# Connection pool
A common connection pool based on Swoole is usually used as the database connection pool.

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[![License](https://poser.pugx.org/open-smf/connection-pool/license)](LICENSE)

## Requirements

| Dependency | Requirement |
| -------- | -------- |
| [PHP](https://secure.php.net/manual/en/install.php) | `>=7.0.0` |
| [Swoole](https://github.com/swoole/swoole-src) | `>=4.2.9` `Recommend 4.2.13+` |

## Install
> Install package via [Composer](https://getcomposer.org/).

```shell
composer require "open-smf/connection-pool:~1.0"
```

## Usage
> See more [examples](examples).

- Available connectors

| Connector | Connection description |
| -------- | -------- |
| CoroutineMySQLConnector | Instance of `Swoole\Coroutine\MySQL` |
| CoroutinePostgreSQLConnector | Instance of `Swoole\Coroutine\PostgreSQL`, require configuring `Swoole` with `--enable-coroutine-postgresql`|
| CoroutineRedisConnector | Instance of `Swoole\Coroutine\Redis` |
| PhpRedisConnector | Instance of `Redis`, require [redis](https://pecl.php.net/package/redis) |
| PDOConnector | Instance of `PDO`, require [PDO](https://www.php.net/manual/en/book.pdo.php) |
| YourConnector | `YourConnector` must implement interface `ConnectorInterface`, any object can be used as a connection instance |

- Basic usage

```php
use Smf\ConnectionPool\ConnectionPool;
use Smf\ConnectionPool\Connectors\CoroutineMySQLConnector;
use Swoole\Coroutine\MySQL;

go(function () {
    // All MySQL connections: [10, 30]
    $pool = new ConnectionPool(
        [
            'minActive'         => 10,
            'maxActive'         => 30,
            'maxWaitTime'       => 5,
            'maxIdleTime'       => 20,
            'idleCheckInterval' => 10,
        ],
        new CoroutineMySQLConnector,
        [
            'host'        => '127.0.0.1',
            'port'        => '3306',
            'user'        => 'root',
            'password'    => 'xy123456',
            'database'    => 'mysql',
            'timeout'     => 10,
            'charset'     => 'utf8mb4',
            'strict_type' => true,
            'fetch_mode'  => true,
        ]
    );
    echo "Initializing connection pool\n";
    $pool->init();
    defer(function () use ($pool) {
        echo "Closing connection pool\n";
        $pool->close();
    });

    echo "Borrowing the connection from pool\n";
    /**@var MySQL $connection */
    $connection = $pool->borrow();

    $status = $connection->query('SHOW STATUS LIKE "Threads_connected"');

    echo "Return the connection to pool as soon as possible\n";
    $pool->return($connection);

    var_dump($status);
});
```

- Usage in Swoole Server

```php
use Smf\ConnectionPool\ConnectionPool;
use Smf\ConnectionPool\ConnectionPoolTrait;
use Smf\ConnectionPool\Connectors\CoroutineMySQLConnector;
use Smf\ConnectionPool\Connectors\PhpRedisConnector;
use Swoole\Coroutine\MySQL;
use Swoole\Http\Request;
use Swoole\Http\Response;
use Swoole\Http\Server;

class HttpServer
{
    use ConnectionPoolTrait;

    protected $swoole;

    public function __construct(string $host, int $port)
    {
        $this->swoole = new Server($host, $port);

        $this->setDefault();
        $this->bindWorkerEvents();
        $this->bindHttpEvent();
    }

    protected function setDefault()
    {
        $this->swoole->set([
            'daemonize'             => false,
            'dispatch_mode'         => 1,
            'max_request'           => 8000,
            'open_tcp_nodelay'      => true,
            'reload_async'          => true,
            'max_wait_time'         => 60,
            'enable_reuse_port'     => true,
            'enable_coroutine'      => true,
            'http_compression'      => false,
            'enable_static_handler' => false,
            'buffer_output_size'    => 4 * 1024 * 1024,
            'worker_num'            => 4, // Each worker holds a connection pool
        ]);
    }

    protected function bindHttpEvent()
    {
        $this->swoole->on('Request', function (Request $request, Response $response) {
            $pool1 = $this->getConnectionPool('mysql');
            /**@var MySQL $mysql */
            $mysql = $pool1->borrow();
            $status = $mysql->query('SHOW STATUS LIKE "Threads_connected"');
            // Return the connection to pool as soon as possible
            $pool1->return($mysql);


            $pool2 = $this->getConnectionPool('redis');
            /**@var \Redis $redis */
            $redis = $pool2->borrow();
            $clients = $redis->info('Clients');
            // Return the connection to pool as soon as possible
            $pool2->return($redis);

            $json = [
                'status'  => $status,
                'clients' => $clients,
            ];
            // Other logic
            // ...
            $response->header('Content-Type', 'application/json');
            $response->end(json_encode($json));
        });
    }

    protected function bindWorkerEvents()
    {
        $createPools = function () {
            // All MySQL connections: [4 workers * 2 = 8, 4 workers * 10 = 40]
            $pool1 = new ConnectionPool(
                [
                    'minActive' => 2,
                    'maxActive' => 10,
                ],
                new CoroutineMySQLConnector,
                [
                    'host'        => '127.0.0.1',
                    'port'        => '3306',
                    'user'        => 'root',
                    'password'    => 'xy123456',
                    'database'    => 'mysql',
                    'timeout'     => 10,
                    'charset'     => 'utf8mb4',
                    'strict_type' => true,
                    'fetch_mode'  => true,
                ]);
            $pool1->init();
            $this->addConnectionPool('mysql', $pool1);

            // All Redis connections: [4 workers * 5 = 20, 4 workers * 20 = 80]
            $pool2 = new ConnectionPool(
                [
                    'minActive' => 5,
                    'maxActive' => 20,
                ],
                new PhpRedisConnector,
                [
                    'host'     => '127.0.0.1',
                    'port'     => '6379',
                    'database' => 0,
                    'password' => null,
                ]);
            $pool2->init();
            $this->addConnectionPool('redis', $pool2);
        };
        $closePools = function () {
            $this->closeConnectionPools();
        };
        $this->swoole->on('WorkerStart', $createPools);
        $this->swoole->on('WorkerStop', $closePools);
        $this->swoole->on('WorkerError', $closePools);
    }

    public function start()
    {
        $this->swoole->start();
    }
}

// Enable coroutine for PhpRedis
Swoole\Runtime::enableCoroutine();
$server = new HttpServer('0.0.0.0', 5200);
$server->start();
```

## License

[MIT](LICENSE)