Merge pull request #561 from favicode/graphql-stale-content

GraphQL header directive stale-while-revalidate

Author: vvuksan

Diff for: Plugin/GraphQl/AfterRenderResult.php

@@ -0,0 +1,60 @@
+<?php
+declare(strict_types=1);
+
+namespace Fastly\Cdn\Plugin\GraphQl;
+
+use Magento\Framework\App\ResponseInterface;
+use Magento\Framework\Controller\ResultInterface;
+use Magento\GraphQlCache\Model\CacheableQuery;
+use Fastly\Cdn\Model\Config;
+
+class AfterRenderResult
+{
+    /**
+     * @var Config
+     */
+    private $config;
+
+    /**
+     * @var CacheableQuery
+     */
+    private $cacheableQuery;
+
+    /**
+     * AfterRenderResult constructor.
+     *
+     * @param Config $config
+     * @param CacheableQuery $cacheableQuery
+     */
+    public function __construct(
+        Config $config,
+        CacheableQuery $cacheableQuery
+    ) {
+        $this->config = $config;
+        $this->cacheableQuery = $cacheableQuery;
+    }
+
+    /**
+     * Add header directive stale-while-revalidate
+     *
+     * @param ResultInterface $subject
+     * @param ResultInterface $result
+     * @param ResponseInterface $response
+     * @return ResultInterface
+     */
+    public function afterRenderResult(
+        ResultInterface $subject,
+        ResultInterface $result,
+        ResponseInterface $response
+    ): ResultInterface {
+        if ($this->config->isEnabled()
+            && $this->config->getType() === Config::FASTLY
+            && $this->cacheableQuery->isCacheable()) {
+            $header = $response->getHeader('cache-control');
+            if ($header && $ttl = $this->config->getStaleTtl()) {
+                $header->addDirective('stale-while-revalidate', $ttl);
+            }
+        }
+        return $result;
+    }
+}

Diff for: etc/graphql/di.xml

@@ -6,4 +6,7 @@
     <type name="Magento\GraphQl\Controller\GraphQl">
         <plugin name="fastly_graphql_rate_limiter" type="Fastly\Cdn\Model\FrontControllerPlugin" sortOrder="1"/>
     </type>
+    <type name="Magento\Framework\Controller\ResultInterface">
+        <plugin name="fastly-graphql-stale-header" type="Fastly\Cdn\Plugin\GraphQl\AfterRenderResult"/>
+    </type>
 </config>