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Fixes stable borrow debt

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This commit is contained in:
The3D 2020-11-11 15:54:08 +01:00
parent c01e77b55b
commit 81c0fbcb02
2 changed files with 19 additions and 11 deletions
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28
contracts/tokenization/StableDebtToken.sol
View File

@ -18,7 +18,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
uint256 internal _avgStableRate;
mapping(address => uint40) internal _timestamps;
mapping(address => uint256) internal _usersData;
mapping(address => uint256) internal _usersStableRate;
uint40 internal _totalSupplyTimestamp;
constructor(
@ -59,7 +59,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
* @return the stable rate of user
**/
function getUserStableRate(address user) external virtual override view returns (uint256) {
return _usersData[user];
return _usersStableRate[user];
}
/**
@ -68,7 +68,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
**/
function balanceOf(address account) public virtual override view returns (uint256) {
uint256 accountBalance = super.balanceOf(account);
uint256 stableRate = _usersData[account];
uint256 stableRate = _usersStableRate[account];
if (accountBalance == 0) {
return 0;
}
@ -117,13 +117,13 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
vars.amountInRay = amount.wadToRay();
//calculates the new stable rate for the user
vars.newStableRate = _usersData[onBehalfOf]
vars.newStableRate = _usersStableRate[onBehalfOf]
.rayMul(currentBalance.wadToRay())
.add(vars.amountInRay.rayMul(rate))
.rayDiv(currentBalance.add(amount).wadToRay());
require(vars.newStableRate < (1 << 128), 'Debt token: stable rate overflow');
_usersData[onBehalfOf] = vars.newStableRate;
_usersStableRate[onBehalfOf] = vars.newStableRate;
//updating the user and supply timestamp
//solium-disable-next-line
@ -166,6 +166,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
uint256 previousSupply = totalSupply();
uint256 newStableRate = 0;
uint256 nextSupply = 0;
uint256 userStableRate = _usersStableRate[user];
//since the total supply and each single user debt accrue separately,
//there might be accumulation errors so that the last borrower repaying
@ -176,14 +177,21 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
_totalSupply = 0;
} else {
nextSupply = _totalSupply = previousSupply.sub(amount);
newStableRate = _avgStableRate = _avgStableRate
.rayMul(previousSupply.wadToRay())
.sub(_usersData[user].rayMul(amount.wadToRay()))
.rayDiv(nextSupply.wadToRay());
uint256 firstTerm = _avgStableRate.rayMul(previousSupply.wadToRay());
uint256 secondTerm = userStableRate.rayMul(amount.wadToRay());
//for the same reason described above, when the last user is repaying it might
//happen that user rate * user balance > avg rate * total supply. In that case,
//we simply set the avg rate to 0
if (secondTerm >= firstTerm) {
newStableRate = _avgStableRate = _totalSupply = 0;
} else {
newStableRate = _avgStableRate = firstTerm.sub(secondTerm).rayDiv(nextSupply.wadToRay());
}
}
if (amount == currentBalance) {
_usersData[user] = 0;
_usersStableRate[user] = 0;
_timestamps[user] = 0;
} else {
//solium-disable-next-line

2
deployed-contracts.json
View File

@ -1285,4 +1285,4 @@
"address": "0xaDF23b1cAa6a7B3b077c432794FfF80A4b935cdF"
}
}
}
}