Expose async (promise-returning) methods in ImageAnnotatorClient

[mikethea1]

Thanks for stopping by to let us know something could be better!

Is your feature request related to a problem? Please describe.
I'm using the ImageAnnotatorClient to OCR some pages from a document. Because the API only accepts 5 pages at a time (and sometimes fails with a full 5, doing this serially takes many seconds to finish; sometimes the request times out just processing a modest number of pages.

Describe the solution you'd like

Under the hood, the annotator client is actually calling ->wait() on an async promise before returning. I'd like for an API like batchAnnotateImagesAsync() which just returned the promise directly. This would allow me to process in parallel:

$promises = array_map(fn($r) => $imageAnnotator->batchAnnotateImagesAsync($r), $requests);
foreach ($promises as $promise) {
    $result = $promise->wait();
    // do something with $result
}

Describe alternatives you've considered
The current client DOES have a asyncBatchAnnotateImages() function, but this synchronously sets up an offline operation. I'm still doing online operations; I'd just like to parallelize for speed.

[bshaffer]

@mikethea1 the method asyncBatchAnnotateImages exists! You can call it like this:

use Google\Cloud\Vision\V1\AnnotateImageRequest;
use Google\Cloud\Vision\V1\BatchAnnotateImagesRequest;
use Google\Cloud\Vision\V1\Client\ImageAnnotatorClient;
use Google\Cloud\Vision\V1\Feature;
use Google\Cloud\Vision\V1\Image;

$client = new ImageAnnotatorClient();

// Prepare the request
$content = file_get_contents('/data/photos/family-photo.jpg', 'r');
$image = (new Image())
    ->setContent($content);
$feature = (new Feature())
    ->setType(Feature\Type::FACE_DETECTION);
$request = (new AnnotateImageRequest())
    ->setImage($image)
    ->setFeatures([$feature]);
$batchRequest = (new BatchAnnotateImagesRequest())
    ->setRequests([$request]);

// Annotate an image, detecting faces.
$promise = $client-> batchAnnotateImagesAsync($batchRequest);
$promise->wait();