DatabaseQueue.php

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<?php
namespace Elgg\Queue;

class DatabaseQueue implements \Elgg\Queue\Queue {

    protected $name;

    protected $db;

    protected $workerId;

    public function __construct($name, \Elgg\Database $db) {
        $this->db = $db;
        $this->name = $name;
        $this->workerId = md5(microtime() . getmypid());
    }

    public function enqueue($item) {
        $prefix = $this->db->prefix;
        $name = $this->db->sanitizeString($this->name);
        $blob = $this->db->sanitizeString(serialize($item));
        $time = time();

        $query = "INSERT INTO {$prefix}queue
            SET name = '$name', data = '$blob', timestamp = $time";
        return $this->db->insertData($query) !== false;
    }

    public function dequeue() {
        $prefix = $this->db->prefix;
        $name = $this->db->sanitizeString($this->name);
        $worker_id = $this->db->sanitizeString($this->workerId);

        $update = "UPDATE {$prefix}queue 
            SET worker = '$worker_id'
            WHERE name = '$name' AND worker IS NULL
            ORDER BY id ASC LIMIT 1";
        $num = $this->db->updateData($update, true);
        if ($num === 1) {
            $select = "SELECT data FROM {$prefix}queue
                WHERE worker = '$worker_id'";
            $obj = $this->db->getDataRow($select);
            if ($obj) {
                $data = unserialize($obj->data);
                $delete = "DELETE FROM {$prefix}queue
                    WHERE name = '$name' AND worker = '$worker_id'";
                $this->db->deleteData($delete);
                return $data;
            }
        }

        return null;
    }

    public function clear() {
        $prefix = $this->db->prefix;
        $name = $this->db->sanitizeString($this->name);

        $this->db->deleteData("DELETE FROM {$prefix}queue WHERE name = '$name'");
    }

    public function size() {
        $prefix = $this->db->prefix;
        $name = $this->db->sanitizeString($this->name);

        $result = $this->db->getDataRow("SELECT COUNT(id) AS total FROM {$prefix}queue WHERE name = '$name'");
        return (int)$result->total;
    }
}