From 7258ef113a0daa8478dc86afd41859dc8e659239 Mon Sep 17 00:00:00 2001
From: Ming Deng <mingflycash@gmail.com>
Date: Sun, 19 Jul 2020 14:34:57 +0000
Subject: [PATCH] Store nearest error info

---
 toolbox/task.go      | 12 +++++++++---
 toolbox/task_test.go | 22 ++++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/toolbox/task.go b/toolbox/task.go
index d2a94ba9..c902fdfc 100644
--- a/toolbox/task.go
+++ b/toolbox/task.go
@@ -102,6 +102,8 @@ type taskerr struct {
 }
 
 // Task task struct
+// It's not a thread-safe structure.
+// Only nearest errors will be saved in ErrList
 type Task struct {
 	Taskname string
 	Spec     *Schedule
@@ -111,6 +113,7 @@ type Task struct {
 	Next     time.Time
 	Errlist  []*taskerr // like errtime:errinfo
 	ErrLimit int        // max length for the errlist, 0 stand for no limit
+	errCnt int // records the error count during the execution
 }
 
 // NewTask add new task with name, time and func
@@ -119,8 +122,11 @@ func NewTask(tname string, spec string, f TaskFunc) *Task {
 	task := &Task{
 		Taskname: tname,
 		DoFunc:   f,
+		// Make configurable
 		ErrLimit: 100,
 		SpecStr:  spec,
+		// we only store the pointer, so it won't use too many space
+		Errlist: make([]*taskerr, 100, 100),
 	}
 	task.SetCron(spec)
 	return task
@@ -144,9 +150,9 @@ func (t *Task) GetStatus() string {
 func (t *Task) Run() error {
 	err := t.DoFunc()
 	if err != nil {
-		if t.ErrLimit > 0 && t.ErrLimit > len(t.Errlist) {
-			t.Errlist = append(t.Errlist, &taskerr{t: t.Next, errinfo: err.Error()})
-		}
+		index := t.errCnt % t.ErrLimit
+		t.Errlist[index] = &taskerr{t: t.Next, errinfo: err.Error()}
+		t.errCnt++
 	}
 	return err
 }
diff --git a/toolbox/task_test.go b/toolbox/task_test.go
index 596bc9c5..3a4cce2f 100644
--- a/toolbox/task_test.go
+++ b/toolbox/task_test.go
@@ -15,10 +15,13 @@
 package toolbox
 
 import (
+	"errors"
 	"fmt"
 	"sync"
 	"testing"
 	"time"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestParse(t *testing.T) {
@@ -53,6 +56,25 @@ func TestSpec(t *testing.T) {
 	}
 }
 
+func TestTask_Run(t *testing.T) {
+	cnt := -1
+	task := func() error {
+		cnt ++
+		fmt.Printf("Hello, world! %d \n", cnt)
+		return errors.New(fmt.Sprintf("Hello, world! %d", cnt))
+	}
+	tk := NewTask("taska", "0/30 * * * * *", task)
+	for i := 0; i < 200 ; i ++ {
+		e := tk.Run()
+		assert.NotNil(t, e)
+	}
+
+	l := tk.Errlist
+	assert.Equal(t, 100, len(l))
+	assert.Equal(t, "Hello, world! 100", l[0].errinfo)
+	assert.Equal(t, "Hello, world! 101", l[1].errinfo)
+}
+
 func wait(wg *sync.WaitGroup) chan bool {
 	ch := make(chan bool)
 	go func() {