| We often want to execute Go code at some point in the future, or repeatedly at some interval. Go's built-in _timer_ and _ticker_ features make both of these tasks easy. We'll look first at timers and then at [tickers](tickers). | ||
package main |
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import ( |
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"fmt" |
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"time" |
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) |
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func main() { |
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| Timers represent a single event in the future. You tell the timer how long you want to wait, and it provides a channel that will be notified at that time. This timer will wait 2 seconds. | timer1 := time.NewTimer(2 * time.Second) |
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| The `<-timer1.C` blocks on the timer's channel `C` until it sends a value indicating that the timer fired. | <-timer1.C |
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fmt.Println("Timer 1 fired") |
Timer 1 fired |
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| If you just wanted to wait, you could have used `time.Sleep`. One reason a timer may be useful is that you can cancel the timer before it fires. Here's an example of that. | timer2 := time.NewTimer(time.Second) |
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go func() { |
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<-timer2.C |
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fmt.Println("Timer 2 fired") |
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}() |
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stop2 := timer2.Stop() |
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if stop2 { |
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fmt.Println("Timer 2 stopped") |
Timer 2 stopped |
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} |
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| Give the `timer2` enough time to fire, if it ever was going to, to show it is in fact stopped. | time.Sleep(2 * time.Second) |
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} |