<?php
/**
 * Simple Locking
 *
 * @author gERD Schaufelberger <gerd@php-tools.net>
 * @package WB
 * @subpackage Lock
 */

/**
 * Simple Locking
 *
 * @todo use drivers instead of actual implementing file lock in this class
 * @version 0.1.0
 * @package WB
 * @subpackage Lock
 */
class WBLock extends WBStdClass
{
    const SHARED    =   1;
    const EXCLUSIVE =   2;

    private $name   =   '';
    private $block  =   false;

    private $path   =   '%s/var/lock/%s.lock';
    private $hdl    =   null;


    /**
     * Constructor
     */
    final public function __construct($parameter = array())
    {
        if (!empty($parameter['name'])) {
            $this->setName($parameter['name']);
        }
    }

    /**
     * Destructor
     */
    final public function __destruct()
    {
        if (empty($this->hdl)) {
            return;
        }
        fclose($this->hdl);
    }

    /**
     * Switch Blocking
     *
     * Set locking mode to blocking or non blocking
     * @param bool true for blocking
     */
    public function useBlocking($use = true)
    {
        $this->block    =   $use;
    }

    /**
     * Set Lock Name
     *
     * @param string name for lock
     */
    public function setName($name)
    {
        if (!empty($this->hdl)) {
            fclose($this->hdl);
        }
        $this->name =   $name;
        $file       =   sprintf($this->path, WBParam::get('wb/dir/base'), $this->name);
        if (!file_exists($file)) {
            touch($file);
            chmod($file, 0666);
        }
        $this->hdl  =   fopen($file, 'w');
    }

    /**
     * Aquire Lock
     *
     * @param int EXCLUSIVE|SHARED
     */
    public function acquire($type = self::EXCLUSIVE)
    {
        $mode   =   0;
        if (!$this->block) {
            $mode   |=  LOCK_NB;
        }
        switch ($type) {
            case self::EXCLUSIVE:
                $mode   |=  LOCK_EX;
                break;

            case self::SHARED:
                $mode   |=  LOCK_SH;
                break;
        }
        return flock($this->hdl, $mode);
    }

    /**
     * Release Lock
     */
    public function release()
    {
        flock($this->hdl, LOCK_UN);
    }
}