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The majority of last week I spent tinkering with Subspace codebase after importing it here in preparation for building an actual blockchain.

This week I’ve gone a bit deeper into the design of the multi-shard Subspace protocol idea which I briefly introduced in my last update. The protocol is conformed by the following parts: Sharded archiving, responsible for creating a global canonical history of the whole system, and of creating the history records that will eventually become part of farmers’ plots. Sharded plotting, which takes records from the global history and seals them in plots that include segments of the history of every shard of the system, and that will be used for the farming process. And finally, merged farming, which is the protocol responsible for challenging farmer plots, and deriving the corresponding winning tickets that elect block proposers in specific shards. Let me introduce the high-level operation behind each of these sub-protocols, while digging deep in the one that I’ve focused the most on this week: sharded archiving.

After a lot of thinking, this week I came to the realisation that a sharded architecture like the one we are trying to build can be designed leveraging the current design of the Subspace protocol and all its underlying mechanisms as a base. While this was the idea from the beginning, either for lack of familiarity with the protocol or plain ignorance, I was missing the big picture of how this could be done.

The majority of the last two weeks I’ve been busy with the installation of the antivirus system update for my immune system. It was neither pleasant nor quick, but now that it is slowly approaching 100%, I’m back with another update of what I managed to do since the last update.

Overall, I am really happy with the progress I’ve made this week. I’ve been mainly focused on unravelling one of the papers that I mentioned in my last update, Proof-of-Stake Sidechains. While is true that we don’t want our system to have anything to do with PoS, and there is no 1:1 matching of the concepts from the paper with what we are trying to build, the paper presents a framework that can come pretty handy to evaluate the correctness of our designs. This paper is from 2018, and after a first pass the first thing that I did is to check if there were any follow-up papers that built upon the abstractions of this paper. I came across Proof-of-Work Sidechains from the same authors, but without a doubt, the most complete proposal is the one that I started with. Let’s dive right into it.

The plan was to get to transaction pool implementation, but it didn’t quite happen. I did a lot of investigation around performance though. For example, transaction processing was several orders of magnitude slower than direct method calls without a transaction, which concerned me, but after optimizations of last week the difference is ~10x. And it makes sense given how much more work the wallet has to do on top of the method call itself.

I want to kick-off my first weekly update in the project thanking Nazar for the warm welcome and the opportunity to work with him on this exciting project. I was really pumped to see other teams actively working on a similar problem to the one I started researching more than three years ago. For several reasons, I wasn’t actively contributing to this problem any more, but this opportunity was the perfect excuse to get back to the game.

The big change from the last update is that Alfonso de la Rocha has joined me as a part-time researcher to help with sharding designing. Code-wise, there were also a bunch of performance benchmarks and optimizations.

The most important progress from last week is initial work on transactions. I’ve spent quite some time thinking about the design and even implemented an initial wallet contract alongside with related infrastructure.

It was a challenging week working on storage access checks for slots, but it is over, and I’m quite happy with how things are looking right now. Some extra refactoring also allowed running tests under Miri and spotted some things that violate the Rust safety rules.