Coming in 2023! A book that goes through Drupal's cacheable metadata and caching systems from render pipeline to reverse proxies. It is in the early stages, with an outline 90% complete and a few chapters written. I will be self-publishing through Leanpub. You can register your interest here: https://leanpub.com/understanding-drupal-complete-guide-caching-layers
Here is a preview at the chapter and a quick summary
- Cacheable metadata: tags, contexts, and max age explains the building blocks of Drupal's Cache API: cacheable metadata.
- Cache items, their backends, and stores demonstrate through interaction with cache items and backends.
- Render (fragment) cache explains Drupal's render pipeline and how Drupal implements fragment caching for parts of its render tree.
- Caching responses explains how Drupal implements response caching, and the ability to stream partially cached responses.
- HTTP caching headers explains HTTP caching headers; these are not specific to Drupal but can be affected by cacheable metadata values within Drupal.
- Reverse proxies and CDNs explains how Drupal's Cache API can influence reverse proxies and CDNs sitting before Drupal.
- Debugging your cache walks through debugging Drupal's caching layers.
- Writing code with cacheability in mind provides examples and tips for writing code with cacheability in mind.