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/>.

namespace core\lock;

use coding_exception;

/**

 * Timing wrapper around a lock factory.

 *

 * This passes all calls through to the underlying lock factory, but adds timing information on how

 * long it takes to get a lock and how long the lock is held for.

 *

 * @package core

 * @category lock

 * @copyright 2022 The Open University

 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class timing_wrapper_lock_factory implements lock_factory {

    /** @var lock_factory Real lock factory */

    protected $factory;

    /** @var string Type (Frankenstyle) used for these locks */

    protected $type;

    /**

     * Constructor required by interface.

     *

     * @param string $type Type (should be same as passed to real lock factory)

     * @param lock_factory $factory Real lock factory

     */

    public function __construct($type, lock_factory $factory = null) {

        $this->type = $type;

        if (!$factory) {

            // This parameter has to be optional because of the interface, but it is actually

            // required.

            throw new \coding_exception('The $factory parameter must be specified');

        }

        $this->factory = $factory;

    }

    /**

     * Gets the real lock factory that this is wrapping.

     *

     * @return lock_factory ReaL lock factory

     */

    public function get_real_factory(): lock_factory {

        return $this->factory;

    }

    /**

     * Implementation of lock_factory::get_lock that defers to function inner_get_lock and keeps

     * track of how long it took.

     *

     * @param string $resource Identifier for the lock

     * @param int $timeout Number of seconds to wait for a lock before giving up

     * @param int $maxlifetime Number of seconds to wait before reclaiming a stale lock

     * @return \core\lock\lock|boolean - An instance of \core\lock\lock if the lock was obtained, or false.

     */

    public function get_lock($resource, $timeout, $maxlifetime = 86400) {

        $before = microtime(true);

        $result = $this->factory->get_lock($resource, $timeout, $maxlifetime);

        $after = microtime(true);

        self::record_lock_data($after, $before, $this->type, $resource, (bool)$result, $result);

        if ($result) {

            $result->init_factory($this);

        }

        return $result;

    }

    /**

     * Records statistics about a lock to the performance data.

     *

     * @param float $after The time after the lock was achieved.

     * @param float $before The time before the lock was requested.

     * @param string $type The type of lock.

     * @param string $resource The resource being locked.

     * @param bool $result Whether the lock was successful.

     * @param lock|string $lock A value uniquely identifying the lock.

     * @return void

     */

    public static function record_lock_data(float $after, float $before, string $type, string $resource, bool $result, $lock) {

        global $PERF;

        $duration = $after - $before;

        if (empty($PERF->locks)) {

            $PERF->locks = [];

        }

        $lockdata = (object) [

            'type' => $type,

            'resource' => $resource,

            'wait' => $duration,

            'success' => $result

        ];

        if ($result) {

            $lockdata->lock = $lock;

            $lockdata->timestart = $after;

        }

        $PERF->locks[] = $lockdata;

    }

    /**

     * Release a lock that was previously obtained with {@see get_lock}.

     *

     * @param lock $lock - The lock to release.

     * @return boolean - True if the lock is no longer held (including if it was never held).

     */

    public function release_lock(lock $lock) {

        self::record_lock_released_data($lock);

        return $this->factory->release_lock($lock);

    }

    /**

     * Find the lock in the performance info and update it with the time held.

     *

     * @param lock|string $lock A value uniquely identifying the lock.

     * @return void

     */

    public static function record_lock_released_data($lock) {

        global $PERF;

        // Find this lock in the list of locks we got, looking backwards since it is probably

        // the last one.

        for ($index = count($PERF->locks) - 1; $index >= 0; $index--) {

            $lockdata = $PERF->locks[$index];

            if (!empty($lockdata->lock) && $lockdata->lock === $lock) {

                // Update the time held.

                unset($lockdata->lock);

                $lockdata->held = microtime(true) - $lockdata->timestart;

                break;

            }

        }

    }

    /**

     * Calls parent factory to check if it supports timeout.

     *

     * @return boolean False if attempting to get a lock will block indefinitely.

     */

    public function supports_timeout() {

        return $this->factory->supports_timeout();

    }

    /**

     * Calls parent factory to check if it auto-releases locks.

     *

     * @return boolean True if this lock type will be automatically released when the current process ends.

     */

    public function supports_auto_release() {

        return $this->factory->supports_auto_release();

    }

    /**

     * @deprecated since Moodle 3.10.

     */

    public function supports_recursion() {

        throw new coding_exception('The function supports_recursion() has been removed, please do not use it anymore.');

    }

    /**

     * Calls parent factory to check if it is available.

     *

     * @return boolean True if this lock type is available in this environment.

     */

    public function is_available() {

        return $this->factory->is_available();

    }

    /**

     * @deprecated since Moodle 3.10.

     */

    public function extend_lock() {

        throw new coding_exception('The function extend_lock() has been removed, please do not use it anymore.');

    }

}