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 <?php
 /**
  * Zend Framework
  *
  * LICENSE
  *
  * This source file is subject to the new BSD license that is bundled
  * with this package in the file LICENSE.txt.
  * It is also available through the world-wide-web at this URL:
  * http://framework.zend.com/license/new-bsd
  * If you did not receive a copy of the license and are unable to
  * obtain it through the world-wide-web, please send an email
  * to license@zend.com so we can send you a copy immediately.
  *
  * @category   Zend
  * @package    Zend_Memory
  * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  * @version    $Id$
  */
 
 /** Zend_Memory_Container_Movable */
 // require_once 'Zend/Memory/Container/Movable.php';
 
 /** Zend_Memory_Container_Locked */
 // require_once 'Zend/Memory/Container/Locked.php';
 
 /** Zend_Memory_AccessController */
 // require_once 'Zend/Memory/AccessController.php';
 
 
 /**
  * Memory manager
  *
  * This class encapsulates memory menagement operations, when PHP works
  * in limited memory mode.
  *
  *
  * @category   Zend
  * @package    Zend_Memory
  * @copyright  Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
  * @license    http://framework.zend.com/license/new-bsd     New BSD License
  */
 class Zend_Memory_Manager
 {
     /**
      * Object storage backend
      *
      * @var Zend_Cache_Backend_Interface
      */
     private $_backend = null;
 
     /**
      * Memory grow limit.
      * Default value is 2/3 of memory_limit php.ini variable
      * Negative value means no limit
      *
      * @var integer
      */
     private $_memoryLimit = -1;
 
     /**
      * Minimum value size to be swapped.
      * Default value is 16K
      * Negative value means that memory objects are never swapped
      *
      * @var integer
      */
     private $_minSize = 16384;
 
     /**
      * Overall size of memory, used by values
      *
      * @var integer
      */
     private $_memorySize = 0;
 
     /**
      * Id for next Zend_Memory object
      *
      * @var integer
      */
     private $_nextId = 0;
 
     /**
      * List of candidates to unload
      *
      * It also represents objects access history. Last accessed objects are moved to the end of array
      *
      * array(
      *     <id> => <memory container object>,
      *     ...
      *      )
      *
      * @var array
      */
     private $_unloadCandidates = array();
 
     /**
      * List of object sizes.
      *
      * This list is used to calculate modification of object sizes
      *
      * array( <id> => <size>, ...)
      *
      * @var array
      */
     private $_sizes = array();
 
     /**
      * Last modified object
      *
      * It's used to reduce number of calls necessary to trace objects' modifications
      * Modification is not processed by memory manager until we do not switch to another
      * object.
      * So we have to trace only _first_ object modification and do nothing for others
      *
      * @var Zend_Memory_Container_Movable
      */
     private $_lastModified = null;
 
     /**
      * Unique memory manager id
      *
      * @var integer
      */
     private $_managerId;
 
     /**
      * Tags array, used by backend to categorize stored values
      *
      * @var array
      */
     private $_tags;
 
     /**
      * This function is intended to generate unique id, used by memory manager
      */
     private function _generateMemManagerId()
     {
         /**
          * @todo !!!
          * uniqid() php function doesn't really garantee the id to be unique
          * it should be changed by something else
          * (Ex. backend interface should be extended to provide this functionality)
          */
         $this->_managerId = uniqid('ZendMemManager', true);
         $this->_tags = array($this->_managerId);
         $this->_managerId .= '_';
     }
 
 
     /**
      * Memory manager constructor
      *
      * If backend is not specified, then memory objects are never swapped
      *
      * @param Zend_Cache_Backend $backend
      * @param array $backendOptions associative array of options for the corresponding backend constructor
      */
     public function __construct($backend = null)
     {
         if ($backend === null) {
             return;
         }
 
         $this->_backend = $backend;
         $this->_generateMemManagerId();
 
         $memoryLimitStr = trim(ini_get('memory_limit'));
         if ($memoryLimitStr != ''  &&  $memoryLimitStr != -1) {
             $this->_memoryLimit = (integer)$memoryLimitStr;
             switch (strtolower($memoryLimitStr[strlen($memoryLimitStr)-1])) {
                 case 'g':
                     $this->_memoryLimit *= 1024;
                     // Break intentionally omitted
                 case 'm':
                     $this->_memoryLimit *= 1024;
                     // Break intentionally omitted
                 case 'k':
                     $this->_memoryLimit *= 1024;
                     break;
 
                 default:
                     break;
             }
 
             $this->_memoryLimit = (int)($this->_memoryLimit*2/3);
         } // No limit otherwise
     }
 
     /**
      * Object destructor
      *
      * Clean up backend storage
      */
     public function __destruct()
     {
         if ($this->_backend !== null) {
             $this->_backend->clean(Zend_Cache::CLEANING_MODE_MATCHING_TAG, $this->_tags);
         }
     }
 
     /**
      * Set memory grow limit
      *
      * @param integer $newLimit
      * @throws Zend_Exception
      */
     public function setMemoryLimit($newLimit)
     {
         $this->_memoryLimit = $newLimit;
 
         $this->_swapCheck();
     }
 
     /**
      * Get memory grow limit
      *
      * @return integer
      */
     public function getMemoryLimit()
     {
         return $this->_memoryLimit;
     }
 
     /**
      * Set minimum size of values, which may be swapped
      *
      * @param integer $newSize
      */
     public function setMinSize($newSize)
     {
         $this->_minSize = $newSize;
     }
 
     /**
      * Get minimum size of values, which may be swapped
      *
      * @return integer
      */
     public function getMinSize()
     {
         return $this->_minSize;
     }
 
     /**
      * Create new Zend_Memory value container
      *
      * @param string $value
      * @return Zend_Memory_Container_Interface
      * @throws Zend_Memory_Exception
      */
     public function create($value = '')
     {
         return $this->_create($value,  false);
     }
 
     /**
      * Create new Zend_Memory value container, which has value always
      * locked in memory
      *
      * @param string $value
      * @return Zend_Memory_Container_Interface
      * @throws Zend_Memory_Exception
      */
     public function createLocked($value = '')
     {
         return $this->_create($value, true);
     }
 
     /**
      * Create new Zend_Memory object
      *
      * @param string $value
      * @param boolean $locked
      * @return Zend_Memory_Container_Interface
      * @throws Zend_Memory_Exception
      */
     private function _create($value, $locked)
     {
         $id = $this->_nextId++;
 
         if ($locked  ||  ($this->_backend === null) /* Use only memory locked objects if backend is not specified */) {
             return new Zend_Memory_Container_Locked($value);
         }
 
         // Commit other objects modifications
         $this->_commit();
 
         $valueObject = new Zend_Memory_Container_Movable($this, $id, $value);
 
         // Store last object size as 0
         $this->_sizes[$id] = 0;
         // prepare object for next modifications
         $this->_lastModified = $valueObject;
 
         return new Zend_Memory_AccessController($valueObject);
     }
 
     /**
      * Unlink value container from memory manager
      *
      * Used by Memory container destroy() method
      *
      * @internal
      * @param integer $id
      * @return Zend_Memory_Container
      */
     public function unlink(Zend_Memory_Container_Movable $container, $id)
     {
         if ($this->_lastModified === $container) {
             // Drop all object modifications
             $this->_lastModified = null;
             unset($this->_sizes[$id]);
             return;
         }
 
         if (isset($this->_unloadCandidates[$id])) {
             unset($this->_unloadCandidates[$id]);
         }
 
         $this->_memorySize -= $this->_sizes[$id];
         unset($this->_sizes[$id]);
     }
 
     /**
      * Process value update
      *
      * @internal
      * @param Zend_Memory_Container_Movable $container
      * @param integer $id
      */
     public function processUpdate(Zend_Memory_Container_Movable $container, $id)
     {
         /**
          * This method is automatically invoked by memory container only once per
          * "modification session", but user may call memory container touch() method
          * several times depending on used algorithm. So we have to use this check
          * to optimize this case.
          */
         if ($container === $this->_lastModified) {
             return;
         }
 
         // Remove just updated object from list of candidates to unload
         if( isset($this->_unloadCandidates[$id])) {
             unset($this->_unloadCandidates[$id]);
         }
 
         // Reduce used memory mark
         $this->_memorySize -= $this->_sizes[$id];
 
         // Commit changes of previously modified object if necessary
         $this->_commit();
 
         $this->_lastModified = $container;
     }
 
     /**
      * Commit modified object and put it back to the loaded objects list
      */
     private function _commit()
     {
         if (($container = $this->_lastModified) === null) {
             return;
         }
 
         $this->_lastModified = null;
 
         $id = $container->getId();
 
         // Calculate new object size and increase used memory size by this value
         $this->_memorySize += ($this->_sizes[$id] = strlen($container->getRef()));
 
         if ($this->_sizes[$id] > $this->_minSize) {
             // Move object to "unload candidates list"
             $this->_unloadCandidates[$id] = $container;
         }
 
         $container->startTrace();
 
         $this->_swapCheck();
     }
 
     /**
      * Check and swap objects if necessary
      *
      * @throws Zend_MemoryException
      */
     private function _swapCheck()
     {
         if ($this->_memoryLimit < 0  ||  $this->_memorySize < $this->_memoryLimit) {
             // Memory limit is not reached
             // Do nothing
             return;
         }
 
         // walk through loaded objects in access history order
         foreach ($this->_unloadCandidates as $id => $container) {
             $this->_swap($container, $id);
             unset($this->_unloadCandidates[$id]);
 
             if ($this->_memorySize < $this->_memoryLimit) {
                 // We've swapped enough objects
                 return;
             }
         }
 
         // require_once 'Zend/Memory/Exception.php';
         throw new Zend_Memory_Exception('Memory manager can\'t get enough space.');
     }
 
 
     /**
      * Swap object data to disk
      * Actualy swaps data or only unloads it from memory,
      * if object is not changed since last swap
      *
      * @param Zend_Memory_Container_Movable $container
      * @param integer $id
      */
     private function _swap(Zend_Memory_Container_Movable $container, $id)
     {
         if ($container->isLocked()) {
             return;
         }
 
         if (!$container->isSwapped()) {
             $this->_backend->save($container->getRef(), $this->_managerId . $id, $this->_tags);
         }
 
         $this->_memorySize -= $this->_sizes[$id];
 
         $container->markAsSwapped();
         $container->unloadValue();
     }
 
     /**
      * Load value from swap file.
      *
      * @internal
      * @param Zend_Memory_Container_Movable $container
      * @param integer $id
      */
     public function load(Zend_Memory_Container_Movable $container, $id)
     {
         $value = $this->_backend->load($this->_managerId . $id, true);
 
         // Try to swap other objects if necessary
         // (do not include specified object into check)
         $this->_memorySize += strlen($value);
         $this->_swapCheck();
 
         // Add loaded obect to the end of loaded objects list
         $container->setValue($value);
 
         if ($this->_sizes[$id] > $this->_minSize) {
             // Add object to the end of "unload candidates list"
             $this->_unloadCandidates[$id] = $container;
         }
     }
 }