feat: init

postgresql/main.go

@@ -0,0 +1,90 @@
+package main
+
+import (
+	"context"
+	"database/sql"
+	"log"
+	"net/url"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/joho/godotenv"
+	_ "github.com/lib/pq"
+)
+
+func main() {
+	if err := godotenv.Load(); err != nil {
+		log.Println("Warning: .env file not found")
+	}
+
+	serviceURI, isExist := os.LookupEnv("SERVICE_URI")
+	if !isExist {
+		log.Fatal("Warning: SERVICE_URI not set!")
+		return
+	}
+	conn, _ := url.Parse(serviceURI)
+	conn.RawQuery = "sslmode=verify-ca;sslrootcert=ca.pem"
+
+	db, err := sql.Open("postgres", conn.String())
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+
+	go func() {
+		ticker := time.NewTicker(time.Minute)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ticker.C:
+				if err := incrementCounter(ctx, db); err != nil {
+					log.Printf("Keepalive increment error: %v", err)
+				}
+			case <-ctx.Done():
+				return
+			}
+		}
+	}()
+
+	defer func() {
+		cancel()
+		if err := db.Close(); err != nil {
+			log.Printf("Close error: %v", err)
+			return
+		}
+	}()
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+	<-sigCh
+}
+
+func incrementCounter(ctx context.Context, db *sql.DB) error {
+	ctx, cancel := context.WithTimeout(ctx, 3*time.Second)
+	defer cancel()
+
+	tx, err := db.BeginTx(ctx, &sql.TxOptions{Isolation: sql.LevelReadCommitted})
+	if err != nil {
+		return err
+	}
+
+	var value int64
+	err = tx.QueryRowContext(ctx,
+		"UPDATE keepalive SET value = value + 1 WHERE key = 'counter' RETURNING value",
+	).Scan(&value)
+	if err != nil {
+		tx.Rollback()
+		return err
+	}
+
+	if err := tx.Commit(); err != nil {
+		return err
+	}
+
+	log.Printf("Counter: %d\n", value)
+	return nil
+}