Cleanup timelockId on execution for gas refund by Amxx · Pull Request #4118 · OpenZeppelin/openzeppelin-contracts (original) (raw)

When calling execute, the state is checked. We expect to be in Queued. That means the state call done by execute is going to read _timelockIds[proposalId] and check the operation status. This sload makes the slot "hot".

As a consequence, cleaning it will cost 2900 and refund 4800, resulting in a theoretical 1900 gas savings. Because of the hash necessary to compute storage slot, this saving is reduced to 1825, which is still "nice to have".

• This does not change the behavior of the state(uint256) function
  • execute() sets the executed flag, which means the state will be returns without even looking at _timelockIds[proposalId]
• This does not change the behavior of the proposalEta(uint256) function
  • before this change, calling proposalEta on an executed proposal would lookup the deadline on the timelock. That returns _DONE_TIMESTAMP (1) which is rewritten to 0 by the governor
  • after this change, calling proposalEta on an executed proposal would lookup the deadline of 0x0 on the timelock, which should be 0.

PR Checklist

• Tests
• Documentation
• Changeset entry (run npx changeset add)