FastPriceFeed Code Style Findings

FPF-01C: Inexistent Usage of Existing Calculation

Type	Severity	Location
Gas Optimization		FastPriceFeed.sol:L146, L147

Description:

The referenced statements will re-calculate the value of the local index variable redundantly.

Example:

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142uint256 index = i * 8 + j;
143
144if (index >= _optionTokenIds.length) { return; }
145
146uint256 optionTokenId = _optionTokenIds[i * 8 + j];
147uint256 requestIndex = _requestIndexes[i * 8 + j];

Recommendation:

We advise the index variable to be utilized properly, optimizing their gas cost.

Alleviation (a8720219a6a97e10b8d9c6a70c6345747f0fdcb3):

The index variable is correctly re-used in place of the referenced re-calculations, optimizing each loop's gas cost.

FPF-02C: Loop Iterator Optimizations

Type	Severity	Location
Gas Optimization		FastPriceFeed.sol:L74, L136, L141

Description:

The linked for loops increment / decrement their iterator "safely" due to Solidity's built - in safe arithmetics (post-0.8.X).

Example:

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74for (uint256 i = 0; i < _optionTokenIds.length; i++) {

Recommendation:

We advise the increment / decrement operations to be performed in an unchecked code block as the last statement within each for loop to optimize their execution cost.

Alleviation (a8720219a6a97e10b8d9c6a70c6345747f0fdcb3):

The referenced loop iterator increment statements have been relocated at the end of each respective for loop's body and have been unwrapped in an unchecked code block, optimizing their gas cost.

FPF-03C: Redundant Validation of Literal

Type	Severity	Location
Gas Optimization		FastPriceFeed.sol:L39-L40, L42

Description:

The FastPriceFeed::initialize function will validate a known value literal which is inefficient.

Example:

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39uint256 _updateDuration = 60; // 60s
40require(_updateDuration <= MAX_UPDATE_DURATION, "FastPriceFeed: invalid _updateDuration");
41
42updateDuration = _updateDuration;

Recommendation:

We advise the validation to be omitted, and the updateDuration variable to be assigned to 60 directly.

Alleviation (b02fae335f62cc1f5f4236fb4d982ad16a32bd26):

The redundant validation of the value literal has been safely removed from the codebase, optimizing it in the process.