add chapter about data repositories, and start work on perfomance chapter

implementation/15-adding-content/src/Repository/CachedMarkdownPageRepo.php

@@ -0,0 +1,62 @@
+<?php declare(strict_types=1);
+
+namespace Lubian\NoFramework\Repository;
+
+use Lubian\NoFramework\Model\MarkdownPage;
+use Lubian\NoFramework\Settings;
+use Symfony\Contracts\Cache\CacheInterface;
+use Symfony\Contracts\Cache\ItemInterface;
+
+class CachedMarkdownPageRepo implements MarkdownPageRepo
+{
+    public function __construct(
+        private readonly CacheInterface $cache,
+        private readonly MarkdownPageRepo $repo,
+        private readonly Settings $settings,
+    ) {
+    }
+
+    /**
+     * @inheritDoc
+     */
+    public function all(): array
+    {
+        $callback = fn () => $this->repo->all();
+        if ($this->settings->isDev()) {
+            return $callback();
+        }
+        return $this->cache->get('ALLPAGES', function (ItemInterface $item) use ($callback) {
+            $item->expiresAfter(30);
+            return $callback();
+        });
+    }
+
+    public function byId(int $id): MarkdownPage
+    {
+        $callback = fn () => $this->repo->byId($id);
+        if ($this->settings->isDev()) {
+            return $callback();
+        }
+        return $this->cache->get('PAGE' . $id, function (ItemInterface $item) use ($callback) {
+            $item->expiresAfter(30);
+            return $callback();
+        });
+    }
+
+    public function byTitle(string $title): MarkdownPage
+    {
+        $callback = fn () => $this->repo->byTitle($title);
+        if ($this->settings->isDev()) {
+            return $callback();
+        }
+        return $this->cache->get('PAGE' . $title, function (ItemInterface $item) use ($callback) {
+            $item->expiresAfter(30);
+            return $callback();
+        });
+    }
+
+    public function save(MarkdownPage $page): MarkdownPage
+    {
+        return $this->repo->save($page);
+    }
+}