docs(suggestion): adding a list of supported Nextjs cache functionalities

[Jordaneisenburger]

Hi all,

I'm currently working with the latest Next.js 15 canary release and have been testing some of the new experimental caching features like:

cacheTag();
cacheLife();

Alongside more stable APIs such as:

revalidateTag();

So far, some of the the experimental features appear to be working well which is great!

That said, I believe it would really help adoption within the Next.js community if there were clearer guidance or documentation indicating which caching APIs are supported, and to what extent. A simple compatibility matrix or stability indicator would make it easier for developers to use this package.

Keep up the great work, and thanks for continuing to push the platform forward!

[AyronK]

To be honest if any experimental features work out of the box, it's rather a coincidence coming from the original neshca package. Which is great, but so far the main focus was to make the package compatible with the core functionalities 😅. We don't have enough recourses right now to do that but if you'd be willing to help with at least writing some compatibility matrix, that would be very helpful!

[Jordaneisenburger]

Hi @AyronK thanks for the quick reply!

Although I'm not a Redis expert, I'd like to help out and try to somehow get use cache working as per the docs by default it is stored in-memory (https://nextjs.org/docs/app/api-reference/directives/use-cache#use-cache-at-runtime) which means it should be able to also be stored in Redis. If you have any idea on where where to start investigating this feature that would be super helpful.

As for the compatibility Matrix, I will do more testing and report back. Would it be possible for you to enable GH discussions as I think that would be better than opening issues.

[Jordaneisenburger]

We should also track this discussion: vercel/next.js#81811

[AyronK]

Would it be possible for you to enable GH discussions as I think that would be better than opening issues.

Yes, done, but it's an empty template for now :D

[AyronK]

Although I'm not a Redis expert, I'd like to help out and try to somehow get use cache working as per the docs by default it is stored in-memory (https://nextjs.org/docs/app/api-reference/directives/use-cache#use-cache-at-runtime) which means it should be able to also be stored in Redis. If you have any idea on where where to start investigating this feature that would be super helpful.

This has nothing to do with redis itself, it probably does not work at all on any handlers in this package then, as the use cache , cacheTag(), cacheLife(); were experimental in Next 14. I see use-cache is "stable" now, but you're right that we missed that when we started Next15 migration as we don't use that feature internally in our projects (yet).

What I can recommend is trying to write your own in-memory cache handler based on this NextJS example and adjust it to make it work with use cache (or other features you want to work with) on minimal in-memory setup. Then it should be fairly easy to integrate it into this package (and redis handler).

EDIT
Now after I saw the discussion on vercel, I understand that this actually work on in-memory handler, which is a good lead. Then I think I might know what is wrong and where I should start looking at. If you would like to help you could prepare an example in the minimal example project - for example by adding a route using the features you experienced not working with this package.

[fturmel]

In case this is helpful:

"use cache" is still not stable: https://nextjs.org/docs/app/api-reference/directives/use-cache

I don't know how much things have changed since march, but it was mentioned that there is a new cache handler interface for use cache, and that eventually all cache features (including unstable_cache, fetch) would adopt this interface. Until this interface is more properly documented and under an experimental flag, I anticipate that it can still change at any moment.
vercel/next.js#76581

Relevant source code to better understand the internals:
https://github.com/vercel/next.js/tree/canary/packages/next/src/server/lib/incremental-cache
https://github.com/vercel/next.js/tree/canary/packages/next/src/server/lib/cache-handlers

[Jordaneisenburger]

Although I'm not a Redis expert, I'd like to help out and try to somehow get use cache working as per the docs by default it is stored in-memory (https://nextjs.org/docs/app/api-reference/directives/use-cache#use-cache-at-runtime) which means it should be able to also be stored in Redis. If you have any idea on where where to start investigating this feature that would be super helpful.

This has nothing to do with redis itself, it probably does not work at all on any handlers in this package then, as the use cache , cacheTag(), cacheLife(); were experimental in Next 14. I see use-cache is "stable" now, but you're right that we missed that when we started Next15 migration as we don't use that feature internally in our projects (yet).

What I can recommend is trying to write your own in-memory cache handler based on this NextJS example and adjust it to make it work with use cache (or other features you want to work with) on minimal in-memory setup. Then it should be fairly easy to integrate it into this package (and redis handler).

EDIT Now after I saw the discussion on vercel, I understand that this actually work on in-memory handler, which is a good lead. Then I think I might know what is wrong and where I should start looking at. If you would like to help you could prepare an example in the minimal example project - for example by adding a route using the features you experienced not working with this package.

Awesome, I will create a PR to that minimal repo with the functionalities that are not working right now.

[magnusriga]

@Jordaneisenburger and @AyronK : I made a bug report in the vercel/next repo about this, including an MRE you can fork/play with, if helpful:

vercel/next.js#82993

For now, "use cache" uses a default in-memory cache, and seems out of our reach until Next.js changes how it works.

PPR via instrumentation, on the other hand, can probably be easily solved, by looking for files with suffix preload.rsc instead of just rsc. See: #59 and #60

---

EDIT: I just heard from a Next.js team member that there is a hidden option to enable cacheHandler for "use cache". See the issue linked above for full info.

[AyronK]

ppr is now supported in 2.1.0-canary.12.

[AyronK]

A list of supported Nextjs cache functionalities will be part of the README.md as soon as we release 3.0.0.