Cleaned up reserveLogic

contracts/libraries/ReserveLogic.sol

@@ -25,16 +25,35 @@ library ReserveLogic {
   using SafeMath for uint256;
   using WadRayMath for uint256;
   using SafeERC20 for IERC20;
-  using Address for address;
+
+  /**
+   * @dev Emitted when the state of a reserve is updated
+   * @dev NOTE: This event replaces the Deprecated ReserveUpdated() event, which didn't emit the average stable borrow rate
+   * @param reserve the address of the reserve
+   * @param liquidityRate the new liquidity rate
+   * @param stableBorrowRate the new stable borrow rate
+   * @param averageStableBorrowRate the new average stable borrow rate
+   * @param variableBorrowRate the new variable borrow rate
+   * @param liquidityIndex the new liquidity index
+   * @param variableBorrowIndex the new variable borrow index
+   **/
+  event ReserveDataUpdated(
+    address indexed reserve,
+    uint256 liquidityRate,
+    uint256 stableBorrowRate,
+    uint256 averageStableBorrowRate,
+    uint256 variableBorrowRate,
+    uint256 liquidityIndex,
+    uint256 variableBorrowIndex
+  );
+
   using ReserveLogic for ReserveLogic.ReserveData;
   using ReserveConfiguration for ReserveConfiguration.Map;
 
   enum InterestRateMode {NONE, STABLE, VARIABLE}
 
+  // refer to the whitepaper, section 1.1 basic concepts for a formal description of these properties.
   struct ReserveData {
-    /**
-     * @dev refer to the whitepaper, section 1.1 basic concepts for a formal description of these properties.
-     **/
     //the liquidity index. Expressed in ray
     uint256 lastLiquidityCumulativeIndex;
     //the current supply rate. Expressed in ray
@@ -45,27 +64,21 @@ library ReserveLogic {
     uint256 currentStableBorrowRate;
     //variable borrow index. Expressed in ray
     uint256 lastVariableBorrowCumulativeIndex;
+    //stores the reserve configuration
     ReserveConfiguration.Map configuration;
-    /**
-     * @dev address of the aToken representing the asset
-     **/
     address payable aTokenAddress;
     address stableDebtTokenAddress;
     address variableDebtTokenAddress;
-    /**
-     * @dev address of the interest rate strategy contract
-     **/
     address interestRateStrategyAddress;
     uint40 lastUpdateTimestamp;
-    // isStableBorrowRateEnabled = true means users can borrow at a stable rate
+    //the index of the reserve in the list of the active reserves
-    bool isStableBorrowRateEnabled;
     uint8 index;
   }
 
   /**
    * @dev returns the ongoing normalized income for the reserve.
    * a value of 1e27 means there is no income. As time passes, the income is accrued.
-   * A value of 2*1e27 means that the income of the reserve is double the initial amount.
+   * A value of 2*1e27 means for each unit of assset two units of income have been accrued.
    * @param _reserve the reserve object
    * @return the normalized income. expressed in ray
    **/
@@ -114,10 +127,11 @@ library ReserveLogic {
    * @param _self the reserve object
    **/
   function updateCumulativeIndexesAndTimestamp(ReserveData storage _self) internal {
-    uint256 totalBorrows = getTotalBorrows(_self);
-
-    if (totalBorrows > 0) {
     //only cumulating if there is any income being produced
+    if (
+      IERC20(_self.variableDebtTokenAddress).totalSupply() > 0 ||
+      IERC20(_self.stableDebtTokenAddress).totalSupply() > 0
+    ) {
       uint256 cumulatedLiquidityInterest = MathUtils.calculateLinearInterest(
         _self.currentLiquidityRate,
         _self.lastUpdateTimestamp
@@ -190,34 +204,6 @@ library ReserveLogic {
     _self.interestRateStrategyAddress = _interestRateStrategyAddress;
   }
 
-  function getTotalBorrows(ReserveData storage _self) internal view returns (uint256) {
-    return
-      IERC20(_self.stableDebtTokenAddress).totalSupply().add(
-        IERC20(_self.variableDebtTokenAddress).totalSupply()
-      );
-  }
-
-  /**
-   * @dev Emitted when the state of a reserve is updated
-   * @dev NOTE: This event replaces the Deprecated ReserveUpdated() event, which didn't emit the average stable borrow rate
-   * @param reserve the address of the reserve
-   * @param liquidityRate the new liquidity rate
-   * @param stableBorrowRate the new stable borrow rate
-   * @param averageStableBorrowRate the new average stable borrow rate
-   * @param variableBorrowRate the new variable borrow rate
-   * @param liquidityIndex the new liquidity index
-   * @param variableBorrowIndex the new variable borrow index
-   **/
-  event ReserveDataUpdated(
-    address indexed reserve,
-    uint256 liquidityRate,
-    uint256 stableBorrowRate,
-    uint256 averageStableBorrowRate,
-    uint256 variableBorrowRate,
-    uint256 liquidityIndex,
-    uint256 variableBorrowIndex
-  );
-
   /**
    * @dev updates the state of the core as a result of a flashloan action
    * @param _reserve the address of the reserve in which the flashloan is happening
@@ -233,7 +219,9 @@ library ReserveLogic {
     //compounding the cumulated interest
     _reserve.updateCumulativeIndexesAndTimestamp();
 
-    uint256 totalLiquidityBefore = _availableLiquidityBefore.add(_reserve.getTotalBorrows());
+    uint256 totalLiquidityBefore = _availableLiquidityBefore
+      .add(IERC20(_reserve.variableDebtTokenAddress).totalSupply())
+      .add(IERC20(_reserve.stableDebtTokenAddress).totalSupply());
 
     //compounding the received fee into the reserve
     _reserve.cumulateToLiquidityIndex(totalLiquidityBefore, _income);
@@ -242,20 +230,6 @@ library ReserveLogic {
     updateInterestRates(_reserve, _reserveAddress, _income, 0);
   }
 
-  /**
-   * @dev gets the total liquidity in the reserve. The total liquidity is the balance of the core contract + total borrows
-   * @param _reserve the reserve address
-   * @return the total liquidity
-   **/
-  function getTotalLiquidity(ReserveData storage _reserve, address _reserveAddress)
-    public
-    view
-    returns (uint256)
-  {
-    return
-      IERC20(_reserveAddress).balanceOf(address(this)).add(_reserve.getTotalBorrows());
-  }
-
   /**
    * @dev Updates the reserve current stable borrow rate Rf, the current variable borrow rate Rv and the current liquidity rate Rl.
    * Also updates the lastUpdateTimestamp value. Please refer to the whitepaper for further information.
@@ -300,56 +274,4 @@ library ReserveLogic {
       _reserve.lastVariableBorrowCumulativeIndex
     );
   }
-
-  /**
-   * @dev gets the reserve current variable borrow rate. Is the base variable borrow rate if the reserve is empty
-   * @param _reserve the reserve address
-   * @return the reserve current variable borrow rate
-   **/
-  function getReserveCurrentVariableBorrowRate(ReserveData storage _reserve)
-    external
-    view
-    returns (uint256)
-  {
-    if (_reserve.currentVariableBorrowRate == 0) {
-      return
-        IReserveInterestRateStrategy(_reserve.interestRateStrategyAddress)
-          .getBaseVariableBorrowRate();
-    }
-    return _reserve.currentVariableBorrowRate;
-  }
-
-  /**
-   * @dev gets the reserve current stable borrow rate. Is the market rate if the reserve is empty
-   * @param _reserve the reserve address
-   * @return the reserve current stable borrow rate
-   **/
-  function getReserveCurrentStableBorrowRate(ReserveData storage _reserve, uint256 _baseRate)
-    public
-    view
-    returns (uint256)
-  {
-    return _reserve.currentStableBorrowRate == 0 ? _baseRate : _reserve.currentStableBorrowRate;
-  }
-
-  /**
-   * @dev returns the utilization rate U of a specific reserve
-   * @param _reserve the reserve for which the information is needed
-   * @return the utilization rate in ray
-   **/
-  function getUtilizationRate(ReserveData storage _reserve, address _reserveAddress)
-    public
-    view
-    returns (uint256)
-  {
-    uint256 totalBorrows = _reserve.getTotalBorrows();
-
-    if (totalBorrows == 0) {
-      return 0;
-    }
-
-    uint256 availableLiquidity = IERC20(_reserveAddress).balanceOf(address(this));
-
-    return totalBorrows.rayDiv(availableLiquidity.add(totalBorrows));
-  }
 }