original_string: public function cron() {
          $fs = get_file_storage();
          $files = $fs->get_external_files($this->id);
          $fetchedreferences = [];
          foreach ($files as $file) {
              if (isset($fetchedreferences[$file->get_referencefileid()])) {
                  continue;
              }
              try {
                  // This call will cache all files that are smaller than max_cache_bytes()
                  // and synchronise file size of all others.
                  $this->import_external_file_contents($file, $this->max_cache_bytes());
                  $fetchedreferences[$file->get_referencefileid()] = true;
              } catch (moodle_exception $e) {
                  // If an exception is thrown, just continue. This is only a pre-fetch to help speed up general use.
              }
          }
      }
code: public function cron() {
          $fs = get_file_storage();
          $files = $fs->get_external_files($this->id);
          $fetchedreferences = [];
          foreach ($files as $file) {
              if (isset($fetchedreferences[$file->get_referencefileid()])) {
                  continue;
              }
              try {
                  // This call will cache all files that are smaller than max_cache_bytes()
                  // and synchronise file size of all others.
                  $this->import_external_file_contents($file, $this->max_cache_bytes());
                  $fetchedreferences[$file->get_referencefileid()] = true;
              } catch (moodle_exception $e) {
                  // If an exception is thrown, just continue. This is only a pre-fetch to help speed up general use.
              }
          }
      }
code_tokens: public function cron ( ) { $ fs = get_file_storage ( ) ; $ files = $ fs -> get_external_files ( $ this -> id ) ; $ fetchedreferences = [ ] ; foreach ( $ files as $ file ) { if ( isset ( $ fetchedreferences [ $ file -> get_referencefileid ( ) ] ) ) { continue ; } try { // This call will cache all files that are smaller than max_cache_bytes() // and synchronise file size of all others. $ this -> import_external_file_contents ( $ file , $ this -> max_cache_bytes ( ) ) ; $ fetchedreferences [ $ file -> get_referencefileid ( ) ] = true ; } catch ( moodle_exception $ e ) { // If an exception is thrown, just continue. This is only a pre-fetch to help speed up general use. } } }
docstring: Caches all references to Dropbox files in moodle filepool.
  
  Invoked by {@link repository_dropbox_cron()}. Only files smaller than
  {@link repository_dropbox::max_cache_bytes()} and only files which
  synchronisation timeout have not expired are cached.
  
  @inheritDocs
docstring_tokens: Caches all references to Dropbox files in moodle filepool .