/**
 * Function to be run periodically according to the scheduled task.
 *
 * Finds all posts that have yet to be mailed out, and mails them
 * out to all subscribers as well as other maintance tasks.
 *
 * NOTE: Since 2.7.2 this function is run by scheduled task rather
 * than standard cron.
 *
 * @todo MDL-44734 The function will be split up into seperate tasks.
 */
function forum_cron()
{
    global $CFG, $USER, $DB, $PAGE;
    $site = get_site();
    // The main renderers.
    $htmlout = $PAGE->get_renderer('mod_forum', 'email', 'htmlemail');
    $textout = $PAGE->get_renderer('mod_forum', 'email', 'textemail');
    $htmldigestfullout = $PAGE->get_renderer('mod_forum', 'emaildigestfull', 'htmlemail');
    $textdigestfullout = $PAGE->get_renderer('mod_forum', 'emaildigestfull', 'textemail');
    $htmldigestbasicout = $PAGE->get_renderer('mod_forum', 'emaildigestbasic', 'htmlemail');
    $textdigestbasicout = $PAGE->get_renderer('mod_forum', 'emaildigestbasic', 'textemail');
    // All users that are subscribed to any post that needs sending,
    // please increase $CFG->extramemorylimit on large sites that
    // send notifications to a large number of users.
    $users = array();
    $userscount = 0;
    // Cached user counter - count($users) in PHP is horribly slow!!!
    // Status arrays.
    $mailcount = array();
    $errorcount = array();
    // caches
    $discussions = array();
    $forums = array();
    $courses = array();
    $coursemodules = array();
    $subscribedusers = array();
    $messageinboundhandlers = array();
    // Posts older than 2 days will not be mailed.  This is to avoid the problem where
    // cron has not been running for a long time, and then suddenly people are flooded
    // with mail from the past few weeks or months
    $timenow = time();
    $endtime = $timenow - $CFG->maxeditingtime;
    $starttime = $endtime - 48 * 3600;
    // Two days earlier
    // Get the list of forum subscriptions for per-user per-forum maildigest settings.
    $digestsset = $DB->get_recordset('forum_digests', null, '', 'id, userid, forum, maildigest');
    $digests = array();
    foreach ($digestsset as $thisrow) {
        if (!isset($digests[$thisrow->forum])) {
            $digests[$thisrow->forum] = array();
        }
        $digests[$thisrow->forum][$thisrow->userid] = $thisrow->maildigest;
    }
    $digestsset->close();
    // Create the generic messageinboundgenerator.
    $messageinboundgenerator = new \core\message\inbound\address_manager();
    $messageinboundgenerator->set_handler('\\mod_forum\\message\\inbound\\reply_handler');
    if ($posts = forum_get_unmailed_posts($starttime, $endtime, $timenow)) {
        // Mark them all now as being mailed.  It's unlikely but possible there
        // might be an error later so that a post is NOT actually mailed out,
        // but since mail isn't crucial, we can accept this risk.  Doing it now
        // prevents the risk of duplicated mails, which is a worse problem.
        if (!forum_mark_old_posts_as_mailed($endtime)) {
            mtrace('Errors occurred while trying to mark some posts as being mailed.');
            return false;
            // Don't continue trying to mail them, in case we are in a cron loop
        }
        // checking post validity, and adding users to loop through later
        foreach ($posts as $pid => $post) {
            $discussionid = $post->discussion;
            if (!isset($discussions[$discussionid])) {
                if ($discussion = $DB->get_record('forum_discussions', array('id' => $post->discussion))) {
                    $discussions[$discussionid] = $discussion;
                    \mod_forum\subscriptions::fill_subscription_cache($discussion->forum);
                    \mod_forum\subscriptions::fill_discussion_subscription_cache($discussion->forum);
                } else {
                    mtrace('Could not find discussion ' . $discussionid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            $forumid = $discussions[$discussionid]->forum;
            if (!isset($forums[$forumid])) {
                if ($forum = $DB->get_record('forum', array('id' => $forumid))) {
                    $forums[$forumid] = $forum;
                } else {
                    mtrace('Could not find forum ' . $forumid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            $courseid = $forums[$forumid]->course;
            if (!isset($courses[$courseid])) {
                if ($course = $DB->get_record('course', array('id' => $courseid))) {
                    $courses[$courseid] = $course;
                } else {
                    mtrace('Could not find course ' . $courseid);
                    unset($posts[$pid]);
                    continue;
//.........这里部分代码省略.........

/**
 * Function to be run periodically according to the moodle cron
 * Finds all posts that have yet to be mailed out, and mails them
 * out to all subscribers
 *
 * @global object
 * @global object
 * @global object
 * @uses CONTEXT_MODULE
 * @uses CONTEXT_COURSE
 * @uses SITEID
 * @uses FORMAT_PLAIN
 * @return void
 */
function forum_cron() {
    global $CFG, $USER, $DB;

    $site = get_site();

    // All users that are subscribed to any post that needs sending,
    // please increase $CFG->extramemorylimit on large sites that
    // send notifications to a large number of users.
    $users = array();
    $userscount = 0; // Cached user counter - count($users) in PHP is horribly slow!!!

    // status arrays
    $mailcount  = array();
    $errorcount = array();

    // caches
    $discussions     = array();
    $forums          = array();
    $courses         = array();
    $coursemodules   = array();
    $subscribedusers = array();


    // Posts older than 2 days will not be mailed.  This is to avoid the problem where
    // cron has not been running for a long time, and then suddenly people are flooded
    // with mail from the past few weeks or months
    $timenow   = time();
    $endtime   = $timenow - $CFG->maxeditingtime;
    $starttime = $endtime - 48 * 3600;   // Two days earlier

    if ($posts = forum_get_unmailed_posts($starttime, $endtime, $timenow)) {
        // Mark them all now as being mailed.  It's unlikely but possible there
        // might be an error later so that a post is NOT actually mailed out,
        // but since mail isn't crucial, we can accept this risk.  Doing it now
        // prevents the risk of duplicated mails, which is a worse problem.

        if (!forum_mark_old_posts_as_mailed($endtime)) {
            mtrace('Errors occurred while trying to mark some posts as being mailed.');
            return false;  // Don't continue trying to mail them, in case we are in a cron loop
        }

        // checking post validity, and adding users to loop through later
        foreach ($posts as $pid => $post) {

            $discussionid = $post->discussion;
            if (!isset($discussions[$discussionid])) {
                if ($discussion = $DB->get_record('forum_discussions', array('id'=> $post->discussion))) {
                    $discussions[$discussionid] = $discussion;
                } else {
                    mtrace('Could not find discussion '.$discussionid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            $forumid = $discussions[$discussionid]->forum;
            if (!isset($forums[$forumid])) {
                if ($forum = $DB->get_record('forum', array('id' => $forumid))) {
                    $forums[$forumid] = $forum;
                } else {
                    mtrace('Could not find forum '.$forumid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            $courseid = $forums[$forumid]->course;
            if (!isset($courses[$courseid])) {
                if ($course = $DB->get_record('course', array('id' => $courseid))) {
                    $courses[$courseid] = $course;
                } else {
                    mtrace('Could not find course '.$courseid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            if (!isset($coursemodules[$forumid])) {
                if ($cm = get_coursemodule_from_instance('forum', $forumid, $courseid)) {
                    $coursemodules[$forumid] = $cm;
                } else {
                    mtrace('Could not find course module for forum '.$forumid);
                    unset($posts[$pid]);
                    continue;
                }
            }


            // caching subscribed users of each forum
//.........这里部分代码省略.........

/**
 * Function to be run periodically according to the moodle cron
 * Finds all posts that have yet to be mailed out, and mails them
 * out to all subscribers
 * @return void
 */
function forum_cron()
{
    global $CFG, $USER;
    $cronuser = clone $USER;
    $site = get_site();
    // all users that are subscribed to any post that needs sending
    $users = array();
    // status arrays
    $mailcount = array();
    $errorcount = array();
    // caches
    $discussions = array();
    $forums = array();
    $courses = array();
    $coursemodules = array();
    $subscribedusers = array();
    // Posts older than 2 days will not be mailed.  This is to avoid the problem where
    // cron has not been running for a long time, and then suddenly people are flooded
    // with mail from the past few weeks or months
    $timenow = time();
    $endtime = $timenow - $CFG->maxeditingtime;
    $starttime = $endtime - 48 * 3600;
    // Two days earlier
    if ($posts = forum_get_unmailed_posts($starttime, $endtime, $timenow)) {
        // Mark them all now as being mailed.  It's unlikely but possible there
        // might be an error later so that a post is NOT actually mailed out,
        // but since mail isn't crucial, we can accept this risk.  Doing it now
        // prevents the risk of duplicated mails, which is a worse problem.
        if (!forum_mark_old_posts_as_mailed($endtime)) {
            mtrace('Errors occurred while trying to mark some posts as being mailed.');
            return false;
            // Don't continue trying to mail them, in case we are in a cron loop
        }
        // checking post validity, and adding users to loop through later
        foreach ($posts as $pid => $post) {
            $discussionid = $post->discussion;
            if (!isset($discussions[$discussionid])) {
                if ($discussion = get_record('forum_discussions', 'id', $post->discussion)) {
                    $discussions[$discussionid] = $discussion;
                } else {
                    mtrace('Could not find discussion ' . $discussionid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            $forumid = $discussions[$discussionid]->forum;
            if (!isset($forums[$forumid])) {
                if ($forum = get_record('forum', 'id', $forumid)) {
                    $forums[$forumid] = $forum;
                } else {
                    mtrace('Could not find forum ' . $forumid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            $courseid = $forums[$forumid]->course;
            if (!isset($courses[$courseid])) {
                if ($course = get_record('course', 'id', $courseid)) {
                    $courses[$courseid] = $course;
                } else {
                    mtrace('Could not find course ' . $courseid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            if (!isset($coursemodules[$forumid])) {
                if ($cm = get_coursemodule_from_instance('forum', $forumid, $courseid)) {
                    $coursemodules[$forumid] = $cm;
                } else {
                    mtrace('Could not course module for forum ' . $forumid);
                    unset($posts[$pid]);
                    continue;
                }
            }
            // caching subscribed users of each forum
            if (!isset($subscribedusers[$forumid])) {
                if ($subusers = forum_subscribed_users($courses[$courseid], $forums[$forumid], 0, false)) {
                    foreach ($subusers as $postuser) {
                        // do not try to mail users with stopped email
                        if ($postuser->emailstop) {
                            if (!empty($CFG->forum_logblocked)) {
                                add_to_log(SITEID, 'forum', 'mail blocked', '', '', 0, $postuser->id);
                            }
                            continue;
                        }
                        // this user is subscribed to this forum
                        $subscribedusers[$forumid][$postuser->id] = $postuser->id;
                        // this user is a user we have to process later
                        $users[$postuser->id] = $postuser;
                    }
                    unset($subusers);
                    // release memory
                }
            }
//.........这里部分代码省略.........