two ways to call a function every 2 seconds

golang-nuts.go

package main

import (
	"fmt"
	"time"
)

// Suggestions from golang-nuts
// http://play.golang.org/p/Ctg3_AQisl

func doEvery(d time.Duration, f func(time.Time)) {
	for x := range time.Tick(d) {
		f(x)
	}
}

func helloworld(t time.Time) {
	fmt.Printf("%v: Hello, World!\n", t)
}

func main() {
	doEvery(20*time.Millisecond, helloworld)
}

polling.go

package main

import (
  "fmt"
  "time"
  "net/http"
)

func doSomething(s string) {
  fmt.Println("doing something", s)
}

func startPolling1() {
  for {
    time.Sleep(2 * time.Second)
    go doSomething("from polling 1")
  }
}

func startPolling2() {
  for {
    <-time.After(2 * time.Second)
    go doSomething("from polling 2")
  }
}

func handler(w http.ResponseWriter, r *http.Request) {
  fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}

func main() {
  go startPolling1()
  go startPolling2()

  http.HandleFunc("/", handler)
  http.ListenAndServe(":8080", nil)
}

restart_panic.go

package main

import (
	"fmt"
	"time"
)

func main() {
	var pCount int
	ch := make(chan int, 5)

	f := func(i int) {
		defer func() {
			if err := recover(); err != nil {
				ch <- i
			}
		}()

		fmt.Printf("goroutine f(%v) started\n", i)
		time.Sleep(1000 * time.Millisecond)
		panic("goroutine in panic")
	}

	go f(1)
	go f(2)
	go f(3)
	go f(4)

	for {
		i := <-ch
		pCount++
		if pCount >= 5 {
			fmt.Println("Too many panics")
			break
		}
		fmt.Printf("Detected goroutine f(%v) panic, will restart\n", i)
		f(i)
	}
}