队列技术在PHP与MySQL中的延迟任务处理和流量控制的应用

class Queue
{
    private $queue;

    public function __construct()
    {
        $this->queue = array();
    }

    public function enqueue($item)
    {
        array_push($this->queue, $item);
    }

    public function dequeue()
    {
        return array_shift($this->queue);
    }

    public function isEmpty()
    {
        return empty($this->queue);
    }
}

CREATE TABLE queue (
  id INT(11) AUTO_INCREMENT PRIMARY KEY,
  data TEXT NOT NULL,
  created_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
);

class Queue
{
    private $db;

    public function __construct()
    {
        $this->db = new PDO('mysql:host=localhost;dbname=your_db_name', 'your_username', 'your_passWord');
    }

    public function enqueue($item)
    {
        $stmt = $this->db->prepare("INSERT INTO queue (data) VALUES (:data)");
        $stmt->bindValue(':data', $item);
        $stmt->execute();
    }

    public function dequeue()
    {
        $stmt = $this->db->query("SELECT * FROM queue ORDER BY created_at ASC LIMIT 1");
        $item = $stmt->fetch(PDO::FETCH_ASSOC);

        if ($item) {
            $this->db->exec("DELETE FROM queue WHERE id = {$item['id']}");
            return $item['data'];
        }

        return null;
    }
}

class TrafficControl
{
    private $queue;
    private $maxConcurrentTasks;

    public function __construct($maxConcurrentTasks)
    {
        $this->queue = new Queue();
        $this->maxConcurrentTasks = $maxConcurrentTasks;
    }

    public function addTask($task)
    {
        if (count($this->queue) >= $this->maxConcurrentTasks) {
            echo "Too many tasks, please try again later.";
            return;
        }

        $this->queue->enqueue($task);
    }

    public function processTasks()
    {
        while (!$this->queue->isEmpty()) {
            $task = $this->queue->dequeue();
            // 处理任务...
        }
    }
}

// 创建TrafficControl实例并添加任务
$trafficControl = new TrafficControl(5);
$trafficControl->addTask('task1');
$trafficControl->addTask('task2');

// 处理任务
$trafficControl->processTasks();