如何在每天的特定时间运行作业？

Question

我想在每天晚上 9 点打印出do my job。如何在 Go 中执行此操作？

这是我目前所得到的：

timer := time.NewTimer(3 * time.Second)
for {
    now := time.Now()
    next := now.Add(time.Hour * 24)
    todayNine := time.Date(next.Year(), next.Month(), next.Day(), 9, 0, 0, 0, next.Location()).AddDate(0, 0, -1)
    todayFifteen := time.Date(next.Year(), next.Month(), next.Day(), 15, 0, 0, 0, next.Location()).AddDate(0, 0, -1)
    todayEnd := time.Date(next.Year(), next.Month(), next.Day(), 0, 0, 0, 0, next.Location()).AddDate(0, 0,  -1)
    if now.Before(todayNine) {
        timer.Reset(todayNine.Sub(now))
    } else if now.Before(todayFifteen) {
        timer.Reset(todayFifteen.Sub(now))
    } else if now.Before(todayEnd) {
        timer.Reset(todayEnd.Sub(now))
    }
    <- timer.C
    fmt.Println("do my job")
}

Answer 1

我会使用cron 包。 https://pkg.go.dev/github.com/robfig/cron

文档中的示例：

c := cron.New()
c.AddFunc("0 30 * * * *", func() { fmt.Println("Every hour on the half hour") })
c.AddFunc("@hourly",      func() { fmt.Println("Every hour") })
c.AddFunc("@every 1h30m", func() { fmt.Println("Every hour thirty") })
c.Start()
..
// Funcs are invoked in their own goroutine, asynchronously.
...
// Funcs may also be added to a running Cron
c.AddFunc("@daily", func() { fmt.Println("Every day") })
..
// Inspect the cron job entries' next and previous run times.
inspect(c.Entries())
..
c.Stop()  // Stop the scheduler (does not stop any jobs already running).

Answer 2

我会探索操作系统级别或基础架构级别的系统以在这些时间触发执行（*nix 中的 Cron 作业，k8s 中的 Cron 等）

但是，如果您想纯粹使用 go 来实现，您可以尝试同时使用 ticker 和 Clock

package main

import (
    "context"
    "fmt"
    "os"
    "time"
    "os/signal"
)

func main() {
    ticker := time.NewTicker(time.Minute)
    done := make(chan bool)
    ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
    defer stop()
    go func() {
        for {
            select {
            case <-done:
                return
            case <-ticker.C:
                h, m, _ := time.Now().Clock()
                if m == 0 && (  h == 9 || h == 15 ) {
                    fmt.Printf("Doing the job")
                }
            }
        }
    }()

    <-ctx.Done()
    stop()
    done <- true
}

链接到plaground