golang 第三方定时任务库 github.com/robfig/cron/v3 核心源码解读

package _1_demo

import (
	"fmt"
	"github.com/robfig/cron/v3"
	"testing"
	"time"
)

// 定时任务
func jobTask() {
	fmt.Printf( "任务启动: %s \n",time.Now().Format("2006-01-02 15:04:05"))
}

func TestCron(t *testing.T) {
	// 创建一个cron对象
	c := cron.New()

	// 任务调度
	enterId, err := c.AddFunc("@every 3s", jobTask)
	if err!=nil{
		panic(err)
	}
	fmt.Printf("任务id是 %d \n", enterId)
	
	// 启动定时任务
	c.Start()
	
	// 用于阻塞 后面可以使用 select {} 阻塞
	time.Sleep(time.Second * 9)
}

type Cron struct {
	entries   []*Entry                         // 用于存放job指针对象的数组
	chain     Chain
	stop      chan struct{}                  // 定制调度任务
	add       chan *Entry                    // 添加一个调度任务
	remove    chan EntryID               // 移除 一个调度任务
	snapshot  chan chan []Entry     // 正在运行中的调度任务 
	running   bool                             // 保证整个Cron对象只启动一次 和启动后其他chan正常
	logger    Logger                          // 记录日志
	runningMu sync.Mutex              // 协程锁，确保执行安全
	location  *time.Location            // 时区
	parser    ScheduleParser           // 解析参数
	nextID    EntryID                         // 下一个调度任务的id
	jobWaiter sync.WaitGroup        // 确保单一的调度任务执行完毕
}

// Entry consists of a schedule and the func to execute on that schedule.
type Entry struct {
	// ID is the cron-assigned ID of this entry, which may be used to look up a
	// snapshot or remove it.
	ID EntryID  // 任务调度Id，默认是自增 创建任务时返回

	// Schedule on which this job should be run.
	Schedule Schedule // 调度任务运行

	// Next time the job will run, or the zero time if Cron has not been
	// started or this entry's schedule is unsatisfiable
	Next time.Time       // 下次执行时间

	// Prev is the last time this job was run, or the zero time if never.
	Prev time.Time      // 上次执行时间

	// WrappedJob is the thing to run when the Schedule is activated.
	WrappedJob Job      // 执行的任务

	// Job is the thing that was submitted to cron.
	// It is kept around so that user code that needs to get at the job later,
	// e.g. via Entries() can do so.
	Job Job
}