home/main.go

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net"
	"net/http"
	"os"
	"os/signal"
	"runtime"
	"runtime/pprof"
	"syscall"
	"time"

	"github.com/caarlos0/env/v10"

	"source.toby3d.me/toby3d/home/internal/domain"
)

var (
	config = new(domain.Config)
	logger = log.New(os.Stdout, "home\t", log.Lmsgprefix|log.LstdFlags|log.LUTC)
)

var cpuProfilePath, memProfilePath string

func init() {
	flag.StringVar(&cpuProfilePath, "cpuprofile", "", "set path to saving CPU memory profile")
	flag.StringVar(&memProfilePath, "memprofile", "", "set path to saving pprof memory profile")
	flag.Parse()

	if err := env.ParseWithOptions(config, env.Options{
		Prefix: "HOME_",
	}); err != nil {
		logger.Fatalln("cannot unmarshal configuration into domain:", err)
	}
}

func main() {
	ctx := context.Background()

	server := &http.Server{
		Addr: config.AddrPort().String(),
		Handler: http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			fmt.Fprintln(w, "hello, world!")
		}),
		ErrorLog:     logger,
		BaseContext:  func(ln net.Listener) context.Context { return ctx },
		WriteTimeout: 500 * time.Millisecond,
	}

	done := make(chan os.Signal, 1)
	signal.Notify(done, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)

	if cpuProfilePath != "" {
		cpuProfile, err := os.Create(cpuProfilePath)
		if err != nil {
			logger.Fatalln("could not create CPU profile:", err)
		}
		defer cpuProfile.Close()

		if err = pprof.StartCPUProfile(cpuProfile); err != nil {
			logger.Fatalln("could not start CPU profile:", err)
		}
		defer pprof.StopCPUProfile()
	}

	go func(server *http.Server) {
		logger.Printf("starting server on %d...", config.Port)

		if err := server.ListenAndServe(); err != nil {
			logger.Fatalln("cannot listen and serve server:", err)
		}
	}(server)

	<-done

	if err := server.Shutdown(ctx); err != nil {
		logger.Fatalln("failed shutdown server:", err)
	}

	if memProfilePath == "" {
		return
	}

	memProfile, err := os.Create(memProfilePath)
	if err != nil {
		logger.Fatalln("could not create memory profile:", err)
	}
	defer memProfile.Close()

	runtime.GC() // NOTE(toby3d): get up-to-date statistics

	if err = pprof.WriteHeapProfile(memProfile); err != nil {
		logger.Fatalln("could not write memory profile:", err)
	}
}