<?
/**
 * Semaphore class
 *
 * Intended to lock a process till its end.
 * Use it under GPL.
 * Visit our home page at http://www.tortuga.pp.ru
 *
 * @author   Eugene Panin <hide@address.com>
 * @author   Mike Kopylov <hide@address.com>
 * @package  Semaphore
 * @access   public
 */
class Semaphore {

  //-- Properties -----------------------------------------------------
  //-- Please access properties only by related methods ---------------

  /**
   * Path to lock file
   *
   * @var path string  
   * @access private
   */
  var $path;

  /**
   * Process identity
   *
   * @var name string  
   * @access private
   */
  var $name;

  /**
   * Lock file name
   *
   * @var name string  
   * @access private
   */
  var $fname;

  /**
   *  Process timeout
   *
   * @var timeout integer   
   * @access private
   */
  var $timeout;

  //------------------- Methods ----------------------------------------

  /**
   * Constructor creates object
   *
   * @param $name String Process identity
   * @param $path String Lock file place, default to /tmp
   * @access public
   */
  function Semaphore($name,$path='/tmp') {
    $this->timeout = 5;
    $this->path = $path;
    $this->fname = md5($name) . ".sem.tmp"; 
  }


  /**
   * Is the process locked or not and if not then lock it 
   *
   * @return boolean
   * @access public
   * @return void   
   */
  function lock() {
    $lf = $this->fname;
    $curDir = getcwd();
    chdir($this->path);
    if (file_exists($lf)) {
      $delta = time() - filectime($lf) - $this->timeout;
      if ( $delta > 0 ) {
        $fp = fopen($lf,"w");
        fwrite($fp,"1");
        fclose($fp);
        chdir($curDir); 
        return TRUE;
      }
      else {
        chdir($curDir);
        return FALSE;
      }  
    } 
    else {
      $fp = fopen($lf,"w");
      fwrite($fp,"1");
      fclose($fp);
      chdir($curDir); 
      return TRUE;
    }
  }

  /**
   * Unlocks process
   *
   * @access  public
   * @return void
   */
  function unlock() {
    $lf = $this->fname;
    $curDir = getcwd();
    chdir($this->path);
    if (file_exists($lf)) {
      unlink($lf);
      chdir($curDir); 
    }
    else {
      chdir($curDir);
      die("ERROR: Attempt to unlink nonexistent file!");
    } 
  }

  /**
   * Sets lock timeout  
   *
   * @param integer Timeout in seconds
   * @access  public
   * @return void
   */
  function setTimeout($val) {
    $this->timeout = $val;
  }

  /**
   * Returns lock timeout
   * 
   * @return integer Timeout in seconds
   * @access  public
   */
  function getTimeout() {
    return $this->timeout;
  }

  /**
   * Sets process identity  
   *
   * @param string Identity
   * @access  public
   * @return void
   */
  function setName($val) {
    $this->name = $val;
  }

  /**
   * Returns process identity
   *
   * @return string Identity
   * @access  public
   */
  function getName() {
    return $this->name;
  } 

  /**
   * Sets lock file place
   *
   * @param string
   * @access  public
   * @return void
   */
  function setPath($val) {
    $this->path = $val;
  }

  /**
   * Returns lock file place
   *
   * @return string Path to lock file directory
   * @access  public
   */

  function getPath() {
    return $this->path;
  }
}
?>