Add Async Backing guide

[DrW3RK]

Update the instructions to work with the latest parachain template on Polkadot SDK

[DrW3RK]

I have embedded the code from Parachain template wherever applicable using docify.

@kianenigma Perhaps the Async Guide upgrade doc is not a great candidate to showcase docify as most of the hardcoded example snippets serve as guidance for parachain devs to edit the code on their repositories which may be built from older versions of Substrate SDK. Here are a few pitfalls of using docify on this document:

• Can't highlight specific lines like the example in step 1.4
• Can't make edits to the exported code. This is problematic for guides like these, as it is very common that the readers will copy paste the snippet. Reference example - step 1.5 where the exported code shows "TRUE" and we want the reader to have it set to "FALSE"
• I was unable to export "spawn-tasks" in step 2.2 and "AuraParams" in step 2.5
• Can't show partial code snippet like in step 2.3. The function start_consensus is huge and we just want to instruct the reader to add a single line of extra code to it.
• How to export the comments/documentation from the source code as well? docify just captures the actual code and ignores the documentation.

Any input on the above items is appreciated. Will be helpful for future docs.

@alexggh If you are able to do a walk through of the rendered doc and ensure its integrity, that would be of huge help. Thank you!

[kianenigma]

Your observation is a bit unfortunate, but correct in that I might have been wrong in thinking that this doc is better demonstrated in docify.

Some of the points you mentioned can be improved by enhancing docify. For example:

• #[docify::hidden] to hide unneeded stuff
• #[docify::diff] to showcase just the diff of two snippets#4365

I had the intention to ask for a small treasury tip to incentivize @sam0x17 to implement some of these. But this is a midterm effort and I don't have a better solution in the short term.

My only suggestion in the short term is to not expect to re-use production code as-is in docify, and sometimes you might need to first relocate a subset of a working code in a new module/crate, and then use that.

Whether this is worth the effort or not, we will have to evaluate. Thank you for giving this a try in the meantime!

[DrW3RK]

Sounds good! Docify is for sure very resourceful in embedding code, especially within the tutorial docs. If we are making a tutorial on Parachain template itself, I do see the potential of using docify.

I see you have created issues on the docify repo https://github.com/sam0x17/docify/issues Let's ask for a treasury tip to have them addressed!

[alexggh]

The content is correct, but I think the rendering is a bit weird and makes it hard to pass through the guide.

[DrW3RK]

@kianenigma The doc is ready to be merged. Please review.

[kianenigma]

I have some further ideas about how to improve, you can take a look here: DrW3RK/polkadot-sdk@async-backing-docs...paritytech:polkadot-sdk:kiz-feedback-kian-radha

[kianenigma]

@DrW3RK in the commit of mine that you have merged, I have demonstrated how you can use docify, but I have left the rest of it for you to do with the same mindset. Please follow the same pattern, and try and make as many of the code snippets as you can use real code.

[DrW3RK]

on it

[DrW3RK]

@kianenigma I've refined the document based on your feedback and used docify where it made sense.

On closer look, I observed that a few of the Docify imports in Phase 1 from your commit were misleading. As @alexggh mentioned here: #4363 (comment), this guide is for parachains that have not used the template and need to make modifications in multiple phases to activate the Async Backing feature.

For instance, with the usage of docify in Phase 1, the capacity is already 3 instead of 1, and the block time is 6000 instead of 12000.

I've attempted to make the code snippets concise throughout.

However, I failed to get this part of your commit to compile.

6. Update [sp_consensus_aura::AuraApi::slot_duration] in [sp_api::impl_runtime_apis] to match the constant SLOT_DURATION

and got these errors. I can investigate this further, but if this is something trivial, please let me know. Thanks!

  = note: no item named `sp_consensus_aura` in scope
note: the lint level is defined here
   --> docs/sdk/src/guides/async_backing_guide.rs:252:9
    |
252 | #![deny(rustdoc::broken_intra_doc_links)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[alindima]

As @alexggh mentioned here: #4363 (comment), this guide is for parachains that have not used the template and need to make modifications in multiple phases to activate the Async Backing feature.
For instance, with the usage of docify in Phase 1, the capacity is already 3 instead of 1, and the block time is 6000 instead of 12000.

This was also my point here: #4663 (comment)

I don't think we should be referencing the most up to date parachain template in the guide, because the template should already have all these features enabled.
These guides are IMO targeted at existing parachains that want to upgrade

[kianenigma]

I see, this was a misunderstanding from my side though.

I personally think it is better to show someone the latest code and expect them to follow the instruction of "make it look like this", as opposed to trying to "imagine" what their code looks like, and then showing them exactly what line they have to change in the imaginary code.

But I will leave it up to you, and which one you and the rest of the parachains' team think it is a more worthwhile way to maintain it.

End of the day, all of my nitpicks here are in the direction of reducing the burdeon on all of you to not need to think about maintaining this. If you are okay with the task, our goal is reached and I'd be happy.

[DrW3RK]

@kianenigma This was a good learning exercise for me on how Docify works. Happy to put this to use in Polkadot SDK docs.

[paritytech-cicd-pr]

The CI pipeline was cancelled due to failure one of the required jobs.
Job name: cargo-clippy
Logs: https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/6499208

[DrW3RK]

Could we add R0-silent and T11-documentation labels to this PR similar to #4244 ? I think that should take care of the failing CI jobs.

[alindima]

Could we add R0-silent and T11-documentation labels to this PR similar to #4244 ? I think that should take care of the failing CI jobs.

Done. This can be queued for merge now