Introduction

Cache Review provides tools to help review and analyze how the internal (IPC) and dynamic page cache (DPC) work.
The module also provide several demo pages with cached and non-cached items.
The main goal of Cache Review project is to help developers to learn how cache works for
anonymous and authenticated users.
Also, it should help to review and found possible problems with caching in projects.

Inspired by https://www.drupal.org/project/renderviz and
the article https://weknowinc.com/blog/drupal-8-add-cache-metadata-render-arrays.

If you need to get detailed information about
cache metadata of each element on the page, please use console + renderviz.

Additional about cache

- Cache API: https://www.drupal.org/docs/8/api/cache-api/cache-api !
- Lazy Builders: https://www.hashbangcode.com/article/drupal-9-using-lazy-builders
- IPC: https://www.drupal.org/docs/administering-a-drupal-site/internal-page-cache
- DPC: https://www.drupal.org/docs/8/core/modules/dynamic-page-cache/overview
- Render arrays caching: https://www.drupal.org/docs/drupal-apis/render-api/cacheability-of-rende...
- Auto-placeholdering https://www.drupal.org/docs/drupal-apis/render-api/auto-placeholdering

Requirements

This module requires no modules outside of Drupal core.

Installation

* Please, don't use this module in Production environment!
* Install and enable this module like any other Drupal 9 module.

Configuration

The module has no configuration.

Use case

Checking cache status
The status of cache will be displayed at the top of each non-admin page.
There you can find information about current auto-placeholder-conditions, current time, IPC and DPC status and meanings of cache marks on the page.

Playing with cache :)
There is an ability to test how the cache works with different pre-defined settings. Just open any page of your project and research.

And for the first, you can open /cache-review path, open pages with different cache cases and playing with different cache setting
for elements on the pages. There each cache mark (C, L, N) shows cache metadata of element on hover.
You can try to change cache settings (tags, contexts, max-age and lazy builder settings) in cache_review module code.
Just refresh page and see the results. Also the time value on each elements will help to see if item is cached or not.

For instance, on the attached screenshot we can see:
- X-Drupal-Cache is empty, that is mean the current user is authenticated;
- DPC status is UNCACHABLE - so, the response is not from cache;
- On hover each mark in tooltip we can see cache options of the item;
- Let's find mark with red color. The (4) at the bottom is covered by lazy_builder.
- But (2) item has red C mark. It is cached due to 'keys' options, but it 'user' context bubbled up to top level including whole html.

Documentation

Thanks Philip Norton for such detailed guide and so high mark of this work: https://www.hashbangcode.com/article/drupal-9-debugging-cache-problems-c....
I couldn't have described it better.

Known constraints

Need to disable big_pipe during working with cache_review module. Big pipe shows rendered output in its specific order and along with cache_review lazy built item will be empty. Working with big pipe can be improved further.

RTBC issues for Cache review

Filters