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@vaskoz
Created October 10, 2017 05:08
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package main
import (
"context"
"log"
"math/rand"
"os"
"runtime/trace"
"sync"
"time"
)
type Application struct {
done chan struct{}
}
func New() *Application {
return &Application{make(chan struct{}, 1)}
}
func (a *Application) Start(ctx context.Context, wg *sync.WaitGroup) chan struct{} {
go func() {
select {
case <-ctx.Done():
log.Println("Started goroutine received a cancellation order")
case <-time.After(15 * time.Minute):
log.Println("Yikes")
}
a.done <- struct{}{}
wg.Done()
}()
return a.done
}
func main() {
rand.Seed(time.Now().UnixNano())
traceFile, err := os.Create("/tmp/aws_spot_main.trace")
if err != nil {
log.Fatalln("could not create a temp file")
}
trace.Start(traceFile)
defer trace.Stop()
ctx, cancel := context.WithCancel(context.Background())
ticker := time.NewTicker(1 * time.Second)
app := New()
wg := &sync.WaitGroup{}
wg.Add(1)
done := app.Start(ctx, wg)
for {
select {
case <-done:
log.Println("app completed successfully and normally")
wg.Wait()
log.Println("exiting the main function. All goroutines shutdown")
ticker.Stop()
return
case <-ticker.C:
log.Println("checking AWS spot instance termination notice")
if rand.Intn(10) == 0 {
log.Println("sending cancel message")
cancel()
} else {
log.Println("keep running")
}
}
}
}
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