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Increasing Treasury Reimbursement

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.

{% hint style="warning" %} 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. {% endhint %}

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)