File: include/datasources/FastObjectSource.lib

<?php

/*
    FastObjectSource.lib, DomCore, the WebAbility(r) Core System
    Contains the Fast Object 2-level access
    (c) 2008-2012 Philippe Thomassigny

    This file is part of DomCore

    DomCore is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    DomCore is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with DomCore.  If not, see <http://www.gnu.org/licenses/>.
*/

/* @UML_Box -- Do not edit
|------------------------------------------------------------------|
| FastObjectSource : Fast Object 2-level access object             |
|------------------------------------------------------------------|
| # datasource : DataSource extended object                        |
| # shmsource : SHMSource object                                   |
| # loaded : boolean                                               |
| - tm1 : timestamp of datasource                                  |
| - tm2 : timestamp of shmsource                                   |
|------------------------------------------------------------------|
| + new FastObjectSource($datasource: DataSource, $shmsource: SHMSource) |
| + isValid() : boolean                                            |
| + getTimestamp() : float                                         |
| + read() : mixed                                                 |
| + write($data: mixed) : void                                     |
| + unlink() : void                                                |
|------------------------------------------------------------------|
|------------------------------------------------------------------|
@End_UML_Box */

// A Fast Object is ALWAYS serialized into the datasource

class FastObjectSource extends DataSource
{
  protected $datasource = null;
  protected $shmsource = null;
  protected $loaded = false;

  private $tm1;
  private $tm2;

  public function __construct($datasource, $shmsource = null)
  {
    parent::__construct(null);
    if (self::$debug || $this->localdebug)
      $this->doDebug("include/datasources/FastObjectSource->__construct($datasource, $shmsource)", WADebug::SYSTEM);

    $this->datasource = $datasource;
    $this->shmsource = $shmsource;
  }

  public function isValid()
  {
    if (self::$debug || $this->localdebug)
      $this->doDebug('include/datasources/FastObjectSource->isValid()', WADebug::SYSTEM);

    $this->tm1 = $this->datasource->getTimeStamp();
    $this->tm2 = ($this->shmsource?$this->shmsource->getTimeStamp():$this->tm1);

    // true if the afo in shared memory is OK
    // local cache does NOT change validity
    return ($this->tm1 && $this->tm2 && $this->tm1 <= $this->tm2);
  }

  public function getTimeStamp()
  {
    if (self::$debug || $this->localdebug)
      $this->doDebug("include/datasources/FastObjectSource->getTimeStamp()", WADebug::SYSTEM);
    if ($this->shmsource)
      return $this->shmsource->getTimeStamp();
    return $this->datasource->getTimeStamp();
  }

  public function write($data)
  {
    if (self::$debug || $this->localdebug)
      $this->doDebug("include/datasources/FastObjectSource->write($data)", WADebug::SYSTEM);

    $this->datasource->write(serialize($data));
    if($this->shmsource)
      $this->shmsource->write($data);
    $this->data = $data;
    $this->loaded = true;
  }

  public function read()
  {
    if (self::$debug || $this->localdebug)
      $this->doDebug('include/datasources/FastObjectSource->read()', WADebug::SYSTEM);

    if ($this->isValid() && $this->loaded)
      return $this->data;

    // we sinchronize
    // origin source is new, we recalculate all the chain
    if ($this->tm1 > $this->tm2)
    {
      parent::write($this->datasource->read());
      if ($this->data)
        $this->data = unserialize($this->data);
      // shared memory EXISTS or tm2 cannot be != tm1
      $this->shmsource->write($this->data);
    }
    elseif ($this->shmsource)
    {
      parent::write($this->shmsource->read());
      $this->loaded = true;
    }
    else
    {
      parent::write($this->datasource->read());
      if ($this->data)
        $this->data = unserialize($this->data);
    }
    return $this->data;
  }

  public function unlink()
  {
    if (self::$debug || $this->localdebug)
      $this->doDebug('include/datasource/FastObjectSource->unlink()', WADebug::SYSTEM);
    $this->datasource->unlink();
    if ($this->shmsource)
      $this->shmsource->unlink();
    parent::unlink();
  }
}

?>