php多用户读写文件冲突的解决办法

$fp = fopen("/tmp/lock.txt", "w+");
if (flock($fp, LOCK_EX)) {
    fwrite($fp, "Write something heren");
    flock($fp, LOCK_UN);
} else {
    echo "Couldn't lock the file !";
}
fclose($fp);

if($fp = fopen($fileName, 'a')) {
 $startTime = microtime();
 do {
         $canWrite = flock($fp, LOCK_EX);
  if(!$canWrite) usleep(round(rand(0, 100)*1000));
 } while ((!$canWrite)&& ((microtime()-$startTime) < 1000));
 if ($canWrite) {
   fwrite($fp, $dataToSave);
 }
 fclose($fp);
}
 

$dir_fileopen = "tmp";

function randomid() {
    return time().substr(md5(microtime()), 0, rand(5, 12));
}
function cfopen($filename, $mode） {
    global $dir_fileopen;
    clearstatcache();
    do {
        $id = md5(randomid(rand(), TRUE));
        $tempfilename = $dir_fileopen."/".$id.md5($filename);
    } while(file_exists($tempfilename));
    if (file_exists($filename)) {
        $newfile = false;
        copy($filename, $tempfilename);
    }else{
        $newfile = true;
    }
    $fp = fopen($tempfilename, $mode);
    return $fp ? array($fp, $filename, $id, @filemtime($filename)) : false;
}
function cfwrite($fp,$string) { return fwrite($fp[0], $string); }
function cfclose($fp, $debug = "off") {
    global $dir_fileopen;
    $success = fclose($fp[0]);
    clearstatcache();
    $tempfilename = $dir_fileopen."/".$fp[2].md5($fp[1]);
    if ((@filemtime($fp[1]) == $fp[3]) || ($fp[4]==true && !file_exists($fp[1])) || $fp[5]==true) {
        rename($tempfilename, $fp[1]);
    }else{
        unlink($tempfilename);
  //说明有其它进程 在操作目标文件，当前进程被拒绝
        $success = false;
    }
    return $success;
}
$fp = cfopen('lock.txt','a+');
cfwrite($fp,"welcome to beijing.n");
fclose($fp,'on');