Performance issue: Move GoogleAdsFailures::init to error_handler middleware

[jorgemd24]

Changes proposed in this Pull Request:

Closes part of #1250

The GoogleAdsClient:init is an expensive operation that is currently loaded whenever the Google Ads client is created. It gets triggered by the GoogleServiceProvider and is executed each time there's an admin page load or a request to wp-json.

See the full details of this issue: #1250 (comment)

In this PR, we relocate GoogleAdsFailures::init from the GoogleAdsClient constructor to the error_handler middleware. This change means that GoogleAdsFailure will only be loaded when there is a request made to the google-ads API.

Before this PR:

After this PR:

Shifting GoogleAdsFailure:init to the error_handler will help in cutting down the time allocated for the Google protobufs functions. However, the GL&A container is still consuming roughly 4.88% of the total loading process, therefore still some room for improvement.

Screenshots:

Detailed test instructions:

General Testing

1. Connect your Ads account and test that you can create, edit, and delete ads campaigns.

Simulate an Ads API error

1. Change this line:

   google-listings-and-ads/src/API/Google/AdsCampaign.php

   Line 268 in 9546add

   $campaign_fields['status'] = CampaignStatus::number( $params['status'] );

To: $campaign_fields['status'] = 999999

2. Go to the dashboard page, and change the status of one of your campaigns.
3. You should see the following error:

Simulate a partial failure error.

1. Keep the change that you made in the previous testing (campaign_status = 99999).
2. Change this:

google-listings-and-ads/src/API/Google/AdsCampaign.php

Lines 557 to 560 in 9546add

	$responses = $this->client->getGoogleAdsServiceClient()->mutate(
	$this->options->get_ads_id(),
	$operations
	);

With:

		$responses = $this->client->getGoogleAdsServiceClient()->mutate(
			$this->options->get_ads_id(),
			$operations,
			[
				'partialFailure' => true,
			]
		);

3. You should see the following error:

It shows an invalid campaign ID, because the current code is not expecting partial failures.

4. If you comment out GoogleAdsFailures::init(); and try to change the campaign status, you will get the following error:

Additional details:

Changelog entry

Fix - Performance issue with GoogleAdsFailures::init

[mikkamp]

Thanks for the changes. I've tested failures and partial failures and I get the expected response regardless of when it happens.

Just wanted to note that the before and after screenshots in the PR are identical, but I've seen the ones in #1250 (comment).

It's a shame that we can't initialize only on an error response, but it's still a great improvement to only initialize when there has actually been a request to the Google Ads API.

[mikkamp]

I was wondering what happens if we ever send two requests (one after the other). However it seems that the init function only initializes a new instance if it can't find a previously initialized one.

[jorgemd24]

Yes that's correct.

[jorgemd24]

Thanks @mikkamp for reviewing this PR.

Just wanted to note that the before and after screenshots in the PR are identical, but I've seen the ones in #1250 (comment).

I updated the description with the right images.

Thanks again!