Y2k Finance contest - Samatak's results

++I COSTS LESS GAS THAN I++, ESPECIALLY WHEN IT’S USED IN FOR-LOOPS (--I/I-- TOO)

Saves 6 gas PER LOOP

There is 1 instance of this issue:

File: Vault.sol
443:   for (uint256 i = 0; i < epochsLength(); i++) {

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<ARRAY>.LENGTH SHOULD NOT BE LOOKED UP IN EVERY LOOP OF A FORLOOP

The overheads outlined below are PER LOOP, excluding the first loop

• storage arrays incur a Gwarmaccess (100 gas)
• memory arrays use MLOAD (3 gas)
• calldata arrays use CALLDATALOAD (3 gas)

Caching the length changes each of these to a DUP<N> (3 gas), and gets rid of the extra DUP<N> needed to store the stack offset.

There is 1 instance of this issue:

File: Vault.sol
443:   for (uint256 i = 0; i < epochsLength(); i++) {

With epochsLength() defined as follow :

File: Vault.sol
430:    function epochsLength() public view returns (uint256) {
	        return epochs.length;
		    }

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DON’T USE SAFEMATH ONCE THE SOLIDITY VERSION IS 0.8.0 OR GREATER

Version 0.8.0 introduces internal overflow checks, so using SafeMath is redundant and adds overhead

There is 1 instance of this issue:

File: rewards/StakingRewards.sol 
5:   import {SafeTransferLib} from "@solmate/utils/SafeTransferLib.sol";

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USING PRIVATE RATHER THAN PUBLIC FOR CONSTANTS, SAVES GAS

If needed, the value can be read from the verified contract source code. Savings are due to the compiler not having to create non-payable getter functions for deployment calldata, and not adding another entry to the method ID table.

There is 2 instances of this issue:

File: Controller.sol
16:   uint256 public constant VAULTS_LENGTH = 2;

File: SemiFungibleVault.sol
22:   bytes internal constant EMPTY = "";

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**State variables only set in the constructor should be declared immutable

Avoids a Gsset (20000 gas) in the constructor, and replaces each Gwarmacces (100 gas) with a PUSH32(3 gas).

File:   oracles/PegOracle.sol
10:     address public oracle1;
11:     address public oracle2;
13:     uint8 public decimals;

File:   SemiFungibleVault.sol
20:     string public name;
21:     string public symbol;

File:   rewards/RewardsFactory.sol
9:      address public admin;
10:     address public govToken;
11:     address public factory; 

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PUBLIC FUNCTIONS NOT CALLED BY THE CONTRACT SHOULD BE DECLARED EXTERNAL INSTEAD

Contracts are allowed to override their parents’ functions and change the visibility from external to publicand can save gas by doing so.

There is 25 instances of this issue:

File:  Controller.sol
148:   function triggerDepeg(uint256 marketIndex, uint256 epochEnd)
	        public
	        isDisaster(marketIndex, epochEnd)
		   {
198:   function triggerEndEpoch(uint256 marketIndex, uint256 epochEnd) public {

File:  oracles/PegOracle.sol
89:    function getOracle1_Price() public view returns (int256 price) {

File:  src/SemiFungibleVault.sol
85:    function deposit(
        uint256 id,
        uint256 assets,
        address receiver
    ) public virtual returns (uint256 shares) {
110:   function withdraw(
        uint256 id,
        uint256 assets,
        address receiver,
        address owner
    ) external virtual returns (uint256 shares) {
189:    function previewMint(uint256 id, uint256 shares)
        public
        view
        virtual
        returns (uint256)
    {
221:    function previewRedeem(uint256 id, uint256 shares)
        public
        view
        virtual
        returns (uint256)
    {
237:    function maxDeposit(address) public view virtual returns (uint256) {
244:    function maxMint(address) public view virtual returns (uint256) {
251:    function maxWithdraw(uint256 id, address owner)
        public
        view
        virtual
        returns (uint256)
    {
263:    function maxRedeem(uint256 id, address owner)
        public
        view
        virtual
        returns (uint256)
    {

File:   Vault.sol
277:    function changeTreasury(address _treasury) public onlyFactory {
287:    function changeTimewindow(uint256 _timewindow) public onlyFactory {
295:    function changeController(address _controller) public onlyFactory {
307:    function createAssets(uint256 epochBegin, uint256 epochEnd, uint256 _withdrawalFee)
        public
        onlyFactory
    {
336:    function endEpoch(uint256 id, bool depeg)
        public
        onlyController
        marketExists(id)
    {
350:    function setClaimTVL(uint256 id, uint256 claimTVL) public onlyController {
360:    function sendTokens(uint256 id, address _counterparty)
        public
        onlyController
        marketExists(id)
    {
438:    function getNextEpoch(uint256 _epoch)
        public
        view
        returns (uint256 nextEpochEnd)
    {

File:  VaultFactory.sol
178:   function createNewMarket(
        uint256 _withdrawalFee,
        address _token,
        int256 _strikePrice,
        uint256 epochBegin,
        uint256 epochEnd,
        address _oracle,
        string memory _name
    ) public onlyAdmin returns (address insr, address rsk) {
248:    function deployMoreAssets(
        uint256 index,
        uint256 epochBegin,
        uint256 epochEnd,
        uint256 _withdrawalFee
    ) public onlyAdmin {
295:    function setController(address _controller) public onlyAdmin {
366:    function changeOracle(address _token, address _oracle) public onlyAdmin {
385:    function getVaults(uint256 index)
        public
        view
        returns (address[] memory vaults)
    {

File    rewards/RewardsFactory.sol
145:    function getHashedIndex(uint256 _index, uint256 _epoch)
        public
        pure
        returns (bytes32 hashedIndex)
    {