SSZ Query Language Meta Tracking Issue

[syjn99]

Must have

Items are sorted by chronological order.

Implement the SSZ-QL engine.

• Initialize the encoding/ssz/query package with the following features. Mostly migrating from my previous PoC work.
  • Basic path parser (e.g., .data.target.root)
  • Define sszInfo struct that contains all necessary information about the corresponding SSZ type.
  • Precalculate the given Go struct, only supporting fixed-size types.
  • Calculate offset and length in bytes to read in marshalled (= serialized) SSZ object.
  • Unmarshal (= deserialize) a requested value.
• Support multi-dimensional parsing for tags.
• Implement various-sized types.
  • Implement List.
• Implement Bitlist and Bitvector
• Add more features on the path parser (e.g., access the n-th element in List/Vector).

Expose SSZ-QL as a new endpoint.

• Add endpoint (/prysm/v1/beacon/states/{state_id}/query) without proof generation.
• Add endpoint (/prysm/v1/beacon/blocks/{block_id}/query) without proof generation.
• Integrate Merkle Proofs feature. Related issue: Merkle proofs of everything #15344
• Benchmark the SSZ-QL engine (and Optimize it if it shows the worst performance.).

Nice to have

There is no specific sort order here.

• Propose these new endpoints to ethereum/beacon-APIs.
• Parse len() for List and Bitlist.
• Implement more advanced features for V2.
• Determine to introduce a cache or not: sszInfo of BeaconState from the current fork. (Related discussion in Discord)
• Use encoded bytes of BeaconState if it is in the DB. (Related write-up)
• Support more SSZ data types like Union, ProgressiveList.
• Use SSZ fuzzer to test more crazier cases.

Fixes

TBD

Other

TBD

References

Specification

• postStateQuery & postBlockQuery API Specification: This specification contains the very first version of SSZ-QL API, as well as our primary goal for the EPF6.
• SSZ-QL: Full Specification: This specification contains the endgame of SSZ-QL, including advanced features for fine-grained queries.

Write-ups

• Navigating Options for Implementing SSZ-QL on Prysm
• SSZ-QL: Proof-of-Concept
• Struct Tags used in sszgen
• Delving into dynamic-ssz (dynssz)