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Add PrudentiaInterestRateModel
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‎contracts/ionic/irms/PrudentiaInterestRateModel.sol

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// SPDX-License-Identifier: UNLICENSED
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pragma solidity >=0.8.0;
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import { InterestRateModel } from "../../compound/InterestRateModel.sol";
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import { IRateComputer } from "adrastia-periphery/rates/IRateComputer.sol";
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import { Math } from "@openzeppelin/contracts/utils/math/Math.sol";
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/**
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* @title Adrastia Prudentia Interest Rate Model
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* @author TRILEZ SOFTWARE INC.
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*/
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contract PrudentiaInterestRateModel is InterestRateModel {
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using Math for uint256;
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/**
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* @notice The address of the underlying token for which the interest rate model calculates rates.
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*/
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address public immutable underlyingToken;
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/**
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* @notice The address of the Adrastia Prudentia interest rate controller.
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*/
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IRateComputer public immutable rateController;
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/**
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* @notice The approximate number of blocks per year that is assumed by the interest rate model.
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*/
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uint256 public immutable blocksPerYear;
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/**
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* @notice Construct a new interest rate model that reads from an Adrastia Prudentia interest rate controller.
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*
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* @param blocksPerYear_ The approximate number of blocks per year that is assumed by the interest rate model.
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* @param underlyingToken_ The address of the underlying token for which the interest rate model calculates rates.
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* @param rateController_ The address of the Adrastia Prudentia interest rate controller.
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*/
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constructor(
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uint256 blocksPerYear_,
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address underlyingToken_,
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IRateComputer rateController_
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) {
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if (underlyingToken_ == address(0)) {
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revert("PrudentiaInterestRateModel: underlyingToken is the zero address");
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}
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if (address(rateController_) == address(0)) {
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revert("PrudentiaInterestRateModel: rateController is the zero address");
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}
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blocksPerYear = blocksPerYear_;
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underlyingToken = underlyingToken_;
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rateController = rateController_;
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}
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/**
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* @notice Calculates the utilization rate of the market: `borrows / (cash + borrows - reserves)`.
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*
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* @param cash The amount of cash in the market.
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* @param borrows The amount of borrows in the market.
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* @param reserves The amount of reserves in the market.
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*
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* @return The utilization rate as a mantissa between [0, 1e18].
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*/
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function utilizationRate(
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uint256 cash,
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uint256 borrows,
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uint256 reserves
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) public pure returns (uint256) {
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uint256 total = cash + borrows - reserves;
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if (total == 0) {
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// Utilization rate is zero when nothing is available (prevents division by zero)
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return 0;
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}
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return (borrows * 1e18) / total;
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}
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/**
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* @notice Calculates the current borrow rate per block by reading the current rate from the Adrastia Prudentia
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* interest rate controller.
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*
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* @param cash Not used.
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* @param borrows Not used.
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* @param reserves Not used.
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*
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* @return The borrow rate percentage per block as a mantissa (scaled by 1e18).
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*/
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function getBorrowRate(
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uint256 cash,
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uint256 borrows,
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uint256 reserves
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) public view override returns (uint256) {
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// Silence unused variable warnings
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cash;
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borrows;
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reserves;
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uint256 annualRate = rateController.computeRate(underlyingToken);
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return annualRate.ceilDiv(blocksPerYear); // Convert the annual rate to a per-block rate, rounding up
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}
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/**
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* @notice Calculates the current supply rate per block.
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*
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* @param cash The amount of cash in the market.
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* @param borrows The amount of borrows in the market.
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* @param reserves The amount of reserves in the market.
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* @param reserveFactorMantissa The current reserve factor for the market.
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*
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* @return The supply rate percentage per block as a mantissa (scaled by 1e18).
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*/
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function getSupplyRate(
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uint256 cash,
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uint256 borrows,
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uint256 reserves,
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uint256 reserveFactorMantissa
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) public view virtual override returns (uint256) {
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uint256 oneMinusReserveFactor = 1e18 - reserveFactorMantissa;
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uint256 borrowRate = getBorrowRate(cash, borrows, reserves);
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uint256 rateToPool = (borrowRate * oneMinusReserveFactor) / 1e18;
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return (utilizationRate(cash, borrows, reserves) * rateToPool) / 1e18;
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}
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}

‎contracts/test/irm/PrudentiaIrmTest.t.sol

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// SPDX-License-Identifier: UNLICENSED
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pragma solidity >=0.8.0;
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import { Math } from "@openzeppelin/contracts/utils/math/Math.sol";
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import { IRateComputer } from "adrastia-periphery/rates/IRateComputer.sol";
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import { BaseTest } from "../config/BaseTest.t.sol";
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import { PrudentiaInterestRateModel } from "../../ionic/irms/PrudentiaInterestRateModel.sol";
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contract MockRateComputer is IRateComputer {
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mapping(address => uint64) public rates;
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function computeRate(address token) external view override returns (uint64) {
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return rates[token];
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}
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function setRate(address token, uint64 rate) public {
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rates[token] = rate;
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}
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}
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contract PrudentiaIrmTest is BaseTest {
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using Math for uint64;
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MockRateComputer rateComputer;
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address token;
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PrudentiaInterestRateModel irm;
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uint256 blocksPerYear;
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function setUp() public {
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rateComputer = new MockRateComputer();
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token = address(0x1);
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blocksPerYear = 10512000;
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irm = new PrudentiaInterestRateModel(blocksPerYear, token, rateComputer);
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}
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function test_utilizationRate_zeroTotal() public {
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uint256 cash = 0;
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uint256 borrows = 0;
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uint256 reserves = 0;
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assertEq(irm.utilizationRate(cash, borrows, reserves), 0);
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}
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function test_utilizationRate_zero() public {
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uint256 cash = 100;
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uint256 borrows = 0;
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uint256 reserves = 0;
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assertEq(irm.utilizationRate(cash, borrows, reserves), 0);
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}
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function test_utilizationRate_50() public {
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uint256 cash = 100;
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uint256 borrows = 100;
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uint256 reserves = 0;
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assertEq(irm.utilizationRate(cash, borrows, reserves), 5e17);
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}
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function test_utilizationRate_100() public {
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uint256 cash = 0;
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uint256 borrows = 100;
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uint256 reserves = 0;
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assertEq(irm.utilizationRate(cash, borrows, reserves), 1e18);
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}
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function test_getBorrowRate_100_a() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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// These should have no effect
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uint256 cash = 0;
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uint256 borrows = 100;
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uint256 reserves = 0;
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assertEq(irm.getBorrowRate(cash, borrows, reserves), rate.ceilDiv(blocksPerYear));
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}
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function test_getBorrowRate_100_b() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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// These should have no effect
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uint256 cash = 100;
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uint256 borrows = 100;
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uint256 reserves = 0;
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assertEq(irm.getBorrowRate(cash, borrows, reserves), rate.ceilDiv(blocksPerYear));
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}
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function test_getBorrowRate_50() public {
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uint64 rate = 5e17;
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rateComputer.setRate(token, rate);
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// These should have no effect
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uint256 cash = 0;
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uint256 borrows = 0;
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uint256 reserves = 0;
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assertEq(irm.getBorrowRate(cash, borrows, reserves), rate.ceilDiv(blocksPerYear));
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}
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function test_getBorrowRate_1() public {
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uint64 rate = 1e16;
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rateComputer.setRate(token, rate);
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// These should have no effect
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uint256 cash = 0;
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uint256 borrows = 0;
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uint256 reserves = 0;
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assertEq(irm.getBorrowRate(cash, borrows, reserves), rate.ceilDiv(blocksPerYear));
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}
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function test_getBorrowRate_0() public {
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uint64 rate = 0;
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rateComputer.setRate(token, rate);
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// These should have no effect
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uint256 cash = 0;
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uint256 borrows = 0;
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uint256 reserves = 0;
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assertEq(irm.getBorrowRate(cash, borrows, reserves), rate.ceilDiv(blocksPerYear));
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}
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function test_getBorrowRate_1mantissa() public {
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uint64 rate = 1;
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rateComputer.setRate(token, rate);
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// These should have no effect
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uint256 cash = 0;
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uint256 borrows = 0;
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uint256 reserves = 0;
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assertEq(irm.getBorrowRate(cash, borrows, reserves), 1); // Rounds up to 1. We don't want to return 0.
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}
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function test_getSupplyRate_100_100util() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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uint256 cash = 0;
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uint256 borrows = 100;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), rate.ceilDiv(blocksPerYear));
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}
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function test_getSupplyRate_100_50util() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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uint256 cash = 100;
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uint256 borrows = 100;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), rate.ceilDiv(blocksPerYear) / 2);
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}
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function test_getSupplyRate_100_1util() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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uint256 cash = 99;
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uint256 borrows = 1;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), rate.ceilDiv(blocksPerYear) / 100);
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}
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function test_getSupplyRate_100_0util() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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uint256 cash = 100;
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uint256 borrows = 0;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), 0);
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}
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function test_getSupplyRate_0_0util() public {
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uint64 rate = 0;
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rateComputer.setRate(token, rate);
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uint256 cash = 0;
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uint256 borrows = 0;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), 0);
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}
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function test_getSupplyRate_0_100util() public {
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uint64 rate = 0;
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rateComputer.setRate(token, rate);
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uint256 cash = 0;
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uint256 borrows = 100;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), 0);
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}
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function test_getSupplyRate_0_50util() public {
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uint64 rate = 0;
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rateComputer.setRate(token, rate);
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uint256 cash = 50;
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uint256 borrows = 50;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), 0);
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}
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function test_getSupplyRate_0_1util() public {
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uint64 rate = 0;
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rateComputer.setRate(token, rate);
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uint256 cash = 99;
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uint256 borrows = 1;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 0;
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assertEq(irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa), 0);
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}
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function test_getSupplyRate_100_50util_10rf() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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uint256 cash = 100;
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uint256 borrows = 100;
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uint256 reserves = 0;
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uint256 reserveFactorMantissa = 1e17;
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assertEq(
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irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa),
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(uint256(rate.ceilDiv(blocksPerYear) / 2) * (1e18 - reserveFactorMantissa)) / 1e18
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);
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}
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function test_getSupplyRate_100_50util_10rf_10reserves() public {
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uint64 rate = 1e18;
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rateComputer.setRate(token, rate);
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uint256 cash = 100;
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uint256 borrows = 100;
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uint256 reserves = 10;
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cash += reserves;
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uint256 reserveFactorMantissa = 1e17;
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assertEq(
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irm.getSupplyRate(cash, borrows, reserves, reserveFactorMantissa),
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(uint256(rate.ceilDiv(blocksPerYear) / 2) * (1e18 - reserveFactorMantissa)) / 1e18
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);
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}
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}

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