连接池

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2023-12-01

Swoole 在 v4 版本后内置了 Library 模块，使用 PHP 代码编写内核功能，使得底层设施更加稳定可靠，并且提供了内置协程连接池，本章节会说明如何使用对应的连接池。

也可以观看Swoole微课程视频教程学习内置连接池的使用。

ConnectionPool

ConnectionPool，原始连接池，基于Channel自动调度，支持传入任意构造器(callable)，构造器需返回一个连接对象

get方法获取连接（连接池未满时会创建新的连接）
put方法回收连接
fill方法填充连接池（提前创建连接）
close关闭连接池

Database

各种数据库连接池和对象代理的高级封装，支持自动断线重连。目前包含PDO，Mysqli，Redis三种类型的数据库支持：

PDOConfig, PDOProxy, PDOPool
MysqliConfig, MysqliProxy, MysqliPool
RedisConfig, RedisProxy, RedisPool

!> MySQL断线重连可自动恢复大部分连接上下文(fetch模式，已设置的attribute，已编译的Statement等等)，但诸如事务等上下文无法恢复，若处于事务中的连接断开，将会抛出异常，请自行评估重连的可靠性；
将处于事务中的连接归还给连接池是未定义行为，开发者需要自己保证归还的连接是可重用的；
若有连接对象出现异常不可重用，开发者需要调用$pool->put(null);归还一个空连接以保证连接池的数量平衡。

PDO

<?php
declare(strict_types=1);

use Swoole\Coroutine;
use Swoole\Database\PDOConfig;
use Swoole\Database\PDOPool;
use Swoole\Runtime;

const N = 1024;

Runtime::enableCoroutine();
$s = microtime(true);
Coroutine\run(function () {
    $pool = new PDOPool((new PDOConfig)
        ->withHost('127.0.0.1')
        ->withPort(3306)
        // ->withUnixSocket('/tmp/mysql.sock')
        ->withDbName('test')
        ->withCharset('utf8mb4')
        ->withUsername('root')
        ->withPassword('root')
    );
    for ($n = N; $n--;) {
        Coroutine::create(function () use ($pool) {
            $pdo = $pool->get();
            $statement = $pdo->prepare('SELECT ? + ?');
            if (!$statement) {
                throw new RuntimeException('Prepare failed');
            }
            $a = mt_rand(1, 100);
            $b = mt_rand(1, 100);
            $result = $statement->execute([$a, $b]);
            if (!$result) {
                throw new RuntimeException('Execute failed');
            }
            $result = $statement->fetchAll();
            if ($a + $b !== (int)$result[0][0]) {
                throw new RuntimeException('Bad result');
            }
            $pool->put($pdo);
        });
    }
});
$s = microtime(true) - $s;
echo 'Use ' . $s . 's for ' . N . ' queries' . PHP_EOL;

Redis

<?php
declare(strict_types=1);

use Swoole\Coroutine;
use Swoole\Database\RedisConfig;
use Swoole\Database\RedisPool;
use Swoole\Runtime;

const N = 1024;

Runtime::enableCoroutine();
$s = microtime(true);
Coroutine\run(function () {
    $pool = new RedisPool((new RedisConfig)
        ->withHost('127.0.0.1')
        ->withPort(6379)
        ->withAuth('')
        ->withDbIndex(0)
        ->withTimeout(1)
    );
    for ($n = N; $n--;) {
        Coroutine::create(function () use ($pool) {
            $redis = $pool->get();
            $result = $redis->set('foo', 'bar');
            if (!$result) {
                throw new RuntimeException('Set failed');
            }
            $result = $redis->get('foo');
            if ($result !== 'bar') {
                throw new RuntimeException('Get failed');
            }
            $pool->put($redis);
        });
    }
});
$s = microtime(true) - $s;
echo 'Use ' . $s . 's for ' . (N * 2) . ' queries' . PHP_EOL;

Mysqli

<?php
declare(strict_types=1);

use Swoole\Coroutine;
use Swoole\Database\MysqliConfig;
use Swoole\Database\MysqliPool;
use Swoole\Runtime;

const N = 1024;

Runtime::enableCoroutine();
$s = microtime(true);
Coroutine\run(function () {
    $pool = new MysqliPool((new MysqliConfig)
        ->withHost('127.0.0.1')
        ->withPort(3306)
        // ->withUnixSocket('/tmp/mysql.sock')
        ->withDbName('test')
        ->withCharset('utf8mb4')
        ->withUsername('root')
        ->withPassword('root')
    );
    for ($n = N; $n--;) {
        Coroutine::create(function () use ($pool) {
            $mysqli = $pool->get();
            $statement = $mysqli->prepare('SELECT ? + ?');
            if (!$statement) {
                throw new RuntimeException('Prepare failed');
            }
            $a = mt_rand(1, 100);
            $b = mt_rand(1, 100);
            if (!$statement->bind_param('dd', $a, $b)) {
                throw new RuntimeException('Bind param failed');
            }
            if (!$statement->execute()) {
                throw new RuntimeException('Execute failed');
            }
            if (!$statement->bind_result($result)) {
                throw new RuntimeException('Bind result failed');
            }
            if (!$statement->fetch()) {
                throw new RuntimeException('Fetch failed');
            }
            if ($a + $b !== (int)$result) {
                throw new RuntimeException('Bad result');
            }
            while ($statement->fetch()) {
                continue;
            }
            $pool->put($mysqli);
        });
    }
});
$s = microtime(true) - $s;
echo 'Use ' . $s . 's for ' . N . ' queries' . PHP_EOL;