SIP-182 Wrapper Factory

contracts/BaseDebtCache.sol

@@ -16,7 +16,7 @@ import "./interfaces/IExchangeRates.sol";
 import "./interfaces/ISystemStatus.sol";
 import "./interfaces/IERC20.sol";
 import "./interfaces/ICollateralManager.sol";
-import "./interfaces/IEtherWrapper.sol";
+import "./interfaces/IWrapperFactory.sol";
 
 // https://docs.synthetix.io/contracts/source/contracts/debtcache
 contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
@@ -25,6 +25,7 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
 
     uint internal _cachedDebt;
     mapping(bytes32 => uint) internal _cachedSynthDebt;
+    mapping(bytes32 => uint) internal _excludedIssuedDebt;
     uint internal _cacheTimestamp;
     bool internal _cacheInvalid = true;
 
@@ -40,7 +41,7 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
     bytes32 private constant CONTRACT_EXRATES = "ExchangeRates";
     bytes32 private constant CONTRACT_SYSTEMSTATUS = "SystemStatus";
     bytes32 private constant CONTRACT_COLLATERALMANAGER = "CollateralManager";
-    bytes32 private constant CONTRACT_ETHER_WRAPPER = "EtherWrapper";
+    bytes32 private constant CONTRACT_WRAPPERFACTORY = "WrapperFactory";
 
     constructor(address _owner, address _resolver) public Owned(_owner) MixinSystemSettings(_resolver) {}
 
@@ -54,7 +55,7 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         newAddresses[2] = CONTRACT_EXRATES;
         newAddresses[3] = CONTRACT_SYSTEMSTATUS;
         newAddresses[4] = CONTRACT_COLLATERALMANAGER;
-        newAddresses[5] = CONTRACT_ETHER_WRAPPER;
+        newAddresses[5] = CONTRACT_WRAPPERFACTORY;
         addresses = combineArrays(existingAddresses, newAddresses);
     }
 
@@ -78,8 +79,8 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         return ICollateralManager(requireAndGetAddress(CONTRACT_COLLATERALMANAGER));
     }
 
-    function etherWrapper() internal view returns (IEtherWrapper) {
-        return IEtherWrapper(requireAndGetAddress(CONTRACT_ETHER_WRAPPER));
+    function wrapperFactory() internal view returns (IWrapperFactory) {
+        return IWrapperFactory(requireAndGetAddress(CONTRACT_WRAPPERFACTORY));
     }
 
     function debtSnapshotStaleTime() external view returns (uint) {
@@ -144,6 +145,11 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         (uint[] memory rates, bool isInvalid) = exchangeRates().ratesAndInvalidForCurrencies(currencyKeys);
         uint[] memory values = _issuedSynthValues(currencyKeys, rates);
         (uint excludedDebt, bool isAnyNonSnxDebtRateInvalid) = _totalNonSnxBackedDebt();
+
+        for (uint i = 0; i < currencyKeys.length; i++) {
+            excludedDebt = excludedDebt.add(_excludedIssuedDebt[currencyKeys[i]].multiplyDecimalRound(rates[i]));
+        }
+
         return (values, excludedDebt, isInvalid || isAnyNonSnxDebtRateInvalid);
     }
 
@@ -172,7 +178,20 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         return _cachedSynthDebts(currencyKeys);
     }
 
-    // Returns the total sUSD debt backed by non-SNX collateral.
+    function _excludedIssuedDebts(bytes32[] memory currencyKeys) internal view returns (uint[] memory) {
+        uint numKeys = currencyKeys.length;
+        uint[] memory debts = new uint[](numKeys);
+        for (uint i = 0; i < numKeys; i++) {
+            debts[i] = _excludedIssuedDebt[currencyKeys[i]];
+        }
+        return debts;
+    }
+
+    function excludedIssuedDebts(bytes32[] calldata currencyKeys) external view returns (uint[] memory excludedDebts) {
+        return _excludedIssuedDebts(currencyKeys);
+    }
+
+    // Returns the total sUSD debt backed by non-SNX collateral, excluding debts recorded with _excludedIssuedDebt
     function totalNonSnxBackedDebt() external view returns (uint excludedDebt, bool isInvalid) {
         return _totalNonSnxBackedDebt();
     }
@@ -185,9 +204,9 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         isInvalid = anyTotalLongRateIsInvalid || anyTotalShortRateIsInvalid;
         excludedDebt = longValue.add(shortValue);
 
-        // 2. EtherWrapper.
-        // Subtract sETH and sUSD issued by EtherWrapper.
-        excludedDebt = excludedDebt.add(etherWrapper().totalIssuedSynths());
+        // 2. Wrapper.
+        // Subtract totalIssuedSynths issued by all wrappers.
+        excludedDebt = excludedDebt.add(wrapperFactory().totalIssuedSynths());
 
         return (excludedDebt, isInvalid);
     }
@@ -204,6 +223,7 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         uint total;
         for (uint i; i < numValues; i++) {
             total = total.add(values[i]);
+            excludedDebt = excludedDebt.add(_excludedIssuedDebt[currencyKeys[i]].multiplyDecimalRound(rates[i]));
         }
         total = total < excludedDebt ? 0 : total.sub(excludedDebt);
 
@@ -245,6 +265,8 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
 
     function takeDebtSnapshot() external {}
 
+    function recordExcludedDebtChange(bytes32 currencyKey, int256 delta) external {}
+
     /* ========== MODIFIERS ========== */
 
     function _requireSystemActiveIfNotOwner() internal view {
@@ -275,4 +297,18 @@ contract BaseDebtCache is Owned, MixinSystemSettings, IDebtCache {
         _onlyIssuerOrExchanger();
         _;
     }
+
+    function _onlyDebtIssuer() internal view {
+        bool isWrapper = wrapperFactory().isWrapper(msg.sender);
+
+        // owner included for debugging and fixing in emergency situation
+        bool isOwner = msg.sender == owner;
+
+        require(isOwner || isWrapper, "Only debt issuers may call this");
+    }
+
+    modifier onlyDebtIssuer() {
+        _onlyDebtIssuer();
+        _;
+    }
 }

contracts/DebtCache.sol

@@ -48,28 +48,36 @@ contract DebtCache is BaseDebtCache {
 
     function updateCachedSynthDebts(bytes32[] calldata currencyKeys) external requireSystemActiveIfNotOwner {
         (uint[] memory rates, bool anyRateInvalid) = exchangeRates().ratesAndInvalidForCurrencies(currencyKeys);
-        _updateCachedSynthDebtsWithRates(currencyKeys, rates, anyRateInvalid, false);
+        _updateCachedSynthDebtsWithRates(currencyKeys, rates, anyRateInvalid);
     }
 
     function updateCachedSynthDebtWithRate(bytes32 currencyKey, uint currencyRate) external onlyIssuer {
         bytes32[] memory synthKeyArray = new bytes32[](1);
         synthKeyArray[0] = currencyKey;
         uint[] memory synthRateArray = new uint[](1);
         synthRateArray[0] = currencyRate;
-        _updateCachedSynthDebtsWithRates(synthKeyArray, synthRateArray, false, false);
+        _updateCachedSynthDebtsWithRates(synthKeyArray, synthRateArray, false);
     }
 
     function updateCachedSynthDebtsWithRates(bytes32[] calldata currencyKeys, uint[] calldata currencyRates)
         external
         onlyIssuerOrExchanger
     {
-        _updateCachedSynthDebtsWithRates(currencyKeys, currencyRates, false, false);
+        _updateCachedSynthDebtsWithRates(currencyKeys, currencyRates, false);
     }
 
     function updateDebtCacheValidity(bool currentlyInvalid) external onlyIssuer {
         _updateDebtCacheValidity(currentlyInvalid);
     }
 
+    function recordExcludedDebtChange(bytes32 currencyKey, int256 delta) external onlyDebtIssuer {
+        int256 newExcludedDebt = int256(_excludedIssuedDebt[currencyKey]) + delta;
+
+        require(newExcludedDebt >= 0, "Excluded debt cannot become negative");
+
+        _excludedIssuedDebt[currencyKey] = uint(newExcludedDebt);
+    }
+
     /* ========== INTERNAL FUNCTIONS ========== */
 
     function _updateDebtCacheValidity(bool currentlyInvalid) internal {
@@ -82,8 +90,7 @@ contract DebtCache is BaseDebtCache {
     function _updateCachedSynthDebtsWithRates(
         bytes32[] memory currencyKeys,
         uint[] memory currentRates,
-        bool anyRateIsInvalid,
-        bool recomputeExcludedDebt
+        bool anyRateIsInvalid
     ) internal {
         uint numKeys = currencyKeys.length;
         require(numKeys == currentRates.length, "Input array lengths differ");
@@ -102,16 +109,8 @@ contract DebtCache is BaseDebtCache {
             _cachedSynthDebt[key] = currentSynthDebt;
         }
 
-        // Always update the cached value of the excluded debt -- it's computed anyway.
-        if (recomputeExcludedDebt) {
-            (uint excludedDebt, bool anyNonSnxDebtRateIsInvalid) = _totalNonSnxBackedDebt();
-            anyRateIsInvalid = anyRateIsInvalid || anyNonSnxDebtRateIsInvalid;
-            excludedDebtSum = excludedDebt;
-        }
-
         cachedSum = cachedSum.floorsub(_cachedSynthDebt[EXCLUDED_DEBT_KEY]);
         currentSum = currentSum.floorsub(excludedDebtSum);
-        _cachedSynthDebt[EXCLUDED_DEBT_KEY] = excludedDebtSum;
 
         // Compute the difference and apply it to the snapshot
         if (cachedSum != currentSum) {