Interest Rate Strategy

Implements the calculation of the interest rates depending on the reserve state. The model of interest rate is based on two slopes, one before the OPTIMAL_USAGE_RATIO point of usage and another from that point to 100%.

An instance of this same contract can't be used across different Nexus markets due to the caching of the PoolAddressesProvider.

The source code is available on GitHub.

View Methods

getVariableRateSlope1

function getVariableRateSlope1(address reserve) external view returns (uint256)

Returns the variable rate slope below the optimal usage ratio for the specified reserve. This is the variable rate when the usage ratio is between 0 and OPTIMAL_USAGE_RATIO.

Input Parameters:

Name	Type	Description
reserve	address	The address of the reserve

Return Values:

Type	Description
uint256	The variable rate slope

getVariableRateSlope2

function getVariableRateSlope2(address reserve) external view returns (uint256)

Returns the variable rate slope above the optimal usage ratio for the specified reserve. This is the variable rate when the usage ratio is greater than OPTIMAL_USAGE_RATIO.

Input Parameters:

Name	Type	Description
reserve	address	The address of the reserve

Return Values:

Type	Description
uint256	The variable rate slope

getBaseVariableBorrowRate

function getBaseVariableBorrowRate(address reserve) external view override returns (uint256)

Returns the base variable borrow rate for the specified reserve.

Input Parameters:

Name	Type	Description
reserve	address	The address of the reserve

Return Values:

Type	Description
uint256	The base variable borrow rate, expressed in ray

getMaxVariableBorrowRate

function getMaxVariableBorrowRate(address reserve) external view override returns (uint256)

Returns the maximum variable borrow rate for the specified reserve.

Input Parameters:

Name	Type	Description
reserve	address	The address of the reserve

Return Values:

Type	Description
uint256	The maximum variable borrow rate, expressed in ray

calculateInterestRates

function calculateInterestRates(    DataTypes.CalculateInterestRatesParams memory params) external view override returns (uint256, uint256)

Calculates the interest rates depending on the reserve's state and configurations. This function returns only two values: the liquidity rate and the variable borrow rate.

Input Parameters:

Name	Type	Description
params	DataTypes.CalculateInterestRatesParams	The parameters needed to calculate interest rates

The DataTypes.CalculateInterestRatesParams struct is composed of the following fields:

Name	Type	Description
unbacked	uint256	The amount of unbacked tokens
liquidityAdded	uint256	The liquidity added during the operation
liquidityTaken	uint256	The liquidity taken during the operation
totalDebt	uint256	The total borrowed from the reserve
reserveFactor	uint256	The reserve portion of the interest that goes to the treasury of the market
reserve	address	The address of the reserve
usingVirtualBalance	bool	Flag to indicate if the virtual balance is being used
virtualUnderlyingBalance	uint256	The virtual balance of underlying asset used for mintable assets

Return Values:

Name	Type	Description
liquidityRate	uint256	The liquidity rate, expressed in ray
variableBorrowRate	uint256	The variable borrow rate, expressed in ray