php 实现mysql连接池

<?php
class MySQLConnectionPool {
    private $pool = [];
    private $minConnections;
    private $maxConnections;
    private $connectionParams;

    public function __construct($host, $user, $password, $database, $minConnections = 5, $maxConnections = 10) {
        $this->connectionParams = [
            'host' => $host,
            'user' => $user,
            'password' => $password,
            'database' => $database
        ];
        $this->minConnections = $minConnections;
        $this->maxConnections = $maxConnections;
        $this->initializePool();
    }

    private function initializePool() {
        for ($i = 0; $i < $this->minConnections; $i++) {
            $this->pool[] = $this->createConnection();
        }
    }

    private function createConnection() {
        try {
            $conn = new mysqli($this->connectionParams['host'], $this->connectionParams['user'], $this->connectionParams['password'], $this->connectionParams['database']);
            if ($conn->connect_error) {
                die("Connection failed: " . $conn->connect_error);
            }
            return $conn;
        } catch (Exception $e) {
            echo "Error: " . $e->getMessage();
        }
    }

    public function getConnection() {
        if (empty($this->pool)) {
            if (count($this->pool) < $this->maxConnections) {
                $this->pool[] = $this->createConnection();
            } else {
                throw new Exception("No available connections in the pool.");
            }
        }
        return array_pop($this->pool);
    }

    public function releaseConnection($conn) {
        if (count($this->pool) < $this->maxConnections) {
            array_push($this->pool, $conn);
        } else {
            $conn->close();
        }
    }
}

// 使用示例
$pool = new MySQLConnectionPool('localhost', 'user', 'password', 'database');
$conn = $pool->getConnection();
// 执行数据库操作
$pool->releaseConnection($conn);
?>