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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Extra information generated during the analysis by calculable elements.
*
* @package core_analytics
* @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core_analytics;
defined('MOODLE_INTERNAL') || die();
/**
* Extra information generated during the analysis by calculable elements.
*
* The main purpose of this request cache is to allow calculable elements to
* store data during their calculations for further use at a later stage efficiently.
*
* @package core_analytics
* @copyright 2019 David Monllao {@link http://www.davidmonllao.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class calculation_info {
/**
* @var array
*/
private $info = [];
/**
* @var mixed[]
*/
private $samplesinfo = [];
/**
* Adds info related to the current calculation for later use when generating insights.
*
* Note that the data in $info array is reused across multiple samples, if you want to add data just for this
* sample you can use the sample id as key.
*
* We store two different arrays so objects that appear multiple times for different samples
* appear just once in memory.
*
* @param int $sampleid The sample id this data is associated with
* @param array $info The data. Indexed by an id unique across the site. E.g. an activity id.
* @return null
*/
public function add_shared(int $sampleid, array $info) {
// We can safely overwrite the existing keys because the provided info is supposed to be unique
// for the indicator.
$this->info = $info + $this->info;
// We also need to store the association between the info provided and the sample.
$this->samplesinfo[$sampleid] = array_keys($info);
}
/**
* Stores in MUC the previously added data and it associates it to the provided $calculable.
*
* @param \core_analytics\calculable $calculable
* @param \core_analytics\local\time_splitting\base $timesplitting
* @param int $rangeindex
* @return null
*/
public function save(\core_analytics\calculable $calculable, \core_analytics\local\time_splitting\base $timesplitting,
int $rangeindex) {
$calculableclass = get_class($calculable);
$cache = \cache::make('core', 'calculablesinfo');
foreach ($this->info as $key => $value) {
$datakey = self::get_data_key($calculableclass, $key);
// We do not overwrite existing data.
if (!$cache->has($datakey)) {
$cache->set($datakey, $value);
}
}
foreach ($this->samplesinfo as $sampleid => $infokeys) {
$uniquesampleid = $timesplitting->append_rangeindex($sampleid, $rangeindex);
$samplekey = self::get_sample_key($uniquesampleid);
// Update the cached data adding the new indicator data.
$cacheddata = $cache->get($samplekey);
$cacheddata[$calculableclass] = $infokeys;
$cache->set($samplekey, $cacheddata);
}
// Empty the in-memory arrays now that it is in the cache.
$this->info = [];
$this->samplesinfo = [];
}
/**
* Pulls the info related to the provided records out from the cache.
*
* Note that this function purges 'calculablesinfo' cache.
*
* @param \stdClass[] $predictionrecords
* @return array|false
*/
public static function pull_info(array $predictionrecords) {
$cache = \cache::make('core', 'calculablesinfo');
foreach ($predictionrecords as $uniquesampleid => $predictionrecord) {
$sampleid = $predictionrecord->sampleid;
$sampleinfo = $cache->get(self::get_sample_key($uniquesampleid));
// MUC returns (or should return) copies of the data and we want a single copy of it so
// we store the data here and reference it from each sample. Samples data should not be
// changed afterwards.
$data = [];
if ($sampleinfo) {
foreach ($sampleinfo as $calculableclass => $infokeys) {
foreach ($infokeys as $infokey) {
// We don't need to retrieve data back from MUC if we already have it.
if (!isset($data[$calculableclass][$infokey])) {
$datakey = self::get_data_key($calculableclass, $infokey);
$data[$calculableclass][$infokey] = $cache->get($datakey);
}
$samplesdatakey = $calculableclass . ':extradata';
$samplesdata[$sampleid][$samplesdatakey][$infokey] = & $data[$calculableclass][$infokey];
}
}
}
}
// Free memory ASAP. We can replace the purge call by a delete_many if we are interested on allowing
// multiple calls to pull_info passing in different $sampleids.
$cache->purge();
if (empty($samplesdata)) {
return false;
}
return $samplesdata;
}
/**
* Gets the key used to store data.
*
* @param string $calculableclass
* @param string|int $key
* @return string
*/
private static function get_data_key(string $calculableclass, $key): string {
return 'data:' . $calculableclass . ':' . $key;
}
/**
* Gets the key used to store samples.
*
* @param string $uniquesampleid
* @return string
*/
private static function get_sample_key(string $uniquesampleid): string {
return 'sample:' . $uniquesampleid;
}
}