asset_cache.inc

<?php
// If 1, getForgottenItemsReport() will include the callers of the cache
// which forgot to release their reference to the assets
define('SQ_ASSET_CACHE_DEBUG', 0);

class Asset_Cache extends MySource_Object
{

    var $_items = Array();

    var $_items_released = Array();

    var $_size_rules;


    function Asset_Cache()
    {
        $this->setSizeRules();

    }//end constructor


    function setSizeRules($size=-1, $all_items=false)
    {
        $this->_size_rules['max'] = $size;
        $this->_size_rules['all_items'] = $all_items;

    }//end setSizeRules()


    function add($item, $itemid=-1)
    {
        if ($itemid == -1) {
            // no valid id
            if (!isset($item) || !isset($item->id)) {
                return false;
            }
            $itemid = $item->id;
        }

        // already in the cache
        if ($this->get($itemid)) return false;

        $this->_items[$itemid] = Array('item' => $item, 'reference_count' => 1);

        if (SQ_ASSET_CACHE_DEBUG) {
            $this->_trackCaller($itemid, 1);
        }

        return true;

    }//end add()


    function get($itemid)
    {
        $ret = null;

        if (isset($this->_items[$itemid])) {
            $item_info = &$this->_items[$itemid];

            $ret = &$item_info['item'];

            if ($item_info['reference_count'] == 0) {
                unset($this->_items_released[$itemid]);
            }

            $item_info['reference_count']++;

            if (SQ_ASSET_CACHE_DEBUG) {
                $this->_trackCaller($itemid, 1);
            }
        }

        return $ret;

    }//end get()


    function release($itemid)
    {
        if (!isset($this->_items[$itemid])) return false;

        $item_info = &$this->_items[$itemid];

        if ($item_info['reference_count'] <= 0) return false;

        $item_info['reference_count']--;

        if (SQ_ASSET_CACHE_DEBUG) {
            $this->_trackCaller($itemid, -1);
        }

        if ($item_info['reference_count'] == 0) {
            $this->_items_released[$itemid] = $itemid;
            $this->_applySizeRules();
        }

        return true;

    }//end release()


    function _applySizeRules()
    {
        // size -1 disable automatic remove
        if ($this->_size_rules['max'] == -1) return;

        if (count($this->_items_released) && $this->getSize(true)) {
            $current_size = $this->getSize(!$this->_size_rules['all_items']);

            if ($current_size > $this->_size_rules['max']) {
                // rules not respected, remove the oldest item
                reset($this->_items_released);
                $this->remove(current($this->_items_released));
            }
        }

    }//end _applySizeRules()


    function remove($itemid, $force=false)
    {
        if (!$force && ($this->_items[$itemid]['reference_count'] != 0)) {
            return false;
        }

        unset($this->_items[$itemid]);
        unset($this->_items_released[$itemid]);

        return true;

    }//end remove()


    function removeAll()
    {
        $itemsid = array_keys($this->_items_released);
        foreach ($itemsid as $itemid) {
            $this->remove($itemid);
        }

    }//end removeAll()


    function getSize($released=false)
    {
        return $released ? count($this->_items_released) : count($this->_items);

    }//end getSize()


    function getForgottenItemsReport()
    {
        $ret = '';

        ob_start();

        echo "Asset Cache report:\n";

        $item_count = 0;
        foreach ($this->_items as $itemid => $item_info) {
            if ($item_info['reference_count'] > 0) {
                echo 'Asset #'.$itemid.'  ('.get_class($item_info['item']).')  RC='.$item_info['reference_count']."\n";
                if (isset($item_info['callers'])) {
                    print_r ($item_info['callers']);
                }
                $item_count++;
            }
        }
        echo $item_count." items \n";

        $ret = ob_get_clean();

        return $ret;

    }//end getForgottenItemsReport()


    function _trackCaller($itemid, $rc_diff)
    {
        // 1. get class name
        $bt = debug_backtrace();

        $caller = '???';
        $excluded_classes = Array('asset_manager', 'asset', strtolower(__CLASS__));
        for ($caller_idx = 0; $caller_idx < count($bt); $caller_idx++) {
            $class = (isset($bt[$caller_idx]['class'])) ? $bt[$caller_idx]['class'] : '';
            if (!in_array(strtolower($class), $excluded_classes)) {
                break;
            }
        }
        if ($caller_idx < count($bt)) {
            $caller = (isset($bt[$caller_idx]['class'])) ? $bt[$caller_idx]['class'] : '';
            $caller .= ':'.$bt[$caller_idx]['file'];
        }

        // 2. add info to the cache
        if (!isset($this->_items[$itemid]['callers'])) {
            $this->_items[$itemid]['callers'] = Array();
        }
        if (!isset($this->_items[$itemid]['callers'][$caller])) {
            $this->_items[$itemid]['callers'][$caller] = 0;
        }
        $this->_items[$itemid]['callers'][$caller] += $rc_diff;

    }//end _trackCaller()


    function getAssetKeys()
    {
        return array_keys($this->_items);

    }//end getAssetKeys()


}//end class

?>