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;

use coding_exception;

use core_php_time_limit;

use moodle_exception;

use stdClass;

// Disable the moodle.PHP.ForbiddenFunctions.FoundWithAlternative sniff for this file.

// It detects uses of error_log() which are valid in this file.

// phpcs:disable moodle.PHP.ForbiddenFunctions.FoundWithAlternative

/**

 * Cron and adhoc task functionality.

 *

 * @package    core

 * @copyright  2023 Andrew Lyons <andrew@nicols.co.uk>

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

 */

class cron {

    /** @var ?stdClass A copy of the standard cron 'user' */

    protected static ?stdClass $cronuser = null;

    /** @var ?stdClass The cron user's session data */

    protected static ?stdClass $cronsession = null;

    /**

     * Use a default value of 3 minutes.

     * The recommended cron frequency is every minute, and the default adhoc concurrency is 3.

     * A default value of 3 minutes allows all adhoc tasks to be run concurrently at their default value.

     *

     * @var int The default keepalive value for the main cron runner

     */

    public const DEFAULT_MAIN_PROCESS_KEEPALIVE = 3 * MINSECS;

    /**

     * @var int The max keepalive value for the main cron runner

     */

    public const MAX_MAIN_PROCESS_KEEPALIVE = 15 * MINSECS;

    /**

     * Execute cron tasks

     *

     * @param int|null $keepalive The keepalive time for this cron run.

     */

    public static function run_main_process(?int $keepalive = null): void {

        global $CFG, $DB;

        if (CLI_MAINTENANCE) {

            echo "CLI maintenance mode active, cron execution suspended.\n";

            exit(1);

        }

        if (moodle_needs_upgrading()) {

            echo "Moodle upgrade pending, cron execution suspended.\n";

            exit(1);

        }

        require_once($CFG->libdir . '/adminlib.php');

        if (!empty($CFG->showcronsql)) {

            $DB->set_debug(true);

        }

        if (!empty($CFG->showcrondebugging)) {

            set_debugging(DEBUG_DEVELOPER, true);

        }

        core_php_time_limit::raise();

        // Increase memory limit.

        raise_memory_limit(MEMORY_EXTRA);

        // Emulate normal session. - we use admin account by default.

        self::setup_user();

        // Start output log.

        $timenow = time();

        mtrace("Server Time: " . date('r', $timenow) . "\n\n");

        // Record start time and interval between the last cron runs.

        $laststart = get_config('tool_task', 'lastcronstart');

        set_config('lastcronstart', $timenow, 'tool_task');

        if ($laststart) {

            // Record the interval between last two runs (always store at least 1 second).

            set_config('lastcroninterval', max(1, $timenow - $laststart), 'tool_task');

        }

        // Determine the time when the cron should finish.

        if ($keepalive === null) {

            $keepalive = get_config('core', 'cron_keepalive');

            if ($keepalive === false) {

                $keepalive = self::DEFAULT_MAIN_PROCESS_KEEPALIVE;

            }

        }

        if ($keepalive > self::MAX_MAIN_PROCESS_KEEPALIVE) {

            // Attempt to prevent abnormally long keepalives.

            mtrace("Cron keepalive time is too long, reducing to 15 minutes.");

            $keepalive = self::MAX_MAIN_PROCESS_KEEPALIVE;

        }

        // Calculate the finish time based on the start time and keepalive.

        $finishtime = $timenow + $keepalive;

        do {

            $startruntime = microtime();

            // Run all scheduled tasks.

            self::run_scheduled_tasks(time(), $timenow);

            // Run adhoc tasks.

            self::run_adhoc_tasks(time(), 0, true, $timenow);

            mtrace("Cron run completed correctly");

            gc_collect_cycles();

            $completiontime = date('H:i:s');

            $difftime = microtime_diff($startruntime, microtime());

            $memoryused = display_size(memory_get_usage());

            $message = "Cron completed at {$completiontime} in {$difftime} seconds. Memory used: {$memoryused}.";

            // Check if we should continue to run.

            // Only continue to run if:

            // - The finish time has not been reached; and

            // - The graceful exit flag has not been set; and

            // - The static caches have not been cleared since the start of the cron run.

            $remaining = $finishtime - time();

            $runagain = $remaining > 0;

            $runagain = $runagain && !\core\local\cli\shutdown::should_gracefully_exit();

            $runagain = $runagain && !\core\task\manager::static_caches_cleared_since($timenow);

            if ($runagain) {

                $message .= " Continuing to check for tasks for {$remaining} more seconds.";

                mtrace($message);

                sleep(1);

                // Re-check the graceful exit and cache clear flags after sleeping as these may have changed.

                $runagain = $runagain && !\core\local\cli\shutdown::should_gracefully_exit();

                $runagain = $runagain && !\core\task\manager::static_caches_cleared_since($timenow);

            } else {

                mtrace($message);

            }

        } while ($runagain);

    }

    /**

     * Execute all queued scheduled tasks, applying necessary concurrency limits and time limits.

     *

     * @param   int       $startruntime The time this run started.

     * @param   null|int  $startprocesstime The time the process that owns this runner started.

     * @throws \moodle_exception

     */

    public static function run_scheduled_tasks(

        int $startruntime,

        ?int $startprocesstime = null,

    ): void {

        // Allow a restriction on the number of scheduled task runners at once.

        $cronlockfactory = \core\lock\lock_config::get_lock_factory('cron');

        $maxruns = get_config('core', 'task_scheduled_concurrency_limit');

        $maxruntime = get_config('core', 'task_scheduled_max_runtime');

        if ($startprocesstime === null) {

            $startprocesstime = $startruntime;

        }

        $scheduledlock = null;

        for ($run = 0; $run < $maxruns; $run++) {

            // If we can't get a lock instantly it means runner N is already running

            // so fail as fast as possible and try N+1 so we don't limit the speed at

            // which we bring new runners into the pool.

            if ($scheduledlock = $cronlockfactory->get_lock("scheduled_task_runner_{$run}", 0)) {

                break;

            }

        }

        if (!$scheduledlock) {

            mtrace("Skipping processing of scheduled tasks. Concurrency limit reached.");

            return;

        }

        $starttime = time();

        // Run all scheduled tasks.

        try {

            while (

                !\core\local\cli\shutdown::should_gracefully_exit() &&

                !\core\task\manager::static_caches_cleared_since($startprocesstime) &&

                $task = \core\task\manager::get_next_scheduled_task($startruntime)

            ) {

                self::run_inner_scheduled_task($task);

                unset($task);

                if ((time() - $starttime) > $maxruntime) {

                    mtrace("Stopping processing of scheduled tasks as time limit has been reached.");

                    break;

                }

            }

        } finally {

            // Release the scheduled task runner lock.

            $scheduledlock->release();

        }

    }

    /**

     * Execute all queued adhoc tasks, applying necessary concurrency limits and time limits.

     *

     * @param   int     $startruntime The time this run started.

     * @param   int     $keepalive Keep this public static function alive for N seconds and poll for new adhoc tasks.

     * @param   bool    $checklimits Should we check limits?

     * @param   null|int $startprocesstime The time this process started.

     * @param   int|null $maxtasks Limit number of tasks to run`

     * @param   null|string $classname Run only tasks of this class

     * @throws \moodle_exception

     */

    public static function run_adhoc_tasks(

        int $startruntime,

        $keepalive = 0,

        $checklimits = true,

        ?int $startprocesstime = null,

        ?int $maxtasks = null,

        ?string $classname = null,

    ): void {

        // Allow a restriction on the number of adhoc task runners at once.

        $cronlockfactory = \core\lock\lock_config::get_lock_factory('cron');

        $maxruns = get_config('core', 'task_adhoc_concurrency_limit');

        $maxruntime = get_config('core', 'task_adhoc_max_runtime');

        if ($startprocesstime === null) {

            $startprocesstime = $startruntime;

        }

        $adhoclock = null;

        if ($checklimits) {

            for ($run = 0; $run < $maxruns; $run++) {

                // If we can't get a lock instantly it means runner N is already running

                // so fail as fast as possible and try N+1 so we don't limit the speed at

                // which we bring new runners into the pool.

                if ($adhoclock = $cronlockfactory->get_lock("adhoc_task_runner_{$run}", 0)) {

                    break;

                }

            }

            if (!$adhoclock) {

                mtrace("Skipping processing of adhoc tasks. Concurrency limit reached.");

                return;

            }

        }

        $humantimenow = date('r', $startruntime);

        $finishtime = $startruntime + $keepalive;

        $waiting = false;

        $taskcount = 0;

        // Run all adhoc tasks.

        while (

            !\core\local\cli\shutdown::should_gracefully_exit() &&

            !\core\task\manager::static_caches_cleared_since($startprocesstime)

        ) {

            if ($checklimits && (time() - $startruntime) >= $maxruntime) {

                if ($waiting) {

                    $waiting = false;

                    mtrace('');

                }

                mtrace("Stopping processing of adhoc tasks as time limit has been reached.");

                break;

            }

            try {

                $task = \core\task\manager::get_next_adhoc_task(time(), $checklimits, $classname);

            } catch (\Throwable $e) {

                if ($adhoclock) {

                    // Release the adhoc task runner lock.

                    $adhoclock->release();

                }

                throw $e;

            }

            if ($task) {

                if ($waiting) {

                    mtrace('');

                }

                $waiting = false;

                self::run_inner_adhoc_task($task);

                self::set_process_title("Waiting for next adhoc task");

                $taskcount++;

                if ($maxtasks && $taskcount >= $maxtasks) {

                    break;

                }

                unset($task);

            } else {

                $timeleft = $finishtime - time();

                if ($timeleft <= 0) {

                    break;

                }

                if (!$waiting) {

                    mtrace('Waiting for more adhoc tasks to be queued ', '');

                } else {

                    mtrace('.', '');

                }

                $waiting = true;

                self::set_process_title("Waiting {$timeleft}s for next adhoc task");

                sleep(1);

            }

        }

        if ($waiting) {

            mtrace('');

        }

        mtrace("Ran {$taskcount} adhoc tasks found at {$humantimenow}");

        if ($adhoclock) {

            // Release the adhoc task runner lock.

            $adhoclock->release();

        }

    }

    /**

     * Execute an adhoc task.

     *

     * @param   int       $taskid

     */

    public static function run_adhoc_task(int $taskid): void {

        $task = \core\task\manager::get_adhoc_task($taskid);

        if (!$task->get_fail_delay() && $task->get_next_run_time() > time()) {

            throw new \moodle_exception('wontrunfuturescheduledtask');

        }

        self::run_inner_adhoc_task($task);

        self::set_process_title("Running adhoc task $taskid");

    }

    /**

     * Execute all failed adhoc tasks.

     *

     * @param string|null  $classname Run only tasks of this class

     */

    public static function run_failed_adhoc_tasks(?string $classname = null): void {

        global $DB;

        $where = 'faildelay > 0';

        $params = [];

        if ($classname) {

            $where .= ' AND classname = :classname';

            $params['classname'] = \core\task\manager::get_canonical_class_name($classname);

        }

        // Only rerun the failed tasks that allow to be re-tried or have the remaining attempts available.

        $where .= ' AND (attemptsavailable > 0 OR attemptsavailable IS NULL)';

        $tasks = $DB->get_records_sql("SELECT * from {task_adhoc} WHERE $where", $params);

        foreach ($tasks as $t) {

            self::run_adhoc_task($t->id);

        }

    }

    /**

     * Shared code that handles running of a single scheduled task within the cron.

     *

     * Not intended for calling directly outside of this library!

     *

     * @param \core\task\task_base $task

     */

    public static function run_inner_scheduled_task(\core\task\task_base $task) {

        global $CFG, $DB;

        $debuglevel = $CFG->debug;

        $debugdisplay = $CFG->debugdisplay;

        $CFG->debugdisplay = 1;

        \core\task\manager::scheduled_task_starting($task);

        \core\task\logmanager::start_logging($task);

        $fullname = $task->get_name() . ' (' . get_class($task) . ')';

        mtrace('Execute scheduled task: ' . $fullname);

        self::set_process_title('Scheduled task: ' . get_class($task));

        self::trace_time_and_memory();

        $predbqueries = null;

        $predbqueries = $DB->perf_get_queries();

        $pretime = microtime(1);

        // Ensure that we have a clean session with the correct cron user.

        self::setup_user();

        try {

            get_mailer('buffer');

            self::prepare_core_renderer();

            // Temporarily increase debug level if task has failed and debugging isn't already at maximum.

            if ($debuglevel !== DEBUG_DEVELOPER && $faildelay = $task->get_fail_delay()) {

                mtrace('Debugging increased temporarily due to faildelay of ' . $faildelay);

                set_debugging(DEBUG_DEVELOPER, 1);

            }

            $task->execute();

            if ($DB->is_transaction_started()) {

                throw new coding_exception("Task left transaction open");

            }

            if (isset($predbqueries)) {

                mtrace("... used " . ($DB->perf_get_queries() - $predbqueries) . " dbqueries");

                mtrace("... used " . (microtime(1) - $pretime) . " seconds");

            }

            mtrace('Scheduled task complete: ' . $fullname);

            \core\task\manager::scheduled_task_complete($task);

        } catch (\Throwable $e) {

            if ($DB && $DB->is_transaction_started()) {

                error_log('Database transaction aborted automatically in ' . get_class($task));

                $DB->force_transaction_rollback();

            }

            if (isset($predbqueries)) {

                mtrace("... used " . ($DB->perf_get_queries() - $predbqueries) . " dbqueries");

                mtrace("... used " . (microtime(1) - $pretime) . " seconds");

            }

            mtrace('Scheduled task failed: ' . $fullname . ',' . $e->getMessage());

            if ($CFG->debugdeveloper) {

                if (!empty($e->debuginfo)) {

                    mtrace("Debug info:");

                    mtrace($e->debuginfo);

                }

                mtrace("Backtrace:");

                mtrace(format_backtrace($e->getTrace(), true));

            }

            \core\task\manager::scheduled_task_failed($task);

        } finally {

            // Reset debugging if it changed.

            if ($CFG->debug !== $debuglevel) {

                set_debugging($debuglevel);

            }

            // Reset debugdisplay back.

            $CFG->debugdisplay = $debugdisplay;

            // Reset back to the standard admin user.

            self::setup_user();

            self::set_process_title('Waiting for next scheduled task');

            self::prepare_core_renderer(true);

        }

        get_mailer('close');

    }

    /**

     * Shared code that handles running of a single adhoc task within the cron.

     *

     * @param \core\task\adhoc_task $task

     */

    public static function run_inner_adhoc_task(\core\task\adhoc_task $task) {

        global $CFG, $DB;

        $debuglevel = $CFG->debug;

        $debugdisplay = $CFG->debugdisplay;

        $CFG->debugdisplay = 1;

        \core\task\manager::adhoc_task_starting($task);

        \core\task\logmanager::start_logging($task);

        mtrace("Execute adhoc task: " . get_class($task));

        mtrace("Adhoc task id: " . $task->get_id());

        mtrace("Adhoc task custom data: " . $task->get_custom_data_as_string());

        self::set_process_title('Adhoc task: ' . $task->get_id() . ' ' . get_class($task));

        self::trace_time_and_memory();

        $predbqueries = null;

        $predbqueries = $DB->perf_get_queries();

        $pretime = microtime(1);

        if ($userid = $task->get_userid()) {

            // This task has a userid specified.

            if ($user = \core_user::get_user($userid)) {

                // User found. Check that they are suitable.

                try {

                    \core_user::require_active_user($user, true, true);

                } catch (moodle_exception $e) {

                    mtrace("User {$userid} cannot be used to run an adhoc task: " . get_class($task) . ". Cancelling task.");

                    $user = null;

                }

            } else {

                // Unable to find the user for this task.

                // A user missing in the database will never reappear.

                mtrace("User {$userid} could not be found for adhoc task: " . get_class($task) . ". Cancelling task.");

            }

            if (empty($user)) {

                // A user missing in the database will never reappear so the task needs to be failed to ensure that locks are

                // removed, and then removed to prevent future runs.

                // A task running as a user should only be run as that user.

                \core\task\manager::adhoc_task_failed($task);

                $DB->delete_records('task_adhoc', ['id' => $task->get_id()]);

                return;

            }

            self::setup_user($user);

        } else {

            // No user specified, ensure that we have a clean session with the correct cron user.

            self::setup_user();

        }

        try {

            get_mailer('buffer');

            self::prepare_core_renderer();

            // Temporarily increase debug level if task has failed and debugging isn't already at maximum.

            if ($debuglevel !== DEBUG_DEVELOPER && $faildelay = $task->get_fail_delay()) {

                mtrace('Debugging increased temporarily due to faildelay of ' . $faildelay);

                set_debugging(DEBUG_DEVELOPER, 1);

            }

            $task->execute();

            if ($DB->is_transaction_started()) {

                throw new coding_exception("Task left transaction open");

            }

            if (isset($predbqueries)) {

                mtrace("... used " . ($DB->perf_get_queries() - $predbqueries) . " dbqueries");

                mtrace("... used " . (microtime(1) - $pretime) . " seconds");

            }

            mtrace("Adhoc task complete: " . get_class($task));

            \core\task\manager::adhoc_task_complete($task);

        } catch (\Throwable $e) {

            if ($DB && $DB->is_transaction_started()) {

                error_log('Database transaction aborted automatically in ' . get_class($task));

                $DB->force_transaction_rollback();

            }

            if (isset($predbqueries)) {

                mtrace("... used " . ($DB->perf_get_queries() - $predbqueries) . " dbqueries");

                mtrace("... used " . (microtime(1) - $pretime) . " seconds");

            }

            mtrace("Adhoc task failed: " . get_class($task) . "," . $e->getMessage());

            if ($CFG->debugdeveloper) {

                if (!empty($e->debuginfo)) {

                    mtrace("Debug info:");

                    mtrace($e->debuginfo);

                }

                mtrace("Backtrace:");

                mtrace(format_backtrace($e->getTrace(), true));

            }

            \core\task\manager::adhoc_task_failed($task);

        } finally {

            // Reset debug level if it changed.

            if ($CFG->debug !== $debuglevel) {

                set_debugging($debuglevel);

            }

            // Reset debugdisplay back.

            $CFG->debugdisplay = $debugdisplay;

            // Reset back to the standard admin user.

            self::setup_user();

            self::prepare_core_renderer(true);

        }

        get_mailer('close');

    }

    /**

     * Sets the process title

     *

     * This makes it very easy for a sysadmin to immediately see what task

     * a cron process is running at any given moment.

     *

     * @param string $title process status title

     */

    public static function set_process_title(string $title) {

        global $CFG;

        if (CLI_SCRIPT) {

            require_once($CFG->libdir . '/clilib.php');

            $datetime = userdate(time(), '%b %d, %H:%M:%S');

            cli_set_process_title_suffix("$datetime $title");

        }

    }

    /**

     * Output some standard information during cron runs. Specifically current time

     * and memory usage. This method also does gc_collect_cycles() (before displaying

     * memory usage) to try to help PHP manage memory better.

     */

    public static function trace_time_and_memory() {

        gc_collect_cycles();

        mtrace('... started ' . date('H:i:s') . '. Current memory use ' . display_size(memory_get_usage()) . '.');

    }

    /**

     * Prepare the output renderer for the cron run.

     *

     * This involves creating a new $PAGE, and $OUTPUT fresh for each task and prevents any one task from influencing

     * any other.

     *

     * @param   bool    $restore Whether to restore the original PAGE and OUTPUT

     */

    public static function prepare_core_renderer($restore = false) {

        global $OUTPUT, $PAGE;

        // Store the original PAGE and OUTPUT values so that they can be reset at a later point to the original.

        // This should not normally be required, but may be used in places such as the scheduled task tool's "Run now"

        // functionality.

        static $page = null;

        static $output = null;

        if (null === $page) {

            $page = $PAGE;

        }

        if (null === $output) {

            $output = $OUTPUT;

        }

        if (!empty($restore)) {

            $PAGE = $page;

            $page = null;

            $OUTPUT = $output;

            $output = null;

        } else {

            // Setup a new General renderer.

            // Cron tasks may produce output to be used in web, so we must use the appropriate renderer target.

            // This allows correct use of templates, etc.

            $PAGE = new \moodle_page();

            $OUTPUT = new \core_renderer($PAGE, RENDERER_TARGET_GENERAL);

        }

    }

    /**

     * Sets up a user and course environment in cron.

     *

     * Note: This function is intended only for use in:

     * - the cron runner scripts

     * - individual tasks which extend the adhoc_task and scheduled_task classes

     * - unit tests related to tasks

     * - other parts of the cron/task system

     *

     * Please note that this function stores cache data statically.

     * @see reset_user_cache() to reset this cache.

     *

     * @param null|stdClass $user full user object, null means default cron user (admin)

     * @param null|stdClass $course full course record, null means $SITE

     * @param null|bool $leavepagealone If specified, stops it messing with global page object

     */

    public static function setup_user(?stdClass $user = null, ?stdClass $course = null, bool $leavepagealone = false): void {

        // This function uses the $GLOBALS super global. Disable the VariableNameLowerCase sniff for this function.

        // phpcs:disable moodle.NamingConventions.ValidVariableName.VariableNameLowerCase

        global $CFG, $SITE, $PAGE;

        if (!CLI_SCRIPT && !$leavepagealone) {

            throw new coding_exception('It is not possible to use \core\cron\setup_user() in normal requests!');

        }

        if (empty(self::$cronuser)) {

            // The cron user is essentially the admin user, but with some value removed.

            // We ginore the timezone language, and locale preferences - use the site default instead.

            self::$cronuser = get_admin();

            self::$cronuser->timezone = $CFG->timezone;

            self::$cronuser->lang = '';

            self::$cronuser->theme = '';

            unset(self::$cronuser->description);

            self::$cronsession = new stdClass();

        }

        if (!$user) {

            // Cached default cron user (==modified admin for now).

            \core\session\manager::init_empty_session();

            \core\session\manager::set_user(self::$cronuser);

            $GLOBALS['SESSION'] = self::$cronsession;

        } else {

            // Emulate real user session - needed for caps in cron.

            if ($GLOBALS['USER']->id != $user->id) {

                \core\session\manager::init_empty_session();

                \core\session\manager::set_user($user);

            }

        }

        // TODO MDL-19774 relying on global $PAGE in cron is a bad idea.

        // Temporary hack so that cron does not give fatal errors.

        if (!$leavepagealone) {

            $PAGE = new \moodle_page();

            $PAGE->set_course($course ?? $SITE);

        }

        // TODO: it should be possible to improve perf by caching some limited number of users here.

        // phpcs:enable

    }

    /**

     * Resets the cache for the cron user used by `setup_user()`.

     */

    public static function reset_user_cache(): void {

        self::$cronuser = null;

        self::$cronsession = null;

        \core\session\manager::init_empty_session();

    }

}