PHP高性能API开发实战：Swoole协程与数据库连接池优化指南

二、电商秒杀系统高性能API实战

2.1 业务场景与技术挑战

秒杀系统核心需求：

1. 万级并发商品抢购
2. 库存精确扣减，防止超卖
3. 高响应速度（毫秒级）
4. 系统稳定性保障

2.2 传统架构的性能问题

// 传统PHP-FPM秒杀逻辑
class SeckillController {
    public function seckill($productId, $userId) {
        // 开始数据库事务
        DB::beginTransaction();
        
        try {
            // 查询商品库存
            $product = Product::where('id', $productId)
                ->where('stock', '>', 0)
                ->lockForUpdate()
                ->first();
            
            if (!$product) {
                throw new Exception('商品已售罄');
            }
            
            // 扣减库存
            $affected = Product::where('id', $productId)
                ->where('stock', $product->stock)
                ->decrement('stock');
            
            if ($affected === 0) {
                throw new Exception('库存扣减失败');
            }
            
            // 创建订单
            $order = Order::create([
                'user_id' => $userId,
                'product_id' => $productId,
                'status' => 'paid'
            ]);
            
            DB::commit();
            return ['success' => true, 'order_id' => $order->id];
            
        } catch (Exception $e) {
            DB::rollBack();
            return ['success' => false, 'message' => $e->getMessage()];
        }
    }
}

2.3 基于Swoole的高性能优化方案

// Swoole HTTP服务器配置
$http = new SwooleHttpServer("0.0.0.0", 9501, SWOOLE_BASE);
$http->set([
    'worker_num' => 4,
    'task_worker_num' => 8,
    'enable_coroutine' => true,
    'max_coroutine' => 3000
]);

// 数据库连接池配置
$http->on('WorkerStart', function ($server, $workerId) {
    global $dbPool;
    $dbPool = new SplQueue;
    for ($i = 0; $i  true]
        );
        $dbPool->push($db);
    }
});

// 秒杀接口协程实现
$http->on('Request', function ($request, $response) {
    // 使用协程处理请求
    go(function () use ($request, $response) {
        $productId = $request->get['product_id'];
        $userId = $request->get['user_id'];
        
        // 从连接池获取数据库连接
        global $dbPool;
        $db = $dbPool->pop();
        
        try {
            // Redis原子操作验证库存
            $redis = new SwooleCoroutineRedis();
            $redis->connect('127.0.0.1', 6379);
            
            $stockKey = "seckill:stock:{$productId}";
            $remaining = $redis->decr($stockKey);
            
            if ($remaining incr($stockKey); // 恢复库存
                throw new Exception('商品已售罄');
            }
            
            // 异步写入数据库
            $server->task([
                'type' => 'create_order',
                'product_id' => $productId,
                'user_id' => $userId
            ]);
            
            $response->header('Content-Type', 'application/json');
            $response->end(json_encode([
                'success' => true,
                'message' => '抢购成功'
            ]));
            
        } catch (Exception $e) {
            $response->end(json_encode([
                'success' => false,
                'message' => $e->getMessage()
            ]));
        } finally {
            // 归还数据库连接到连接池
            $dbPool->push($db);
        }
    });
});

2.4 异步任务处理器

// 任务 worker 处理数据库写入
$http->on('Task', function ($server, $taskId, $workerId, $data) {
    switch ($data['type']) {
        case 'create_order':
            // 从连接池获取数据库连接
            global $dbPool;
            $db = $dbPool->pop();
            
            try {
                $db->beginTransaction();
                
                // 最终库存扣减
                $stmt = $db->prepare(
                    "UPDATE products SET stock = stock - 1 
                     WHERE id = ? AND stock > 0"
                );
                $stmt->execute([$data['product_id']]);
                
                if ($stmt->rowCount() === 0) {
                    throw new Exception('库存不足');
                }
                
                // 创建订单记录
                $stmt = $db->prepare(
                    "INSERT INTO orders (user_id, product_id, created_at) 
                     VALUES (?, ?, NOW())"
                );
                $stmt->execute([$data['user_id'], $data['product_id']]);
                
                $db->commit();
                
            } catch (Exception $e) {
                $db->rollBack();
                // 记录错误日志
                error_log("订单创建失败: " . $e->getMessage());
            } finally {
                $dbPool->push($db);
            }
            break;
    }
});