<?php
/**
* @package VikBooking
* @subpackage core
* @author E4J s.r.l.
* @copyright Copyright (C) 2021 E4J s.r.l. All Rights Reserved.
* @license http://www.gnu.org/licenses/gpl-2.0.html GNU/GPL
* @link https://vikwp.com
*/
// No direct access
defined('ABSPATH') or die('No script kiddies please!');
/**
* VikBooking cron job scalar-elements array tracker.
*
* @since 1.5.10
*/
trait VBOCronTrackerArray
{
/**
* Defines the maximum number of characters that can occupy the list
* containing all the tracked elements. Children classes can alter
* this value according to their needs.
*
* @var int
*/
protected $maximumCharsTrackableElements = 10000;
/**
* Helper method used to flag the specified element as tracked. This is really helpful to easily
* check whether a specific record has been already parsed, which can be done by passing the same
* element argument to the `isTracked` method.
*
* It is recommended to register only scalar values in order to prevent an uncontrolled increase of the
* total length, which can arrive up to 2^16-1 characters (65535). It's up to the sub-classes to take care of
* this limit, which should clean the flag_char property in order to always have less than 65536 characters.
*
* @param mixed $element The element to track.
*
* @return boolean True on success, false otherwise.
*/
protected function track($element)
{
if ($this->isTracked($element) || !is_scalar($element))
{
// element already tracked, avoid duplicate registration
return false;
}
if (is_numeric($element))
{
// cast to number to save some space occupied by json_encode for strings
$element = is_float($element) ? (float) $element : (int) $element;
}
// make sure this trait has been attached only to a cron job instance
if (!$this instanceof VBOCronJob)
{
throw new Exception('This tracker can be attached only to a VBOCronJob instance', 500);
}
// register the element at the beginning of the list
$data = $this->getData();
array_unshift($data->flag_char, $element);
// sanitize the elements contained within the cache in order
// avoid a length exceeding the maximum threshold
$this->sanitizeFlagCache($data);
return true;
}
/**
* Checks whether the specified element has been already processed.
*
* @param mixed $element The element to check.
*
* @return boolean True if already processed, false otherwise.
*/
protected function isTracked($element)
{
// make sure this trait has been attached only to a cron job instance
if (!$this instanceof VBOCronJob)
{
throw new Exception('This tracker can be attached only to a VBOCronJob instance', 500);
}
return in_array($element, $this->getData()->flag_char);
}
/**
* Ensures the array with the tracked elements doesn't exceed the maximum limit.
*
* @param object $data The cron job data.
*
* @return void
*/
private function sanitizeFlagCache($data)
{
// count the total number of characters that occupy the cache
$len = 0;
foreach ($data->flag_char as $element)
{
// sum value with the total number of characters
$len += strlen((string) $element);
if (!is_numeric($element))
{
// we have a string element, we need to include other 2 characters reserved for wrapping
$len += 2;
}
// increase the length by 1 to include also the elements separator (,)
$len++;
}
if ($data->flag_char)
{
// remove the trailing comma separator
$len--;
}
// sum also the initial and trailing brackets
$len += 2;
// even if the maximum number of allowed characters is 65535, we prefer to always stay under
// 10000 elements, since json_encode may use a specific encoding for some characters
if ($len > $this->maximumCharsTrackableElements)
{
// it is enough to pop the last 2 items from the list in order to stay under the desired limit,
// since this method always triggers while registering a new element
array_pop($data->flag_char);
array_pop($data->flag_char);
}
}
}