Fantom Technical Update 12

By Michael Kong

Go-Lachesis

New consensus implementation based on modified version of early Lachesis, including fast gossip implementation for more efficient transfer of events between nodes: https://github.com/Fantom-foundation/go-lachesis/commit/232ea6b15af9e0cae46411ae6fe152900dfc3e1e

Identified a number of quality issues with recently added code into go-lachesis, fixed some and reported the rest as issues;
https://github.com/Fantom-foundation/go-lachesis/issues/210
https://github.com/Fantom-foundation/go-lachesis/issues/211
https://github.com/Fantom-foundation/go-lachesis/issues/212
https://github.com/Fantom-foundation/go-lachesis/issues/230
https://github.com/Fantom-foundation/go-lachesis/issues/231
https://github.com/Fantom-foundation/go-lachesis/issues/232

Restored `testnet` test in Travis;
https://github.com/Fantom-foundation/go-lachesis/commit/24b5e93102e086217c0bf8c5ceb5575b232330dc

Developed a schema of possible Byzantine attack on go-lachesis and reported it as an issue;
https://github.com/Fantom-foundation/go-lachesis/issues/253

Rust

• Defined `libconsensus` and `libtransport`, for abstract consensus — Raft (for benchmarking against), Fantom-consensus, and various transport protocol (TCP, SCTP), RPCs, and UDP.
  https://github.com/Fantom-foundation/libtransport
  https://github.com/Fantom-foundation/libtransport-rpc
  https://github.com/Fantom-foundation/libtransport-http
  https://github.com/Fantom-foundation/libconsensus
• Made number of fixes into tests to allow Travis effectively control quality of PRs;
  https://github.com/Fantom-foundation/go-lachesis/commit/ff2533cec50f0cd6cb3ae936468dee87d2393239
  https://github.com/Fantom-foundation/go-lachesis/commit/4c18395d4d13a9f81ba774b11ad74c191d81871a
• [WIP] Research into feasibility of DAG-based asynchronous consensus architecture that able to track node failure.
• Raft-rs integration for benchmarking and testing against:
  https://github.com/Fantom-foundation/libconsensus-raft-rs
• Finished representation in memory of modifiers for solidity.
  https://github.com/Fantom-foundation/libvm-rs
  https://github.com/Fantom-foundation/solidity-rs
• Refactored code to remove unnecessary complexity by using default null values instead of complicated Result<Option<Value>, Error> types when code/type generating.
• Working on expressions to try to figure out how to add side effects.

Research

• Learned TLA+
• Researched TLA+ consensus specs online.
• Started a Coq development of the theory of Concurrent Common Knowledge (CCK) intended as a dependency for proofs about our DAG consensus. Using CertiChain and ToyChain as a reference.
• Started designing how modifiers will be _called_ in memory and how to use placeholder statement.
  https://github.com/Fantom-foundation/solidity-rs/commit/97d47bae892a160ace3a9e584374d97b5d2f05ac
• Similar work with functions to make them work with modifiers.
  https://github.com/Fantom-foundation/solidity-rs/commit/8fc90863c66dd4ae20c6dc1f6715d57c6187b2f7
  https://github.com/Fantom-foundation/solidity-rs/commit/4d0d17315c60b8341069de1669f9cc75c9950036
• Formalising the CCK paper, proved some lemmas needed for the type class hierarchy of Ssreflect to function
  https://www.cs.mcgill.ca/~prakash/Pubs/cck.pdf