REPL example app with statsd metrics

metrics.go

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"os"
	"time"

	"github.com/etsy/statsd/examples/go"
)

func main() {
	br := bufio.NewReader(os.Stdin)

	host := "127.0.0.1"
	port := 8125
	client := statsd.New(host, port)
	client.Open()
	defer client.Close()

	// repl is the read, evaluate, print, loop
	for {
		if err := readEvaluateProcess(client, br); err != nil {
			if err == io.EOF {
				return
			}
			client.Increment("error")
		}
	}
}

func readEvaluateProcess(client *statsd.StatsdClient, br *bufio.Reader) error {
	t1 := time.Now()
	client.Increment("service.repl")
	fmt.Printf("> ")

	line, err := readLine(client, br)
	if err != nil {
		client.Increment("error")
		return err
	}

	out, err := processLine(client, line)
	if err != nil {
		client.Increment("error")
		return err
	}

	fmt.Printf("< %s\n\n", out)

	t2 := time.Now()
	duration := int64(t2.Sub(t1) / time.Millisecond)

	client.Timing("stat.timer", duration)
	return nil
}

func readLine(client *statsd.StatsdClient, br *bufio.Reader) ([]byte, error) {
	line, _, err := br.ReadLine()
	client.Increment("service.repl.readLine")
	if err != nil {
		return nil, err
	}

	return line, nil
}

func processLine(client *statsd.StatsdClient, in []byte) (out []byte, err error) {
	output := bytes.ToUpper(in)
	client.Increment("service.repl.processLine")
	return output, nil
}