Ensure that Eager caches are only created once at runtime for the same parameters

Author: Cyperghost

wcfsetup/install/files/lib/system/cache/builder/AbstractLegacyCacheBuilder.class.php

@@ -2,6 +2,7 @@
 
 namespace wcf\system\cache\builder;
 
+use wcf\system\cache\CacheHandler;
 use wcf\system\exception\SystemException;
 use wcf\system\SingletonFactory;
 
@@ -17,10 +18,18 @@
  */
 abstract class AbstractLegacyCacheBuilder extends SingletonFactory implements ICacheBuilder
 {
+    protected array $cache = [];
+
     #[\Override]
     public function getData(array $parameters = [], $arrayIndex = '')
     {
-        $cache = $this->rebuild($parameters);
+        $index = CacheHandler::getInstance()->getCacheIndex($parameters);
+        if (isset($this->cache[$index])) {
+            $cache = $this->cache[$index];
+        } else {
+            $cache = $this->rebuild($parameters);
+            $this->cache[$index] = $cache;
+        }
 
         if (!empty($arrayIndex)) {
             if (!\array_key_exists($arrayIndex, $cache)) {

wcfsetup/install/files/lib/system/cache/eager/AbstractEagerCache.class.php

@@ -80,8 +80,15 @@ private function getCacheKey(): string
     final public function rebuild(): void
     {
         $key = $this->getCacheKey();
-        AbstractEagerCache::$caches[$key] = $this->getCacheData();
-        CacheHandler::getInstance()->getCacheSource()->set($key, AbstractEagerCache::$caches[$key], 0);
+        $newCacheData = $this->getCacheData();
+
+        // The existing cache must not be overwritten, otherwise this can cause errors at runtime.
+        // The new data will be available at the next request.
+        if (!\array_key_exists($key, AbstractEagerCache::$caches)) {
+            AbstractEagerCache::$caches[$key] = $newCacheData;
+        }
+
+        CacheHandler::getInstance()->getCacheSource()->set($key, $newCacheData, 0);
     }
 
     /**