在php中同时保存xml文件后损坏的XML文件

Question

I have a php-Script, that save some Data into a XML-File. But if two Users save some Data at the same Time, the XML become broken and all Data are lost.

Here is my Code:

$dom                     = new DOMDocument();
$dom->preserveWhiteSpace = false;
$dom->load($szFile);

... Actions...

$dom->formatOutput = true;
$dom->save($szFile);

Is there a recommend way to save the XML-File without this Problem?

Answer 1

Maybe I must rename the File to be sure no one can acess it?

Open:

function openXML($szFile){

  $szPath = '../path/';
  $szDummyFile = 'dummy.xml';

  $i = 0;
  $bRepeat = true;
  $bContinue = false;
  while($i < 20 && $bRepeat){ // Timeout: 10 s

    if(file_exists($szPath . $szFile)){

      rename($szPath . $szFile, $szPath . $szDummyFile);
      $bRepeat = false;
      $bContinue = true;
    }else{
      usleep(500000); // 0,5 s
    }
    $i++;
  }

  if($bContinue){
    $dom                     = new DOMDocument();
    $dom->preserveWhiteSpace = false;
    $dom->load($szPath . $szDummyFile);

    return $dom;

  }else{
    return false;
  }
}

Save:

function saveXML($dom, $szFile){

  $szPath = '../path/';
  $szDummyFile = 'dummy.xml';

  $dom->formatOutput = true;
  $dom->save($szPath . $szDummyFile);

  rename($szPath . $szDummyFile, $szPath . $szFile);

}