Manager.php

Go to the documentation of this file.

<?php
#require_once 'Zend/Memory/Container/Movable.php';

#require_once 'Zend/Memory/Container/Locked.php';

#require_once 'Zend/Memory/AccessController.php';


class Zend_Memory_Manager
{
    private $_backend = null;

    private $_memoryLimit = -1;

    private $_minSize = 16384;

    private $_memorySize = 0;

    private $_nextId = 0;

    private $_unloadCandidates = array();

    private $_sizes = array();

    private $_lastModified = null;

    private $_managerId;

    private $_tags;

    private function _generateMemManagerId()
    {
        $this->_managerId = uniqid('ZendMemManager', true);
        $this->_tags = array($this->_managerId);
        $this->_managerId .= '_';
    }


    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
    }

    public function __destruct()
    {
        if ($this->_backend !== null) {
            $this->_backend->clean(Zend_Cache::CLEANING_MODE_MATCHING_TAG, $this->_tags);
        }
    }

    public function setMemoryLimit($newLimit)
    {
        $this->_memoryLimit = $newLimit;

        $this->_swapCheck();
    }

    public function getMemoryLimit()
    {
        return $this->_memoryLimit;
    }

    public function setMinSize($newSize)
    {
        $this->_minSize = $newSize;
    }

    public function getMinSize()
    {
        return $this->_minSize;
    }

    public function create($value = '')
    {
        return $this->_create($value,  false);
    }

    public function createLocked($value = '')
    {
        return $this->_create($value, true);
    }

    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);
    }

    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]);
    }

    public function processUpdate(Zend_Memory_Container_Movable $container, $id)
    {
        if ($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;
    }

    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();
    }

    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.');
    }


    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();
    }

    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;
        }
    }
}