Merge pull request #3 from pooltogether/fix/46

reduce SLOAD calls in _withdrawFromVault

.gitignore

@@ -15,6 +15,7 @@ artifacts
 cache
 node_modules
 types
+deployments/localhost/
 
 # Solidity Coverage
 coverage

contracts/yield-source/YearnV2YieldSource.sol

@@ -20,11 +20,11 @@ import "@openzeppelin/contracts-upgradeable/utils/ReentrancyGuardUpgradeable.sol
 contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeable, ReentrancyGuardUpgradeable {
     using SafeERC20Upgradeable for IERC20Upgradeable;
     using SafeMathUpgradeable for uint;
-    
+
     /// @notice Yearn Vault which manages `token` to generate yield
     IYVaultV2 public vault;
     /// @dev Deposit Token contract address
-    IERC20Upgradeable internal token; 
+    IERC20Upgradeable internal token;
     /// @dev Max % of losses that the Yield Source will accept from the Vault in BPS
     uint256 public maxLosses = 0; // 100% would be 10_000
 
@@ -33,7 +33,7 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
         address indexed user,
         uint256 amount
     );
-    
+
     /// @notice Emitted when the yield source is initialized
     event YieldSourceYearnV2Initialized(
         IYVaultV2 vault,
@@ -60,14 +60,14 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
         uint256 amount
     );
 
-    /// @notice Initializes the yield source with 
+    /// @notice Initializes the yield source with
     /// @param _vault YearnV2 Vault in which the Yield Source will deposit `token` to generate Yield
     /// @param _token Underlying Token / Deposit Token
     function initialize(
         IYVaultV2 _vault,
         IERC20Upgradeable _token
-    ) 
-        public 
+    )
+        public
         initializer
     {
         require(address(vault) == address(0), "YearnV2YieldSource:: already initialized");
@@ -168,7 +168,7 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
     /// @return The actual amount of shares that were received for the deposited tokens
     function _depositInVault() internal returns (uint256) {
         IYVaultV2 v = vault; // NOTE: for gas usage
-        if(token.allowance(address(this), address(v)) < token.balanceOf(address(this))) {
+        if (token.allowance(address(this), address(v)) < token.balanceOf(address(this))) {
             token.safeApprove(address(v), type(uint256).max);
         }
         // this will deposit full balance (for cases like not enough room in Vault)
@@ -184,8 +184,9 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
         uint256 yShares = _tokenToYShares(amount);
         uint256 previousBalance = token.balanceOf(address(this));
         // we accept losses to avoid being locked in the Vault (if losses happened for some reason)
-        if(maxLosses != 0) {
-            vault.withdraw(yShares, address(this), maxLosses);
+        uint256 _maxLosses = maxLosses;
+        if (_maxLosses != 0) {
+            vault.withdraw(yShares, address(this), _maxLosses);
         } else {
             vault.withdraw(yShares);
         }
@@ -222,7 +223,7 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
     }
 
     /// @notice Support function to retrieve used by Vault
-    /// @dev used to correctly scale prices 
+    /// @dev used to correctly scale prices
     /// @return decimals of vault's shares (and underlying token)
     function _vaultDecimals() internal view returns (uint256) {
         return vault.decimals();
@@ -237,7 +238,7 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
         return tokens.mul(10 ** _vaultDecimals()).div(_pricePerYShare());
     }
 
-    /// @notice Converter from deposit yShares (yearn vault's shares) to token 
+    /// @notice Converter from deposit yShares (yearn vault's shares) to token
     /// @param yShares Vault's shares to be converted
     /// @return tokens that will be received if yShares shares are redeemed
     function _ySharesToToken(uint256 yShares) internal view returns (uint256) {
@@ -248,7 +249,7 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
     /// @param tokens amount of tokens to be converted
     /// @return shares number of shares equivalent to the amount of tokens
     function _tokenToShares(uint256 tokens) internal view returns (uint256 shares) {
-        if(totalSupply() == 0) {
+        if (totalSupply() == 0) {
             shares = tokens;
         } else {
             uint256 _totalTokens = _totalAssetsInToken();
@@ -261,7 +262,7 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
     /// @dev used to calculate how many shares to mint / burn when depositing / withdrawing
     /// @return tokens number of tokens equivalent (in value) to the amount of Yield Source shares
     function _sharesToToken(uint256 shares) internal view returns (uint256 tokens) {
-        if(totalSupply() == 0) {
+        if (totalSupply() == 0) {
             tokens = shares;
         } else {
             uint256 _totalTokens = _totalAssetsInToken();
@@ -276,4 +277,4 @@ contract YearnV2YieldSource is IYieldSource, ERC20Upgradeable, OwnableUpgradeabl
     function areEqualStrings(string memory a, string memory b) internal pure returns (bool) {
         return keccak256(abi.encodePacked(a)) == keccak256(abi.encodePacked(b));
     }
-}
+}

package.json

@@ -54,7 +54,7 @@
     "hardhat-deploy-ethers": "0.3.0-beta.7",
     "hardhat-gas-reporter": "1.0.4",
     "prettier": "2.2.1",
-    "solhint": "3.3.3",
+    "solhint": "3.3.6",
     "solidity-coverage": "0.7.16",
     "ts-generator": "0.1.1",
     "ts-node": "9.1.1",

yarn.lock

@@ -895,7 +895,7 @@ __metadata:
     hardhat-deploy-ethers: 0.3.0-beta.7
     hardhat-gas-reporter: 1.0.4
     prettier: 2.2.1
-    solhint: 3.3.3
+    solhint: 3.3.6
     solidity-coverage: 0.7.16
     ts-generator: 0.1.1
     ts-node: 9.1.1
@@ -1066,6 +1066,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@solidity-parser/parser@npm:^0.13.2":
+  version: 0.13.2
+  resolution: "@solidity-parser/parser@npm:0.13.2"
+  dependencies:
+    antlr4ts: ^0.5.0-alpha.4
+  checksum: ad2f8ca981bf7564711e5d9e709c79d3a44116419b21391692b356387c9528fc8056178378a5118d08389d2c73b93ca30cca9df2bd06de17bb0092b433077b33
+  languageName: node
+  linkType: hard
+
 "@solidity-parser/parser@npm:^0.5.2":
   version: 0.5.2
   resolution: "@solidity-parser/parser@npm:0.5.2"
@@ -1645,6 +1654,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"antlr4ts@npm:^0.5.0-alpha.4":
+  version: 0.5.0-dev
+  resolution: "antlr4ts@npm:0.5.0-dev"
+  dependencies:
+    source-map-support: ^0.5.16
+  checksum: 0f206ef5ef5793456de66545a1bf6d8d52343bc6c6689d941cc16ea3f0b6b18a7710b4cc3946a61d021fda51f93b89adcd7c5d7fe249ea1739b0459e7a85b42c
+  languageName: node
+  linkType: hard
+
 "anymatch@npm:~3.1.1":
   version: 3.1.1
   resolution: "anymatch@npm:3.1.1"
@@ -10939,11 +10957,11 @@ resolve@1.1.x:
   languageName: node
   linkType: hard
 
-"solhint@npm:3.3.3":
-  version: 3.3.3
-  resolution: "solhint@npm:3.3.3"
+"solhint@npm:3.3.6":
+  version: 3.3.6
+  resolution: "solhint@npm:3.3.6"
   dependencies:
-    "@solidity-parser/parser": ^0.12.0
+    "@solidity-parser/parser": ^0.13.2
     ajv: ^6.6.1
     antlr4: 4.7.1
     ast-parents: 0.0.1
@@ -10963,7 +10981,7 @@ resolve@1.1.x:
       optional: true
   bin:
     solhint: solhint.js
-  checksum: 671c02462d97865b19d3058ceb6159c4afa86795390c08280b4a137c6022a434911cb2418befcfaf5262585e9ba13eb7b3010b6f06eef246e3bf1501dac7c414
+  checksum: 3e8320a03932913fb45de1964563f1b8f4f92e3e8cc086d21dd0763fb17a035a1ae1665983e15c1fe57517e9b3b0820c5ec4210288fa7240b06806918d831e55
   languageName: node
   linkType: hard
 
@@ -11082,7 +11100,7 @@ resolve@1.1.x:
   languageName: node
   linkType: hard
 
-"source-map-support@npm:^0.5.13, source-map-support@npm:^0.5.17":
+"source-map-support@npm:^0.5.13, source-map-support@npm:^0.5.16, source-map-support@npm:^0.5.17":
   version: 0.5.19
   resolution: "source-map-support@npm:0.5.19"
   dependencies: