[ticket/16891] Add new method for deferring cache purge to end of request

PHPBB3-16891

phpBB/config/default/container/services.yml

@@ -40,6 +40,7 @@ services:
              - '@cache.driver'
              - '@config'
              - '@dbal.conn'
+             - '@dispatcher'
              - '%core.root_path%'
              - '%core.php_ext%'
 

phpBB/phpbb/cache/service.php

@@ -13,11 +13,20 @@
 
 namespace phpbb\cache;
 
+use Symfony\Component\EventDispatcher\Event;
+use Symfony\Component\HttpKernel\KernelEvents;
+
 /**
 * Class for grabbing/handling cached entries
 */
 class service
 {
+	/** @var string Name of event used for cache purging */
+	private const CACHE_PURGE_EVENT = 'core.garbage_collection';
+
+	/** @var bool Flag whether cache purge has been deferred */
+	private $cache_purge_deferred = false;
+
 	/**
 	* Cache driver.
 	*
@@ -39,6 +48,9 @@ class service
 	*/
 	protected $db;
 
+	/** @var \phpbb\event\dispatcher phpBB Event dispatcher */
+	protected $dispatcher;
+
 	/**
 	* Root path.
 	*
@@ -59,14 +71,16 @@ class service
 	* @param \phpbb\cache\driver\driver_interface $driver The cache driver
 	* @param \phpbb\config\config $config The config
 	* @param \phpbb\db\driver\driver_interface $db Database connection
+	* @param \phpbb\event\dispatcher $dispatcher Event dispatcher
 	* @param string $phpbb_root_path Root path
 	* @param string $php_ext PHP file extension
 	*/
-	public function __construct(\phpbb\cache\driver\driver_interface $driver, \phpbb\config\config $config, \phpbb\db\driver\driver_interface $db, $phpbb_root_path, $php_ext)
+	public function __construct(\phpbb\cache\driver\driver_interface $driver, \phpbb\config\config $config, \phpbb\db\driver\driver_interface $db, \phpbb\event\dispatcher $dispatcher, $phpbb_root_path, $php_ext)
 	{
 		$this->set_driver($driver);
 		$this->config = $config;
 		$this->db = $db;
+		$this->dispatcher = $dispatcher;
 		$this->phpbb_root_path = $phpbb_root_path;
 		$this->php_ext = $php_ext;
 	}
@@ -81,6 +95,25 @@ class service
 		return $this->driver;
 	}
 
+	/**
+	 * Deferred purge of the cache.
+	 *
+	 * A deferred purge will be executed after rendering a page.
+	 * It is recommended to be used in cases where an instant purge of the cache
+	 * is not required, i.e. when the goal of a cache purge is to start from a
+	 * clear cache at the next page load.
+	 *
+	 * @return void
+	 */
+	public function deferred_purge(): void
+	{
+		if (!$this->cache_purge_deferred)
+		{
+			$this->dispatcher->addListener(self::CACHE_PURGE_EVENT, [$this, 'purge']);
+			$this->cache_purge_deferred = true;
+		}
+	}
+
 	/**
 	* Replaces the cache driver used by this cache service.
 	*

phpBB/phpbb/extension/manager.php

@@ -197,7 +197,7 @@ class manager
 
 		if ($this->cache)
 		{
-			$this->cache->purge();
+			$this->cache->deferred_purge();
 		}
 	}