Omniscia Mean Finance Audit

TransformerOracle Code Style Findings

TransformerOracle Code Style Findings

TOE-01C: Potential Quote Code Simplification

Description:

The linked code statements contain a lot of repetition as the joint transformer case is identical in statements to each independent transformer case.

Example:

solidity/contracts/TransformerOracle.sol
89if (address(_transformerTokenIn) != address(0) && address(_transformerTokenOut) != address(0)) {
90  // If both tokens have a transformer, then we need to transform both in and out data
91  ITransformer.UnderlyingAmount[] memory _transformedIn = _transformerTokenIn.calculateTransformToUnderlying(_tokenIn, _amountIn);
92  address[] memory _underlyingOut = _transformerTokenOut.getUnderlying(_tokenOut);
93  uint256 _amountOutUnderlying = UNDERLYING_ORACLE.quote(_transformedIn[0].underlying, _transformedIn[0].amount, _underlyingOut[0], _data);
94  return _transformerTokenOut.calculateTransformToDependent(_tokenOut, _toUnderlyingAmount(_underlyingOut[0], _amountOutUnderlying));
95} else if (address(_transformerTokenIn) != address(0)) {
96  // If token in has a transformer, then calculate how much amount it would be in underlying, and calculate the quote for that
97  ITransformer.UnderlyingAmount[] memory _transformedIn = _transformerTokenIn.calculateTransformToUnderlying(_tokenIn, _amountIn);
98  return UNDERLYING_ORACLE.quote(_transformedIn[0].underlying, _transformedIn[0].amount, _tokenOut, _data);
99} else if (address(_transformerTokenOut) != address(0)) {
100  // If token out has a transformer, then calculate the quote for the underlying and then transform the result
101  address[] memory _underlyingOut = _transformerTokenOut.getUnderlying(_tokenOut);
102  uint256 _amountOutUnderlying = UNDERLYING_ORACLE.quote(_tokenIn, _amountIn, _underlyingOut[0], _data);
103  return _transformerTokenOut.calculateTransformToDependent(_tokenOut, _toUnderlyingAmount(_underlyingOut[0], _amountOutUnderlying));
104} else {
105  // If there are no transformers, then just call the underlying oracle
106  return UNDERLYING_ORACLE.quote(_tokenIn, _amountIn, _tokenOut, _data);
107}

Recommendation:

We advise local variables to be utilized for the final calculation and the code to be simplified by simply performing assignments in each transformer presence case thus greatly increasing the legibility and maintainability of the codebase and achieving a minor gas optimization.

Alleviation:

The code was greatly simplified by applying the recommended optimization and requiring only two if clauses and a total of 8 "complex" statements rather than 11 optimizing the codebase's legibility and gas cost in the process.

TOE-02C: Potential Transformer Code Simplification

Description:

The _getTransformers function can be greatly simplified by querying the transformers function of REGISTRY directly and then zeroing out the entries based on the _avoidMappingA and _avoidMappingB evaluations.

Example:

solidity/contracts/TransformerOracle.sol
150function _getTransformers(address _tokenA, address _tokenB) internal view virtual returns (ITransformer[] memory _transformers) {
151  bool _avoidMappingA = willAvoidMappingToUnderlying[_tokenA];
152  bool _avoidMappingB = willAvoidMappingToUnderlying[_tokenB];
153  if (!_avoidMappingA && !_avoidMappingB) {
154    address[] memory _tokens = new address[](2);
155    _tokens[0] = _tokenA;
156    _tokens[1] = _tokenB;
157    return REGISTRY.transformers(_tokens);
158  } else {
159    _transformers = new ITransformer[](2);
160    if (_avoidMappingA && _avoidMappingB) {
161      _transformers[0] = ITransformer(address(0));
162      _transformers[1] = ITransformer(address(0));
163    } else if (_avoidMappingA) {
164      _transformers[0] = ITransformer(address(0));
165      address[] memory _tokens = new address[](1);
166      _tokens[0] = _tokenB;
167      ITransformer[] memory _returnedTransformers = REGISTRY.transformers(_tokens);
168      _transformers[1] = _returnedTransformers[0];
169    } else {
170      address[] memory _tokens = new address[](1);
171      _tokens[0] = _tokenA;
172      ITransformer[] memory _returnedTransformers = REGISTRY.transformers(_tokens);
173      _transformers[0] = _returnedTransformers[0];
174      _transformers[1] = ITransformer(address(0));
175    }
176  }
177}

Recommendation:

We advise this to be done so greatly optimizing the gas cost of the function and simplifying its execution.

Alleviation:

The code was optimized based on our recommendation and simply overwrites the _transformerTokenA and _transformerTokenB entries (previously _transformers) based on whether their "avoidance" flags have been set, optimizing the code's readability significantly.

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