Merge pull request #132 from aave/feat/gas-optimization-3

Feat/gas optimization 3

contracts/interfaces/ILendingPool.sol

@@ -167,6 +167,16 @@ interface ILendingPool {
     uint256 variableBorrowIndex
   );
 
+  /**
+  * @dev Emitted when the protocol treasury receives minted aTokens from the accrued interest.
+  * @param reserve the address of the reserve
+  * @param amountMinted the amount minted to the treasury
+  **/
+  event MintedToTreasury(
+    address indexed reserve,
+    uint256 amountMinted
+  );
+
   /**
    * @dev Deposits an `amount` of underlying asset into the reserve, receiving in return overlying aTokens.
    * - E.g. User deposits 100 USDC and gets in return 100 aUSDC

contracts/protocol/lendingpool/LendingPool.sol

@@ -537,6 +537,34 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     }
   }
 
+  /**
+   * @dev Mints the assets accrued through the reserve factor to the treasury in the form of aTokens
+   * @param reserves The list of reserves for which the minting needs to be executed
+   **/
+  function mintToTreasury(address[] calldata reserves) public {
+    for (uint256 i = 0; i < reserves.length; i++) {
+      address reserveAddress = reserves[i];
+      
+      DataTypes.ReserveData storage reserve = _reserves[reserveAddress];
+
+      // this cover both inactive reserves and invalid reserves since the flag will be 0 for both
+      if(!reserve.configuration.getActive()){
+        continue;
+      }
+
+      uint256 accruedToTreasury = reserve.accruedToTreasury;
+
+      if (accruedToTreasury != 0) {
+        uint256 normalizedIncome = reserve.getNormalizedIncome();
+        uint256 amountToMint = accruedToTreasury.rayMul(normalizedIncome);
+        IAToken(reserve.aTokenAddress).mintToTreasury(amountToMint, normalizedIncome);
+
+        reserve.accruedToTreasury = 0;
+        emit MintedToTreasury(reserveAddress, amountToMint);
+      }
+    }
+  }
+
   /**
    * @dev Returns the state and configuration of the reserve
    * @param asset The address of the underlying asset of the reserve

contracts/protocol/libraries/logic/ReserveLogic.sol

@@ -123,7 +123,7 @@ library ReserveLogic {
         lastUpdatedTimestamp
       );
 
-    _mintToTreasury(
+    _accrueToTreasury(
       reserve,
       scaledVariableDebt,
       previousVariableBorrowIndex,
@@ -271,7 +271,7 @@ library ReserveLogic {
    * @param newLiquidityIndex The new liquidity index
    * @param newVariableBorrowIndex The variable borrow index after the last accumulation of the interest
    **/
-  function _mintToTreasury(
+  function _accrueToTreasury(
     DataTypes.ReserveData storage reserve,
     uint256 scaledVariableDebt,
     uint256 previousVariableBorrowIndex,
@@ -320,7 +320,7 @@ library ReserveLogic {
     vars.amountToMint = vars.totalDebtAccrued.percentMul(vars.reserveFactor);
 
     if (vars.amountToMint != 0) {
-      IAToken(reserve.aTokenAddress).mintToTreasury(vars.amountToMint, newLiquidityIndex);
+      reserve.accruedToTreasury = reserve.accruedToTreasury.add(vars.amountToMint.rayDiv(newLiquidityIndex));
     }
   }
 

contracts/protocol/libraries/types/DataTypes.sol

@@ -25,6 +25,8 @@ library DataTypes {
     address interestRateStrategyAddress;
     //the id of the reserve. Represents the position in the list of the active reserves
     uint8 id;
+    //the current treasury balance, scaled
+    uint256 accruedToTreasury;
   }
 
   struct ReserveConfigurationMap {

test-suites/test-aave/helpers/utils/calculations.ts

@@ -1196,7 +1196,7 @@ const calcLinearInterest = (
   return cumulatedInterest;
 };
 
-const calcCompoundedInterest = (
+export const calcCompoundedInterest = (
   rate: BigNumber,
   currentTimestamp: BigNumber,
   lastUpdateTimestamp: BigNumber

test-suites/test-aave/mint-to-treasury.spec.ts

@@ -0,0 +1,90 @@
+import { makeSuite, TestEnv } from './helpers/make-suite';
+import { RateMode } from '../../helpers/types';
+import { APPROVAL_AMOUNT_LENDING_POOL, ONE_YEAR } from '../../helpers/constants';
+import { convertToCurrencyDecimals } from '../../helpers/contracts-helpers';
+import { BigNumber } from 'bignumber.js';
+import { advanceTimeAndBlock, waitForTx } from '../../helpers/misc-utils';
+import './helpers/utils/math';
+
+const { expect } = require('chai');
+
+makeSuite('Mint to treasury', (testEnv: TestEnv) => {
+  it('User 0 deposits 1000 DAI. Borrower borrows 100 DAI. Clock moved forward one year. Calculates and verifies the amount accrued to the treasury', async () => {
+    const { users, pool, dai, helpersContract } = testEnv;
+
+    const amountDAItoDeposit = await convertToCurrencyDecimals(dai.address, '1000');
+    const amountDAItoBorrow = await convertToCurrencyDecimals(dai.address, '100');
+
+    await waitForTx(await dai.connect(users[0].signer).mint(amountDAItoDeposit));
+
+    // user 0 deposits 1000 DAI
+    await waitForTx(
+      await dai.connect(users[0].signer).approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL)
+    );
+    await waitForTx(
+      await pool
+        .connect(users[0].signer)
+        .deposit(dai.address, amountDAItoDeposit, users[0].address, '0')
+    );
+
+    await waitForTx(
+      await pool
+        .connect(users[0].signer)
+        .borrow(dai.address, amountDAItoBorrow, RateMode.Variable, '0', users[0].address)
+    );
+
+    const { reserveFactor } = await helpersContract.getReserveConfigurationData(dai.address);
+
+    await advanceTimeAndBlock(parseInt(ONE_YEAR));
+
+    await waitForTx(await dai.connect(users[0].signer).mint(amountDAItoDeposit));
+
+    await waitForTx(
+      await pool
+        .connect(users[0].signer)
+        .deposit(dai.address, amountDAItoDeposit, users[0].address, '0')
+    );
+
+    const { liquidityIndex, variableBorrowIndex } = await pool.getReserveData(dai.address);
+
+    const amountBorrowedBN = new BigNumber(amountDAItoBorrow.toString());
+    const liquidityIndexBN = new BigNumber(liquidityIndex.toString());
+    const variableBorrowIndexBN = new BigNumber(variableBorrowIndex.toString());
+
+    const expectedAccruedToTreasury = amountBorrowedBN
+      .rayMul(variableBorrowIndexBN)
+      .minus(amountBorrowedBN)
+      .times(reserveFactor.toString())
+      .div(10000)
+      .rayDiv(liquidityIndexBN)
+      .toFixed(0);
+
+    const { accruedToTreasury } = await pool.getReserveData(dai.address);
+
+    console.log("Accrued to treasury ", accruedToTreasury.toString());
+
+    expect(accruedToTreasury.toString()).to.be.bignumber.almostEqual(
+      expectedAccruedToTreasury,
+      'Invalid amount accrued to the treasury'
+    );
+  });
+
+  it('Mints the accrued to the treasury', async () => {
+    const { users, pool, dai, aDai, helpersContract } = testEnv;
+
+    const treasuryAddress = await aDai.RESERVE_TREASURY_ADDRESS();
+    const { accruedToTreasury } = await pool.getReserveData(dai.address);
+
+    await waitForTx(await pool.connect(users[0].signer).mintToTreasury([dai.address]));
+    const normalizedIncome =  await pool.getReserveNormalizedIncome(dai.address);
+
+    const treasuryBalance = await aDai.balanceOf(treasuryAddress);
+
+    const expectedTreasuryBalance = new BigNumber(accruedToTreasury.toString()).rayMul(
+      new BigNumber(normalizedIncome.toString())
+    );
+    
+    expect(treasuryBalance.toString()).to.be.bignumber.almostEqual(expectedTreasuryBalance, "Invalid treasury balance after minting");
+
+  });
+});

test-suites/test-amm/helpers/utils/calculations.ts

@@ -1195,7 +1195,7 @@ const calcLinearInterest = (
   return cumulatedInterest;
 };
 
-const calcCompoundedInterest = (
+export const calcCompoundedInterest = (
   rate: BigNumber,
   currentTimestamp: BigNumber,
   lastUpdateTimestamp: BigNumber