告别PHP阻塞式等待：如何使用guzzlehttp/promises优雅处理异步操作，提升应用响应速度

<pre class="brush:php;toolbar:false;">// 1. 获取商品详情 (可能耗时200ms)
$productData = $productApiService->getDetails($productId);

// 2. 获取推荐列表 (可能耗时300ms)
$recommendations = $recommendationService->getForUser($userId);

// 3. 检查库存 (可能耗时150ms)
$inventoryStatus = $inventoryService->checkStock($productId);

// ... 更多操作

<code class="bash">composer require guzzlehttp/promises</code>

<pre class="brush:php;toolbar:false;">use GuzzleHttp\Promise\Promise;

$promise = new Promise();

$promise->then(
    function ($value) {
        echo "Promise fulfilled with: " . $value . "\n";
    },
    function ($reason) {
        echo "Promise rejected with: " . $reason . "\n";
    }
);

// 模拟异步操作完成并解决Promise
// 假设这里有一些耗时操作，完成后我们调用resolve
// $promise->resolve('Hello, Async World!');
// 或者如果失败了
// $promise->reject('Something went wrong!');

// 为了演示，我们立即解决它
$promise->resolve('Hello, Async World!');
// 输出: Promise fulfilled with: Hello, Async World!

<pre class="brush:php;toolbar:false;">use GuzzleHttp\Promise\Promise;

$firstPromise = new Promise();

$firstPromise
    ->then(function ($value) {
        echo "First promise fulfilled with: " . $value . "\n";
        return $value . " and Next!"; // 返回一个新值，传递给下一个then
    })
    ->then(function ($value) {
        echo "Second promise fulfilled with: " . $value . "\n";
        // 可以在这里返回另一个Promise，实现异步依赖
        $nextAsyncOperation = new Promise(function ($resolve) {
            echo "Starting third async operation...\n";
            sleep(1); // 模拟耗时
            $resolve("Finally done!");
        });
        return $nextAsyncOperation;
    })
    ->then(function ($value) {
        echo "Third promise (from async operation) fulfilled with: " . $value . "\n";
    })
    ->otherwise(function ($reason) { // 统一处理链中任何环节的错误
        echo "An error occurred in the chain: " . $reason . "\n";
    });

$firstPromise->resolve('Initial Data');
// 为了让上面的异步Promise执行，我们需要等待，或者集成到事件循环中
// 在没有事件循环的简单脚本中，可以手动运行任务队列或使用wait()
GuzzleHttp\Promise\Utils::queue()->run();

<pre class="brush:php;toolbar:false;">use GuzzleHttp\Promise\Promise;
use GuzzleHttp\Promise\Utils;

// 模拟异步API调用
$getProductDetails = function ($productId) {
    return new Promise(function ($resolve, $reject) use ($productId) {
        echo "Fetching product details for {$productId}...\n";
        sleep(2); // 模拟网络延迟
        if ($productId === 123) {
            $resolve(['id' => $productId, 'name' => 'Fancy Gadget', 'price' => 99.99]);
        } else {
            $reject("Product {$productId} not found.");
        }
    });
};

$getRecommendations = function ($userId) {
    return new Promise(function ($resolve) use ($userId) {
        echo "Fetching recommendations for user {$userId}...\n";
        sleep(1); // 模拟网络延迟
        $resolve(['item_a', 'item_b', 'item_c']);
    });
};

$checkInventory = function ($productId) {
    return new Promise(function ($resolve) use ($productId) {
        echo "Checking inventory for {$productId}...\n";
        sleep(1.5); // 模拟网络延迟
        $resolve(['productId' => $productId, 'stock' => 50]);
    });
};

$productId = 123;
$userId = 456;

// 并发执行所有异步操作
$allPromises = Utils::all([
    'product'       => $getProductDetails($productId),
    'recommendations' => $getRecommendations($userId),
    'inventory'     => $checkInventory($productId),
]);

echo "All promises initiated, waiting for results...\n";

try {
    // wait() 方法会阻塞当前进程，直到所有 Promise 都完成
    // 在真正的异步环境中，你会将它集成到事件循环中，避免阻塞
    $results = $allPromises->wait();

    echo "\n--- All results received ---\n";
    echo "Product Name: " . $results['product']['name'] . "\n";
    echo "Recommendations: " . implode(', ', $results['recommendations']) . "\n";
    echo "Inventory Stock: " . $results['inventory']['stock'] . "\n";

} catch (\Exception $e) {
    echo "\nAn error occurred: " . $e->getMessage() . "\n";
}

// 模拟总耗时：大约2秒（最慢的那个Promise决定）
// 而不是 2 + 1 + 1.5 = 4.5 秒