队列技术在PHP与MySQL中的消息优先级和持久化存储的应用场景

<?php

class PriorityQueue {

    private $queue = [];

    public function enqueue($data, $priority) {
        if (!isset($this->queue[$priority])) {
            $this->queue[$priority] = new SplPriorityQueue();
        }

        $this->queue[$priority]->insert($data, $priority);
    }

    public function dequeue() {
        $queue = $this->queue;
        krsort($queue); // 根据优先级降序排序

        foreach ($queue as $priority => $data) {
            if (!$data->isEmpty()) {
                return $data->extract();
            }
        }

        return null;
    }
}

// 使用示例
$priorityQueue = new PriorityQueue();

$priorityQueue->enqueue("消息1", 1);
$priorityQueue->enqueue("消息2", 2);
$priorityQueue->enqueue("消息3", 1);

echo $priorityQueue->dequeue() . "
";  // 输出：消息2
echo $priorityQueue->dequeue() . "
";  // 输出：消息1
echo $priorityQueue->dequeue() . "
";  // 输出：消息3
?>

<?php

class MessageQueue {

    private $conn;

    public function __construct($host, $user, $password, $database) {
        $this->conn = new mysqli($host, $user, $password, $database);
        if ($this->conn->connect_error) {
            throw new Exception("数据库连接失败：" . $this->conn->connect_error);
        }
    }

    public function enqueue($data) {
        $query = "INSERT INTO message_queue (data, created_at) VALUES (?, NOW())";

        $stmt = $this->conn->prepare($query);
        $stmt->bind_param("s", $data);
        $stmt->execute();
        $stmt->close();
    }

    public function dequeue() {
        $query = "SELECT data FROM message_queue ORDER BY created_at ASC LIMIT 1";

        $result = $this->conn->query($query);
        $data = $result->fetch_assoc()["data"];

        $deleteQuery = "DELETE FROM message_queue ORDER BY created_at ASC LIMIT 1";
        $this->conn->query($deleteQuery);

        return $data;
    }
}

// 使用示例
$messageQueue = new MessageQueue("localhost", "user", "password", "database");

$messageQueue->enqueue("消息1");
$messageQueue->enqueue("消息2");
$messageQueue->enqueue("消息3");

echo $messageQueue->dequeue() . "
";  // 输出：消息1
echo $messageQueue->dequeue() . "
";  // 输出：消息2
echo $messageQueue->dequeue() . "
";  // 输出：消息3
?>