PoolBase Code Style Findings

PBE-01C: Significantly Inefficient Merging of Pending Gains / Distributed Funds

Type	Severity	Location
Gas Optimization		PoolBase.sol:L43-L68

Description:

The PoolBase::_leftSumColls function is meant to merge whatever pending gains are denoted in _tokens and _amounts to the _coll1 data entry, however, it does so significantly inefficiently. The same inefficiency is observed in the PoolBase::_leftSubColls function.

Example:

Copy
33function _leftSumColls(
34    Colls memory _coll1,
35    address[] memory _tokens,
36    uint256[] memory _amounts
37) internal pure returns (uint256[] memory) {
38    // If nothing on the right side then return the original.
39    if (_amounts.length == 0) {
40        return _coll1.amounts;
41    }
42
43    uint256 coll1Len = _coll1.amounts.length;
44    uint256 tokensLen = _tokens.length;
45    // Result will always be coll1 len size.
46    uint256[] memory sumAmounts = new uint256[](coll1Len);
47
48    uint256 i = 0;
49    uint256 j = 0;
50
51    // Sum through all tokens until either left or right side reaches end.
52    while (i < tokensLen && j < coll1Len) {
53        // If tokens match up then sum them together.
54        if (_tokens[i] == _coll1.tokens[j]) {
55            sumAmounts[j] = _coll1.amounts[j].add(_amounts[i]);
56            ++i;
57        }
58        // Otherwise just take the left side.
59        else {
60            sumAmounts[j] = _coll1.amounts[j];
61        }
62        ++j;
63    }
64    // If right side ran out add the remaining amounts in the left side.
65    while (j < coll1Len) {
66        sumAmounts[j] = _coll1.amounts[j];
67        ++j;
68    }
69
70    return sumAmounts;
71}

Recommendation:

We advise the code to instead sum / subtract the values in the _coll1.amounts data entry directly, rendering the new sumAmounts / diffAmounts array redundant. Additionally, this will significantly optimize the code as only the _tokens array would need to be iterated as the _coll1.amounts data entry will be "pre-filled" with the desirable amounts.

Alleviation:

The code, now located within StabilityPool, has been refactored per our recommendation albeit in a different approach that is still relatively inefficient. We advise the _tokens array to be iterated rather than the _coll1 array, iterating the _coll1 array inside the _tokens loop and issuing a break statement when the correct _coll1 entry has been found to further optimize the code.

PBE-02C: Unused Error Declaration

Type	Severity	Location
Gas Optimization		PoolBase.sol:L22

Description:

The PoolBase__AdminOnly error remains unused in the codebase.

Example:

Copy
22error PoolBase__AdminOnly();

Recommendation:

We advise it to be safely omitted from it.

Alleviation:

The PoolBase contract is no longer present in the codebase rendering this exhibit no longer applicable.