The file name for the CSS or JS cache file is generated from the hash of the aggregated contents of the files in $data. This forces proxies and browsers to download new CSS when the CSS changes.

Parameters

string $data: An (optimized) asset's contents.

string $file_extension: The file extension of this asset.

Return value

string A URI to access the dumped asset.

Overrides AssetDumperInterface::dump

File

core/lib/Drupal/Core/Asset/AssetDumper.php, line 38

Class

AssetDumper

Dumps a CSS or JavaScript asset.

Namespace

Drupal\Core\Asset

Code

public function dump($data, $file_extension) {
  // Prefix filename to prevent blocking by firewalls which reject files
  // starting with "ad*".
  $filename = $file_extension . '_' . Crypt::hashBase64($data) . '.' . $file_extension;
  // Create the css/ or js/ path within the files folder.
  $path = 'public://' . $file_extension;
  $uri = $path . '/' . $filename;
  // Create the CSS or JS file.
  $this->fileSystem
    ->prepareDirectory($path, FileSystemInterface::CREATE_DIRECTORY);
  try {
    if (!file_exists($uri) && !$this->fileSystem
      ->saveData($data, $uri, FileSystemInterface::EXISTS_REPLACE)) {
      return FALSE;
    }
  } catch (FileException $e) {
    return FALSE;
  }
  // If CSS/JS gzip compression is enabled and the zlib extension is available
  // then create a gzipped version of this file. This file is served
  // conditionally to browsers that accept gzip using .htaccess rules.
  // It's possible that the rewrite rules in .htaccess aren't working on this
  // server, but there's no harm (other than the time spent generating the
  // file) in generating the file anyway. Sites on servers where rewrite rules
  // aren't working can set css.gzip to FALSE in order to skip
  // generating a file that won't be used.
  if (extension_loaded('zlib') && \Drupal::config('system.performance')->get($file_extension . '.gzip')) {
    try {
      if (!file_exists($uri . '.gz') && !$this->fileSystem
        ->saveData(gzencode($data, 9, FORCE_GZIP), $uri . '.gz', FileSystemInterface::EXISTS_REPLACE)) {
        return FALSE;
      }
    } catch (FileException $e) {
      return FALSE;
    }
  }
  return $uri;
}

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