Cauldron V3

Third version of the cauldrons, implementing the following changes:

• Dynamic Interest Rate

• Borrow Limit (per user & global)

• Liquidations emit an event

• exchangeRate is automatically updated before solvency checks.

Functions starting with '✨' are new in V3.

It is deployed directly and then used as a masterContract to deploy each market, as clones, following the minimal proxy pattern.

You can find the full contract here.

constructor nonpayable (address)

This will create the masterContract that will be used by all the clones (markets).

Write Functions

accrue

function accrue() public

Accrues the interest on the borrowed tokens and handles the accumulation of fees.

updateExchangeRate

function updateExchangeRate() public returns (bool updated, uint256 rate)

Gets the exchange rate, ie how much collateral to buy 1e18 asset. Invoked if needed since Oracle queries can be expensive.

Returns

addCollateral

function addCollateral(
        address to,
        bool skim,
        uint256 share
    ) public

Adds share amount of collateral from msg.sender to the account to.

Parameters

removeCollateral

function removeCollateral(address to, uint256 share) public solvent

Calls _removeCollateral, which removes the amount share of collateral and transfers it to the account to.

Parameters

borrow

function borrow(address to, uint256 amount) public solvent returns (uint256 part, uint256 share)

Calls _borrow, which allows the sender to borrow amount and transfer to to.

Parameters

Returns

repay

function repay(
        address to,
        bool skim,
        uint256 part
    ) public returns (uint256 amount)

Calls _repay, which repays a loan.

Parameters

Returns

✨ changeBorrowLimit​ | New in V3

function changeBorrowLimit(
        uint128 newBorrowLimit, 
        uint128 perAddressPart
    ) public onlyMasterContractOwner {

Allows MasterContractOwner to change the borrow limits of the cauldron, both globally and per user.

Parameters

✨ changeInterestRate | New in V3

function changeInterestRate(uint64 newInterestRate) public onlyMasterContractOwner {

Allows MasterContractOwner to change the interest rate of the Cauldron. The rate can only be change every 3 days The newInterestRate can't be bigger than 175% of the old rate (the rate can't increase by more than 75% at the time) If rate was 0%, the rate can be increased to 1%, the previous rule then applies.

Parameters

cook

function cook(
        uint8[] calldata actions,
        uint256[] calldata values,
        bytes[] calldata datas
    ) external payable returns (uint256 value1, uint256 value2)

Executes a set of actions and allows composability (contract calls) to other contracts.

The cook function allows to bundle functionality within one contract call while passing return values from one call to the next one. Actions are defined by a numeric identifier and can return two values, value1 and value2 to the next function. The input arrays actions, values and datas define the sequential actions. In the Value array the ether value of a call may be defined.

Whereas calling functions like borrow that have the solvent modifier requires solvency at the end of the function, solvency only needs to be guaranteed at the end of the cook function, thereby allowing more complicated operations such as leveraging within one call.

For certain parameters either an external value can be passed in or the identifier USE_VALUE1 (-1) or USE__VALUE2 (-2) to access either of the local variables. The following variables are marked in bold italic in the table below. If an action returns one value it is saved as value1, if two are returned they are saved as value1 and value2 respectively. Any action can access these values during the whole duration of the cook call.

The call data for the actions is ABI encoded as listed below.

Available actions and their ID:

// Functions that need accrue to be called
uint8 internal constant ACTION_REPAY = 2;
uint8 internal constant ACTION_REMOVE_COLLATERAL = 4;
uint8 internal constant ACTION_BORROW = 5;
uint8 internal constant ACTION_GET_REPAY_SHARE = 6;
uint8 internal constant ACTION_GET_REPAY_PART = 7;
uint8 internal constant ACTION_ACCRUE = 8;

// Functions that don't need accrue to be called
uint8 internal constant ACTION_ADD_COLLATERAL = 10;
uint8 internal constant ACTION_UPDATE_EXCHANGE_RATE = 11;

// Function on BentoBox
uint8 internal constant ACTION_BENTO_DEPOSIT = 20;
uint8 internal constant ACTION_BENTO_WITHDRAW = 21;
uint8 internal constant ACTION_BENTO_TRANSFER = 22;
uint8 internal constant ACTION_BENTO_TRANSFER_MULTIPLE = 23;
uint8 internal constant ACTION_BENTO_SETAPPROVAL = 24;

// Any external call (except to BentoBox)
uint8 internal constant ACTION_CALL = 30;

int256 internal constant USE_VALUE1 = -1;
int256 internal constant USE_VALUE2 = -2;

Parameters

Returns

liquidate

function liquidate(
        address[] calldata users,
        uint256[] calldata maxBorrowParts,
        address to,
        ISwapper swapper,
    ) public

Handles the liquidation of users' balances once the users' amount of collateral is too low.

Parameters

withdrawFees

function withdrawFees() public

Withdraw the fees accumulated to the feeTo address.

setFeeTo

function setFeeTo(address newFeeTo) public onlyOwner

Sets the beneficiary of fees accrued in liquidations. Can only be called by the owner of the contract.

Parameters

reduceSupply

function reduceSupply(uint256 amount) public 

Reduces the supply of MIM

Parameters

View Functions

BORROW_OPENING_FEE

Returns the opening fee (charged instantly, added to user debt upon borrowing) in Basis Points.

COLLATERIZATION_RATE

Returns the Collateralization Rate (maximum % borrowable with this collateral) in Basis Points. eg: 75000 = 75%

LIQUIDATION_MULTIPLIER

Returns the liquidation fee in Basis Points. eg: 112000 would add 12% (it's a multiplier, so the value is 112%)

accrueInfo​

Return values

bentoBox

Return values

✨ borrowLimit | new in V3

Returns the current borrowLimit, expressed in borrowParts at the cauldron level and at the address level.

Return values

collateral

Return values

exchangeRate

Return values

feeTo​

Return values

magicInternetMoney

Return values

masterContract

Return values

oracle​

Return values

oracleData​

Return values

owner

Return values

pendingOwner​

When transferring ownership, the future owner is pending until they claims ownership.

Return values

totalBorrow​

Returns the total amounts borrowed from the cauldron.

Return values

totalCollateralShare​

Returns the amount (in shares) of the token collateral used as collateral in this cauldron.

Return values

userBorrowPart

Returns the amount of borrowParts held by a user. To convert that amount into a numerical MIM debt amount, you must do totalBorrow.elastic / totalBorrow.base * borrowParts.

Parameters

Return values

userCollateralShare​

Amount (in shares) of the token collateral used as collateral by the user.

Parameters

Return values