Merge pull request #136 from marginswap/werg-interest-handling

bettter interest handling when extinguishing
marginswap · May 3, 2021 · b009658 · b009658
2 parents 76cdc83 + 5284ee8
commit b009658
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Showing 3 changed files with 25 additions and 19 deletions.
diff --git a/contracts/CrossMarginAccounts.sol b/contracts/CrossMarginAccounts.sol
@@ -36,8 +36,6 @@ abstract contract CrossMarginAccounts is RoleAware, PriceAware {
     mapping(address => CrossMarginAccount) internal marginAccounts;
     /// @dev total token caps
     mapping(address => uint256) public tokenCaps;
-    /// @dev tracks total of short positions per token
-    mapping(address => uint256) public totalShort;
     /// @dev tracks total of long positions per token
     mapping(address => uint256) public totalLong;
     uint256 public coolingOffPeriod = 10;
@@ -285,7 +283,6 @@ abstract contract CrossMarginAccounts is RoleAware, PriceAware {
         uint256 len = account.borrowTokens.length;
         for (uint256 borrowIdx; len > borrowIdx; borrowIdx++) {
             address borrowToken = account.borrowTokens[borrowIdx];
-            totalShort[borrowToken] -= account.borrowed[borrowToken];
             account.borrowed[borrowToken] = 0;
             account.borrowedYieldQuotientsFP[borrowToken] = 0;
         }

diff --git a/contracts/CrossMarginTrading.sol b/contracts/CrossMarginTrading.sol
@@ -57,10 +57,18 @@ contract CrossMarginTrading is CrossMarginLiquidation, IMarginTrading {
         CrossMarginAccount storage account = marginAccounts[trader];
         account.lastDepositBlock = block.number;
 
-        if (account.borrowed[token] > 0) {
-            extinguishableDebt = min(depositAmount, account.borrowed[token]);
+        uint256 currentBorrowed = account.borrowed[token];
+        if (currentBorrowed > 0) {
+            (uint256 borrowAmount, uint256 yieldQuotientFP) =
+                Lending(lending()).applyBorrowInterest(
+                    currentBorrowed,
+                    token,
+                    account.borrowedYieldQuotientsFP[token]
+                );
+            account.borrowed[token] = borrowAmount;
+            account.borrowedYieldQuotientsFP[token] = yieldQuotientFP;
+            extinguishableDebt = min(depositAmount, borrowAmount);
             extinguishDebt(account, token, extinguishableDebt);
-            totalShort[token] -= extinguishableDebt;
         }
 
         // no overflow because depositAmount >= extinguishableDebt
@@ -99,11 +107,9 @@ contract CrossMarginTrading is CrossMarginLiquidation, IMarginTrading {
         address borrowToken,
         uint256 borrowAmount
     ) internal {
-        totalShort[borrowToken] += borrowAmount;
         totalLong[borrowToken] += borrowAmount;
         require(
-            tokenCaps[borrowToken] >= totalShort[borrowToken] &&
-                tokenCaps[borrowToken] >= totalLong[borrowToken],
+            tokenCaps[borrowToken] >= totalLong[borrowToken],
             "Exceeds global token cap"
         );
 
@@ -175,9 +181,17 @@ contract CrossMarginTrading is CrossMarginLiquidation, IMarginTrading {
         CrossMarginAccount storage account = marginAccounts[trader];
 
         if (account.borrowed[tokenTo] > 0) {
-            extinguishableDebt = min(outAmount, account.borrowed[tokenTo]);
+            (uint256 extantBorrow, uint256 yieldQuotientFP) =
+                Lending(lending()).applyBorrowInterest(
+                    account.borrowed[tokenTo],
+                    tokenTo,
+                    account.borrowedYieldQuotientsFP[tokenTo]
+                );
+            account.borrowed[tokenTo] = extantBorrow;
+            account.borrowedYieldQuotientsFP[tokenTo] = yieldQuotientFP;
+
+            extinguishableDebt = min(outAmount, extantBorrow);
             extinguishDebt(account, tokenTo, extinguishableDebt);
-            totalShort[tokenTo] -= extinguishableDebt;
         }
 
         uint256 sellAmount = inAmount;
@@ -208,11 +222,6 @@ contract CrossMarginTrading is CrossMarginLiquidation, IMarginTrading {
         );
 
         if (borrowAmount > 0) {
-            totalShort[tokenFrom] += borrowAmount;
-            require(
-                tokenCaps[tokenFrom] >= totalShort[tokenFrom],
-                "Exceeds global token cap"
-            );
             borrow(account, tokenFrom, borrowAmount);
         }
     }

diff --git a/contracts/PriceAware.sol b/contracts/PriceAware.sol
@@ -39,8 +39,8 @@ struct PairPrice {
 ///    of front-running and other price manipulation.
 abstract contract PriceAware is RoleAware {
     uint256 constant FP112 = 2**112;
-    uint256 constant FP8 = 2 ** 8;
-    uint256 constant FP96 = 2 ** (112 - 2 * 8);
+    uint256 constant FP8 = 2**8;
+    uint256 constant FP96 = 2**(112 - 2 * 8);
 
     address public immutable peg;
 
@@ -292,7 +292,7 @@ abstract contract PriceAware is RoleAware {
     }
 
     function scaleMul(uint256 a, uint256 b) internal pure returns (uint256) {
-        return (a / FP8) * (b / FP8) / FP96;
+        return ((a / FP8) * (b / FP8)) / FP96;
     }
 
     function initPairPrice(