gnu-social/plugins/Msn/msn_waiting_message.php

<?php
/**
 * Table Definition for msn_waiting_message
 */
require_once INSTALLDIR.'/classes/Memcached_DataObject.php';

class Msn_waiting_message extends Managed_DataObject {

    public $__table = 'msn_waiting_message'; // table name
    public $id;                              // int primary_key not_null auto_increment
    public $screenname;                      // varchar(255) not_null
    public $message;                         // text not_null
    public $claimed;                         // datetime()
    public $created;                         // datetime()   not_null
    public $modified;                        // timestamp()   not_null default_CURRENT_TIMESTAMP

    public static function schemaDef()
    {
        return array(
            'fields' => array(
                'id' => array('type' => 'int', 'not null' => true, 'description' => 'Unique ID for entry'),
                'screenname' => array('type' => 'varchar', 'length' => 255, 'description' => 'from screenname'),
                'message' => array('type' => 'text', 'not null' => true, 'description' => 'MSN message text'),
                'claimed' => array('type' => 'datetime', 'description' => 'date this irc message was claimed'),
                'created' => array('type' => 'datetime', 'not null' => true, 'description' => 'date this record was created'),
                'modified' => array('type' => 'timestamp', 'not null' => true, 'description' => 'date this record was modified'),
            ),
            'primary key' => array('id'),
            'indexes' => array(
                'msn_waiting_message_prioritise_idx' => array('screenname'),
            ),
        );
    }

    /**
     * @param string $screenname screenname or array of screennames to pull from
     *                          If not specified, checks all queues in the system.
     */
    public static function top($screenname = null) {
        $wm = new Msn_waiting_message();
        if ($screenname) {
            if (is_array($screenname)) {
                // @fixme use safer escaping
                $list = implode("','", array_map('addslashes', $screenname));
                $wm->whereAdd("screenname in ('$list')");
            } else {
                $wm->screenname = $screenname;
            }
        }
        $wm->orderBy('created');
        $wm->whereAdd('claimed is null');

        $wm->limit(1);

        $cnt = $wm->find(true);

        if ($cnt) {
            // XXX: potential race condition
            // can we force it to only update if claimed is still null
            // (or old)?
            common_log(LOG_INFO, 'claiming msn waiting message id = ' . $wm->id);
            $orig = clone($wm);
            $wm->claimed = common_sql_now();
            $result = $wm->update($orig);
            if ($result) {
                common_log(LOG_INFO, 'claim succeeded.');
                return $wm;
            } else {
                common_log(LOG_INFO, 'claim failed.');
            }
        }
        $wm = null;
        return null;
    }

    /**
     * Release a claimed item.
     */
    public function releaseClaim() {
        // DB_DataObject doesn't let us save nulls right now
        $sql = sprintf("UPDATE msn_waiting_message SET claimed=NULL WHERE id=%d", $this->id);
        $this->query($sql);

        $this->claimed = null;
        $this->encache();
    }
}