将请求增量添加到 Guzzle 5.0 池（滚动请求）

Question

我正在使用 Guzzle 使用 pool 并行（或异步）获取大量 URL：

$client = new GuzzleHttp\Client([
    'base_url' => 'http://httpbin.org',
]);

$requests = [];

for ($i = 0; $i < 8; ++$i) {
    $requests[] = $client->createRequest('GET', '/get');
}

$pool = new GuzzleHttp\Pool($client, $requests, [
    'pool_size' => 4,
    'complete' => function (GuzzleHttp\Event\CompleteEvent $event) {
        var_dump($event->getRequest()->getUrl());
    },
]);

$pool->wait();

var_dump(count($requests));

如果我在控制台中运行上述命令，它会显示预期的输出：

string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
int(8)

现在，我希望能够根据某些条件向同一个池中添加额外的请求，我相信这种行为通常被称为滚动[并行]请求，但在阅读并重新-阅读我没有设法弄清楚的文档。这是我尝试过的：

$client = new GuzzleHttp\Client([
    'base_url' => 'http://httpbin.org',
]);

$requests = [];

for ($i = 0; $i < 8; ++$i) {
    $requests[] = $client->createRequest('GET', '/get');
}

$i = 0;
$pool = new GuzzleHttp\Pool($client, $requests, [
    'pool_size' => 4,
    'complete' => function (GuzzleHttp\Event\CompleteEvent $event) use (&$i, $client, &$requests) {
        var_dump($event->getRequest()->getUrl());

        if (++$i % 3 == 0) {
            $requests[] = $client->createRequest('GET', '/ip');
        }
    },
]);

$pool->wait();

var_dump(count($requests));

对/get 的每第三个请求都应该向/ip 添加一个新请求，$requests 数组实际上正在增长（达到 10 个元素，而不是预期的 11 个元素），但这些请求从未真正执行。有没有办法让 Guzzle 池执行初始化后请求？

Answer 1

有可能，请参阅我在guzzle issue Suggestions to GuzzleHttp\Pool #946 上的评论以获取完整示例，或者查看此要点以获取更深入的generator, retry and sequential send with guzzle 之间的比较示例。

关于您的示例，请参阅我的内联 cmets：

$client = new GuzzleHttp\Client([
    'base_url' => 'http://httpbin.org',
]);

$requests = [];

for ($i = 0; $i < 8; ++$i) {
    $requests[] = $client->createRequest('GET', '/get');
}

$generator = new ArrayIterator($requests); // use an iterator instead of an array

$i = 0;
$pool = new GuzzleHttp\Pool($client, $generator, [ // use the iterator in the pool
    'pool_size' => 4,
    'complete' => function (GuzzleHttp\Event\CompleteEvent $event) use (&$i, $client, &$generator) {
        var_dump($event->getRequest()->getUrl());

        if (++$i % 3 == 0) {
            $generator->append($client->createRequest('GET', '/ip')); // append new requests on the fly
        }
    },
]);

$pool->wait();

这会产生您的预期输出：

string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(22) "http://httpbin.org/get"
string(21) "http://httpbin.org/ip"
string(21) "http://httpbin.org/ip"
string(21) "http://httpbin.org/ip"

请注意，请求会附加在末尾​​strong>。这与AbstractRetryableEvent::retry 的工作方式相反，后者将在当前队列之间的某处挤压重试，而不是将其附加到末尾。