Increasing Treasury Reimbursement

Integration contract meant to offer an increasing reward pulled from the SF treasury

1. Summary

The IncreasingTreasuryReimbursement is a contract meant to be inherited from and used as a way to offer an increasing stability fee reward (pulled from the SF treasury) to any address.

2. Contract Variables & Functions

Variables

• authorizedAccounts[usr: address] - addAuthorization/removeAuthorization - auth mechanisms

• baseUpdateCallerReward - starting reward offer to a fee receiver

• maxUpdateCallerReward - max possible reward for a fee receiver

• maxRewardIncreaseDelay - max delay taken into consideration when calculating the adjusted reward

• perSecondCallerRewardIncrease - rate applied to baseUpdateCallerReward every extra second passed beyond a certain date (e.g next time when a specific function needs to be called)

• treasury - stability fee treasury contract

Functions

• treasuryAllowance() public view returns (uint256) - this returns the stability fee treasury allowance for the reimbursement contract by taking the minimum between the per block and the total allowances

• getCallerReward(uint256 timeOfLastUpdate, uint256 defaultDelayBetweenCalls) public view returns (uint256) - get the SF reward that can be sent to an address right now

• rewardCaller(proposedFeeReceiver: address, reward: uint256) internal - internal function that's meant to send a SF reward to a proposedFeeReceiver

Modifiers

• isAuthorized - checks whether an address is part of authorizedAddresses (and thus can call authed functions)

Events

• AddAuthorization - emitted when a new address becomes authorized. Contains:

  • account - the new authorized account

• RemoveAuthorization - emitted when an address is de-authorized. Contains:

  • account - the address that was de-authorized

• ModifyParameters - emitted when a parameter is updated.

• FailRewardCaller - emitted when the contract cannot reward an address. Contains:

  • revertReason - the reason why the contract could not send the reward

  • feeReceiver - the address that was supposed to get the reward

  • amount - the reward that had to be sent

3. Walkthrough

rewardCaller is the most important function in this contract. It takes care of pulling the SF reward from the treasury and then sending it to a proposedFeeReceiver.

getCallerReward can be used to retrieve the current SF fee that can be pulled from the treasury. If baseUpdateCallerReward and maxUpdateCallerReward are both zero or if timeOfLastUpdate >= now, getCallerReward will return zero.

Large maxRewardIncreaseDelay and perSecondCallerRewardIncreasecan make getCallerReward revert

If perSecondCallerRewardIncrease is set to a large value and maxRewardIncreaseDelay is also large, getCallerReward may revert. In most scenarios, maxRewardIncreaseDelay should be set to a very conservative value (a couple of hours at most) in order to avoid this scenario.

4. Increasing Treasury Reimbursement Flavours

There are two alternative Increasing Treasury Reimbursement contract flavours aside from the core one:

• NoSetupIncreasingTreasuryReimbursement - this contract has the exact same logic as the core one but it does not set any parameters in its constructor

• NoSetupNoAuthIncreasingTreasuryReimbursement - this contract has the same logic as the core one but it does not set any parameters in its constructor and it also does not have any authorization logic (addAuthorization/removeAuthorization)