*: Convert string to terror in DDL Job (pingcap#1699)

* *: convert string to terror

ddl/bg_worker.go

@@ -93,7 +93,7 @@ func (d *ddl) runBgJob(t *meta.Meta, job *model.Job) {
 			log.Errorf("[ddl] run background job err %v", errors.ErrorStack(err))
 		}
 
-		job.Error = err.Error()
+		job.Error = toTError(err)
 		job.ErrorCount++
 	}
 }

ddl/ddl_worker.go

@@ -81,7 +81,7 @@ func (d *ddl) doDDLJob(ctx context.Context, job *model.Job) error {
 			return nil
 		}
 
-		return errors.Errorf(historyJob.Error)
+		return errors.Trace(historyJob.Error)
 	}
 }
 
@@ -379,11 +379,22 @@ func (d *ddl) runDDLJob(t *meta.Meta, job *model.Job) {
 			log.Errorf("run ddl job err %v", errors.ErrorStack(err))
 		}
 
-		job.Error = err.Error()
+		job.Error = toTError(err)
 		job.ErrorCount++
 	}
 }
 
+func toTError(err error) *terror.Error {
+	originErr := errors.Cause(err)
+	tErr, ok := originErr.(*terror.Error)
+	if ok {
+		return tErr
+	}
+
+	// TODO: add the error code
+	return terror.ClassDDL.New(terror.CodeUnknown, err.Error())
+}
+
 // for every lease seconds, we will re-update the whole schema, so we will wait 2 * lease time
 // to guarantee that all servers have already updated schema.
 func (d *ddl) waitSchemaChanged(waitTime time.Duration) {

ddl/stat.go

@@ -89,7 +89,11 @@ func (d *ddl) Stats() (map[string]interface{}, error) {
 		m[ddlJobAction] = ddlInfo.Job.Type.String()
 		m[ddlJobLastUpdateTS] = ddlInfo.Job.LastUpdateTS / 1e9
 		m[ddlJobState] = ddlInfo.Job.State.String()
-		m[ddlJobError] = ddlInfo.Job.Error
+		if ddlInfo.Job.Error == nil {
+			m[ddlJobError] = ""
+		} else {
+			m[ddlJobError] = ddlInfo.Job.Error.Error()
+		}
 		m[ddlJobSchemaState] = ddlInfo.Job.SchemaState.String()
 		m[ddlJobSchemaID] = ddlInfo.Job.SchemaID
 		m[ddlJobTableID] = ddlInfo.Job.TableID
@@ -110,7 +114,11 @@ func (d *ddl) Stats() (map[string]interface{}, error) {
 		m[bgJobAction] = bgInfo.Job.Type.String()
 		m[bgJobLastUpdateTS] = bgInfo.Job.LastUpdateTS / 1e9
 		m[bgJobState] = bgInfo.Job.State.String()
-		m[bgJobError] = bgInfo.Job.Error
+		if bgInfo.Job.Error == nil {
+			m[bgJobError] = ""
+		} else {
+			m[bgJobError] = bgInfo.Job.Error.Error()
+		}
 		m[bgJobSchemaState] = bgInfo.Job.SchemaState.String()
 		m[bgJobSchemaID] = bgInfo.Job.SchemaID
 		m[bgJobTableID] = bgInfo.Job.TableID

model/ddl.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 
 	"github.com/juju/errors"
+	"github.com/pingcap/tidb/terror"
 )
 
 // ActionType is the type for DDL action.
@@ -67,12 +68,12 @@ func (action ActionType) String() string {
 
 // Job is for a DDL operation.
 type Job struct {
-	ID       int64      `json:"id"`
-	Type     ActionType `json:"type"`
-	SchemaID int64      `json:"schema_id"`
-	TableID  int64      `json:"table_id"`
-	State    JobState   `json:"state"`
-	Error    string     `json:"err"`
+	ID       int64         `json:"id"`
+	Type     ActionType    `json:"type"`
+	SchemaID int64         `json:"schema_id"`
+	TableID  int64         `json:"table_id"`
+	State    JobState      `json:"state"`
+	Error    *terror.Error `json:"err"`
 	// every time we meet an error when running job, we will increase it
 	ErrorCount int64         `json:"err_count"`
 	Args       []interface{} `json:"-"`

mysql/error.go

@@ -60,7 +60,7 @@ func NewErr(errCode uint16, args ...interface{}) *SQLError {
 	return e
 }
 
-// NewErrf creates a SQL error, with an error code and a format specifier
+// NewErrf creates a SQL error, with an error code and a format specifier.
 func NewErrf(errCode uint16, format string, args ...interface{}) *SQLError {
 	e := &SQLError{Code: errCode}
 

terror/terror.go

@@ -14,6 +14,7 @@
 package terror
 
 import (
+	"encoding/json"
 	"fmt"
 	"runtime"
 	"strconv"
@@ -38,7 +39,8 @@ type ErrCode int
 
 // Executor error codes.
 const (
-	CodeCommitNotInTransaction   ErrCode = 1
+	CodeUnknown                  ErrCode = -1
+	CodeCommitNotInTransaction           = 1
 	CodeRollbackNotInTransaction         = 2
 	CodeExecResultIsEmpty                = 3
 )
@@ -165,6 +167,35 @@ func (e *Error) Code() ErrCode {
 	return e.code
 }
 
+func (e *Error) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&struct {
+		Class ErrClass `json:"class"`
+		Code  ErrCode  `json:"code"`
+		Msg   string   `json:"message"`
+	}{
+		Class: e.class,
+		Code:  e.code,
+		Msg:   e.message,
+	})
+}
+
+func (e *Error) UnmarshalJSON(data []byte) error {
+	err := &struct {
+		Class ErrClass `json:"class"`
+		Code  ErrCode  `json:"code"`
+		Msg   string   `json:"message"`
+	}{}
+
+	if err := json.Unmarshal(data, &err); err != nil {
+		return errors.Trace(err)
+	}
+
+	e.class = err.Class
+	e.code = err.Code
+	e.message = err.Msg
+	return nil
+}
+
 // Location returns the location where the error is created,
 // implements juju/errors locationer interface.
 func (e *Error) Location() (file string, line int) {

terror/terror_test.go

@@ -14,6 +14,7 @@
 package terror
 
 import (
+	"encoding/json"
 	"strings"
 	"testing"
 
@@ -66,6 +67,21 @@ func (s *testTErrorSuite) TestTError(c *C) {
 	c.Assert(sqlErr.Code, Equals, uint16(1062))
 }
 
+func (s *testTErrorSuite) TestJson(c *C) {
+	prevTErr := &Error{
+		class:   ClassTable,
+		code:    CodeExecResultIsEmpty,
+		message: "json test",
+	}
+	buf, err := json.Marshal(prevTErr)
+	c.Assert(err, IsNil)
+	var curTErr Error
+	err = json.Unmarshal(buf, &curTErr)
+	c.Assert(err, IsNil)
+	isEqual := prevTErr.Equal(&curTErr)
+	c.Assert(isEqual, IsTrue)
+}
+
 var predefinedErr = ClassExecutor.New(ErrCode(123), "predefiend error")
 
 func example() error {