CODEWITHSUNDEEP
goticker
damoiser
damoiser

Reputation: 6238

dynamically change ticker interval

I would like to change my ticker interval dynamically.

I've written down an example to show you how I did. My use case is something else than an "accelerometer" but I hope that it gives you an idea.

http://play.golang.org/p/6ANFnoE6pA

package main

import (
    "time"
    "log"
    "fmt"
)

func main() {
    interval := float64(1000)

    ticker := time.NewTicker(time.Duration(interval) * time.Millisecond)
    go func(){
        counter := 1.0
        for range ticker.C {
            log.Println("ticker accelerating to " + fmt.Sprint(interval/counter) + " ms")
            ticker = time.NewTicker(time.Duration(interval/counter) * time.Millisecond)
            counter++
        }
        log.Println("stopped")
    }()
    time.Sleep(5 * time.Second)
    log.Println("stopping ticker")
    ticker.Stop()
}

What is wrong is that the ticker will always "tick" every seconds and it doesn't accelerate... Any idea?

Upvotes: 10

Views: 14689

Answers (4)

Isaac Weingarten
Isaac Weingarten

Reputation: 1180

that why in go1.15 ticker.Reset is Introduced, you don't need to create a new ticker update the existing ticker's duration with ticker.Reset("new duration"), and now you will not have any cache issues

Go playground

package main

import (
    "fmt"
    "log"
    "time"
)

func main() {
    interval := float64(1000)

    ticker := time.NewTicker(time.Duration(interval) * time.Millisecond)
    go func(){
        counter := 1.0
        for range ticker.C {
            log.Println("ticker accelerating to " + fmt.Sprint(interval/counter) + " ms")
            ticker.Reset(time.Duration(interval/counter) * time.Millisecond)
            counter++
        }
        log.Println("stopped")
    }()
    time.Sleep(5 * time.Second)
    log.Println("stopping ticker")
    ticker.Stop()
}

The reason your example have a cache issue is that when you reassign the ticker variable with a *time.ticker struct you just unlink the original *time.ticker struct from the ticker variable but the loop is still tide to the original ticker channel you need to reassin a new loop to the new time.ticker.c

Upvotes: 5

sgon00
sgon00

Reputation: 5757

What about this code:

https://play.golang.org/p/wyOTVxUW5Xj

package main

import (
    "fmt"
    "log"
    "time"
)

func main() {
    startInterval := float64(1000)
    quit := make(chan bool)

    go func() {
        counter := 1.0
        for {
            select {
            case <-time.After(time.Duration(startInterval/counter) * time.Millisecond):
                log.Println("ticker accelerating to " + fmt.Sprint(startInterval/counter) + " ms")
                counter++
            case <-quit:
                log.Println("..ticker stopped!")
                return
            }
        }
    }()

    time.Sleep(5 * time.Second)
    log.Println("stopping ticker...")
    quit <- true
    time.Sleep(500 * time.Millisecond) // just to see quit messages
}

Upvotes: 0

damoiser
damoiser

Reputation: 6238

Following the answer to @fzerorubigd but a little more complete.

As said before, we can't use the range for this case, because the range loop caches the variable to be lopped and then it can't be overwritten (example here: http://play.golang.org/p/yZvrgURz4o )

Then, we should use a for-select combination loop. Hereafter the working solution:

http://play.golang.org/p/3uJrAIhnTQ

package main

import (
    "time"
    "log"
    "fmt"
)

func main() {
    start_interval := float64(1000)
    quit := make(chan bool)

    go func(){
        ticker := time.NewTicker(time.Duration(start_interval) * time.Millisecond)
        counter := 1.0

        for {
            select {
            case <-ticker.C:
                log.Println("ticker accelerating to " + fmt.Sprint(start_interval/counter) + " ms")
                ticker.Stop()
                ticker = time.NewTicker(time.Duration(start_interval/counter) * time.Millisecond)
                counter++
            case <-quit:
                ticker.Stop()
                log.Println("..ticker stopped!")
                return
            }
        }
    }()

    time.Sleep(5 * time.Second)

    log.Println("stopping ticker...")
    quit<-true

    time.Sleep(500 * time.Millisecond) // just to see quit messages
}

Upvotes: 8

fzerorubigd
fzerorubigd

Reputation: 1874

As Nipun Talukdar mentioned, the "for" capture the channel and use the same reference for iterate. it fixed if you use it like this :

playground

package main

import (
    "fmt"
    "log"
    "time"
)

func main() {
    interval := float64(1000)

    ticker := time.NewTicker(time.Duration(interval) * time.Millisecond)
    go func() {
        counter := 1.0
        for {
            select {
            case <-ticker.C:
                log.Println("ticker accelerating to " + fmt.Sprint(interval/counter) + " ms")
                ticker = time.NewTicker(time.Duration(interval/counter) * time.Millisecond)
                counter++
            }
        }
        log.Println("stopped")
    }()
    time.Sleep(5 * time.Second)
    log.Println("stopping ticker")
    ticker.Stop()
}

Upvotes: 1

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