Rewrite CustomFractionalFeeAssessor.reclaim() to use safe math operations

netopyr commented 2 months ago

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👾 Description of the issue

The method CustomFractionalFeeAssessor.reclaim() sums up values from a Map:

    private long reclaim(final long amount, @NonNull final Map<AccountID, Long> credits) {
        var availableToReclaim = 0L;
        for (final var entry : credits.entrySet()) {
            availableToReclaim += entry.getValue();
            validateTrue(availableToReclaim >= 0, CUSTOM_FEE_OUTSIDE_NUMERIC_RANGE);
        }
        ...

To ensure there is no overflow, it checks after each add, if the value has become negative. As all summands are positive, this can only happen after an overflow in which case an Exception is thrown.

While technically correct, this implementation is confusing. Adding some comments would help, but changing the code to make the intent more obvious is even better.

Proposed Solution:

Reimplement the above functionality using Math.addExact() which throws an ArithmeticException if an overflow occurs. Feel free to use the Stream-API instead of an explicit loop.

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Ayush-Baranwal commented 2 months ago

hi @netopyr I would like to contribute to this issue.

SanikaBhalerao1345 commented 1 month ago

hii @netopyr, being a beginner i would like to contribute to this issue

boooby19 commented 1 month ago

Hello ! I am new to open-source projects. I am working as junior dev in c#/React, also have 3 year experience with Java. Can I work on this issue? Thanks ! :)

netopyr commented 1 month ago

@SanikaBhalerao1345 please go ahead. If you have any questions, do not hesitate to ask.

@boooby19 I assigned to you the other issue you were interested in.

Ndacyayisenga-droid commented 3 weeks ago

@boooby19 are you still interested in this issue??. Otherwise I can take it up

hashgraph / hedera-services