refs matomo-org#4074 in case we know it is a plugins or a core class,…

… try to load it directly from there and do not look in other folders first. Unfortunately we still need the other logic for backwards compatibility

core/Loader.php

@@ -60,6 +60,16 @@ protected static function removePrefix($class, $vendorPrefixToRemove)
         return $class;
     }
 
+    private static function isPluginClass($class)
+    {
+        return 0 === strpos($class, 'Piwik\Plugins') || 0 === strpos($class, '\Piwik\Plugins');
+    }
+
+    private static function usesPiwikNamespace($class)
+    {
+        return 0 === strpos($class, 'Piwik\\') || 0 === strpos($class, '\Piwik\\');
+    }
+
     /**
      * Load class by name
      *
@@ -69,19 +79,27 @@ protected static function removePrefix($class, $vendorPrefixToRemove)
     public static function loadClass($class)
     {
         $classPath = self::getClassFileName($class);
+
+        $loaded = false;
+        if (static::isPluginClass($class)) {
+            $loaded = static::tryToLoadClass($class, '/plugins/', $classPath);
+        } else if (static::usesPiwikNamespace($class)) {
+            $loaded = static::tryToLoadClass($class, '/core/', $classPath);
+        }
+
+        if ($loaded) {
+            return;
+        }
+
         if (strpos($class, '\Piwik') === 0
             || strpos($class, 'Piwik') === 0
         ) {
-            // Piwik classes are in core/ or plugins/
+            // only used for files that declare multiple classes (ie Piwik/Live.php declares Piwik\Live\VisitorLog)
             do {
                 // auto-discover class location
                 foreach (self::$dirs as $dir) {
-                    $path = PIWIK_INCLUDE_PATH . $dir . $classPath . '.php';
-                    if (file_exists($path)) {
-                        require_once $path; // prefixed by PIWIK_INCLUDE_PATH
-                        if (class_exists($class, false) || interface_exists($class, false)) {
-                            return;
-                        }
+                    if (static::tryToLoadClass($class, $dir, $classPath)) {
+                        return;
                     }
                 }
 
@@ -91,16 +109,23 @@ public static function loadClass($class)
             } while (!empty($classPath));
         } else {
             // non-Piwik classes (e.g., Zend Framework) are in libs/
-            $path = PIWIK_INCLUDE_PATH . '/libs/' . $classPath . '.php';
-            if (file_exists($path)) {
-                require_once $path; // prefixed by PIWIK_INCLUDE_PATH
-                if (class_exists($class, false) || interface_exists($class, false)) {
-                    return;
-                }
-            }
+            static::tryToLoadClass($class, '/libs/', $classPath);
         }
     }
 
+    private static function tryToLoadClass($class, $dir, $classPath)
+    {
+        $path = PIWIK_INCLUDE_PATH . $dir . $classPath . '.php';
+
+        if (file_exists($path)) {
+            require_once $path; // prefixed by PIWIK_INCLUDE_PATH
+
+            return class_exists($class, false) || interface_exists($class, false);
+        }
+
+        return false;
+    }
+
     /**
      * Autoloader
      *