vegaprotocol / wendy

Wendy, the good little fairness widget

The good little fairness widget

Wendy acts as an additional widget for an existing blockchain, and is largely agnostic to the underlying blockchain and its security assumptions. Furthermore, it is possible to apply it to the protocol only for a subset of the transactions, and thus run several independent fair markets on the same chain. We have implemented Wendy to run on a simulator to get first performance estimates. As Wendy runs parallel to the actual blockchain, the core impact it has (apart from adding some network traffic) is that some transactions are put into a later block than they would be without fairness.

This repository contains a simulation of Wendy, a protocol for implementing different concepts of fairness. This implementation is not close to production ready, but it does demonstrate how Wendy impacts performance given various parameters.

Research paper

Dr Klaus Kursawe's original research paper is available on IACR or on the Vega website. Or you can watch him talk through the paper on YouTube:

Tendermint

We are currently working on a Wendy implementation for Tendermint. Wendy is implemented as a mempool replacement.

Notes

The initial Wendy implementation can be found under v0.0.1 tag.

wendy's Issues

Learn about seed nodes and PEX reactor.

Wendy voting system might have specific topology requirements.
We need to understand how these requirements can be achieved. Investigate how customizable is the topology in Tendermint. One particular point to investigate are seeds nodes and PEX reactor.

Implement Recompute

Recompute is an internal function that's triggered on new vote, new tx or new block and it evaluates if there are unblocked tx that are ready to be written in a block.

Gossip Voting

Along with Tx broadcasting, Wendy need to broadcast a vote each time a node sees a new Tx (seeing a tx in the mempool, not in the block).
It is likely that the reactor needs to be connected to the mempool and be notified when a new Tx is broadcasted.

The fields that the vote needs to provide are:
sequence_number, tx_hash, time (when seen), pubkey, signature

Review consensus gossiping / reactor code

We need to follow the same behavior when broadcasting Wendy's votes/sequences.

Handle full blocks

Wendy needs to handle full blocks. This is covered in the spec.

Two thing to consider:

• Full blocks from a single bucket
• Full blocks, multiple buckets

Implementing TX bucketing

Fix reactor bug.

When adding a new reactor (with a new custom namespace) using the CustomReactor API the channels are not registered on the peer, making the communication to fail.

Consider this feature is only needed if we need to make use of the Tendermint's gossip protocol.

Follow simulation tests cases in the new implementation

Verify that the new implementation either matches or improves on the simulation implementation

Being able to make use of a custom Mempool implementation.

Replacing the Mempool via CustomReactors API (as suggested by the Tendermint team) is NOT well implemented on the Tendermint side making it impossible to use that approach.

We've opened tendermint/tendermint#6243 to ask how should be the right way to do it.

Implement block validity

@Vegaklaus to specify

Add changelog, project board Github actions and linked PR action version

To align with discussed processes in other repos and new processes discussed we will:

Add the GH Action to move new issues to the new project board for triage
Add the linked PR GH Action
Add a GH Action to validate the changelog is updated
Back date the changelog so it can be updated moving forward from now on

Implement bucketing

Implement IsBlockedBy(tx1, tx2)

IsBlockedBy determines if tx2 might have priority over tx1.
We say that tx1 is NOT blocked by tx2 if there are t+1 (Honest parties) votes reporting tx1 before tx2.

Write a basic custom mempool that can support the Wendy Framework

Since Wendy requires custom mempool behavior, we need to adapt the current mempool implementation (which at the moment is a CList taken from tendermint) to satisfy Wendy's needs.

Implement IsBlocked(tx)

IsBlockedBy determines if tx2 might have priority over tx1.
We say that tx1 is NOT blocked by tx2 if there are t+1 votes reporting tx1 before tx2.