0/sql"
 )
@@ -60,12 +59,12 @@ func (t *LockTables) RowIter(ctx *sql.Context) (sql.RowIter, error) {
 		lockable, err := getLockable(l.Table)
 		if err != nil {
 			// If a table is not lockable, just skip it
-			logrus.Warn(err.Error())
+			ctx.Warn(0, err.Error())
 			continue
 		}
 
 		if err := lockable.Lock(ctx, l.Write); err != nil {
-			logrus.Error(err.Error())
+			ctx.Error(0, "unable to lock table: %s", err)
 		} else {
 			t.Catalog.LockTable(id, lockable.Name())
 		}

sql/session.go

@@ -2,6 +2,7 @@ package sql
 
 import (
 	"context"
+	"fmt"
 	"io"
 	"math"
 	"sync"
@@ -238,6 +239,24 @@ func (c *Context) WithContext(ctx context.Context) *Context {
 	return &Context{ctx, c.Session, c.Pid(), c.tracer}
 }
 
+// Error adds an error as warning to the session.
+func (c *Context) Error(code int, msg string, args ...interface{}) {
+	c.Session.Warn(&Warning{
+		Level:   "Error",
+		Code:    code,
+		Message: fmt.Sprintf(msg, args...),
+	})
+}
+
+// Warn adds a warning to the session.
+func (c *Context) Warn(code int, msg string, args ...interface{}) {
+	c.Session.Warn(&Warning{
+		Level:   "Warning",
+		Code:    code,
+		Message: fmt.Sprintf(msg, args...),
+	})
+}
+
 // NewSpanIter creates a RowIter executed in the given span.
 func NewSpanIter(span opentracing.Span, iter RowIter) RowIter {
 	return &spanIter{