> For the complete documentation index, see [llms.txt](https://docs.union.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.union.finance/developers/core/lendingmarket.md). # uToken @title UToken Contract @dev Union accountBorrows can borrow and repay thru this component. ### BorrowSnapshot ```solidity struct BorrowSnapshot { uint256 principal; uint256 interest; uint256 interestIndex; uint256 lastRepay; } ``` ### WAD ```solidity uint256 WAD ``` *Wad do you want* ### BORROW\_RATE\_MAX\_MANTISSA ```solidity uint256 BORROW_RATE_MAX_MANTISSA ``` *Maximum borrow rate that can ever be applied (.005% / block)* ### RESERVE\_FACTORY\_MAX\_MANTISSA ```solidity uint256 RESERVE_FACTORY_MAX_MANTISSA ``` @dev Maximum fraction of interest that can be set aside for reserves ### initialExchangeRateMantissa ```solidity uint256 initialExchangeRateMantissa ``` @dev Initial exchange rate used when minting the first UTokens (used when totalSupply = 0) ### reserveFactorMantissa ```solidity uint256 reserveFactorMantissa ``` @dev Fraction of interest currently set aside for reserves ### accrualBlockNumber ```solidity uint256 accrualBlockNumber ``` @dev Block number that interest was last accrued at ### borrowIndex ```solidity uint256 borrowIndex ``` @dev Accumulator of the total earned interest rate since the opening of the market ### totalBorrows ```solidity uint256 totalBorrows ``` @dev Total amount of outstanding borrows of the underlying in this market ### totalReserves ```solidity uint256 totalReserves ``` @dev Total amount of reserves of the underlying held in this marke ### totalRedeemable ```solidity uint256 totalRedeemable ``` @dev Calculates the exchange rate from the underlying to the uToken ### overdueBlocks ```solidity uint256 overdueBlocks ``` @dev overdue duration, based on the number of blocks ### originationFee ```solidity uint256 originationFee ``` @dev fee paid at loan origin ### debtCeiling ```solidity uint256 debtCeiling ``` @dev The debt limit for the whole system ### maxBorrow ```solidity uint256 maxBorrow ``` @dev Max amount that can be borrowed by a single member ### minBorrow ```solidity uint256 minBorrow ``` @dev Min amount that can be borrowed by a single member ### assetManager ```solidity address assetManager ``` @dev Asset manager contract address ### userManager ```solidity address userManager ``` @dev User manager contract address ### underlying ```solidity address underlying ``` *Address of underlying token* ### interestRateModel ```solidity contract IInterestRateModel interestRateModel ``` *Interest rate model used for calculating interest rate* ### accountBorrows ```solidity mapping(address => struct UToken.BorrowSnapshot) accountBorrows ``` Mapping of account addresses to outstanding borrow balances ### AccrueInterestFailed ```solidity error AccrueInterestFailed() ``` ### AmountExceedGlobalMax ```solidity error AmountExceedGlobalMax() ``` ### AmountExceedMaxBorrow ```solidity error AmountExceedMaxBorrow() ``` ### AmountLessMinBorrow ```solidity error AmountLessMinBorrow() ``` ### AmountZero ```solidity error AmountZero() ``` ### BorrowRateExceedLimit ```solidity error BorrowRateExceedLimit() ``` ### WithdrawFailed ```solidity error WithdrawFailed() ``` ### CallerNotMember ```solidity error CallerNotMember() ``` ### CallerNotUserManager ```solidity error CallerNotUserManager() ``` ### InitExchangeRateNotZero ```solidity error InitExchangeRateNotZero() ``` ### InsufficientFundsLeft ```solidity error InsufficientFundsLeft() ``` ### MemberIsOverdue ```solidity error MemberIsOverdue() ``` ### ReserveFactoryExceedLimit ```solidity error ReserveFactoryExceedLimit() ``` ### DepositToAssetManagerFailed ```solidity error DepositToAssetManagerFailed() ``` ### LogNewMarketInterestRateModel ```solidity event LogNewMarketInterestRateModel(address oldInterestRateModel, address newInterestRateModel) ``` @dev Change of the interest rate model @param oldInterestRateModel Old interest rate model address @param newInterestRateModel New interest rate model address ### LogMint ```solidity event LogMint(address minter, uint256 underlyingAmount, uint256 uTokenAmount) ``` @dev Mint uToken by depositing token @param minter address of minter @param underlyingAmount amount of underlying token @param uTokenAmount amount of uToken ### LogRedeem ```solidity event LogRedeem(address redeemer, uint256 amountIn, uint256 amountOut, uint256 redeemAmount) ``` @dev Redeem token for uToken ### LogReservesAdded ```solidity event LogReservesAdded(address reserver, uint256 actualAddAmount, uint256 totalReservesNew) ``` @dev Token added to the reserves @param reserver address of sender that added to reservers @param actualAddAmount amount of tokens added @param totalReservesNew new total reserve amount ### LogReservesReduced ```solidity event LogReservesReduced(address receiver, uint256 reduceAmount, uint256 totalReservesNew) ``` @dev Token removed from the reserves @param receiver reciever address of tokens @param reduceAmount amount of tokens to withdraw @param totalReservesNew new total reserves amount ### LogBorrow ```solidity event LogBorrow(address account, address to, uint256 amount, uint256 fee) ``` @dev Event borrow @param account Member address @param amount Borrow amount @param fee Origination fee ### LogRepay ```solidity event LogRepay(address payer, address account, uint256 amount) ``` @dev Event repay @param account Member address @param amount Repay amount ### onlyMember ```solidity modifier onlyMember(address account) ``` @dev modifier limit member ### onlyUserManager ```solidity modifier onlyUserManager() ``` ### \_\_UToken\_init ```solidity function __UToken_init(string name_, string symbol_, address underlying_, uint256 initialExchangeRateMantissa_, uint256 reserveFactorMantissa_, uint256 originationFee_, uint256 debtCeiling_, uint256 maxBorrow_, uint256 minBorrow_, uint256 overdueBlocks_, address admin_) public ``` ### setAssetManager ```solidity function setAssetManager(address assetManager_) external ``` @dev set Asset Manager contract address Accept claims only from the admin ### setUserManager ```solidity function setUserManager(address userManager_) external ``` @dev set User Manager contract address Accept claims only from the admin ### setOriginationFee ```solidity function setOriginationFee(uint256 originationFee_) external ``` @dev Change loan origination fee value Accept claims only from the admin @param originationFee\_ Fees deducted for each loan transaction ### setDebtCeiling ```solidity function setDebtCeiling(uint256 debtCeiling_) external ``` @dev Update the market debt ceiling to a fixed amount, for example, 1 billion DAI etc. Accept claims only from the admin @param debtCeiling\_ The debt limit for the whole system ### setMinBorrow ```solidity function setMinBorrow(uint256 minBorrow_) external ``` @dev Update the minimum loan size Accept claims only from the admin @param minBorrow\_ Minimum loan amount per user ### setMaxBorrow ```solidity function setMaxBorrow(uint256 maxBorrow_) external ``` @dev Update the max loan size Accept claims only from the admin @param maxBorrow\_ Max loan amount per user ### setOverdueBlocks ```solidity function setOverdueBlocks(uint256 overdueBlocks_) external ``` @dev Change loan overdue duration, based on the number of blocks Accept claims only from the admin @param overdueBlocks\_ Maximum late repayment block. The number of arrivals is a default ### setInterestRateModel ```solidity function setInterestRateModel(address newInterestRateModel_) external ``` @dev Change to a different interest rate model Accept claims only from the admin @param newInterestRateModel\_ New interest rate model address ### setReserveFactor ```solidity function setReserveFactor(uint256 reserveFactorMantissa_) external ``` @dev set reserve factor mantissa Accept claims only from the admin ### getRemainingDebtCeiling ```solidity function getRemainingDebtCeiling() public view returns (uint256) ``` @dev Returns the remaining amount that can be borrowed from the market. @return Remaining total amount ### getLastRepay ```solidity function getLastRepay(address account) public view returns (uint256) ``` @dev Get the last repay block @param account Member address @return lastRepay ### checkIsOverdue ```solidity function checkIsOverdue(address account) public view returns (bool isOverdue) ``` @dev Check if the member's loan is overdue @param account Member address @return isOverdue ### calculatingFee ```solidity function calculatingFee(uint256 amount) public view returns (uint256) ``` @dev Get the origination fee @param amount Amount to be calculated @return Handling fee ### getBorrowed ```solidity function getBorrowed(address account) public view returns (uint256) ``` @dev Get the borrowed principle @param account Member address @return borrowed ### borrowBalanceView ```solidity function borrowBalanceView(address account) public view returns (uint256) ``` @dev Get a member's current owed balance, including the principle and interest but without updating the user's states. @param account Member address @return Borrowed amount ### borrowBalanceStoredInternal ```solidity function borrowBalanceStoredInternal(address account) internal view returns (uint256) ``` @dev Get a member's total owed, including the principle and the interest calculated based on the interest index. @param account Member address @return Borrowed amount ### borrowRatePerBlock ```solidity function borrowRatePerBlock() public view returns (uint256) ``` @dev Get the borrowing interest rate per block @return Borrow rate ### supplyRatePerBlock ```solidity function supplyRatePerBlock() external view returns (uint256) ``` Returns the current per-block supply interest rate for this UToken #### Return Values | Name | Type | Description | | ---- | ------- | -------------------------------------------------- | | \[0] | uint256 | The supply interest rate per block, scaled by 1e18 | ### exchangeRateStored ```solidity function exchangeRateStored() public view returns (uint256) ``` Calculates the exchange rate from the underlying to the UToken *This function does not accrue interest before calculating the exchange rate* #### Return Values | Name | Type | Description | | ---- | ------- | --------------------------------------- | | \[0] | uint256 | Calculated exchange rate scaled by 1e18 | ### calculatingInterest ```solidity function calculatingInterest(address account) public view returns (uint256) ``` @dev Calculating member's borrowed interest @param account Member address @return Interest amount ### exchangeRateCurrent ```solidity function exchangeRateCurrent() public returns (uint256) ``` Accrue interest then return the up-to-date exchange rate #### Return Values | Name | Type | Description | | ---- | ------- | --------------------------------------- | | \[0] | uint256 | Calculated exchange rate scaled by 1e18 | ### balanceOfUnderlying ```solidity function balanceOfUnderlying(address owner) external view returns (uint256) ``` Get the underlying balance of the `owner` *This also accrues interest in a transaction* #### Parameters | Name | Type | Description | | ----- | ------- | ----------------------------------- | | owner | address | The address of the account to query | #### Return Values | Name | Type | Description | | ---- | ------- | ----------------------------------------- | | \[0] | uint256 | The amount of underlying owned by `owner` | ### borrow ```solidity function borrow(address to, uint256 amount) external ``` @dev Borrowing from the market Accept claims only from the member Borrow amount must in the range of creditLimit, minBorrow, maxBorrow, debtCeiling and not overdue @param amount Borrow amount ### repayBorrow ```solidity function repayBorrow(address borrower, uint256 repayAmount) external ``` Repay outstanding borrow *Repay borrow see \_repayBorrowFresh* ### \_repayBorrowFresh ```solidity function _repayBorrowFresh(address payer, address borrower, uint256 amount) internal ``` @dev Repay the loan Accept claims only from the member Updated member lastPaymentEpoch only when the repayment amount is greater than interest @param payer Payer address @param borrower Borrower address @param amount Repay amount ### accrueInterest ```solidity function accrueInterest() public returns (bool) ``` @dev Accrue interest @return Accrue interest finished ### debtWriteOff ```solidity function debtWriteOff(address borrower, uint256 amount) external ``` ### mint ```solidity function mint(uint256 mintAmount) external ``` *Mint uTokens by depositing tokens* #### Parameters | Name | Type | Description | | ---------- | ------- | ------------------------- | | mintAmount | uint256 | Amount of uTokens to mint | ### redeem ```solidity function redeem(uint256 amountIn, uint256 amountOut) external ``` User redeems uTokens in exchange for the underlying asset *Assumes interest has already been accrued up to the current block* #### Parameters | Name | Type | Description | | --------- | ------- | --------------------------------------------------------------------------------------------------- | | amountIn | uint256 | The number of uTokens to redeem into underlying (only one of amountIn or amountOut may be non-zero) | | amountOut | uint256 | The number of underlying tokens to receive from (only one of amountIn or amountOut may be non-zero) | ### addReserves ```solidity function addReserves(uint256 addAmount) external ``` *Add tokens to the reseve* #### Parameters | Name | Type | Description | | --------- | ------- | ----------------------- | | addAmount | uint256 | amount of tokens to add | ### removeReserves ```solidity function removeReserves(address receiver, uint256 reduceAmount) external ``` *Remove tokens to the reseve* #### Parameters | Name | Type | Description | | ------------ | ------- | -------------------------- | | receiver | address | address to recieve tokens | | reduceAmount | uint256 | amount of tokens to remove | ### getBlockNumber ```solidity function getBlockNumber() internal view returns (uint256) ``` @dev Function to simply retrieve block number This exists mainly for inheriting test contracts to stub this result. ### \_depositToAssetManager ```solidity function _depositToAssetManager(uint256 amount) internal ``` @dev Deposit tokens to the asset manager