在Swoole中实现MySQL连接池可以提高数据库连接的复用率，减少频繁创建和销毁连接所带来的开销。以下是一个简单的Swoole MySQL连接池的实现示例：

首先，确保你已经安装了Swoole扩展和PDO_MySQL扩展（或mysqli，但在这个示例中我们使用PDO）。

<?phpuse Swoole\Coroutine as co;
use PDO;
use PDOException;class SwooleMysqlConnectionPool
{private $pool;private $config;private $maxConnections;private $availableConnections = [];private $inUseConnections = [];public function __construct($config, $maxConnections = 10){$this->config = $config;$this->maxConnections = $maxConnections;$this->pool = new SplQueue();// Initialize the pool with available connectionsfor ($i = 0; $i < $maxConnections; $i++) {$this->pool->enqueue($this->createConnection());$this->availableConnections[$i] = true;}}private function createConnection(){try {$dsn = "mysql:host={$this->config['host']};dbname={$this->config['dbname']};charset={$this->config['charset']}";$options = [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,PDO::ATTR_PERSISTENT => false,PDO::ATTR_EMULATE_PREPARES => false,];return new PDO($dsn, $this->config['username'], $this->config['password'], $options);} catch (PDOException $e) {throw new Exception("Failed to create MySQL connection: " . $e->getMessage());}}public function getConnection(){if ($this->pool->isEmpty()) {throw new Exception("MySQL connection pool is exhausted");}$connection = $this->pool->dequeue();$this->availableConnections[array_search(true, $this->availableConnections)] = false; // Mark as in useunset($this->availableConnections[array_search(true, $this->availableConnections, true)]); // Remove the true value$this->inUseConnections[] = $connection;return $connection;}public function releaseConnection($connection){if (($key = array_search($connection, $this->inUseConnections)) !== false) {unset($this->inUseConnections[$key]);$this->pool->enqueue($connection);$this->availableConnections[] = true; // Mark as available// Optionally, you can add logic here to close and recreate the connection// if it has been in use for too long or if an error occurs.}}// Optional: Add methods to handle connection recycling, health checks, etc.// Example usage in a Swoole coroutinepublic function queryInCoroutine($sql, $params = []){go(function () use ($sql, $params) {$connection = $this->getConnection();try {$stmt = $connection->prepare($sql);$stmt->execute($params);$result = $stmt->fetchAll(PDO::FETCH_ASSOC);$this->releaseConnection($connection);co::sleep(1); // Simulate some workecho "Query result: " . json_encode($result) . PHP_EOL;} catch (PDOException $e) {echo "Query failed: " . $e->getMessage() . PHP_EOL;// Optionally, handle the connection failure (e.g., remove it from the pool)}});}
}// Example configuration
$config = ['host' => '127.0.0.1','dbname' => 'test','username' => 'root','password' => 'password','charset' => 'utf8mb4',
];// Create the connection pool
$pool = new SwooleMysqlConnectionPool($config, 5);// Use the connection pool in a Swoole coroutine (this is just an example, you would typically do this in a Swoole server handler)
$pool->queryInCoroutine("SELECT * FROM your_table WHERE some_column = ?", ['some_value']);// Note: The queryInCoroutine method is just for demonstration purposes.
// In a real-world application, you would typically handle coroutines and database queries
// within the context of a Swoole server (e.g., Swoole\Http\Server, Swoole\WebSocket\Server).// Since this is a script and not a Swoole server, the coroutine will not actually run.
// To see the coroutine in action, you need to run this code within a Swoole server environment.// Remember to start a Swoole server and use the connection pool within the server's event loop.

重要提示：

1. 上面的queryInCoroutine方法只是为了演示如何在协程中使用连接池。在实际应用中，你需要在Swoole服务器（如Swoole\Http\Server或Swoole\WebSocket\Server）的事件循环中处理协程和数据库查询。
2. 由于这是一个脚本而不是Swoole服务器，因此协程实际上不会运行。要看到协程的实际效果，你需要在Swoole服务器环境中运行此代码。
3. 连接池中的连接应该是持久的，但在这个示例中，为了简单起见，我们每次从池中获取连接时都会创建一个新的PDO实例。在实际应用中，你可能需要实现更复杂的连接管理和回收逻辑。
4. 考虑到Swoole的协程特性，你可能还需要处理连接在协程之间的共享问题，以及如何在协程结束时正确关闭连接（尽管在这个简单的示例中我们没有这样做）。

对于生产环境，建议使用更成熟和经过充分测试的MySQL连接池库，或者根据Swoole的文档和社区资源来构建更健壮的连接池实现。