ussd-data-connect/cmd/main.go

package main

import (
	"context"
	"errors"
	"flag"
	"log/slog"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"

	"git.grassecon.net/urdt/ussd-data-connect/internal/store"
	"git.grassecon.net/urdt/ussd-data-connect/internal/syncer"
	"git.grassecon.net/urdt/ussd-data-connect/internal/util"
	"github.com/knadh/koanf/v2"
)

const defaultGracefulShutdownPeriod = time.Second * 20

var (
	build = "dev"

	confFlag             string
	migrationsFolderFlag string
	queriesFlag          string

	lo *slog.Logger
	ko *koanf.Koanf
)

func init() {
	flag.StringVar(&confFlag, "config", "config.toml", "Config file location")
	flag.StringVar(&migrationsFolderFlag, "migrations", "migrations/", "Migrations folder location")
	flag.StringVar(&queriesFlag, "queries", "queries.sql", "Queries file location")
	flag.Parse()

	lo = util.InitLogger()
	ko = util.InitConfig(lo, confFlag)

	lo.Info("starting ussd data connect", "build", build)
}

func main() {
	var wg sync.WaitGroup
	ctx, stop := notifyShutdown()

	store, err := store.NewStore(store.StoreOpts{
		Logg:                 lo,
		DSN:                  ko.MustString("postgres.dsn"),
		MigrationsFolderPath: migrationsFolderFlag,
		QueriesFolderPath:    queriesFlag,
	})
	if err != nil {
		lo.Error("could not initialize postgres store", "error", err)
		os.Exit(1)
	}

	syncer := syncer.New(syncer.SyncerOpts{
		Logg:  lo,
		Store: store,
	})

	// Trigger an initial sync before the ticker routine takes over
	if err := syncer.Process(context.Background()); err != nil {
		lo.Error("failed to process initial sync", "error", err)
		os.Exit(1)
	}

	wg.Add(1)
	go func() {
		defer wg.Done()
		syncer.Run()
	}()

	<-ctx.Done()
	lo.Info("shutdown signal received")
	shutdownCtx, cancel := context.WithTimeout(context.Background(), defaultGracefulShutdownPeriod)

	wg.Add(1)
	go func() {
		syncer.Stop()
		defer wg.Done()
	}()

	go func() {
		wg.Wait()
		stop()
		cancel()
		os.Exit(0)
	}()

	<-shutdownCtx.Done()
	if errors.Is(shutdownCtx.Err(), context.DeadlineExceeded) {
		stop()
		cancel()
		lo.Error("graceful shutdown period exceeded, forcefully shutting down")
	}
	os.Exit(1)
}

func notifyShutdown() (context.Context, context.CancelFunc) {
	return signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM, syscall.SIGINT)
}