Lock.php

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<?php

namespace Rsi\Fred;

class Lock extends Component{

  public $keySeperator = '_'; //!< String to seperate key info with (may not be present in item type or ID).
  public $multiIndicator = '-----'; //!< String to indicate a lock for all ID's of an item type.

  public $ext = '.lock'; //!< Extension for lock file.

  protected $_timeout = null; //!< Number of seconds after which a lock expires (empty = use double of
    // Rsi\Fred\Alive::interval).
  protected $_path = null; //!< Path to store the lock files (temp path if empty).

  public function ping(){
    $this->refresh();
    $this->purge();
  }
  /**
   * Generate a lock key.
   * @param string $item  Item type.
   * @param mixed $id  Id of the item.
   * @param mixed $user  User ID of the owner (current user when empty).
   * @return string
   */
  protected function key($item,$id,$user = null){
    return implode($this->keySeperator,array_merge([$user ?: $this->component('user')->id,$item],is_array($id) ? $id : [$id]));
  }
  /**
   * Filename for a lock file.
   * @param string $item  Item type.
   * @param mixed $id  Id of the item (true = all ID's).
   * @param mixed $user  User ID of the owner (current user when empty).
   * @return string
   */
  protected function filename($item,$id,$user = null){
    return $this->path . $this->key($item,$id === true ? $this->multiIndicator : $id,$user) . $this->ext;
  }
  /**
   * Find lock files.
   * @param string $item  Item type (empty = return all locks for this user).
   * @param mixed $id  ID of the item (empty = return all locks for this item type).
   * @param mixed $user  User ID of the owner (current user when empty).
   * @return array  Lock filenames.
   */
  protected function find($item = null,$id = null,$user = null){
    return glob($this->filename($item ?: '*',$id ?: '*',$user),GLOB_NOSORT);
  }
  /**
   * Purge old locks.
   */
  public function purge(){
    $this->exists('*');
  }
  /**
   * Check wether a lock exists.
   * @param string $item  Item type.
   * @param mixed $id  ID of the item (empty = check for all items lock).
   * @param mixed $user  User ID of the owner (all users when empty; use false to exclude own locks).
   * @return int  Number of active locks (should be 0 or 1, but in a race condition it could be more).
   */
  public function exists($item,$id = null,$user = null){
    $time = time() - $this->timeout;
    $count = 0;
    foreach($this->find($item,$id,$user ?: '*') as $lock)
      if(filemtime($lock) < $time) \Rsi\File::unlink($lock); //expired
      elseif(($user !== false) || (\Rsi\Str::part(basename($lock),$this->keySeperator) != $this->component('user')->id)) $count++;
    return $count;
  }
  /**
   * Request a lock on an item.
   * @param string $item  Item type.
   * @param mixed $id  ID of the item (empty = lock all items).
   * @return bool  True on success.
   */
  public function request($item,$id = null){
    $this->component('alive')->register($this->_name);
    $lock = $this->filename($item,$id ?: true);
    $error = false;
    try{
      if(!is_file($lock) && ($this->exists($item,$id ?: true,false) || ($id && $this->exists($item,true)))) $lock = false;
      else $error = \Rsi\File::write($lock,null,0666) === false;
    }
    catch(\Exception $e){
      if($this->_fred->debug) throw $e;
      $error = true;
    }
    if($lock && ($error || ($this->exists($item,$id) > 1) || ($id && $this->exists($item,true)))){
      \Rsi\File::unlink($lock);
      $lock = false;
    }
    return $lock && is_file($lock);
  }
  /**
   * Refresh one or multiple lock(s).
   * @param string $item  Item type (empty = refresh all locks for this user).
   * @param mixed $id  ID of the item (empty = refresh all locks for this item type).
   * @return bool  True on success.
   */
  public function refresh($item = null,$id = null){
    $result = count($locks = $this->find($item,$id)) > 0;
    foreach($locks as $lock)
      if(!touch($lock) || ($this->exists($item,$id) > 1) || ($id && $this->exists($item,true))){
        \Rsi\File::unlink($lock);
        $result = false;
      }
    return $result;
  }
  /**
   * Release one or multiple lock(s).
   * @param string $item  Item type (empty = release all locks for this user).
   * @param mixed $id  ID of the item (empty = release all locks for this item type).
   * @return bool  True on success.
   */
  public function release($item = null,$id = null){
    $result = true;
    foreach($this->find($item,$id) as $lock) $result &= \Rsi\File::unlink($lock);
    return $result;
  }
  /**
   * Who owns a lock.
   * @param string $item  Item type.
   * @param mixed $id  ID of the item.
   * @return mixed  User ID of the owner (false when not locked).
   */
  public function owner($item,$id = null){
    return ($filenames = $this->find($item,$id,'*') ?: ($id ? $this->find($item,true,'*') : null))
      ? \Rsi\Str::part(basename(array_pop($filenames)),$this->keySeperator)
      : false;
  }

  protected function getPath(){
    if(!$this->_path) $this->_path = $this->config('path') ?: \Rsi\File::tempDir();
    return $this->_path;
  }

  protected function getTimeout(){
    if($this->_timeout === null) $this->_timeout = $this->config('timeout') ?: $this->component('alive')->interval * 120; //minutes - >seconds, and double of that
    return $this->_timeout;
  }

}