Proyectos de Subversion Moodle

<?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;

    }

}