Contract Name:
DefaultReserveInterestRateStrategy
Contract Source Code:
File 1 of 1 : DefaultReserveInterestRateStrategy
// SPDX-License-Identifier: agpl-3.0
pragma solidity 0.6.12;
/**
* @title IReserveInterestRateStrategyInterface interface
* @dev Interface for the calculation of the interest rates
* @author Aave
*/
interface IReserveInterestRateStrategy {
function baseVariableBorrowRate() external view returns (uint256);
function getMaxVariableBorrowRate() external view returns (uint256);
function calculateInterestRates(
address reserve,
uint256 utilizationRate,
uint256 totalStableDebt,
uint256 totalVariableDebt,
uint256 averageStableBorrowRate,
uint256 reserveFactor
)
external
view
returns (
uint256 liquidityRate,
uint256 stableBorrowRate,
uint256 variableBorrowRate
);
}
/**
* @title WadRayMath library
* @author Aave
* @dev Provides mul and div function for wads (decimal numbers with 18 digits precision) and rays (decimals with 27 digits)
**/
library WadRayMath {
uint256 internal constant WAD = 1e18;
uint256 internal constant halfWAD = WAD / 2;
uint256 internal constant RAY = 1e27;
uint256 internal constant halfRAY = RAY / 2;
uint256 internal constant WAD_RAY_RATIO = 1e9;
/**
* @return One ray, 1e27
**/
function ray() internal pure returns (uint256) {
return RAY;
}
/**
* @return One wad, 1e18
**/
function wad() internal pure returns (uint256) {
return WAD;
}
/**
* @return Half ray, 1e27/2
**/
function halfRay() internal pure returns (uint256) {
return halfRAY;
}
/**
* @return Half ray, 1e18/2
**/
function halfWad() internal pure returns (uint256) {
return halfWAD;
}
/**
* @dev Multiplies two wad, rounding half up to the nearest wad
* @param a Wad
* @param b Wad
* @return The result of a*b, in wad
**/
function wadMul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0 || b == 0) {
return 0;
}
require(a <= (type(uint256).max - halfWAD) / b, Errors.MATH_MULTIPLICATION_OVERFLOW);
return (a * b + halfWAD) / WAD;
}
/**
* @dev Divides two wad, rounding half up to the nearest wad
* @param a Wad
* @param b Wad
* @return The result of a/b, in wad
**/
function wadDiv(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0, Errors.MATH_DIVISION_BY_ZERO);
uint256 halfB = b / 2;
require(a <= (type(uint256).max - halfB) / WAD, Errors.MATH_MULTIPLICATION_OVERFLOW);
return (a * WAD + halfB) / b;
}
/**
* @dev Multiplies two ray, rounding half up to the nearest ray
* @param a Ray
* @param b Ray
* @return The result of a*b, in ray
**/
function rayMul(uint256 a, uint256 b) internal pure returns (uint256) {
if (a == 0 || b == 0) {
return 0;
}
require(a <= (type(uint256).max - halfRAY) / b, Errors.MATH_MULTIPLICATION_OVERFLOW);
return (a * b + halfRAY) / RAY;
}
/**
* @dev Divides two ray, rounding half up to the nearest ray
* @param a Ray
* @param b Ray
* @return The result of a/b, in ray
**/
function rayDiv(uint256 a, uint256 b) internal pure returns (uint256) {
require(b != 0, Errors.MATH_DIVISION_BY_ZERO);
uint256 halfB = b / 2;
require(a <= (type(uint256).max - halfB) / RAY, Errors.MATH_MULTIPLICATION_OVERFLOW);
return (a * RAY + halfB) / b;
}
/**
* @dev Casts ray down to wad
* @param a Ray
* @return a casted to wad, rounded half up to the nearest wad
**/
function rayToWad(uint256 a) internal pure returns (uint256) {
uint256 halfRatio = WAD_RAY_RATIO / 2;
uint256 result = halfRatio + a;
require(result >= halfRatio, Errors.MATH_ADDITION_OVERFLOW);
return result / WAD_RAY_RATIO;
}
/**
* @dev Converts wad up to ray
* @param a Wad
* @return a converted in ray
**/
function wadToRay(uint256 a) internal pure returns (uint256) {
uint256 result = a * WAD_RAY_RATIO;
require(result / WAD_RAY_RATIO == a, Errors.MATH_MULTIPLICATION_OVERFLOW);
return result;
}
}
/**
* @title Errors library
* @author Aave
* @notice Defines the error messages emitted by the different contracts of the Aave protocol
* @dev Error messages prefix glossary:
* - VL = ValidationLogic
* - MATH = Math libraries
* - CT = Common errors between tokens (AToken, VariableDebtToken and StableDebtToken)
* - AT = AToken
* - SDT = StableDebtToken
* - VDT = VariableDebtToken
* - LP = LendingPool
* - LPAPR = LendingPoolAddressesProviderRegistry
* - LPC = LendingPoolConfiguration
* - RL = ReserveLogic
* - LPCM = LendingPoolCollateralManager
* - P = Pausable
*/
library Errors {
//common errors
string public constant CALLER_NOT_POOL_ADMIN = '33'; // 'The caller must be the pool admin'
string public constant BORROW_ALLOWANCE_NOT_ENOUGH = '59'; // User borrows on behalf, but allowance are too small
//contract specific errors
string public constant VL_INVALID_AMOUNT = '1'; // 'Amount must be greater than 0'
string public constant VL_NO_ACTIVE_RESERVE = '2'; // 'Action requires an active reserve'
string public constant VL_RESERVE_FROZEN = '3'; // 'Action cannot be performed because the reserve is frozen'
string public constant VL_CURRENT_AVAILABLE_LIQUIDITY_NOT_ENOUGH = '4'; // 'The current liquidity is not enough'
string public constant VL_NOT_ENOUGH_AVAILABLE_USER_BALANCE = '5'; // 'User cannot withdraw more than the available balance'
string public constant VL_TRANSFER_NOT_ALLOWED = '6'; // 'Transfer cannot be allowed.'
string public constant VL_BORROWING_NOT_ENABLED = '7'; // 'Borrowing is not enabled'
string public constant VL_INVALID_INTEREST_RATE_MODE_SELECTED = '8'; // 'Invalid interest rate mode selected'
string public constant VL_COLLATERAL_BALANCE_IS_0 = '9'; // 'The collateral balance is 0'
string public constant VL_HEALTH_FACTOR_LOWER_THAN_LIQUIDATION_THRESHOLD = '10'; // 'Health factor is lesser than the liquidation threshold'
string public constant VL_COLLATERAL_CANNOT_COVER_NEW_BORROW = '11'; // 'There is not enough collateral to cover a new borrow'
string public constant VL_STABLE_BORROWING_NOT_ENABLED = '12'; // stable borrowing not enabled
string public constant VL_COLLATERAL_SAME_AS_BORROWING_CURRENCY = '13'; // collateral is (mostly) the same currency that is being borrowed
string public constant VL_AMOUNT_BIGGER_THAN_MAX_LOAN_SIZE_STABLE = '14'; // 'The requested amount is greater than the max loan size in stable rate mode
string public constant VL_NO_DEBT_OF_SELECTED_TYPE = '15'; // 'for repayment of stable debt, the user needs to have stable debt, otherwise, he needs to have variable debt'
string public constant VL_NO_EXPLICIT_AMOUNT_TO_REPAY_ON_BEHALF = '16'; // 'To repay on behalf of an user an explicit amount to repay is needed'
string public constant VL_NO_STABLE_RATE_LOAN_IN_RESERVE = '17'; // 'User does not have a stable rate loan in progress on this reserve'
string public constant VL_NO_VARIABLE_RATE_LOAN_IN_RESERVE = '18'; // 'User does not have a variable rate loan in progress on this reserve'
string public constant VL_UNDERLYING_BALANCE_NOT_GREATER_THAN_0 = '19'; // 'The underlying balance needs to be greater than 0'
string public constant VL_DEPOSIT_ALREADY_IN_USE = '20'; // 'User deposit is already being used as collateral'
string public constant LP_NOT_ENOUGH_STABLE_BORROW_BALANCE = '21'; // 'User does not have any stable rate loan for this reserve'
string public constant LP_INTEREST_RATE_REBALANCE_CONDITIONS_NOT_MET = '22'; // 'Interest rate rebalance conditions were not met'
string public constant LP_LIQUIDATION_CALL_FAILED = '23'; // 'Liquidation call failed'
string public constant LP_NOT_ENOUGH_LIQUIDITY_TO_BORROW = '24'; // 'There is not enough liquidity available to borrow'
string public constant LP_REQUESTED_AMOUNT_TOO_SMALL = '25'; // 'The requested amount is too small for a FlashLoan.'
string public constant LP_INCONSISTENT_PROTOCOL_ACTUAL_BALANCE = '26'; // 'The actual balance of the protocol is inconsistent'
string public constant LP_CALLER_NOT_LENDING_POOL_CONFIGURATOR = '27'; // 'The caller of the function is not the lending pool configurator'
string public constant LP_INCONSISTENT_FLASHLOAN_PARAMS = '28';
string public constant CT_CALLER_MUST_BE_LENDING_POOL = '29'; // 'The caller of this function must be a lending pool'
string public constant CT_CANNOT_GIVE_ALLOWANCE_TO_HIMSELF = '30'; // 'User cannot give allowance to himself'
string public constant CT_TRANSFER_AMOUNT_NOT_GT_0 = '31'; // 'Transferred amount needs to be greater than zero'
string public constant RL_RESERVE_ALREADY_INITIALIZED = '32'; // 'Reserve has already been initialized'
string public constant LPC_RESERVE_LIQUIDITY_NOT_0 = '34'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_ATOKEN_POOL_ADDRESS = '35'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_STABLE_DEBT_TOKEN_POOL_ADDRESS = '36'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_VARIABLE_DEBT_TOKEN_POOL_ADDRESS = '37'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_STABLE_DEBT_TOKEN_UNDERLYING_ADDRESS = '38'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_VARIABLE_DEBT_TOKEN_UNDERLYING_ADDRESS = '39'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_ADDRESSES_PROVIDER_ID = '40'; // 'The liquidity of the reserve needs to be 0'
string public constant LPC_INVALID_CONFIGURATION = '75'; // 'Invalid risk parameters for the reserve'
string public constant LPC_CALLER_NOT_EMERGENCY_ADMIN = '76'; // 'The caller must be the emergency admin'
string public constant LPAPR_PROVIDER_NOT_REGISTERED = '41'; // 'Provider is not registered'
string public constant LPCM_HEALTH_FACTOR_NOT_BELOW_THRESHOLD = '42'; // 'Health factor is not below the threshold'
string public constant LPCM_COLLATERAL_CANNOT_BE_LIQUIDATED = '43'; // 'The collateral chosen cannot be liquidated'
string public constant LPCM_SPECIFIED_CURRENCY_NOT_BORROWED_BY_USER = '44'; // 'User did not borrow the specified currency'
string public constant LPCM_NOT_ENOUGH_LIQUIDITY_TO_LIQUIDATE = '45'; // "There isn't enough liquidity available to liquidate"
string public constant LPCM_NO_ERRORS = '46'; // 'No errors'
string public constant LP_INVALID_FLASHLOAN_MODE = '47'; //Invalid flashloan mode selected
string public constant MATH_MULTIPLICATION_OVERFLOW = '48';
string public constant MATH_ADDITION_OVERFLOW = '49';
string public constant MATH_DIVISION_BY_ZERO = '50';
string public constant RL_LIQUIDITY_INDEX_OVERFLOW = '51'; // Liquidity index overflows uint128
string public constant RL_VARIABLE_BORROW_INDEX_OVERFLOW = '52'; // Variable borrow index overflows uint128
string public constant RL_LIQUIDITY_RATE_OVERFLOW = '53'; // Liquidity rate overflows uint128
string public constant RL_VARIABLE_BORROW_RATE_OVERFLOW = '54'; // Variable borrow rate overflows uint128
string public constant RL_STABLE_BORROW_RATE_OVERFLOW = '55'; // Stable borrow rate overflows uint128
string public constant CT_INVALID_MINT_AMOUNT = '56'; //invalid amount to mint
string public constant LP_FAILED_REPAY_WITH_COLLATERAL = '57';
string public constant CT_INVALID_BURN_AMOUNT = '58'; //invalid amount to burn
string public constant LP_FAILED_COLLATERAL_SWAP = '60';
string public constant LP_INVALID_EQUAL_ASSETS_TO_SWAP = '61';
string public constant LP_REENTRANCY_NOT_ALLOWED = '62';
string public constant LP_CALLER_MUST_BE_AN_ATOKEN = '63';
string public constant LP_IS_PAUSED = '64'; // 'Pool is paused'
string public constant LP_NO_MORE_RESERVES_ALLOWED = '65';
string public constant LP_INVALID_FLASH_LOAN_EXECUTOR_RETURN = '66';
string public constant RC_INVALID_LTV = '67';
string public constant RC_INVALID_LIQ_THRESHOLD = '68';
string public constant RC_INVALID_LIQ_BONUS = '69';
string public constant RC_INVALID_DECIMALS = '70';
string public constant RC_INVALID_RESERVE_FACTOR = '71';
string public constant LPAPR_INVALID_ADDRESSES_PROVIDER_ID = '72';
string public constant VL_INCONSISTENT_FLASHLOAN_PARAMS = '73';
string public constant LP_INCONSISTENT_PARAMS_LENGTH = '74';
string public constant UL_INVALID_INDEX = '77';
string public constant LP_NOT_CONTRACT = '78';
string public constant SDT_STABLE_DEBT_OVERFLOW = '79';
string public constant SDT_BURN_EXCEEDS_BALANCE = '80';
enum CollateralManagerErrors {
NO_ERROR,
NO_COLLATERAL_AVAILABLE,
COLLATERAL_CANNOT_BE_LIQUIDATED,
CURRRENCY_NOT_BORROWED,
HEALTH_FACTOR_ABOVE_THRESHOLD,
NOT_ENOUGH_LIQUIDITY,
NO_ACTIVE_RESERVE,
HEALTH_FACTOR_LOWER_THAN_LIQUIDATION_THRESHOLD,
INVALID_EQUAL_ASSETS_TO_SWAP,
FROZEN_RESERVE
}
}
/**
* @title PercentageMath library
* @author Aave
* @notice Provides functions to perform percentage calculations
* @dev Percentages are defined by default with 2 decimals of precision (100.00). The precision is indicated by PERCENTAGE_FACTOR
* @dev Operations are rounded half up
**/
library PercentageMath {
uint256 constant PERCENTAGE_FACTOR = 1e4; //percentage plus two decimals
uint256 constant HALF_PERCENT = PERCENTAGE_FACTOR / 2;
/**
* @dev Executes a percentage multiplication
* @param value The value of which the percentage needs to be calculated
* @param percentage The percentage of the value to be calculated
* @return The percentage of value
**/
function percentMul(uint256 value, uint256 percentage) internal pure returns (uint256) {
if (value == 0 || percentage == 0) {
return 0;
}
require(
value <= (type(uint256).max - HALF_PERCENT) / percentage,
Errors.MATH_MULTIPLICATION_OVERFLOW
);
return (value * percentage + HALF_PERCENT) / PERCENTAGE_FACTOR;
}
/**
* @dev Executes a percentage division
* @param value The value of which the percentage needs to be calculated
* @param percentage The percentage of the value to be calculated
* @return The value divided the percentage
**/
function percentDiv(uint256 value, uint256 percentage) internal pure returns (uint256) {
require(percentage != 0, Errors.MATH_DIVISION_BY_ZERO);
uint256 halfPercentage = percentage / 2;
require(
value <= (type(uint256).max - halfPercentage) / PERCENTAGE_FACTOR,
Errors.MATH_MULTIPLICATION_OVERFLOW
);
return (value * PERCENTAGE_FACTOR + halfPercentage) / percentage;
}
}
/**
* @title LendingPoolAddressesProvider contract
* @dev Main registry of addresses part of or connected to the protocol, including permissioned roles
* - Acting also as factory of proxies and admin of those, so with right to change its implementations
* - Owned by the Aave Governance
* @author Aave
**/
interface ILendingPoolAddressesProvider {
event MarketIdSet(string newMarketId);
event LendingPoolUpdated(address indexed newAddress);
event ConfigurationAdminUpdated(address indexed newAddress);
event EmergencyAdminUpdated(address indexed newAddress);
event LendingPoolConfiguratorUpdated(address indexed newAddress);
event LendingPoolCollateralManagerUpdated(address indexed newAddress);
event PriceOracleUpdated(address indexed newAddress);
event LendingRateOracleUpdated(address indexed newAddress);
event ProxyCreated(bytes32 id, address indexed newAddress);
event AddressSet(bytes32 id, address indexed newAddress, bool hasProxy);
function getMarketId() external view returns (string memory);
function setMarketId(string calldata marketId) external;
function setAddress(bytes32 id, address newAddress) external;
function setAddressAsProxy(bytes32 id, address impl) external;
function getAddress(bytes32 id) external view returns (address);
function getLendingPool() external view returns (address);
function setLendingPoolImpl(address pool) external;
function getLendingPoolConfigurator() external view returns (address);
function setLendingPoolConfiguratorImpl(address configurator) external;
function getLendingPoolCollateralManager() external view returns (address);
function setLendingPoolCollateralManager(address manager) external;
function getPoolAdmin() external view returns (address);
function setPoolAdmin(address admin) external;
function getEmergencyAdmin() external view returns (address);
function setEmergencyAdmin(address admin) external;
function getPriceOracle() external view returns (address);
function setPriceOracle(address priceOracle) external;
function getLendingRateOracle() external view returns (address);
function setLendingRateOracle(address lendingRateOracle) external;
}
/**
* @title ILendingRateOracle interface
* @notice Interface for the Aave borrow rate oracle. Provides the average market borrow rate to be used as a base for the stable borrow rate calculations
**/
interface ILendingRateOracle {
/**
@dev returns the market borrow rate in ray
**/
function getMarketBorrowRate(address asset) external view returns (uint256);
/**
@dev sets the market borrow rate. Rate value must be in ray
**/
function setMarketBorrowRate(address asset, uint256 rate) external;
}
/**
* @dev Wrappers over Solidity's arithmetic operations with added overflow
* checks.
*
* Arithmetic operations in Solidity wrap on overflow. This can easily result
* in bugs, because programmers usually assume that an overflow raises an
* error, which is the standard behavior in high level programming languages.
* `SafeMath` restores this intuition by reverting the transaction when an
* operation overflows.
*
* Using this library instead of the unchecked operations eliminates an entire
* class of bugs, so it's recommended to use it always.
*/
library SafeMath {
/**
* @dev Returns the addition of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `+` operator.
*
* Requirements:
* - Addition cannot overflow.
*/
function add(uint256 a, uint256 b) internal pure returns (uint256) {
uint256 c = a + b;
require(c >= a, 'SafeMath: addition overflow');
return c;
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*/
function sub(uint256 a, uint256 b) internal pure returns (uint256) {
return sub(a, b, 'SafeMath: subtraction overflow');
}
/**
* @dev Returns the subtraction of two unsigned integers, reverting with custom message on
* overflow (when the result is negative).
*
* Counterpart to Solidity's `-` operator.
*
* Requirements:
* - Subtraction cannot overflow.
*/
function sub(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
require(b <= a, errorMessage);
uint256 c = a - b;
return c;
}
/**
* @dev Returns the multiplication of two unsigned integers, reverting on
* overflow.
*
* Counterpart to Solidity's `*` operator.
*
* Requirements:
* - Multiplication cannot overflow.
*/
function mul(uint256 a, uint256 b) internal pure returns (uint256) {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) {
return 0;
}
uint256 c = a * b;
require(c / a == b, 'SafeMath: multiplication overflow');
return c;
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function div(uint256 a, uint256 b) internal pure returns (uint256) {
return div(a, b, 'SafeMath: division by zero');
}
/**
* @dev Returns the integer division of two unsigned integers. Reverts with custom message on
* division by zero. The result is rounded towards zero.
*
* Counterpart to Solidity's `/` operator. Note: this function uses a
* `revert` opcode (which leaves remaining gas untouched) while Solidity
* uses an invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function div(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
// Solidity only automatically asserts when dividing by 0
require(b > 0, errorMessage);
uint256 c = a / b;
// assert(a == b * c + a % b); // There is no case in which this doesn't hold
return c;
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function mod(uint256 a, uint256 b) internal pure returns (uint256) {
return mod(a, b, 'SafeMath: modulo by zero');
}
/**
* @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
* Reverts with custom message when dividing by zero.
*
* Counterpart to Solidity's `%` operator. This function uses a `revert`
* opcode (which leaves remaining gas untouched) while Solidity uses an
* invalid opcode to revert (consuming all remaining gas).
*
* Requirements:
* - The divisor cannot be zero.
*/
function mod(
uint256 a,
uint256 b,
string memory errorMessage
) internal pure returns (uint256) {
require(b != 0, errorMessage);
return a % b;
}
}
/**
* @title DefaultReserveInterestRateStrategy contract
* @notice Implements the calculation of the interest rates depending on the reserve state
* @dev The model of interest rate is based on 2 slopes, one before the `OPTIMAL_UTILIZATION_RATE`
* point of utilization and another from that one to 100%
* - An instance of this same contract, can't be used across different Aave markets, due to the caching
* of the LendingPoolAddressesProvider
* @author Aave
**/
contract DefaultReserveInterestRateStrategy is IReserveInterestRateStrategy {
using WadRayMath for uint256;
using SafeMath for uint256;
using PercentageMath for uint256;
/**
* @dev this constant represents the utilization rate at which the pool aims to obtain most competitive borrow rates.
* Expressed in ray
**/
uint256 public immutable OPTIMAL_UTILIZATION_RATE;
/**
* @dev This constant represents the excess utilization rate above the optimal. It's always equal to
* 1-optimal utilization rate. Added as a constant here for gas optimizations.
* Expressed in ray
**/
uint256 public immutable EXCESS_UTILIZATION_RATE;
ILendingPoolAddressesProvider public immutable addressesProvider;
// Base variable borrow rate when Utilization rate = 0. Expressed in ray
uint256 internal immutable _baseVariableBorrowRate;
// Slope of the variable interest curve when utilization rate > 0 and <= OPTIMAL_UTILIZATION_RATE. Expressed in ray
uint256 internal immutable _variableRateSlope1;
// Slope of the variable interest curve when utilization rate > OPTIMAL_UTILIZATION_RATE. Expressed in ray
uint256 internal immutable _variableRateSlope2;
// Slope of the stable interest curve when utilization rate > 0 and <= OPTIMAL_UTILIZATION_RATE. Expressed in ray
uint256 internal immutable _stableRateSlope1;
// Slope of the stable interest curve when utilization rate > OPTIMAL_UTILIZATION_RATE. Expressed in ray
uint256 internal immutable _stableRateSlope2;
constructor(
ILendingPoolAddressesProvider provider,
uint256 optimalUtilizationRate,
uint256 baseVariableBorrowRate,
uint256 variableRateSlope1,
uint256 variableRateSlope2,
uint256 stableRateSlope1,
uint256 stableRateSlope2
) public {
OPTIMAL_UTILIZATION_RATE = optimalUtilizationRate;
EXCESS_UTILIZATION_RATE = WadRayMath.ray().sub(optimalUtilizationRate);
addressesProvider = provider;
_baseVariableBorrowRate = baseVariableBorrowRate;
_variableRateSlope1 = variableRateSlope1;
_variableRateSlope2 = variableRateSlope2;
_stableRateSlope1 = stableRateSlope1;
_stableRateSlope2 = stableRateSlope2;
}
function variableRateSlope1() external view returns (uint256) {
return _variableRateSlope1;
}
function variableRateSlope2() external view returns (uint256) {
return _variableRateSlope2;
}
function stableRateSlope1() external view returns (uint256) {
return _stableRateSlope1;
}
function stableRateSlope2() external view returns (uint256) {
return _stableRateSlope2;
}
function baseVariableBorrowRate() external view override returns (uint256) {
return _baseVariableBorrowRate;
}
function getMaxVariableBorrowRate() external view override returns (uint256) {
return _baseVariableBorrowRate.add(_variableRateSlope1).add(_variableRateSlope2);
}
struct CalcInterestRatesLocalVars {
uint256 totalDebt;
uint256 currentVariableBorrowRate;
uint256 currentStableBorrowRate;
uint256 currentLiquidityRate;
uint256 utilizationRate;
}
/**
* @dev Calculates the interest rates depending on the reserve's state and configurations
* @param reserve The address of the reserve
* @param availableLiquidity The liquidity available in the reserve
* @param totalStableDebt The total borrowed from the reserve a stable rate
* @param totalVariableDebt The total borrowed from the reserve at a variable rate
* @param averageStableBorrowRate The weighted average of all the stable rate loans
* @param reserveFactor The reserve portion of the interest that goes to the treasury of the market
* @return The liquidity rate, the stable borrow rate and the variable borrow rate
**/
function calculateInterestRates(
address reserve,
uint256 availableLiquidity,
uint256 totalStableDebt,
uint256 totalVariableDebt,
uint256 averageStableBorrowRate,
uint256 reserveFactor
)
external
view
override
returns (
uint256,
uint256,
uint256
)
{
CalcInterestRatesLocalVars memory vars;
vars.totalDebt = totalStableDebt.add(totalVariableDebt);
vars.currentVariableBorrowRate = 0;
vars.currentStableBorrowRate = 0;
vars.currentLiquidityRate = 0;
uint256 utilizationRate =
vars.totalDebt == 0
? 0
: vars.totalDebt.rayDiv(availableLiquidity.add(vars.totalDebt));
vars.currentStableBorrowRate = ILendingRateOracle(addressesProvider.getLendingRateOracle())
.getMarketBorrowRate(reserve);
if (utilizationRate > OPTIMAL_UTILIZATION_RATE) {
uint256 excessUtilizationRateRatio =
utilizationRate.sub(OPTIMAL_UTILIZATION_RATE).rayDiv(EXCESS_UTILIZATION_RATE);
vars.currentStableBorrowRate = vars.currentStableBorrowRate.add(_stableRateSlope1).add(
_stableRateSlope2.rayMul(excessUtilizationRateRatio)
);
vars.currentVariableBorrowRate = _baseVariableBorrowRate.add(_variableRateSlope1).add(
_variableRateSlope2.rayMul(excessUtilizationRateRatio)
);
} else {
vars.currentStableBorrowRate = vars.currentStableBorrowRate.add(
_stableRateSlope1.rayMul(utilizationRate.rayDiv(OPTIMAL_UTILIZATION_RATE))
);
vars.currentVariableBorrowRate = _baseVariableBorrowRate.add(
utilizationRate.rayMul(_variableRateSlope1).rayDiv(OPTIMAL_UTILIZATION_RATE)
);
}
vars.currentLiquidityRate = _getOverallBorrowRate(
totalStableDebt,
totalVariableDebt,
vars
.currentVariableBorrowRate,
averageStableBorrowRate
)
.rayMul(utilizationRate)
.percentMul(PercentageMath.PERCENTAGE_FACTOR.sub(reserveFactor));
return (
vars.currentLiquidityRate,
vars.currentStableBorrowRate,
vars.currentVariableBorrowRate
);
}
/**
* @dev Calculates the overall borrow rate as the weighted average between the total variable debt and total stable debt
* @param totalStableDebt The total borrowed from the reserve a stable rate
* @param totalVariableDebt The total borrowed from the reserve at a variable rate
* @param currentVariableBorrowRate The current variable borrow rate of the reserve
* @param currentAverageStableBorrowRate The current weighted average of all the stable rate loans
* @return The weighted averaged borrow rate
**/
function _getOverallBorrowRate(
uint256 totalStableDebt,
uint256 totalVariableDebt,
uint256 currentVariableBorrowRate,
uint256 currentAverageStableBorrowRate
) internal pure returns (uint256) {
uint256 totalDebt = totalStableDebt.add(totalVariableDebt);
if (totalDebt == 0) return 0;
uint256 weightedVariableRate = totalVariableDebt.wadToRay().rayMul(currentVariableBorrowRate);
uint256 weightedStableRate = totalStableDebt.wadToRay().rayMul(currentAverageStableBorrowRate);
uint256 overallBorrowRate =
weightedVariableRate.add(weightedStableRate).rayDiv(totalDebt.wadToRay());
return overallBorrowRate;
}
}