goroutine example with logging

main.go

package main

import (
	"fmt"
	"io"
	"os"
	"os/signal"
	"sync"
)

type Logger struct {
  write chan string
  wg sync.WaitGroup
}

func New(w io.Writer, s int) *Logger {
  l := Logger {
    write: make(chan string, s),
  }

  l.wg.Add(1)

  go func() {
    for d := range l.write {
      fmt.Fprintln(w, d)
    }

    l.wg.Done()
  }()

  return &l
}

func (l *Logger) Write(d string) {
  select {
  case l.write<-d:
  default:
    fmt.Println("dropping logs")
  }
}

func (l *Logger) Shutdown() {
  close(l.write)
  l.wg.Wait()
}

func main() {

  l := New(os.Stdout, 10)

  for i := 0; i < 10; i++ {
      go func(i int) {
        l.Write(fmt.Sprintf("logging %d", i+1))
      }(i)
  }

  sc := make(chan os.Signal, 1)
  signal.Notify(sc, os.Interrupt)

  loop:
  for {
    select {
    case <-sc:
      fmt.Println("CTRL-C received. Shutting down...")
      l.Shutdown()
      break loop
    }
  }
}

func checkError(err error) {
    if err != nil {
        panic(err)
    }
}