Jetpack Sync: Move 'jetpack_plugins_updated' action to shutdown

[fgiannar]

Moves the jetpack_plugins_updated action to shutdown to decrease its associated lag.

As of the latest WordPress core release, 6.6.1 we noticed a notable increase in Sync’s queue lag (90p). Further analysis revealed that the jetpack_plugins_updated action was the one contributing to this increase.
More specifically, this change in core introduced an extra step in plugin auto-updates, making it now possible to roll back a plugin auto-update with a fatal error.
However, the check itself for a Fatal error will perform a loopback request in order to scrape the home page.
The jetpack_plugins_updated is triggered by the upgrader_process_complete action.
Sync lag is defined as the time between adding an action to Sync's queue and sending that action to WPCOM.
In this case, since the auto-update is triggered via cron, the Sync lag for the jetpack_plugins_updated action is essentially the time between firing the upgrader_process_complete action and the shutdown action.
With core introducing the aforementioned loopback request on auto-updates Sync's lag for the jetpack_plugins_updated action was significantly increased.
And this also affected the 90p of our overall Sync Lag KPI.

In this PR, we attempt to fix this issue by simply moving jetpack_plugins_updated action to shutdown to decrease its associated lag.

Noting that we also attempted to fix this in the past via #39296

Proposed changes:

• Automattic\Jetpack\Sync\Modules\Plugins: Move jetpack_plugins_updated action to shutdown. To make this possible we introduced two extra private class properties: state and updated_plugins in order to store the data associated with this action.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

pf5801-17n-p2

Does this pull request change what data or activity we track or use?

No

Testing instructions:

Pre-requisites: A JP connected site with the WP Rollback and WP Crontrol plugins active. You'll need to enable sandbox access and input your sandbox domain in Settings -> Jetpack Constants -> JETPACK__SANDBOX_DOMAIN

• Rollback a plugin to a previous version via the WP Rollback plugin
• For the same plugin that you rolled back make sure to enable auto-updates
• To speed things up go Tools->Cron Events and trigger the wp_version_check hook (Triggers plugin auto-updates, normally runs twice per day)
• Monitor the action in your sandbox and ensure the corresponding arguments are exactly the same on trunk/feature branch
• Confirm the Sync lag of the jetpack_plugins_updated action on the feature branch is much smaller.
• Repeat the process for more than one plugins (by rolling back and enabling auto-updates) and confirm the same
• Finally, manually update a few plugins and confirm that the behaviour is the same as with trunk

Test assuming WP_Automatic_Updater detected an error and is doing a plugin roll-back:
In order to test this locally I modified WP_Automatic_Updater to return true in has_fatal_error here.
In this case, without the branch we'd see two jetpack_plugins_updated actions, both exactly the same.
With the PR, we'll see only one.

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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This comment will be updated as you work on your PR and make changes. If you think that some of those checks are not needed for your PR, please explain why you think so. Thanks for cooperation 🤖

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The e2e test report can be found here. Please note that it can take a few minutes after the e2e tests checks are complete for the report to be available.

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Follow this PR Review Process:

1. Ensure all required checks appearing at the bottom of this PR are passing.
2. Choose a review path based on your changes:
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Jetpack plugin:

The Jetpack plugin has different release cadences depending on the platform:

• WordPress.com Simple releases happen semi-continuously (PCYsg-Jjm-p2).
• WoA releases happen weekly.
• Releases to self-hosted sites happen monthly. The next release is scheduled for November 5, 2024 (scheduled code freeze on November 4, 2024).

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WordPress.com Simple site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin, and enable the update/jetpack-sync-delay-jetpack_plugins_updated-hook branch.

  • For jetpack-mu-wpcom changes, also add define( 'JETPACK_MU_WPCOM_LOAD_VIA_BETA_PLUGIN', true ); to your wp-config.php file.

• To test on Simple, run the following command on your sandbox:

  bin/jetpack-downloader test jetpack update/jetpack-sync-delay-jetpack_plugins_updated-hook
  

  bin/jetpack-downloader test jetpack-mu-wpcom-plugin update/jetpack-sync-delay-jetpack_plugins_updated-hook
  

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[coder-karen]

Followed the testing instructions and saw the expected behaviour. Nice work with the tests too.

[darssen]

Thanks for working on this one. Tests well for me as described. 🚢