Singleton va uning muammolari

final class Sozlamalar
{
    private static ?self $nusxa = null;

    /** @var array<string, string> */
    private array $qiymatlar = [];

    // tashqaridan new qilib bo'lmaydi
    private function __construct()
    {
        $this->qiymatlar = ['til' => 'uz', 'mavzu' => 'yorug'];
    }

    public static function ol(): self
    {
        // birinchi chaqiruvda yaratiladi, keyin qayta ishlatiladi
        self::$nusxa ??= new self();
        return self::$nusxa;
    }

    public function qiymat(string $kalit): ?string
    {
        return $this->qiymatlar[$kalit] ?? null;
    }

    public function qoy(string $kalit, string $qiymat): void
    {
        $this->qiymatlar[$kalit] = $qiymat;
    }

    // nusxa ko'chirishning oldini olamiz
    private function __clone() {}

    public function __wakeup(): void
    {
        throw new LogicException('Singleton ni deserializatsiya qilib bolmaydi');
    }
}

$a = Sozlamalar::ol();
$b = Sozlamalar::ol();

echo 'bir xil obyektmi: ', $a === $b ? 'ha' : 'yoq', PHP_EOL;
echo 'obyekt raqami: ', spl_object_id($a), ' va ', spl_object_id($b), PHP_EOL;
echo 'til: ', $a->qiymat('til'), PHP_EOL;

// $a orqali o'zgartirsak, $b da ham ko'rinadi
$a->qoy('til', 'ru');
echo 'b dagi til: ', $b->qiymat('til'), PHP_EOL;

try {
    $x = new Sozlamalar();
} catch (Error $e) {
    echo 'new: ', $e->getMessage(), PHP_EOL;
}

try {
    $x = clone Sozlamalar::ol();
} catch (Error $e) {
    echo 'clone: ', $e->getMessage(), PHP_EOL;
}

try {
    $x = unserialize(serialize(Sozlamalar::ol()));
} catch (LogicException $e) {
    echo 'unserialize: ', $e->getMessage(), PHP_EOL;
}

final class HisobotXizmati
{
    public function tayyorla(): string
    {
        // bog'liqlik konstruktorda ko'rinmaydi
        $til = Sozlamalar::ol()->qiymat('til');
        return "hisobot tili: {$til}";
    }
}

$x = new HisobotXizmati();
echo $x->tayyorla(), PHP_EOL;

// birinchi "test" tilni o'zgartiradi
function testRuscha(): string
{
    Sozlamalar::ol()->qoy('til', 'ru');
    return 'testRuscha: ' . Sozlamalar::ol()->qiymat('til');
}

// ikkinchi "test" o'zbekchani kutadi - o'zi hech narsa o'zgartirmaydi
function testOzbekcha(): string
{
    return 'testOzbekcha: ' . Sozlamalar::ol()->qiymat('til');
}

echo testOzbekcha(), PHP_EOL;   // hali toza
echo testRuscha(), PHP_EOL;     // holatni o'zgartirdi
echo testOzbekcha(), PHP_EOL;   // endi ifloslangan

final readonly class Konfiguratsiya
{
    /** @param array<string, string> $qiymatlar */
    public function __construct(private array $qiymatlar) {}

    public function qiymat(string $kalit): ?string
    {
        return $this->qiymatlar[$kalit] ?? null;
    }
}

final readonly class Hisobot
{
    // bog'liqlik ochiq ko'rinadi
    public function __construct(private Konfiguratsiya $konf) {}

    public function tayyorla(): string
    {
        return 'hisobot tili: ' . $this->konf->qiymat('til');
    }
}

// dasturning kirish nuqtasida BIR MARTA yaratiladi
$konf = new Konfiguratsiya(['til' => 'uz', 'mavzu' => 'yorug']);

echo (new Hisobot($konf))->tayyorla(), PHP_EOL;

// testda esa boshqa nusxa - hech narsa ifloslanmaydi
$testKonf = new Konfiguratsiya(['til' => 'ru']);
echo (new Hisobot($testKonf))->tayyorla(), PHP_EOL;
echo (new Hisobot($konf))->tayyorla(), PHP_EOL;

// Har so'rov o'z jarayonida boshlanadi va tugaydi
echo 'jarayon: har HTTP so\'rovi uchun yangi', PHP_EOL;
echo 'xotira: so\'rov tugagach butunlay tozalanadi', PHP_EOL;
echo 'oqimlar: odatiy PHP-FPM da bitta so\'rov = bitta oqim', PHP_EOL;

$boshlanish = memory_get_usage();
$katta = range(1, 100000);
$oxiri = memory_get_usage();

printf('massiv xotirasi: ~%d KB%s',
    intdiv($oxiri - $boshlanish, 1024), PHP_EOL);
unset($katta);
printf('unset dan keyin: ~%d KB%s',
    intdiv(memory_get_usage() - $boshlanish, 1024), PHP_EOL);

final class Jurnal
{
    private static ?self $nusxa = null;
    /** @var list<string> */
    private array $qatorlar = [];

    private function __construct() {}

    public static function ol(): self
    {
        return self::$nusxa ??= new self();
    }

    public function yoz(string $daraja, string $xabar): void
    {
        $this->qatorlar[] = strtoupper($daraja) . ': ' . $xabar;
    }

    /** @return list<string> */
    public function hammasi(): array
    {
        return $this->qatorlar;
    }
}

Jurnal::ol()->yoz('info', 'dastur boshlandi');
Jurnal::ol()->yoz('warning', 'sekin sorov: 1.2s');
Jurnal::ol()->yoz('info', 'dastur tugadi');

foreach (Jurnal::ol()->hammasi() as $i => $q) {
    printf('%d. %s%s', $i + 1, $q, PHP_EOL);
}

final class Matematika
{
    public static function ortacha(float ...$sonlar): float
    {
        if ($sonlar === []) {
            throw new InvalidArgumentException('bosh royxat');
        }
        return array_sum($sonlar) / count($sonlar);
    }
}

printf('%.2f%s', Matematika::ortacha(4.0, 5.5, 6.5), PHP_EOL);