aptos-foundation / mainnet-proposals Goto Github PK

Previously signature checker v2 was disabled due to some backward compatibility issue: #26. That issue has now been resolved, so it is time to re-enable the new signature checker.

The new signature checker is more efficient and fixes a bug in the old implementation that would allow programs with certain invalid types to be published. This bug has been patched in the compiler a long time ago, so users should not run into issues with it.

We're proposing to update consensus config exclude_round from 20 to 40.

For Consensus to operate correctly, all validators need to agree on the same leader. In Aptos, Consensus coordinates leader selection via deterministic formula based on on-chain state (like root hash), that each validator computes independently.
For achieving high efficiency and throughput, we also have decoupled execution, where we have a pipeline of stages (consensus ordering, execution, commit), where each stage has a queue and operates independently. That means that there is a delay between consensus ordering a block and state in storage being updated.

Given decoupled execution, in order for leader election to agree among validators, we have on-chain config called exclude_round which defines which state is used for computing leader for a particular round: leader[round] = selection_formula(round - exclude_round).

If number of blocks in the pipeline is larger than exclude_rounds, then validator hasn't yet computed the state needed for leader election formula, and validators will not agree on the same leader, leading to failed round and increased latency.
We have noticed, that under high load, number of blocks in the pipeline can temporarily grow to ~30, so increasing exlcude_rounds to 40 should improve experience and latency under high load.

We recently became aware of an issue regarding a newly introduced signature checker that caused interruptions for one of our ecosystem projects. The affected contract was compiled and deployed before Nov 2022 and contained a specific struct type ability error that wasn't prohibited completely by the old Move compiler. No new modules deployed after Nov 2022 would be subject to this problem as the updated compiler strictly prohibits this case. We have also verified all modules deployed in mainnet to ensure no other modules are affected.

The proposal is to disable signature checker v2 to allow the affected module to resolve the issue.