FundsLib Code Style Findings

FLB-01C: Ineffectual Usage of Safe Arithmetics

Type	Severity	Location
Language Specific		FundsLib.sol:L328

Description:

The linked mathematical operation is guaranteed to be performed safely by surrounding conditionals evaluated in either require checks or if-else constructs.

Example:

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326// make sure that seller has enough funds in the pool and reduce the available funds
327require(availableFunds >= _amount, INSUFFICIENT_AVAILABLE_FUNDS);
328pl.availableFunds[_entityId][_tokenAddress] = availableFunds - _amount;

Recommendation:

Given that safe arithmetics are toggled on by default in pragma versions of 0.8.X, we advise the linked statement to be wrapped in an unchecked code block thereby optimizing its execution cost.

Alleviation (44009967e4f68092941d841e9e0f5dd2bb31bf0b):

An unchecked code block has been introduced surrounding the linked arithmetic statement thus optimizing its execution cost safely.

FLB-02C: Inefficient mapping Lookups

Type	Severity	Location
Gas Optimization		FundsLib.sol:L295, L296, L298, L302, L324, L328, L332, L334, L338, L340, L342, L345, L347

Description:

The linked statements perform key-based lookup operations on mapping declarations from storage multiple times for the same key redundantly.

Example:

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323// get available funds from storage
324uint256 availableFunds = pl.availableFunds[_entityId][_tokenAddress];
325
326// make sure that seller has enough funds in the pool and reduce the available funds
327require(availableFunds >= _amount, INSUFFICIENT_AVAILABLE_FUNDS);
328pl.availableFunds[_entityId][_tokenAddress] = availableFunds - _amount;
329
330// if availableFunds are totally emptied, the token address is removed from the seller's tokenList
331if (availableFunds == _amount) {
332    uint256 lastTokenIndex = pl.tokenList[_entityId].length - 1;
333    //Get the index in the tokenList array, which is 1 less than the tokenIndexByAccount index
334    uint256 index = pl.tokenIndexByAccount[_entityId][_tokenAddress] - 1;
335    if (index != lastTokenIndex) {
336        // if index == len - 1 then only pop and delete are needed
337        // Need to fill gap caused by delete if more than one element in storage array
338        address tokenToMove = pl.tokenList[_entityId][lastTokenIndex];
339        // Copy the last token in the array to this index to fill the gap
340        pl.tokenList[_entityId][index] = tokenToMove;
341        // Reset index mapping. Should be index in tokenList array + 1
342        pl.tokenIndexByAccount[_entityId][tokenToMove] = index + 1;
343    }
344    // Delete last token address in the array, which was just moved to fill the gap
345    pl.tokenList[_entityId].pop();
346    //Delete from index mapping
347    delete pl.tokenIndexByAccount[_entityId][_tokenAddress];
348}

Recommendation:

As the lookups internally perform an expensive keccak256 operation, we advise the lookups to be cached wherever possible to a single local declaration that either holds the value of the mapping in case of primitive types or holds a storage pointer to the struct contained.

Alleviation (44009967e4f68092941d841e9e0f5dd2bb31bf0b):

The referenced mapping lookups have been optimized to the greatest extent possible thus greatly reducing the gas cost of the codebase.

FLB-03C: Inexplicable Contract Specifier

Type	Severity	Location
Code Style		FundsLib.sol:L261

Description:

The decreaseAvailableFunds function is invoked using the contract specifier FundsLib which is the contract itself.

Example:

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261FundsLib.decreaseAvailableFunds(_entityId, _tokenAddress, _amount);

Recommendation:

We advise the contract specifier to be omitted as decreaseAvailableFunds will refer to the function defined within the contract in this case.

Alleviation (44009967e4f68092941d841e9e0f5dd2bb31bf0b):

The FundsLib specifier has been removed from the referenced function invocation optimizing the code's legibility.