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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.
*
* @package Zend_Memory
* @copyright Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
* @license http://framework.zend.com/license/new-bsd New BSD License
* @version $Id: Manager.php 16971 2009-07-22 18:05:45Z mikaelkael $
*/
/** 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) 2005-2009 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;
}
}
}
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