Running a function in golang at a specific time

Question

How to run a function in golang at a certain time?

I need to run the function myfunc , for example, at 00:00. How to do it?

It will be much more correct, and definitely more transparent than what is offered below.
if the function should be launched in the context of a running application and work with its data, it is unlikely that cron will be more convenient.
In general, without telepathic capabilities, it is hardly possible to say that it is “more transparent” for the task ahead of the top-starter.
I agree with telepathy: that is, you answered, as you yourself understood, without asking the TS what he really needs?
:) Okay, your position is clear to me, we will no longer flood.
@AlexBelyaev, yes no, I read the task, and it is clearly and unambiguously written, "how to start a function in golang at a certain time," that was my answer.
After, yes, when it was clarified that you need to run once a day, then doubts crept in.

Accepted Answer · 2015-07-16T15:29:42

Well, for example like this:

 package main import ( "time" "fmt" ) // Описание формата времени. const timeLayout = "Jan 2, 2006 15:04:05 MST" // Вызов переданной функции в указанное время. func callAt(callTime string, f func()) error { // Разбираем время запуска. ctime, err := time.Parse(timeLayout, callTime) if err != nil { return err } // Вычисляем временной промежуток до запуска. duration := ctime.Sub(time.Now()) go func() { time.Sleep(duration) f() }() return nil } // Ваша функция. func myfunc() { fmt.Printf("+ %v\n", time.Now()) } // Пример использования. func main() { err := callAt("Jul 17, 2015 00:00:00 MSK", myfunc) if err != nil { fmt.Printf("error: %v\n", err) } // Эмуляция дальнейшей работы программы. time.Sleep(time.Hour * 24) }

Actually, there are many ways, for example, you can use time.After , after a specified period of time, a message will be sent to the channel. The main question here is in the calculation of this very interval; One of the possible options I brought.

Update : here's an option for everyday launch:

 package main import ( "time" "fmt" ) // Вызов переданной функции раз в сутки в указанное время. func callAt(hour, min, sec int, f func()) error { loc, err := time.LoadLocation("Local") if err != nil { return err } // Вычисляем время первого запуска. now := time.Now().Local() firstCallTime := time.Date( now.Year(), now.Month(), now.Day(), hour, min, sec, 0, loc) if firstCallTime.Before(now) { // Если получилось время раньше текущего, прибавляем сутки. firstCallTime = firstCallTime.Add(time.Hour * 24) } // Вычисляем временной промежуток до запуска. duration := firstCallTime.Sub(time.Now().Local()) go func() { time.Sleep(duration) for { f() // Следующий запуск через сутки. time.Sleep(time.Hour * 24) } }() return nil } // Ваша функция. func myfunc() { fmt.Printf("+ %v\n", time.Now()) } // Пример использования. func main() { err := callAt(0, 0, 0, myfunc) if err != nil { fmt.Printf("error: %v\n", err) } // Эмуляция дальнейшей работы программы. time.Sleep(time.Hour * 24) }

When once a day there will be a "cleanup" of the data at a certain time-rate.
I think to create in the project for exams the event of the exam for students.
It will be normal if, say, there are 100 current (unfinished) exams in the system (ie, respectively +100 gorutin) and they will wait in the wings, will it not load the application?
Let at least 1000 Gorutin hang in sleep, it will not load the application.

Running a function in golang at a specific time

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