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contracts/, tests/: add getUserHealthFactor #144

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65 changes: 54 additions & 11 deletions contracts/Comptroller.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -340,7 +340,7 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
}

/* Otherwise, perform a hypothetical liquidity check to guard against shortfall */
(Error err, , uint256 shortfall) = getHypotheticalAccountLiquidityInternal(
(Error err, , uint256 shortfall, , ) = getHypotheticalAccountLiquidityInternal(
redeemer,
CToken(cToken),
redeemTokens,
Expand Down Expand Up @@ -424,7 +424,7 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
require(nextTotalBorrows < borrowCap, "market borrow cap reached");
}

(Error err, , uint256 shortfall) = getHypotheticalAccountLiquidityInternal(
(Error err, , uint256 shortfall, , ) = getHypotheticalAccountLiquidityInternal(
borrower,
CToken(cToken),
0,
Expand Down Expand Up @@ -769,7 +769,7 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
uint256
)
{
(Error err, uint256 liquidity, uint256 shortfall) = getHypotheticalAccountLiquidityInternal(
(Error err, uint256 liquidity, uint256 shortfall, , ) = getHypotheticalAccountLiquidityInternal(
account,
CToken(0),
0,
Expand All @@ -779,6 +779,27 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
return (uint256(err), liquidity, shortfall);
}

/**
* @notice Get user current health factor
* @dev The higher the helath factor is, the safer the state of the user's funds are against a liquidation scenario.
* If the health factor reaches 1e18, the liquidation of your deposits will be triggered.
* @return The user health factor, scaled by 1e18
*/
function getUserHealthFactor(address account) public view returns (uint256) {
(Error err, , , uint256 totalCollateral, uint256 totalBorrow) = getHypotheticalAccountLiquidityInternal(
account,
CToken(0),
0,
0
);
require(err == Error.NO_ERROR, "failed to get account liquidity");

if (totalBorrow == 0) {
return uint256(-1);
}
return div_(totalCollateral, Exp({mantissa: totalBorrow}));
}

/**
* @notice Determine the current account liquidity wrt collateral requirements
* @return (possible error code,
Expand All @@ -794,7 +815,13 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
uint256
)
{
return getHypotheticalAccountLiquidityInternal(account, CToken(0), 0, 0);
(Error err, uint256 liquidity, uint256 shortfall, , ) = getHypotheticalAccountLiquidityInternal(
account,
CToken(0),
0,
0
);
return (err, liquidity, shortfall);
}

/**
Expand All @@ -821,7 +848,7 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
uint256
)
{
(Error err, uint256 liquidity, uint256 shortfall) = getHypotheticalAccountLiquidityInternal(
(Error err, uint256 liquidity, uint256 shortfall, , ) = getHypotheticalAccountLiquidityInternal(
account,
CToken(cTokenModify),
redeemTokens,
Expand All @@ -839,8 +866,10 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
* @dev Note that we calculate the exchangeRateStored for each collateral cToken using stored data,
* without calculating accumulated interest.
* @return (possible error code,
hypothetical account liquidity in excess of collateral requirements,
* hypothetical account shortfall below collateral requirements)
* hypothetical account liquidity in excess of collateral requirements,
* hypothetical account shortfall below collateral requirements,
* hypothetical account total collateral value,
* hypothetical account total borrow value)
*/
function getHypotheticalAccountLiquidityInternal(
address account,
Expand All @@ -853,6 +882,8 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
returns (
Error,
uint256,
uint256,
uint256,
uint256
)
{
Expand All @@ -870,7 +901,7 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
);
if (oErr != 0) {
// semi-opaque error code, we assume NO_ERROR == 0 is invariant between upgrades
return (Error.SNAPSHOT_ERROR, 0, 0);
return (Error.SNAPSHOT_ERROR, 0, 0, 0, 0);
}

// Unlike compound protocol, getUnderlyingPrice is relatively expensive because we use ChainLink as our primary price feed.
Expand All @@ -885,7 +916,7 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE
// Get the normalized price of the asset
vars.oraclePriceMantissa = oracle.getUnderlyingPrice(asset);
if (vars.oraclePriceMantissa == 0) {
return (Error.PRICE_ERROR, 0, 0);
return (Error.PRICE_ERROR, 0, 0, 0, 0);
}
vars.oraclePrice = Exp({mantissa: vars.oraclePriceMantissa});

Expand Down Expand Up @@ -924,9 +955,21 @@ contract Comptroller is ComptrollerV7Storage, ComptrollerInterface, ComptrollerE

// These are safe, as the underflow condition is checked first
if (vars.sumCollateral > vars.sumBorrowPlusEffects) {
return (Error.NO_ERROR, vars.sumCollateral - vars.sumBorrowPlusEffects, 0);
return (
Error.NO_ERROR,
vars.sumCollateral - vars.sumBorrowPlusEffects,
0,
vars.sumCollateral,
vars.sumBorrowPlusEffects
);
} else {
return (Error.NO_ERROR, 0, vars.sumBorrowPlusEffects - vars.sumCollateral);
return (
Error.NO_ERROR,
0,
vars.sumBorrowPlusEffects - vars.sumCollateral,
vars.sumCollateral,
vars.sumBorrowPlusEffects
);
}
}

Expand Down
34 changes: 34 additions & 0 deletions tests/Comptroller/accountLiquidityTest.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,10 @@ const {
enterMarkets,
quickMint
} = require('../Utils/Compound');
const {
etherMantissa,
UInt256Max
} = require('../Utils/Ethereum');

describe('Comptroller', () => {
let root, accounts;
Expand All @@ -20,6 +24,8 @@ describe('Comptroller', () => {
await quickMint(cToken, user, amount);
let result = await call(cToken.comptroller, 'getAccountLiquidity', [user]);
expect(result).toHaveTrollError('PRICE_ERROR');

await expect(call(cToken.comptroller, 'getUserHealthFactor', [user])).rejects.toRevert('revert failed to get account liquidity');
});

it("allows a borrow up to collateralFactor, but not more", async () => {
Expand Down Expand Up @@ -71,6 +77,9 @@ describe('Comptroller', () => {
expect(liquidity).toEqualNumber(collateral);
expect(shortfall).toEqualNumber(0);

const healthFactor = await call(cToken3.comptroller, 'getUserHealthFactor', [user]);
expect(healthFactor).toEqualNumber(UInt256Max());

({1: liquidity, 2: shortfall} = await call(cToken3.comptroller, 'getHypotheticalAccountLiquidity', [user, cToken3._address, Math.floor(c2), 0]));
expect(liquidity).toEqualNumber(collateral);
expect(shortfall).toEqualNumber(0);
Expand Down Expand Up @@ -122,4 +131,29 @@ describe('Comptroller', () => {
expect(shortfall).toEqualNumber(0);
});
});

describe("getUserHealthFactor", () => {
it('gets the user health factor', async () => {
const amount1 = 1e6, amount2 = 1e3, amount3 = 1e3, user = accounts[1];
const cf1 = 0.5, cf2 = 0.5, up1 = 1, up2 = 100;
const c1 = amount1 * cf1 * up1, c2 = amount2 * cf2 * up2
const collateral = Math.floor(c1 + c2);
const borrow = amount3 * up1;
const cToken1 = await makeCToken({supportMarket: true, collateralFactor: cf1, underlyingPrice: up1});
const cToken2 = await makeCToken({supportMarket: true, comptroller: cToken1.comptroller, collateralFactor: cf2, underlyingPrice: up2});

await enterMarkets([cToken1, cToken2], user);
await quickMint(cToken1, user, amount1);
await quickMint(cToken2, user, amount2);
await send(cToken1, 'harnessBorrowFresh', [user, amount3]);

({0: error, 1: liquidity, 2: shortfall} = await call(cToken2.comptroller, 'getAccountLiquidity', [user]));
expect(error).toEqualNumber(0);
expect(liquidity).toEqualNumber(collateral - borrow);
expect(shortfall).toEqualNumber(0);

const healthFactor = await call(cToken2.comptroller, 'getUserHealthFactor', [user]);
expect(healthFactor).toEqualNumber(etherMantissa(collateral / borrow));
});
});
});