Improve performance of folder hashing

system/modules/core/drivers/DC_Folder.php

@@ -2227,7 +2227,7 @@ public function sync()
 </div>
 
 <div class="tl_submit_container">
-  <a href="'.$this->getReferer(true).'" class="tl_submit" style="display:inline-block">'.$GLOBALS['TL_LANG']['MSC']['continue'].'</a>
+  <a href="'.$this->getReferer(true).'" class="tl_submit" style="display:inline-block">'.$GLOBALS['TL_LANG']['MSC']['backBT'].'</a>
 </div>
 ';
 

system/modules/core/library/Contao/Database/Updater.php

@@ -627,13 +627,12 @@ public function scanUploadFolder($strPath=null, $pid=null)
 		// Folders
 		foreach ($arrFolders as $strFolder)
 		{
-			$objFolder = new \Folder($strFolder);
 			$strUuid = $this->Database->getUuid();
 
-			$this->Database->prepare("INSERT INTO tl_files (pid, tstamp, uuid, name, type, path, hash) VALUES (?, ?, ?, ?, 'folder', ?, ?)")
-						   ->execute($pid, time(), $strUuid, basename($strFolder), $strFolder, $objFolder->hash);
-
 			$this->scanUploadFolder($strFolder, $strUuid);
+
+			$this->Database->prepare("INSERT INTO tl_files (pid, tstamp, uuid, name, type, path, hash) VALUES (?, ?, ?, ?, 'folder', ?, ?)")
+						   ->execute($pid, time(), $strUuid, basename($strFolder), $strFolder, \Dbafs::getFolderHash($strFolder));
 		}
 
 		// Files

system/modules/core/library/Contao/Dbafs.php

@@ -183,7 +183,6 @@ public static function addResource($strResource, $blnUpdateFolders=true)
 				$objModel->type      = 'folder';
 				$objModel->path      = $objFolder->path;
 				$objModel->extension = '';
-				$objModel->hash      = $objFolder->hash;
 				$objModel->uuid      = $objDatabase->getUuid();
 				$objModel->save();
 
@@ -197,6 +196,17 @@ public static function addResource($strResource, $blnUpdateFolders=true)
 			}
 		}
 
+		// Update folder hashes from bottom up after all file hashes are set
+		foreach (array_reverse($arrPaths) as $strPath)
+		{
+			if (is_dir(TL_ROOT . '/' . $strPath))
+			{
+				$objModel = \FilesModel::findByPath($strPath);
+				$objModel->hash = static::getFolderHash($strPath);
+				$objModel->save();
+			}
+		}
+
 		// Update the folder hashes
 		if ($blnUpdateFolders)
 		{
@@ -445,7 +455,7 @@ public static function updateFolderHashes($varResource)
 				$objModel = static::addResource($strPath, false);
 			}
 
-			$objModel->hash = $objFolder->hash;
+			$objModel->hash = static::getFolderHash($strPath);
 			$objModel->save();
 		}
 	}
@@ -500,6 +510,8 @@ public static function syncFiles()
 		$objLog->truncate();
 
 		$arrModels = array();
+		$arrFoldersToHash = array();
+		$arrFoldersToCompare = array();
 
 		// Create or update the database entries
 		foreach ($objFiles as $objFile)
@@ -584,27 +596,57 @@ public static function syncFiles()
 					$objModel->path      = $objFolder->path;
 					$objModel->extension = '';
 					$objModel->found     = 2;
-					$objModel->hash      = $objFolder->hash;
 					$objModel->uuid      = $objDatabase->getUuid();
 					$objModel->save();
+
+					$arrFoldersToHash[] = $strRelpath;
 				}
 			}
 			else
 			{
-				// Check whether the MD5 hash has changed
-				$objResource = $objFile->isDir() ? new \Folder($strRelpath) : new \File($strRelpath, true);
-				$strType = ($objModel->hash != $objResource->hash) ? 'Changed' : 'Unchanged';
+				if ($objFile->isDir())
+				{
+					$arrFoldersToCompare[] = $objModel;
+				}
+				else
+				{
+					// Check whether the MD5 hash has changed
+					$strHash = (new \File($strRelpath, true))->hash;
+					$strType = ($objModel->hash != $strHash) ? 'Changed' : 'Unchanged';
 
-				// Add a log entry
-				$objLog->append("[$strType] $strRelpath");
+					// Add a log entry
+					$objLog->append("[$strType] $strRelpath");
 
-				// Update the record
-				$objModel->found = 1;
-				$objModel->hash  = $objResource->hash;
-				$objModel->save();
+					// Update the record
+					$objModel->found = 1;
+					$objModel->hash  = $strHash;
+					$objModel->save();
+				}
 			}
 		}
 
+		// Update folder hashes from bottom up after all file hashes are set
+		foreach (array_reverse($arrFoldersToHash) as $strPath) {
+			$objModel = \FilesModel::findByPath($strPath);
+			$objModel->hash = static::getFolderHash($strPath);
+			$objModel->save();
+		}
+
+		// Compare the folders after all hashes are set
+		foreach (array_reverse($arrFoldersToCompare) as $objModel) {
+			// Check whether the MD5 hash has changed
+			$strHash = static::getFolderHash($objModel->path);
+			$strType = ($objModel->hash != $strHash) ? 'Changed' : 'Unchanged';
+
+			// Add a log entry
+			$objLog->append("[$strType] {$objModel->path}");
+
+			// Update the record
+			$objModel->found = 1;
+			$objModel->hash  = $strHash;
+			$objModel->save();
+		}
+
 		// Check for left-over entries in the DB
 		$objFiles = \FilesModel::findByFound('');
 
@@ -708,6 +750,33 @@ public static function syncFiles()
 		return $strLog;
 	}
 
+	/**
+	 * Get the folder hash from the databse by combining the hashes of all children
+	 *
+	 * @param string $strPath The relative path
+	 *
+	 * @return string MD5 hash
+	 */
+	public static function getFolderHash($strPath)
+	{
+		$strPath = str_replace(array('\\', '%', '_'), array('\\\\', '\\%', '\\_'), $strPath);
+		$arrHash = [];
+
+		$objChildren = \Database::getInstance()
+			->prepare("SELECT hash, name FROM tl_files WHERE path LIKE ? AND path NOT LIKE ? ORDER BY name")
+			->execute($strPath.'/%', $strPath.'/%/%');
+
+		if ($objChildren !== null)
+		{
+			while ($objChildren->next())
+			{
+				$arrHash[] = $objChildren->hash . $objChildren->name;
+			}
+		}
+
+		return md5(implode("\0", $arrHash));
+	}
+
 
 	/**
 	 * Check if the current resource should be synchronized with the database

system/modules/core/library/Contao/Folder.php

@@ -368,9 +368,13 @@ public function getModel()
 	 * Return the MD5 hash of the folder
 	 *
 	 * @return string The MD5 has
+	 *
+	 * @deprecated Use Dbafs::getFolderHash() instead
 	 */
 	protected function getHash()
 	{
+		@trigger_error('Using Folder::getHash() has been deprecated and will no longer work in Contao 5.0. Use Dbafs::getFolderHash() instead.', E_USER_DEPRECATED);
+
 		$arrFiles = array();
 
 		/** @var \SplFileInfo[] $it */