iamine in golang

iamine.go

package main

import (
        "sync"
        "bytes"
        "time"
        "bufio"
        "fmt"
        "github.com/sethgrid/pester"
        "os"
        "log"
        "encoding/json"
        "io/ioutil"
)

var logger *log.Logger
var err_logger *log.Logger
func init() {
  logger = log.New(os.Stdout, "", 0)
  err_logger = log.New(os.Stderr, "", 0)
}

type Error struct {
    Message string `json:"error"`
    Id      string `json:"id"`
}

func log_error(id string, message error) {
  e := &Error{Id: id, Message: fmt.Sprintf("%s", message)}
  b, _ := json.Marshal(e)
  go err_logger.Println(string(b))
}


func mine(id string, client *pester.Client, outChan chan string, wg *sync.WaitGroup) {
  url := fmt.Sprintf("https://archive.org/metadata/%s", id)
  defer wg.Done()
  resp, err := client.Get(url)
  defer resp.Body.Close()
  if err != nil {
    log_error(id, err)
  } else {
    body, err := ioutil.ReadAll(resp.Body)
    if err != nil {
      log_error(id, err)
    }
    buffer := new(bytes.Buffer)
    if err := json.Compact(buffer, body); err != nil {
      log_error(id, err)
    } else {
      go logger.Println(buffer)
    }
  }
}

func main() {
  var wg sync.WaitGroup
  inChan, outChan := make(chan string), make(chan string)
  done := make(chan struct{})

  rate := time.Second / 500
  throttle := time.Tick(rate)

  // Use pester for retry support.
  client := pester.New()
  client.MaxRetries = 5
  client.Backoff = pester.ExponentialBackoff

  wg.Add(1)
  go func() {
    defer wg.Done()
    input := bufio.NewScanner(os.Stdin)
    for input.Scan() {
      inChan <- input.Text()
    }
    close(done)
  }()

DONE:
  for {
    select {
    case inStr := <-inChan:
      <-throttle
      wg.Add(1)
      go mine(inStr, client, outChan, &wg)
    case <-done:
      wg.Wait()
      break DONE
    }
  }
}