From 6458f19bc50d3864b66395fed90bd9caa92738a5 Mon Sep 17 00:00:00 2001
From: Gunnar Beushausen <info@gunnar-beushausen.de>
Date: Sat, 13 Jan 2018 09:38:39 +0100
Subject: [PATCH] Introduced Garbage Collector Service

---
 README.md                                     |  7 +-
 .../DynamoDbSessionServiceProvider.php        | 64 +++++++++++++++----
 2 files changed, 58 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index 5a5187e..8e95549 100644
--- a/README.md
+++ b/README.md
@@ -7,8 +7,8 @@ Typically PHP Sessions are not scalable. As soon as a load balanced / multi serv
 a better solution. Amazons DynamoDB NoSQL storage engine is the fast, easy and scalable solution for that problem.
 
 Just implement it in your project ( see below ). You also need a solution to get rid of stale sessions from the table. Since
-deleting many old sessions can take a lot of write capacity units, it's best to write an AWS Lambda function which does that 
-overnight.
+deleting many old sessions can take a lot of write capacity units, it's best to configure a cron job and run the Garbage
+Collector over night. 
 
 Gunnar Beushausen
 
@@ -42,3 +42,6 @@ Basic Usage
 
     $app->register(new SessionServiceProvider());
     $app->register(new DynamoDbSessionServiceProvider());
+    
+    //To run the Garbage Collector in order to remove stale and old sessions from the table, run the following code:
+    $app['session.dynamodb.garbagecollect'];
diff --git a/src/DynamoDbSession/DynamoDbSessionServiceProvider.php b/src/DynamoDbSession/DynamoDbSessionServiceProvider.php
index 31b4862..8dd9367 100644
--- a/src/DynamoDbSession/DynamoDbSessionServiceProvider.php
+++ b/src/DynamoDbSession/DynamoDbSessionServiceProvider.php
@@ -1,7 +1,31 @@
 <?php
 
-namespace DynamoDbSession;
+/*
+ * This file is part of Silex-DynamoDb-Session-Provider.
+ *
+ * Copyright (c) 2018 Gunnar Beushausen
+ * https://www.gunnar-beushausen.de
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is furnished
+ * to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
 
+namespace DynamoDbSession;
 
 use Aws\DynamoDb\SessionHandler;
 use Aws\Sdk;
@@ -14,25 +38,43 @@ public function register(Container $app)
 	{
 		/** @noinspection PhpParamsInspection */
 		$app['session.storage.handler'] = function () use ($app) {
-			$config = $app['session.dynamodb.options'];
-			if (!array_key_exists('dynamodb_client', $config)) {
-				$config['dynamodb_client'] = $this->getDynamoDbClient($app['AwsSdk']);
-			}
-
-			$sessionHandler = SessionHandler::fromClient($config['dynamodb_client'], [
+			$ddbClient = $this->getDynamoDbClient($app);
+			$sessionHandler = SessionHandler::fromClient($ddbClient, [
 				'table_name' => $app['session.dynamodb.options']['table_name'],
 			]);
 			$sessionHandler->register();
 
 			return $sessionHandler;
 		};
+
+		$app['session.dynamodb.garbagecollect'] = function() use ($app) {
+			$ddbClient = $this->getDynamoDbClient($app);
+			$sessionHandler = SessionHandler::fromClient($ddbClient, [
+				'table_name' => $app['session.dynamodb.options']['table_name'],
+				'batch_config' => [
+					'before' => function ($command) use ($app) {
+						//Deleting many small session rows from the DynamoDB table can take a huge amount of write capacity.
+						//We can configure a delay between each delete operation to save write capacity Units
+						$command['@http']['delay'] = isset($app['session.dynamodb.options']['delay']) ? $app['session.dynamodb.options']['delay'] : 500;
+					}
+				]
+			]);
+
+			$sessionHandler->garbageCollect();
+		};
 	}
 	/**
-	 * @param Sdk $aws
+	 * @param Container $app
 	 * @return DynamoDbClient
 	 */
-	private function getDynamoDbClient(Sdk $aws)
+	private function getDynamoDbClient(Container $app)
 	{
-		return $aws->createDynamoDb();
+		$config = $app['session.dynamodb.options'];
+		if (array_key_exists('dynamodb_client', $config)) {
+			return $config['dynamodb_client'];
+		}
+		else {
+			return $app['AwsSdk']->createDynamoDb();
+		}
 	}
-}
\ No newline at end of file
+}