Daily RSS Cache: invalidate cache base on the date

Currently the cache is only invalidated when the datastore changes, while it should rely on selected period of time.

Fixes #1659

4 files changed, 92 insertions, 38 deletions

diff --git a/application/feed/CachedPage.php b/application/feed/CachedPage.php
index d809bdd9..c23c200f 100644
--- a/application/feed/CachedPage.php
+++ b/application/feed/CachedPage.php
@@ -1,34 +1,43 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Shaarli\Feed;
 
+use DatePeriod;
+
 /**
  * Simple cache system, mainly for the RSS/ATOM feeds
  */
 class CachedPage
 {
-    // Directory containing page caches
-    private $cacheDir;
+    /** Directory containing page caches */
+    protected $cacheDir;
+
+    /** Should this URL be cached (boolean)? */
+    protected $shouldBeCached;
 
-    // Should this URL be cached (boolean)?
-    private $shouldBeCached;
+    /** Name of the cache file for this URL */
+    protected $filename;
 
-    // Name of the cache file for this URL
-    private $filename;
+    /** @var DatePeriod|null Optionally specify a period of time for cache validity */
+    protected $validityPeriod;
 
     /**
      * Creates a new CachedPage
      *
-     * @param string $cacheDir       page cache directory
-     * @param string $url            page URL
-     * @param bool   $shouldBeCached whether this page needs to be cached
+     * @param string      $cacheDir       page cache directory
+     * @param string      $url            page URL
+     * @param bool        $shouldBeCached whether this page needs to be cached
+     * @param ?DatePeriod $validityPeriod Optionally specify a time limit on requested cache
      */
-    public function __construct($cacheDir, $url, $shouldBeCached)
+    public function __construct($cacheDir, $url, $shouldBeCached, ?DatePeriod $validityPeriod)
     {
         // TODO: check write access to the cache directory
         $this->cacheDir = $cacheDir;
         $this->filename = $this->cacheDir . '/' . sha1($url) . '.cache';
         $this->shouldBeCached = $shouldBeCached;
+        $this->validityPeriod = $validityPeriod;
     }
 
     /**
@@ -41,10 +50,20 @@ class CachedPage
         if (!$this->shouldBeCached) {
             return null;
         }
-        if (is_file($this->filename)) {
-            return file_get_contents($this->filename);
+        if (!is_file($this->filename)) {
+            return null;
+        }
+        if ($this->validityPeriod !== null) {
+            $cacheDate = \DateTime::createFromFormat('U', (string) filemtime($this->filename));
+            if (
+                $cacheDate < $this->validityPeriod->getStartDate()
+                || $cacheDate > $this->validityPeriod->getEndDate()
+            ) {
+                return null;
+            }
         }
-        return null;
+
+        return file_get_contents($this->filename);
     }
 
     /**
diff --git a/application/front/controller/visitor/DailyController.php b/application/front/controller/visitor/DailyController.php
index 5ae89299..29492a5f 100644
--- a/application/front/controller/visitor/DailyController.php
+++ b/application/front/controller/visitor/DailyController.php
@@ -86,9 +86,11 @@ class DailyController extends ShaarliVisitorController
     public function rss(Request $request, Response $response): Response
     {
         $response = $response->withHeader('Content-Type', 'application/rss+xml; charset=utf-8');
+        $type = DailyPageHelper::extractRequestedType($request);
+        $cacheDuration = DailyPageHelper::getCacheDatePeriodByType($type);
 
         $pageUrl = page_url($this->container->environment);
-        $cache = $this->container->pageCacheManager->getCachePage($pageUrl);
+        $cache = $this->container->pageCacheManager->getCachePage($pageUrl, $cacheDuration);
 
         $cached = $cache->cachedVersion();
         if (!empty($cached)) {
@@ -96,7 +98,6 @@ class DailyController extends ShaarliVisitorController
         }
 
         $days = [];
-        $type = DailyPageHelper::extractRequestedType($request);
         $format = DailyPageHelper::getFormatByType($type);
         $length = DailyPageHelper::getRssLengthByType($type);
         foreach ($this->container->bookmarkService->search() as $bookmark) {
diff --git a/application/helper/DailyPageHelper.php b/application/helper/DailyPageHelper.php
index 9bdb7ba5..05f95812 100644
--- a/application/helper/DailyPageHelper.php
+++ b/application/helper/DailyPageHelper.php
@@ -4,6 +4,9 @@ declare(strict_types=1);
 
 namespace Shaarli\Helper;
 
+use DatePeriod;
+use DateTimeImmutable;
+use Exception;
 use Shaarli\Bookmark\Bookmark;
 use Slim\Http\Request;
 
@@ -40,31 +43,31 @@ class DailyPageHelper
      * @param string|null   $requestedDate  Input string extracted from the request
      * @param Bookmark|null $latestBookmark Latest bookmark found in the datastore (by date)
      *
-     * @return \DateTimeImmutable from input or latest bookmark.
+     * @return DateTimeImmutable from input or latest bookmark.
      *
-     * @throws \Exception Type not supported.
+     * @throws Exception Type not supported.
      */
     public static function extractRequestedDateTime(
         string $type,
         ?string $requestedDate,
         Bookmark $latestBookmark = null
-    ): \DateTimeImmutable {
+    ): DateTimeImmutable {
         $format = static::getFormatByType($type);
         if (empty($requestedDate)) {
             return $latestBookmark instanceof Bookmark
-                ? new \DateTimeImmutable($latestBookmark->getCreated()->format(\DateTime::ATOM))
-                : new \DateTimeImmutable()
+                ? new DateTimeImmutable($latestBookmark->getCreated()->format(\DateTime::ATOM))
+                : new DateTimeImmutable()
             ;
         }
 
         // W is not supported by createFromFormat...
         if ($type === static::WEEK) {
-            return (new \DateTimeImmutable())
+            return (new DateTimeImmutable())
                 ->setISODate((int) substr($requestedDate, 0, 4), (int) substr($requestedDate, 4, 2))
             ;
         }
 
-        return \DateTimeImmutable::createFromFormat($format, $requestedDate);
+        return DateTimeImmutable::createFromFormat($format, $requestedDate);
     }
 
     /**
@@ -80,7 +83,7 @@ class DailyPageHelper
      *
      * @see https://www.php.net/manual/en/datetime.format.php
      *
-     * @throws \Exception Type not supported.
+     * @throws Exception Type not supported.
      */
     public static function getFormatByType(string $type): string
     {
@@ -92,7 +95,7 @@ class DailyPageHelper
             case static::DAY:
                 return 'Ymd';
             default:
-                throw new \Exception('Unsupported daily format type');
+                throw new Exception('Unsupported daily format type');
         }
     }
 
@@ -102,14 +105,14 @@ class DailyPageHelper
      *       and we don't want to alter original datetime.
      *
      * @param string             $type      month/week/day
-     * @param \DateTimeImmutable $requested DateTime extracted from request input
+     * @param DateTimeImmutable $requested DateTime extracted from request input
      *                                      (should come from extractRequestedDateTime)
      *
      * @return \DateTimeInterface First DateTime of the time period
      *
-     * @throws \Exception Type not supported.
+     * @throws Exception Type not supported.
      */
-    public static function getStartDateTimeByType(string $type, \DateTimeImmutable $requested): \DateTimeInterface
+    public static function getStartDateTimeByType(string $type, DateTimeImmutable $requested): \DateTimeInterface
     {
         switch ($type) {
             case static::MONTH:
@@ -119,7 +122,7 @@ class DailyPageHelper
             case static::DAY:
                 return $requested->modify('Today midnight');
             default:
-                throw new \Exception('Unsupported daily format type');
+                throw new Exception('Unsupported daily format type');
         }
     }
 
@@ -129,14 +132,14 @@ class DailyPageHelper
      *       and we don't want to alter original datetime.
      *
      * @param string             $type      month/week/day
-     * @param \DateTimeImmutable $requested DateTime extracted from request input
+     * @param DateTimeImmutable $requested DateTime extracted from request input
      *                                      (should come from extractRequestedDateTime)
      *
      * @return \DateTimeInterface Last DateTime of the time period
      *
-     * @throws \Exception Type not supported.
+     * @throws Exception Type not supported.
      */
-    public static function getEndDateTimeByType(string $type, \DateTimeImmutable $requested): \DateTimeInterface
+    public static function getEndDateTimeByType(string $type, DateTimeImmutable $requested): \DateTimeInterface
     {
         switch ($type) {
             case static::MONTH:
@@ -146,7 +149,7 @@ class DailyPageHelper
             case static::DAY:
                 return $requested->modify('Today 23:59:59');
             default:
-                throw new \Exception('Unsupported daily format type');
+                throw new Exception('Unsupported daily format type');
         }
     }
 
@@ -161,7 +164,7 @@ class DailyPageHelper
      *
      * @return string Localized time period description
      *
-     * @throws \Exception Type not supported.
+     * @throws Exception Type not supported.
      */
     public static function getDescriptionByType(
         string $type,
@@ -183,7 +186,7 @@ class DailyPageHelper
                 }
                 return $out . format_date($requested, false);
             default:
-                throw new \Exception('Unsupported daily format type');
+                throw new Exception('Unsupported daily format type');
         }
     }
 
@@ -194,7 +197,7 @@ class DailyPageHelper
      *
      * @return int number of elements
      *
-     * @throws \Exception Type not supported.
+     * @throws Exception Type not supported.
      */
     public static function getRssLengthByType(string $type): int
     {
@@ -206,7 +209,28 @@ class DailyPageHelper
             case static::DAY:
                 return 30; // ~1 month
             default:
-                throw new \Exception('Unsupported daily format type');
+                throw new Exception('Unsupported daily format type');
         }
     }
+
+    /**
+     * Get the number of items to display in the RSS feed depending on the given type.
+     *
+     * @param string             $type      month/week/day
+     * @param ?DateTimeImmutable $requested Currently only used for UT
+     *
+     * @return DatePeriod number of elements
+     *
+     * @throws Exception Type not supported.
+     */
+    public static function getCacheDatePeriodByType(string $type, DateTimeImmutable $requested = null): DatePeriod
+    {
+        $requested = $requested ?? new DateTimeImmutable();
+
+        return new DatePeriod(
+            static::getStartDateTimeByType($type, $requested),
+            new \DateInterval('P1D'),
+            static::getEndDateTimeByType($type, $requested)
+        );
+    }
 }
diff --git a/application/render/PageCacheManager.php b/application/render/PageCacheManager.php
index 97805c35..fe74bf27 100644
--- a/application/render/PageCacheManager.php
+++ b/application/render/PageCacheManager.php
@@ -2,6 +2,7 @@
 
 namespace Shaarli\Render;
 
+use DatePeriod;
 use Shaarli\Feed\CachedPage;
 
 /**
@@ -49,12 +50,21 @@ class PageCacheManager
         $this->purgeCachedPages();
     }
 
-    public function getCachePage(string $pageUrl): CachedPage
+    /**
+     * Get CachedPage instance for provided URL.
+     *
+     * @param string      $pageUrl
+     * @param ?DatePeriod $validityPeriod Optionally specify a time limit on requested cache
+     *
+     * @return CachedPage
+     */
+    public function getCachePage(string $pageUrl, DatePeriod $validityPeriod = null): CachedPage
     {
         return new CachedPage(
             $this->pageCacheDir,
             $pageUrl,
-            false === $this->isLoggedIn
+            false === $this->isLoggedIn,
+            $validityPeriod
         );
     }
 }