fix: Remove discount lock period mechanism (#293)

* fix: remove discount lock period from GhoDebtToken

* test: Update tests for new rebalance behaviour

src/contracts/facilitators/aave/misc/UiGhoDataProvider.sol

@@ -45,7 +45,6 @@ contract UiGhoDataProvider is IUiGhoDataProvider {
         ghoBaseVariableBorrowRate: baseData.currentVariableBorrowRate,
         ghoDiscountedPerToken: discountRateStrategy.GHO_DISCOUNTED_PER_DISCOUNT_TOKEN(),
         ghoDiscountRate: discountRateStrategy.DISCOUNT_RATE(),
-        ghoDiscountLockPeriod: debtToken.getDiscountLockPeriod(),
         ghoMinDebtTokenBalanceForDiscount: discountRateStrategy.MIN_DISCOUNT_TOKEN_BALANCE(),
         ghoMinDiscountTokenBalanceForDiscount: discountRateStrategy.MIN_DEBT_TOKEN_BALANCE(),
         ghoReserveLastUpdateTimestamp: baseData.lastUpdateTimestamp,
@@ -66,8 +65,7 @@ contract UiGhoDataProvider is IUiGhoDataProvider {
         userGhoDiscountPercent: debtToken.getDiscountPercent(user),
         userDiscountTokenBalance: IERC20(discountToken).balanceOf(user),
         userPreviousGhoBorrowIndex: debtToken.getPreviousIndex(user),
-        userGhoScaledBorrowBalance: debtToken.scaledBalanceOf(user),
-        userDiscountLockPeriodEndTimestamp: debtToken.getUserRebalanceTimestamp(user)
+        userGhoScaledBorrowBalance: debtToken.scaledBalanceOf(user)
       });
   }
 }

src/contracts/facilitators/aave/misc/interfaces/IUiGhoDataProvider.sol

@@ -11,7 +11,6 @@ interface IUiGhoDataProvider {
     uint256 ghoBaseVariableBorrowRate;
     uint256 ghoDiscountedPerToken;
     uint256 ghoDiscountRate;
-    uint256 ghoDiscountLockPeriod;
     uint256 ghoMinDebtTokenBalanceForDiscount;
     uint256 ghoMinDiscountTokenBalanceForDiscount;
     uint40 ghoReserveLastUpdateTimestamp;
@@ -25,7 +24,6 @@ interface IUiGhoDataProvider {
     uint256 userDiscountTokenBalance;
     uint256 userPreviousGhoBorrowIndex;
     uint256 userGhoScaledBorrowBalance;
-    uint256 userDiscountLockPeriodEndTimestamp;
   }
 
   /**

src/contracts/facilitators/aave/tokens/GhoVariableDebtToken.sol

@@ -47,16 +47,11 @@ contract GhoVariableDebtToken is DebtTokenBase, ScaledBalanceTokenBase, IGhoVari
     uint128 accumulatedDebtInterest;
     // Discount percent of the user (expressed in bps)
     uint16 discountPercent;
-    // Timestamp when user's discount can be rebalanced
-    uint40 rebalanceTimestamp;
   }
 
   // Map of users' address and their gho state data (userAddress => ghoUserState)
   mapping(address => GhoUserState) internal _ghoUserState;
 
-  // The amount of time a user's discount is guarded from being rebalanced (expressed in seconds)
-  uint256 internal _discountLockPeriod;
-
   /**
    * @dev Only discount token can call functions marked by this modifier.
    */
@@ -337,12 +332,6 @@ contract GhoVariableDebtToken is DebtTokenBase, ScaledBalanceTokenBase, IGhoVari
 
   /// @inheritdoc IGhoVariableDebtToken
   function rebalanceUserDiscountPercent(address user) external override {
-    require(
-      _ghoUserState[user].rebalanceTimestamp < block.timestamp,
-      'DISCOUNT_LOCK_PERIOD_NOT_OVER'
-    );
-    require(_ghoUserState[user].rebalanceTimestamp != 0, 'NO_USER_DISCOUNT_TO_REBALANCE');
-
     uint256 index = POOL.getReserveNormalizedVariableDebt(_underlyingAsset);
     uint256 previousScaledBalance = super.balanceOf(user);
     uint256 discountPercent = _ghoUserState[user].discountPercent;
@@ -367,23 +356,6 @@ contract GhoVariableDebtToken is DebtTokenBase, ScaledBalanceTokenBase, IGhoVari
     emit Mint(address(0), user, balanceIncrease, balanceIncrease, index);
   }
 
-  /// @inheritdoc IGhoVariableDebtToken
-  function updateDiscountLockPeriod(uint256 newLockPeriod) external override onlyPoolAdmin {
-    uint256 oldLockPeriod = _discountLockPeriod;
-    _discountLockPeriod = uint40(newLockPeriod);
-    emit DiscountLockPeriodUpdated(oldLockPeriod, newLockPeriod);
-  }
-
-  /// @inheritdoc IGhoVariableDebtToken
-  function getDiscountLockPeriod() external view override returns (uint256) {
-    return _discountLockPeriod;
-  }
-
-  /// @inheritdoc IGhoVariableDebtToken
-  function getUserRebalanceTimestamp(address user) external view override returns (uint256) {
-    return _ghoUserState[user].rebalanceTimestamp;
-  }
-
   /**
    * @notice Implements the basic logic to mint a scaled balance token.
    * @param caller The address performing the mint
@@ -532,22 +504,7 @@ contract GhoVariableDebtToken is DebtTokenBase, ScaledBalanceTokenBase, IGhoVari
 
     if (previousDiscountPercent != newDiscountPercent) {
       _ghoUserState[user].discountPercent = newDiscountPercent.toUint16();
-    }
-
-    if (newDiscountPercent != 0) {
-      uint40 newRebalanceTimestamp = uint40(block.timestamp + _discountLockPeriod);
-      _ghoUserState[user].rebalanceTimestamp = newRebalanceTimestamp;
-      emit DiscountPercentLocked(
-        user,
-        previousDiscountPercent,
-        newDiscountPercent,
-        newRebalanceTimestamp
-      );
-    } else {
-      if (previousDiscountPercent != newDiscountPercent) {
-        _ghoUserState[user].rebalanceTimestamp = 0;
-        emit DiscountPercentLocked(user, previousDiscountPercent, 0, 0);
-      }
+      emit DiscountPercentUpdated(user, previousDiscountPercent, newDiscountPercent);
     }
   }
 }

src/contracts/facilitators/aave/tokens/interfaces/IGhoVariableDebtToken.sol

@@ -33,27 +33,15 @@ interface IGhoVariableDebtToken is IVariableDebtToken {
   event DiscountTokenUpdated(address indexed oldDiscountToken, address indexed newDiscountToken);
 
   /**
-   * @dev Emitted when the discount lock period is updated
-   * @param oldDiscountLockPeriod The value of the old DiscountLockPeriod
-   * @param newDiscountLockPeriod The value of the new DiscountLockPeriod
-   */
-  event DiscountLockPeriodUpdated(
-    uint256 indexed oldDiscountLockPeriod,
-    uint256 indexed newDiscountLockPeriod
-  );
-
-  /**
-   * @dev Emitted when a user's discount or rebalanceTimestamp is updated
+   * @dev Emitted when a user's discount is updated
    * @param user The address of the user
    * @param oldDiscountPercent The old discount percent of the user
    * @param newDiscountPercent The new discount percent of the user
-   * @param rebalanceTimestamp Timestamp when a users locked discount can be rebalanced
    */
-  event DiscountPercentLocked(
+  event DiscountPercentUpdated(
     address indexed user,
     uint256 oldDiscountPercent,
-    uint256 indexed newDiscountPercent,
-    uint256 indexed rebalanceTimestamp
+    uint256 indexed newDiscountPercent
   );
 
   /**
@@ -130,27 +118,8 @@ interface IGhoVariableDebtToken is IVariableDebtToken {
   function decreaseBalanceFromInterest(address user, uint256 amount) external;
 
   /**
-   * @notice Rebalances the discount percent of a user if they are past their rebalance timestamp
+   * @notice Rebalances the discount percent of a user
    * @param user The address of the user
    */
   function rebalanceUserDiscountPercent(address user) external;
-
-  /**
-   * @notice Updates the discount percent lock period
-   * @param newLockPeriod The new discount lock period (in seconds)
-   */
-  function updateDiscountLockPeriod(uint256 newLockPeriod) external;
-
-  /**
-   * @notice Returns the discount percent lock period
-   * @return The discount percent lock period (in seconds)
-   */
-  function getDiscountLockPeriod() external view returns (uint256);
-
-  /**
-   * @notice Returns the timestamp at which a user's discount percent can be rebalanced
-   * @param user The address of the user's rebalance timestamp being requested
-   * @return The time when a users discount percent can be rebalanced
-   */
-  function getUserRebalanceTimestamp(address user) external view returns (uint256);
 }

src/helpers/config.ts

@@ -17,7 +17,6 @@ export const ghoTokenConfig = {
 
 export const ghoReserveConfig = {
   INTEREST_RATE: ethers.utils.parseUnits('2.0', 25),
-  DISCOUNT_LOCK_PERIOD: 31556952,
 };
 
 export const ghoEntityConfig = {

src/tasks/testnet-setup/05_set-gho-addresses.ts

@@ -68,14 +68,4 @@ task(
   console.log(
     `VariableDebtToken discount token set to:  ${stkAave} in tx: ${updateDiscountTokenTxReceipt.transactionHash}`
   );
-
-  // Set initial discount lock period
-  const updateDiscountLockPeriodReceipt = await waitForTx(
-    await ghoVariableDebtToken.updateDiscountLockPeriod(ghoReserveConfig.DISCOUNT_LOCK_PERIOD)
-  );
-  console.log(
-    `VariableDebtToken discount lock period set to:   ${await ghoVariableDebtToken.getDiscountLockPeriod()} in tx: ${
-      updateDiscountLockPeriodReceipt.transactionHash
-    }`
-  );
 });

src/test/basic-borrow.test.ts

@@ -43,7 +43,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[0].address, borrowAmount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[0].address, users[0].address, borrowAmount, 0, oneRay)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await gho.balanceOf(users[0].address)).to.be.equal(borrowAmount);
     expect(await variableDebtToken.totalSupply()).to.be.equal(borrowAmount);
@@ -108,7 +108,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[1].address, borrowAmount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[1].address, users[1].address, borrowAmount, 0, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await gho.balanceOf(users[1].address)).to.be.equal(borrowAmount);
 
@@ -152,7 +152,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[0].address, amount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[0].address, users[0].address, amount, user1ExpectedBalanceIncrease, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     const user1Debt = await variableDebtToken.balanceOf(users[0].address);
     const user2Debt = await variableDebtToken.balanceOf(users[1].address);
@@ -200,7 +200,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(users[1].address, ZERO_ADDRESS, borrowAmount)
       .to.emit(variableDebtToken, 'Burn')
       .withArgs(users[1].address, ZERO_ADDRESS, borrowAmount, user2ExpectedInterest, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     const user1Debt = await variableDebtToken.balanceOf(users[0].address);
     const user2Debt = await variableDebtToken.balanceOf(users[1].address);
@@ -245,7 +245,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[2].address, borrowAmount.mul(3))
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[2].address, users[2].address, borrowAmount.mul(3), 0, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await gho.balanceOf(users[2].address)).to.be.equal(borrowAmount.mul(3));
     expect(await variableDebtToken.getBalanceFromInterest(users[2].address)).to.be.equal(0);
@@ -289,7 +289,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[0].address, amount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[0].address, users[0].address, amount, user1ExpectedBalanceIncrease, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await variableDebtToken.balanceOf(users[0].address)).to.be.eq(
       user1ExpectedBalance.sub(repayAmount)
@@ -338,7 +338,7 @@ makeSuite('Gho Basic Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(users[0].address, ZERO_ADDRESS, amount)
       .to.emit(variableDebtToken, 'Burn')
       .withArgs(users[0].address, ZERO_ADDRESS, amount, user1ExpectedBalanceIncrease, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await variableDebtToken.balanceOf(users[0].address)).to.be.eq(0);
     expect(await variableDebtToken.getBalanceFromInterest(users[0].address)).to.be.equal(0);

src/test/borrow-onBehalf.test.ts

@@ -56,7 +56,7 @@ makeSuite('Gho OnBehalf Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[0].address, borrowAmount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[1].address, users[0].address, borrowAmount, 0, oneRay)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await gho.balanceOf(users[1].address)).to.be.equal(borrowAmount);
     expect(await variableDebtToken.getBalanceFromInterest(users[0].address)).to.be.equal(0);
@@ -119,7 +119,7 @@ makeSuite('Gho OnBehalf Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[2].address, borrowAmount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[2].address, users[2].address, borrowAmount, 0, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await gho.balanceOf(users[2].address)).to.be.equal(borrowAmount);
 
@@ -164,7 +164,7 @@ makeSuite('Gho OnBehalf Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(users[0].address, ZERO_ADDRESS, borrowAmount)
       .to.emit(variableDebtToken, 'Burn')
       .withArgs(users[0].address, ZERO_ADDRESS, borrowAmount, user1ExpectedInterest, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     const user1Debt = await variableDebtToken.balanceOf(users[0].address);
     const user2Debt = await variableDebtToken.balanceOf(users[1].address);

src/test/discount-borrow.test.ts

@@ -137,13 +137,8 @@ makeSuite('Gho Discount Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[1].address, borrowAmount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[1].address, users[1].address, borrowAmount, 0, expIndex)
-      .to.emit(variableDebtToken, 'DiscountPercentLocked')
-      .withArgs(
-        users[1].address,
-        discountPercentBefore,
-        discountPercent,
-        txTimestamp.add(ghoReserveConfig.DISCOUNT_LOCK_PERIOD)
-      );
+      .to.emit(variableDebtToken, 'DiscountPercentUpdated')
+      .withArgs(users[1].address, discountPercentBefore, discountPercent);
 
     expect(await variableDebtToken.getDiscountPercent(users[1].address)).to.be.eq(discountPercent);
 
@@ -236,7 +231,7 @@ makeSuite('Gho Discount Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[0].address, amount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[0].address, users[0].address, amount, user1BalanceIncrease, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     const user1Debt = await variableDebtToken.balanceOf(users[0].address);
     const user2Debt = await variableDebtToken.balanceOf(users[1].address);
@@ -306,8 +301,8 @@ makeSuite('Gho Discount Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(users[1].address, ZERO_ADDRESS, borrowAmount)
       .to.emit(variableDebtToken, 'Burn')
       .withArgs(users[1].address, ZERO_ADDRESS, borrowAmount, user2ExpectedInterest, expIndex)
-      .to.emit(variableDebtToken, 'DiscountPercentLocked')
-      .withArgs(users[1].address, user2DiscountPercentBefore, user2DiscountPercent, 0);
+      .to.emit(variableDebtToken, 'DiscountPercentUpdated')
+      .withArgs(users[1].address, user2DiscountPercentBefore, user2DiscountPercent);
 
     const user1Debt = await variableDebtToken.balanceOf(users[0].address);
     const user2Debt = await variableDebtToken.balanceOf(users[1].address);
@@ -358,7 +353,7 @@ makeSuite('Gho Discount Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[2].address, borrowAmount.mul(3))
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[2].address, users[2].address, borrowAmount.mul(3), 0, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await variableDebtToken.getDiscountPercent(users[2].address)).to.be.eq(0);
 
@@ -404,7 +399,7 @@ makeSuite('Gho Discount Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(ZERO_ADDRESS, users[0].address, amount)
       .to.emit(variableDebtToken, 'Mint')
       .withArgs(users[0].address, users[0].address, amount, user1ExpectedBalanceIncrease, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await variableDebtToken.getDiscountPercent(users[0].address)).to.be.eq(0);
 
@@ -455,7 +450,7 @@ makeSuite('Gho Discount Borrow Flow', (testEnv: TestEnv) => {
       .withArgs(users[0].address, ZERO_ADDRESS, amount)
       .to.emit(variableDebtToken, 'Burn')
       .withArgs(users[0].address, ZERO_ADDRESS, amount, user1ExpectedBalanceIncrease, expIndex)
-      .to.not.emit(variableDebtToken, 'DiscountPercentLocked');
+      .to.not.emit(variableDebtToken, 'DiscountPercentUpdated');
 
     expect(await variableDebtToken.getDiscountPercent(users[0].address)).to.be.eq(0);