Full sync: Set chunk size of comments dynamically

[darssen]

Part of https://github.com/Automattic/vulcan/issues/661

Full Syncs always sends a fixed amount of items depending on the sync module (posts, comments, users). That is determined by a setting in which defaults are full_sync_limits.

#34390 created the ability to have a dynamic number of items sent for posts. The final number of items sent will be determined by reaching the MAX_SIZE for a number of items or if we reach the chunk_size in full_sync_limits.

Proposed changes:

• Abstract the code used in posts to the module class by creating the filter_objects_and_metadata_by_size method.
• Use the above method for posts and comments

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

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

Testing instructions:

Repeat the instructions in #34390 but do them for comments as well this time

[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/full-sync-comments-dynamically 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/full-sync-comments-dynamically
  

  bin/jetpack-downloader test jetpack-mu-wpcom-plugin update/full-sync-comments-dynamically
  

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

[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:

• ✅ Include a description of your PR changes.
  
• ✅ Add a "[Status]" label (In Progress, Needs Team Review, ...).
  
• ✅ Add a "[Type]" label (Bug, Enhancement, Janitorial, Task).
  
• ✅ Add testing instructions.
  
• ✅ Specify whether this PR includes any changes to data or privacy.
  
• ✅ Add changelog entries to affected projects
  

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 🤖

---

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.

---

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:
   • A. Team Review: add the "[Status] Needs Team Review" label
     • For most changes, including minor cross-team impacts.
     • Example: Updating a team-specific component or a small change to a shared library.
   • B. Crew Review: add the "[Status] Needs Review" label
     • For significant changes to core functionality.
     • Example: Major updates to a shared library or complex features.
   • C. Both: Start with Team, then request Crew
     • For complex changes or when you need extra confidence.
     • Example: Refactor affecting multiple systems.
3. Get at least one approval before merging.

Still unsure? Reach out in #jetpack-developers for guidance!

---

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 February 4, 2025 (scheduled code freeze on February 4, 2025).

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

[github-actions]

Code Coverage Summary

Coverage changed in 3 files.

File	Coverage	Δ%	Δ Uncovered
projects/packages/sync/src/modules/class-comments.php	44/173 (25.43%)	-1.23%	8 💔
projects/packages/sync/src/modules/class-module.php	43/207 (20.77%)	12.35%	1 💔
projects/packages/sync/src/modules/class-posts.php	23/251 (9.16%)	0.55%	-16 💚

Full summary · PHP report · JS report

[fgiannar]

LGTM 🚢