---
id: 676f2820-f539-4b0a-8633-668fd0630c3c
title: Lazy Sessions
---

# Introduction

PHP 7.0 introduced a new interface called
`SessionUpdateTimestampHandlerInterface`. As of [Symfony
4.0](20201109140137-symfony_4_0) this has been added to the [PHP7
Polyfill component](20201109151215-symfony_php7_polyfill_component)

# Syntax

``` php
interface SessionUpdateTimestampHandlerInterface
{
    // Checks if a session identifier already exists or not.
    public function validateId(string $key) : bool;

    // Updates the timestamp of a session when its data didn't change.
    public function updateTimestamp(string $key, string $val) : bool;
}
```