trying to fix 'database is locked' issue according to the mattn/go-sq…

…lite3 docs: https://github.com/mattn/go-sqlite3/\#faq

cmd/census3/main.go

@@ -28,19 +28,19 @@ func main() {
 	flag.Parse()
 	log.Init(*logLevel, "stdout", nil)
 
-	db, q, err := db.Init(*dataDir)
+	database, q, err := db.Init(*dataDir)
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	// Start the holder scanner
-	hc, err := service.NewHoldersScanner(db, q, *url)
+	hc, err := service.NewHoldersScanner(database, q, *url)
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	// Start the API
-	err = api.Init(db, q, api.Census3APIConf{
+	err = api.Init(database, q, api.Census3APIConf{
 		Hostname: "0.0.0.0",
 		Port:     *port,
 		DataDir:  *dataDir,
@@ -60,6 +60,12 @@ func main() {
 	log.Warnf("received SIGTERM, exiting at %s", time.Now().Format(time.RFC850))
 	cancel()
 	log.Infof("waiting for routines to end gracefully...")
+	// closing database
+	go func() {
+		if err := database.Close(); err != nil {
+			log.Fatal(err)
+		}
+	}()
 	time.Sleep(5 * time.Second)
 	os.Exit(0)
 }

db/db.go

@@ -23,10 +23,14 @@ func Init(dataDir string) (*sql.DB, *queries.Queries, error) {
 		}
 	}
 	// open database file
-	database, err := sql.Open("sqlite3", dbFile)
+	fileURI := fmt.Sprintf("file:%s?cache=shared", dbFile)
+	database, err := sql.Open("sqlite3", fileURI)
 	if err != nil {
 		return nil, nil, fmt.Errorf("error opening database: %w", err)
 	}
+	// trying to fix "database is locked" issue according to the official
+	// mattn/go-sqlite3 docs: https://github.com/mattn/go-sqlite3/#faq
+	database.SetMaxOpenConns(1)
 	// get census3 goose migrations and setup for sqlite3
 	if err := goose.SetDialect("sqlite3"); err != nil {
 		return nil, nil, fmt.Errorf("error setting up driver for sqlite: %w", err)