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Charge fees for use of memo #3007

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Charge fees for use of memo #3007

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15 changes: 14 additions & 1 deletion src/ripple/app/tx/impl/Transactor.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -139,7 +139,20 @@ std::uint64_t Transactor::calculateBaseFee (
if (tx.isFieldPresent (sfSigners))
signerCount = tx.getFieldArray (sfSigners).size();

return baseFee + (signerCount * baseFee);
std::uint32_t memoCount = 0;

if (tx.isFieldPresent(sfMemos) && view.rules().enabled(featureMemoFee))
{
auto const& memos = tx.getFieldArray (sfMemos);

Serializer s (2048);
memos.add (s);

if (s.size() > 32)
memoCount = 2 * static_cast<std::uint32_t>(s.size());
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@nbougalis nbougalis Jul 23, 2019 •
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Seems reasonable. I'd probably consider making the multiplier a function of length too. For example:
memoCount = std::max(1, (s.size() / 128)) * static_cast<std::uint32_t>(s.size());

This gives it a nice stepped "curve" of increasing slope, as you can see on this WolframAlpha graph

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Maybe just s.size() * s.size() / 128 for simplicity. With a minimum s.size() of 32, this expression starts at 8 and scales to 8192.

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@miguelportilla makes a good point that super-linear fee scaling will just encourage splitting into multiple transactions at the point where the marginal cost of a memo byte exceeds the cost of a new transaction. That means we should just use s.size() for memoCount.

}

return baseFee + (signerCount * baseFee) + (memoCount * baseFee);
}

XRPAmount
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1 change: 1 addition & 0 deletions src/ripple/protocol/Feature.h
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Expand Up @@ -374,6 +374,7 @@ extern uint256 const fix1578;
extern uint256 const featureMultiSignReserve;
extern uint256 const fixTakerDryOfferRemoval;
extern uint256 const fixMasterKeyAsRegularKey;
extern uint256 const featureMemoFee;

} // ripple

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2 changes: 2 additions & 0 deletions src/ripple/protocol/impl/Feature.cpp
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Expand Up @@ -118,6 +118,7 @@ detail::supportedAmendments ()
"MultiSignReserve",
"fixTakerDryOfferRemoval",
"fixMasterKeyAsRegularKey",
"MemoFee"
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Need to also add "MemoFee" to featureNames in Feature.h.

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Please add a trailing comma to this line as well.

};
return supported;
}
Expand Down Expand Up @@ -175,5 +176,6 @@ uint256 const fix1578 = *getRegisteredFeature("fix1578");
uint256 const featureMultiSignReserve = *getRegisteredFeature("MultiSignReserve");
uint256 const fixTakerDryOfferRemoval = *getRegisteredFeature("fixTakerDryOfferRemoval");
uint256 const fixMasterKeyAsRegularKey = *getRegisteredFeature("fixMasterKeyAsRegularKey");
uint256 const featureMemoFee = *getRegisteredFeature("MemoFee");

} // ripple