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feature #36692 [HttpClient] add EventSourceHttpClient to consume Server-Sent Events (soyuka)
This PR was squashed before being merged into the 5.2-dev branch. Discussion ---------- [HttpClient] add EventSourceHttpClient to consume Server-Sent Events | Q | A | ------------- | --- | Branch? | master | Bug fix? | no | New feature? | yes | Deprecations? | no | Tickets | na | License | MIT | Doc PR | symfony/symfony-docs#... <details> <summary>First implementation</summary> This patch implements the [w3c Server-Sent Events specification](https://www.w3.org/TR/eventsource/#eventsource) on top of symfony's http client. It provides an `EventSource` class that allows you to interact of server sent events. Comparing to the Javascript implementation, we won't be able to use the same API. Indeed, in php listeners need to be setup before we connect to the HTTP stream. I'm not fond of adding a dependency to EventDispatcher from HTTP Client, therefore I'm all ears if you have better solutions. About event parsing, I wanted to avoid using regular expression and it uses smart data split. Note that I had to concatenate an internal buffer and only handle the data when a newline is found to cover long chunks. This is an alternative to this [react php eventsource](https://github.com/clue/reactphp-eventsource). Note that this implementation is closer to the specification in some cases that are still to be covered by tests (`retry`, `data:value` without space after colon is valid etc.). </details> This is an implementation of the [Server-Sent Events specification](https://html.spec.whatwg.org/multipage/server-sent-events.html) based on symfony's HTTP Client. After a few suggestions on the first implementation (see details above), I've implemented a chunk generator with this kind of API: ```php $client = new EventSourceHttpClient($client, 10); $source = $client->connect('GET', "http://localhost:8080/events"); while($source) { foreach ($client->stream($source, 2) as $r => $chunk) { if ($chunk->isTimeout()) { dump([ 'timeout' => [ 'retry' => 1 + count($r->getInfo('previous_info') ?? []) ], ]); continue; } if ($chunk->isLast()) { dump([ 'eof' => [ 'retries' => count($r->getInfo('previous_info') ?? []) ], ]); $source = null; return; } dump($chunk); } } ``` TODO: - [x] validate implementation (~~don't use EventDispatcher ?~~, need to be implemented as `stream` instead of `message`) - [x] default timeout value - [x] implement retry/reconnection - [x] tests (do test with super long chunk, retry, bad http content-type response) - [ ] update changelog - [ ] document Commits ------- 12ccca3 [HttpClient] add EventSourceHttpClient to consume Server-Sent Events
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‎src/Symfony/Component/HttpClient/CHANGELOG.md‎

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* added support for pausing responses with a new `pause_handler` callable exposed as an info item
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* added `StreamableInterface` to ease turning responses into PHP streams
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* added `MockResponse::getRequestMethod()` and `getRequestUrl()` to allow inspecting which request has been sent
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* added `EventSourceHttpClient` a Server-Sent events stream implementing the [EventSource specification](https://www.w3.org/TR/eventsource/#eventsource)
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5.1.0
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-----

‎src/Symfony/Component/HttpClient/Chunk/ServerSentEvent.php‎

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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\HttpClient\Chunk;
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use Symfony\Contracts\HttpClient\ChunkInterface;
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/**
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* @author Antoine Bluchet <soyuka@gmail.com>
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* @author Nicolas Grekas <p@tchwork.com>
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*/
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final class ServerSentEvent extends DataChunk implements ChunkInterface
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{
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private $data = '';
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private $id = '';
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private $type = 'message';
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private $retry = 0;
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public function __construct(string $content)
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{
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parent::__construct(-1, $content);
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// remove BOM
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if (0 === strpos($content, "\xEF\xBB\xBF")) {
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$content = substr($content, 3);
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}
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foreach (preg_split("/(?:\r\n|[\r\n])/", $content) as $line) {
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if (0 === $i = strpos($line, ':')) {
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continue;
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}
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$i = false === $i ? \strlen($line) : $i;
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$field = substr($line, 0, $i);
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$i += 1 + (' ' === ($line[1 + $i] ?? ''));
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switch ($field) {
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case 'id': $this->id = substr($line, $i); break;
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case 'event': $this->type = substr($line, $i); break;
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case 'data': $this->data .= ('' === $this->data ? '' : "\n").substr($line, $i); break;
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case 'retry':
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$retry = substr($line, $i);
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if ('' !== $retry && \strlen($retry) === strspn($retry, '0123456789')) {
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$this->retry = $retry / 1000.0;
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}
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break;
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}
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}
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}
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public function getId(): string
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{
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return $this->id;
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}
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public function getType(): string
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{
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return $this->type;
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}
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public function getData(): string
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{
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return $this->data;
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}
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public function getRetry(): float
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{
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return $this->retry;
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}
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}

‎src/Symfony/Component/HttpClient/EventSourceHttpClient.php‎

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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\HttpClient;
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use Symfony\Component\HttpClient\Chunk\ServerSentEvent;
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use Symfony\Component\HttpClient\Exception\EventSourceException;
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use Symfony\Component\HttpClient\Response\AsyncContext;
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use Symfony\Component\HttpClient\Response\AsyncResponse;
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use Symfony\Contracts\HttpClient\ChunkInterface;
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use Symfony\Contracts\HttpClient\Exception\TransportExceptionInterface;
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use Symfony\Contracts\HttpClient\HttpClientInterface;
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use Symfony\Contracts\HttpClient\ResponseInterface;
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/**
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* @author Antoine Bluchet <soyuka@gmail.com>
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* @author Nicolas Grekas <p@tchwork.com>
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*/
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final class EventSourceHttpClient implements HttpClientInterface
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{
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use AsyncDecoratorTrait;
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use HttpClientTrait;
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private $reconnectionTime;
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public function __construct(HttpClientInterface $client = null, float $reconnectionTime = 10.0)
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{
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$this->client = $client ?? HttpClient::create();
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$this->reconnectionTime = $reconnectionTime;
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}
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public function connect(string $url, array $options = []): ResponseInterface
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{
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return $this->request('GET', $url, self::mergeDefaultOptions($options, [
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'buffer' => false,
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'headers' => [
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'Accept' => 'text/event-stream',
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'Cache-Control' => 'no-cache',
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],
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], true));
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}
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public function request(string $method, string $url, array $options = []): ResponseInterface
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{
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$state = new class() {
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public $buffer = null;
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public $lastEventId = null;
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public $reconnectionTime;
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public $lastError = null;
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};
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$state->reconnectionTime = $this->reconnectionTime;
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if ($accept = self::normalizeHeaders($options['headers'] ?? [])['accept'] ?? []) {
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$state->buffer = \in_array($accept, [['Accept: text/event-stream'], ['accept: text/event-stream']], true) ? '' : null;
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}
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return new AsyncResponse($this->client, $method, $url, $options, static function (ChunkInterface $chunk, AsyncContext $context) use ($state, $method, $url, $options) {
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if (null !== $state->buffer) {
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$context->setInfo('reconnection_time', $state->reconnectionTime);
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$isTimeout = false;
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}
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$lastError = $state->lastError;
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$state->lastError = null;
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try {
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$isTimeout = $chunk->isTimeout();
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if (null !== $chunk->getInformationalStatus()) {
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yield $chunk;
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return;
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}
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} catch (TransportExceptionInterface $e) {
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$state->lastError = $lastError ?? microtime(true);
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if (null === $state->buffer || ($isTimeout && microtime(true) - $state->lastError < $state->reconnectionTime)) {
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yield $chunk;
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} else {
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$options['headers']['Last-Event-ID'] = $state->lastEventId;
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$state->buffer = '';
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$state->lastError = microtime(true);
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$context->getResponse()->cancel();
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$context->replaceRequest($method, $url, $options);
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if ($isTimeout) {
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yield $chunk;
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} else {
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$context->pause($state->reconnectionTime);
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}
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}
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return;
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}
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if ($chunk->isFirst()) {
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if (preg_match('/^text\/event-stream(;|$)/i', $context->getHeaders()['content-type'][0] ?? '')) {
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$state->buffer = '';
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} elseif (null !== $lastError || (null !== $state->buffer && 200 === $context->getStatusCode())) {
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throw new EventSourceException(sprintf('Response content-type is "%s" while "text/event-stream" was expected for "%s".', $context->getHeaders()['content-type'][0] ?? '', $context->getInfo('url')));
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} else {
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$context->passthru();
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}
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if (null === $lastError) {
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yield $chunk;
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}
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return;
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}
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$rx = '/((?:\r\n|[\r\n]){2,})/';
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$content = $state->buffer.$chunk->getContent();
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if ($chunk->isLast()) {
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$rx = substr_replace($rx, '|$', -2, 0);
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}
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$events = preg_split($rx, $content, -1, PREG_SPLIT_DELIM_CAPTURE);
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$state->buffer = array_pop($events);
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for ($i = 0; isset($events[$i]); $i += 2) {
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$event = new ServerSentEvent($events[$i].$events[1 + $i]);
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if ('' !== $event->getId()) {
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$context->setInfo('last_event_id', $state->lastEventId = $event->getId());
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}
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if ($event->getRetry()) {
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$context->setInfo('reconnection_time', $state->reconnectionTime = $event->getRetry());
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}
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yield $event;
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}
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if (preg_match('/^(?::[^\r\n]*+(?:\r\n|[\r\n]))+$/m', $state->buffer)) {
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$content = $state->buffer;
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$state->buffer = '';
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yield $context->createChunk($content);
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}
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if ($chunk->isLast()) {
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yield $chunk;
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}
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});
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}
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}

‎src/Symfony/Component/HttpClient/Exception/EventSourceException.php‎

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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\HttpClient\Exception;
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use Symfony\Contracts\HttpClient\Exception\DecodingExceptionInterface;
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/**
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* @author Nicolas Grekas <p@tchwork.com>
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*/
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final class EventSourceException extends \RuntimeException implements DecodingExceptionInterface
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{
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}

‎src/Symfony/Component/HttpClient/Tests/Chunk/ServerSentEventTest.php‎

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<?php
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/*
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* This file is part of the Symfony package.
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*
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* (c) Fabien Potencier <fabien@symfony.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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namespace Symfony\Component\HttpClient\Tests\Chunk;
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use PHPUnit\Framework\TestCase;
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use Symfony\Component\HttpClient\Chunk\ServerSentEvent;
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/**
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* @author Antoine Bluchet <soyuka@gmail.com>
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*/
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class ServerSentEventTest extends TestCase
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{
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public function testParse()
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{
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$rawData = <<<STR
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data: test
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data:test
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id: 12
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event: testEvent
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STR;
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$sse = new ServerSentEvent($rawData);
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$this->assertSame("test\ntest", $sse->getData());
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$this->assertSame('12', $sse->getId());
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$this->assertSame('testEvent', $sse->getType());
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}
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public function testParseValid()
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{
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$rawData = <<<STR
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event: testEvent
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data
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STR;
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$sse = new ServerSentEvent($rawData);
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$this->assertSame('', $sse->getData());
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$this->assertSame('', $sse->getId());
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$this->assertSame('testEvent', $sse->getType());
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}
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public function testParseRetry()
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{
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$rawData = <<<STR
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retry: 12
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STR;
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$sse = new ServerSentEvent($rawData);
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$this->assertSame('', $sse->getData());
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$this->assertSame('', $sse->getId());
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$this->assertSame('message', $sse->getType());
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$this->assertSame(0.012, $sse->getRetry());
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}
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public function testParseNewLine()
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{
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$rawData = <<<STR
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data: <tag>
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data
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data: <foo />
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data:
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data:
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data: </tag>
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STR;
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$sse = new ServerSentEvent($rawData);
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$this->assertSame("<tag>\n\n <foo />\n\n\n</tag>", $sse->getData());
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}
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}

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