WIP: [Feature] Stream responses without putting whole to memory

[dmitryuk]

Closes #179 #130
Impossible to adapt Symfony's StreamedResponse class, so I created the custom one

[Nyholm]

Great. Thank you

[dmitryuk]

@Baldinof can you look and merge?

[Baldinof]

2 things:

• ideally it would extend Symfony StreamedResponse so in case the app runs without RR, it would still work and stream the content.
• maybe the constructor could accept Generator<string>|callable() => Generator<string>, so it could be used like this

return new StreamedGeneratorResponse(function () {
    yield "hello";
    yield "world";
});

Instead of

return new StreamedGeneratorResponse((function () {
    yield "hello";
    yield "world";
})());

[dmitryuk]

1. I really tried to convert ob_start/on_flush to \Generator, but it looks impossible

[Baldinof]

I mean do something like this:

class StreamedGeneratorResponse extends StreamedResponse
    public function __construct(private readonly \Generator $generator, int $status = 200, array $headers = [])
    {
        parent::__construct(function () use ($generator) {
            foreach ($generator as $chunk) {
                echo $chunk;
            }
        }, $status, $headers);
    }

    public function getGenerator(): \Generator
    {
        return $this->generator;
    }

So when not using RR, the response will still be streamed the normal way

[dmitryuk]

Thanks for review, I finally reworked the PR as you suggest, please take a look
UPD: I need a time to look in failing tests

[Baldinof]

Suggested change

	$callback = $response->getCallback();
	if (!$callback || (!($content = $callback()) instanceof \Generator)) {
	throw new \RuntimeException('StreamedGeneratorResponse callback must return a Generator');
	}
	$content = $response->getGenerator();

[dmitryuk]

PR frozen. I looking for a way toimplement a feature out-of-box here roadrunner-php/issues#43