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Fix Overpayment ValueChange calculation in Lending Protocol (#6114)

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- Adds loan state to LoanProperties.
- Cleans up computeLoanProperties.
- Fixes missing management fee from overpayment.
This commit is contained in:
Vito Tumas
2025-12-19 01:14:28 +01:00
committed by GitHub
parent 28fd66097b
commit b9aa354782
5 changed files with 354 additions and 209 deletions
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103
src/test/app/LendingHelpers_test.cpp
View File

@@ -620,10 +620,113 @@ class LendingHelpers_test : public beast::unit_test::suite
}
}
void
testTryOverpaymentValueChange()
{
// This test ensures that overpayment value change is computed
// correctly.
testcase("tryOverpayment - Value Change is the decrease in interest");
using namespace jtx;
using namespace xrpl::detail;
Env env{*this};
Account const issuer{"issuer"};
PrettyAsset const asset = issuer["USD"];
// Interest delta is 40 (100 - 50 - 10)
ExtendedPaymentComponents const overpaymentComponents = {
PaymentComponents{
.trackedValueDelta = Number{50, 0},
.trackedPrincipalDelta = Number{50, 0},
.trackedManagementFeeDelta = Number{0, 0},
.specialCase = PaymentSpecialCase::extra,
},
numZero,
numZero,
};
TenthBips16 managementFeeRate{20'000}; // 20%
TenthBips32 loanInterestRate{10'000}; // 10%
Number loanPrincipal{1'000};
std::uint32_t paymentInterval = 30 * 24 * 60 * 60;
std::uint32_t paymentsRemaining = 10;
std::int32_t loanScale = -5;
auto const periodicRate =
loanPeriodicRate(loanInterestRate, paymentInterval);
auto loanProperites = computeLoanProperties(
asset,
loanPrincipal,
loanInterestRate,
paymentInterval,
paymentsRemaining,
managementFeeRate,
loanScale);
Number periodicPayment = loanProperites.periodicPayment;
auto const ret = tryOverpayment(
asset,
loanScale,
overpaymentComponents,
loanProperites.loanState,
periodicPayment,
periodicRate,
paymentsRemaining,
managementFeeRate,
env.journal);
BEAST_EXPECT(ret);
auto const& [actualPaymentParts, newLoanProperties] = *ret;
auto const& newState = newLoanProperties.loanState;
// value change should be equal to interest decrease
BEAST_EXPECTS(
actualPaymentParts.valueChange ==
newState.interestDue - loanProperites.loanState.interestDue,
" valueChange mismatch: expected " +
to_string(
newState.interestDue -
loanProperites.loanState.interestDue) +
", got " + to_string(actualPaymentParts.valueChange));
BEAST_EXPECTS(
actualPaymentParts.feePaid ==
loanProperites.loanState.managementFeeDue -
newState.managementFeeDue,
" feePaid mismatch: expected " +
to_string(
loanProperites.loanState.managementFeeDue -
newState.managementFeeDue) +
", got " + to_string(actualPaymentParts.feePaid));
BEAST_EXPECTS(
actualPaymentParts.principalPaid ==
loanProperites.loanState.principalOutstanding -
newState.principalOutstanding,
" principalPaid mismatch: expected " +
to_string(
loanProperites.loanState.principalOutstanding -
newState.principalOutstanding) +
", got " + to_string(actualPaymentParts.principalPaid));
BEAST_EXPECTS(
actualPaymentParts.interestPaid ==
loanProperites.loanState.interestDue - newState.interestDue,
" interestPaid mismatch: expected " +
to_string(
loanProperites.loanState.interestDue -
newState.interestDue) +
", got " + to_string(actualPaymentParts.interestPaid));
}
public:
void
run() override
{
testTryOverpaymentValueChange();
testComputeFullPaymentInterest();
testLoanAccruedInterest();
testLoanLatePaymentInterest();

104
src/test/app/Loan_test.cpp
View File

@@ -700,8 +700,7 @@ protected:
interval,
total,
feeRate,
asset(brokerParams.vaultDeposit).number().exponent(),
env.journal);
asset(brokerParams.vaultDeposit).number().exponent());
log << "Loan properties:\n"
<< "\tPrincipal: " << principal << std::endl
<< "\tInterest rate: " << interest << std::endl
@@ -709,8 +708,9 @@ protected:
<< "\tManagement Fee Rate: " << feeRate << std::endl
<< "\tTotal Payments: " << total << std::endl
<< "\tPeriodic Payment: " << props.periodicPayment << std::endl
<< "\tTotal Value: " << props.totalValueOutstanding << std::endl
<< "\tManagement Fee: " << props.managementFeeOwedToBroker
<< "\tTotal Value: " << props.loanState.valueOutstanding
<< std::endl
<< "\tManagement Fee: " << props.loanState.managementFeeDue
<< std::endl
<< "\tLoan Scale: " << props.loanScale << std::endl
<< "\tFirst payment principal: " << props.firstPaymentPrincipal
@@ -860,9 +860,6 @@ protected:
using namespace std::chrono_literals;
using d = NetClock::duration;
// Account const evan{"evan"};
// Account const alice{"alice"};
bool const showStepBalances = paymentParams.showStepBalances;
auto const currencyLabel = getCurrencyLabel(broker.asset);
@@ -1482,17 +1479,16 @@ protected:
state.paymentInterval,
state.paymentRemaining,
broker.params.managementFeeRate,
state.loanScale,
env.journal);
state.loanScale);
verifyLoanStatus(
0,
startDate + *loanParams.payInterval,
*loanParams.payTotal,
state.loanScale,
loanProperties.totalValueOutstanding,
loanProperties.loanState.valueOutstanding,
principalRequestAmount,
loanProperties.managementFeeOwedToBroker,
loanProperties.loanState.managementFeeDue,
loanProperties.periodicPayment,
loanFlags | 0);
@@ -1547,9 +1543,9 @@ protected:
nextDueDate,
*loanParams.payTotal,
loanProperties.loanScale,
loanProperties.totalValueOutstanding,
loanProperties.loanState.valueOutstanding,
principalRequestAmount,
loanProperties.managementFeeOwedToBroker,
loanProperties.loanState.managementFeeDue,
loanProperties.periodicPayment,
loanFlags | 0);
@@ -4487,15 +4483,6 @@ protected:
};
}
void
testBasicMath()
{
// Test the functions defined in LendingHelpers.h
testcase("Basic Math");
pass();
}
void
testIssuerLoan()
{
@@ -7040,11 +7027,8 @@ protected:
env.close();
PaymentParameters paymentParams{
//.overpaymentFactor = Number{15, -1},
//.overpaymentExtra = Number{1, -6},
//.flags = tfLoanOverpayment,
.showStepBalances = true,
//.validateBalances = false,
.showStepBalances = false,
.validateBalances = true,
};
makeLoanPayments(
@@ -7059,6 +7043,69 @@ protected:
paymentParams);
}
void
testOverpaymentManagementFee()
{
testcase("testOverpaymentManagementFee");
using namespace jtx;
using namespace loan;
Env env(*this, all);
Account const lender{"lender"}, borrower{"borrower"};
env.fund(XRP(10'000'000), lender, borrower);
env.close();
PrettyAsset const asset{xrpIssue(), 1000};
auto const result = createVaultAndBroker(
env,
asset,
lender,
{
.vaultDeposit = asset(100'000).value(),
.managementFeeRate = TenthBips16(10'000),
});
auto const loanSetFee = fee(env.current()->fees().base * 2);
auto const loanKeylet = keylet::loan(
result.brokerKeylet().key,
(env.le(result.brokerKeylet()))->at(sfLoanSequence));
env(loan::set(
borrower,
result.brokerKeylet().key,
asset(10'000).value(),
tfLoanOverpayment),
sig(sfCounterpartySignature, lender),
loan::paymentInterval(86400 * 30),
loan::paymentTotal(3),
loan::overpaymentInterestRate(
TenthBips32(percentageToTenthBips(20))),
loanSetFee);
// From calculator
auto const expectedOverpaymentManagementFee = Number{33333, 0};
auto const loanBrokerBalanceBefore = env.balance(lender);
auto const loanPayFee = fee(env.current()->fees().base * 2);
env(pay(borrower,
loanKeylet.key,
asset(5'000).value(),
tfLoanOverpayment),
loanPayFee);
env.close();
BEAST_EXPECTS(
env.balance(lender) - loanBrokerBalanceBefore ==
expectedOverpaymentManagementFee,
"overpayment management fee missmatch; expected:" +
to_string(expectedOverpaymentManagementFee) + " got: " +
to_string(env.balance(lender) - loanBrokerBalanceBefore));
}
void
testLoanPayBrokerOwnerMissingTrustline()
{
@@ -7422,8 +7469,6 @@ public:
testServiceFeeOnBrokerDeepFreeze();
testRPC();
testBasicMath();
testInvalidLoanDelete();
testInvalidLoanManage();
testInvalidLoanPay();
@@ -7451,6 +7496,7 @@ public:
testBorrowerIsBroker();
testIssuerIsBorrower();
testLimitExceeded();
testOverpaymentManagementFee();
testLoanPayBrokerOwnerMissingTrustline();
testLoanPayBrokerOwnerUnauthorizedMPT();
testLoanPayBrokerOwnerNoPermissionedDomainMPT();

99
src/xrpld/app/misc/LendingHelpers.h
View File

@@ -84,46 +84,6 @@ struct LoanPaymentParts
operator==(LoanPaymentParts const& other) const;
};
/* Describes the initial computed properties of a loan.
*
* This structure contains the fundamental calculated values that define a
* loan's payment structure and amortization schedule. These properties are
* computed:
* - At loan creation (LoanSet transaction)
* - When loan terms change (e.g., after an overpayment that reduces the loan
* balance)
*/
struct LoanProperties
{
// The unrounded amount to be paid at each regular payment period.
// Calculated using the standard amortization formula based on principal,
// interest rate, and number of payments.
// The actual amount paid in the LoanPay transaction must be rounded up to
// the precision of the asset and loan.
Number periodicPayment;
// The total amount the borrower will pay over the life of the loan.
// Equal to periodicPayment * paymentsRemaining.
// This includes principal, interest, and management fees.
Number totalValueOutstanding;
// The total management fee that will be paid to the broker over the
// loan's lifetime. This is a percentage of the total interest (gross)
// as specified by the broker's management fee rate.
Number managementFeeOwedToBroker;
// The scale (decimal places) used for rounding all loan amounts.
// This is the maximum of:
// - The asset's native scale
// - A minimum scale required to represent the periodic payment accurately
// All loan state values (principal, interest, fees) are rounded to this
// scale.
std::int32_t loanScale;
// The principal portion of the first payment.
Number firstPaymentPrincipal;
};
/** This structure captures the parts of a loan state.
*
* Whether the values are raw (unrounded) or rounded will depend on how it was
@@ -161,6 +121,39 @@ struct LoanState
}
};
/* Describes the initial computed properties of a loan.
*
* This structure contains the fundamental calculated values that define a
* loan's payment structure and amortization schedule. These properties are
* computed:
* - At loan creation (LoanSet transaction)
* - When loan terms change (e.g., after an overpayment that reduces the loan
* balance)
*/
struct LoanProperties
{
// The unrounded amount to be paid at each regular payment period.
// Calculated using the standard amortization formula based on principal,
// interest rate, and number of payments.
// The actual amount paid in the LoanPay transaction must be rounded up to
// the precision of the asset and loan.
Number periodicPayment;
// The loan's current state, with all values rounded to the loan's scale.
LoanState loanState;
// The scale (decimal places) used for rounding all loan amounts.
// This is the maximum of:
// - The asset's native scale
// - A minimum scale required to represent the periodic payment accurately
// All loan state values (principal, interest, fees) are rounded to this
// scale.
std::int32_t loanScale;
// The principal portion of the first payment.
Number firstPaymentPrincipal;
};
// Some values get re-rounded to the vault scale any time they are adjusted. In
// addition, they are prevented from ever going below zero. This helps avoid
// accumulated rounding errors and leftover dust amounts.
@@ -369,6 +362,18 @@ struct LoanStateDeltas
nonNegative();
};
Expected<std::pair<LoanPaymentParts, LoanProperties>, TER>
tryOverpayment(
Asset const& asset,
std::int32_t loanScale,
ExtendedPaymentComponents const& overpaymentComponents,
LoanState const& roundedLoanState,
Number const& periodicPayment,
Number const& periodicRate,
std::uint32_t paymentRemaining,
TenthBips16 const managementFeeRate,
beast::Journal j);
Number
computeRaisedRate(Number const& periodicRate, std::uint32_t paymentsRemaining);
@@ -447,13 +452,21 @@ operator+(LoanState const& lhs, detail::LoanStateDeltas const& rhs);
LoanProperties
computeLoanProperties(
Asset const& asset,
Number principalOutstanding,
Number const& principalOutstanding,
TenthBips32 interestRate,
std::uint32_t paymentInterval,
std::uint32_t paymentsRemaining,
TenthBips32 managementFeeRate,
std::int32_t minimumScale,
beast::Journal j);
std::int32_t minimumScale);
LoanProperties
computeLoanProperties(
Asset const& asset,
Number const& principalOutstanding,
Number const& periodicRate,
std::uint32_t paymentsRemaining,
TenthBips32 managementFeeRate,
std::int32_t minimumScale);
bool
isRounded(Asset const& asset, Number const& value, std::int32_t scale);

233
src/xrpld/app/misc/detail/LendingHelpers.cpp
View File

@@ -380,21 +380,15 @@ doPayment(
* The function preserves accumulated rounding errors across the re-amortization
* to ensure the loan state remains consistent with its payment history.
*/
Expected<LoanPaymentParts, TER>
Expected<std::pair<LoanPaymentParts, LoanProperties>, TER>
tryOverpayment(
Asset const& asset,
std::int32_t loanScale,
ExtendedPaymentComponents const& overpaymentComponents,
Number& totalValueOutstanding,
Number& principalOutstanding,
Number& managementFeeOutstanding,
Number& periodicPayment,
TenthBips32 interestRate,
std::uint32_t paymentInterval,
LoanState const& roundedOldState,
Number const& periodicPayment,
Number const& periodicRate,
std::uint32_t paymentRemaining,
std::uint32_t prevPaymentDate,
std::optional<std::uint32_t> nextDueDate,
TenthBips16 const managementFeeRate,
beast::Journal j)
{
@@ -402,15 +396,11 @@ tryOverpayment(
auto const raw = computeRawLoanState(
periodicPayment, periodicRate, paymentRemaining, managementFeeRate);
// Get the actual loan state (with accumulated rounding from past payments)
auto const rounded = constructLoanState(
totalValueOutstanding, principalOutstanding, managementFeeOutstanding);
// Calculate the accumulated rounding errors. These need to be preserved
// across the re-amortization to maintain consistency with the loan's
// payment history. Without preserving these errors, the loan could end
// up with a different total value than what the borrower has actually paid.
auto const errors = rounded - raw;
auto const errors = roundedOldState - raw;
// Compute the new principal by applying the overpayment to the raw
// (theoretical) principal. Use max with 0 to ensure we never go negative.
@@ -424,17 +414,15 @@ tryOverpayment(
auto newLoanProperties = computeLoanProperties(
asset,
newRawPrincipal,
interestRate,
paymentInterval,
periodicRate,
paymentRemaining,
managementFeeRate,
loanScale,
j);
loanScale);
JLOG(j.debug()) << "new periodic payment: "
<< newLoanProperties.periodicPayment
<< ", new total value: "
<< newLoanProperties.totalValueOutstanding
<< newLoanProperties.loanState.valueOutstanding
<< ", first payment principal: "
<< newLoanProperties.firstPaymentPrincipal;
@@ -453,37 +441,35 @@ tryOverpayment(
// rounding errors. This ensures the loan's tracked state remains
// consistent with its payment history.
principalOutstanding = std::clamp(
auto const principalOutstanding = std::clamp(
roundToAsset(
asset, newRaw.principalOutstanding, loanScale, Number::upward),
numZero,
rounded.principalOutstanding);
totalValueOutstanding = std::clamp(
roundedOldState.principalOutstanding);
auto const totalValueOutstanding = std::clamp(
roundToAsset(
asset,
principalOutstanding + newRaw.interestOutstanding(),
loanScale,
Number::upward),
numZero,
rounded.valueOutstanding);
managementFeeOutstanding = std::clamp(
roundedOldState.valueOutstanding);
auto const managementFeeOutstanding = std::clamp(
roundToAsset(asset, newRaw.managementFeeDue, loanScale),
numZero,
rounded.managementFeeDue);
roundedOldState.managementFeeDue);
auto const newRounded = constructLoanState(
auto const roundedNewState = constructLoanState(
totalValueOutstanding, principalOutstanding, managementFeeOutstanding);
// Update newLoanProperties so that checkLoanGuards can make an accurate
// evaluation.
newLoanProperties.totalValueOutstanding = newRounded.valueOutstanding;
newLoanProperties.loanState = roundedNewState;
JLOG(j.debug()) << "new rounded value: " << newRounded.valueOutstanding
<< ", principal: " << newRounded.principalOutstanding
<< ", interest gross: " << newRounded.interestOutstanding();
// Update the periodic payment to reflect the re-amortized schedule
periodicPayment = newLoanProperties.periodicPayment;
JLOG(j.debug()) << "new rounded value: " << roundedNewState.valueOutstanding
<< ", principal: " << roundedNewState.principalOutstanding
<< ", interest gross: "
<< roundedNewState.interestOutstanding();
// check that the loan is still valid
if (auto const ter = checkLoanGuards(
@@ -493,7 +479,7 @@ tryOverpayment(
// small interest amounts, that may have already been paid
// off. Check what's still outstanding. This should
// guarantee that the interest checks pass.
newRounded.interestOutstanding() != beast::zero,
roundedNewState.interestOutstanding() != beast::zero,
paymentRemaining,
newLoanProperties,
j))
@@ -507,61 +493,64 @@ tryOverpayment(
// Validate that all computed properties are reasonable. These checks should
// never fail under normal circumstances, but we validate defensively.
if (newLoanProperties.periodicPayment <= 0 ||
newLoanProperties.totalValueOutstanding <= 0 ||
newLoanProperties.managementFeeOwedToBroker < 0)
newLoanProperties.loanState.valueOutstanding <= 0 ||
newLoanProperties.loanState.managementFeeDue < 0)
{
// LCOV_EXCL_START
JLOG(j.warn()) << "Overpayment not allowed: Computed loan "
"properties are invalid. Does "
"not compute. TotalValueOutstanding: "
<< newLoanProperties.totalValueOutstanding
<< newLoanProperties.loanState.valueOutstanding
<< ", PeriodicPayment : "
<< newLoanProperties.periodicPayment
<< ", ManagementFeeOwedToBroker: "
<< newLoanProperties.managementFeeOwedToBroker;
<< newLoanProperties.loanState.managementFeeDue;
return Unexpected(tesSUCCESS);
// LCOV_EXCL_STOP
}
auto const deltas = rounded - newRounded;
auto const deltas = roundedOldState - roundedNewState;
// The change in loan management fee is equal to the change between the old
// and the new outstanding management fees
XRPL_ASSERT_PARTS(
deltas.managementFee ==
rounded.managementFeeDue - managementFeeOutstanding,
roundedOldState.managementFeeDue - managementFeeOutstanding,
"xrpl::detail::tryOverpayment",
"no fee change");
auto const hypotheticalValueOutstanding =
rounded.valueOutstanding - deltas.principal;
// Calculate how the loan's value changed due to the overpayment.
// This should be negative (value decreased) or zero. A principal
// overpayment should never increase the loan's value.
auto const valueChange = newRounded.valueOutstanding -
hypotheticalValueOutstanding - deltas.managementFee;
// The value change is derived from the reduction in interest due to
// the lower principal.
auto const valueChange = -deltas.interest;
if (valueChange > 0)
{
JLOG(j.warn()) << "Principal overpayment would increase the value of "
"the loan. Ignore the overpayment";
return Unexpected(tesSUCCESS);
}
return LoanPaymentParts{
// Principal paid is the reduction in principal outstanding
.principalPaid = deltas.principal,
// Interest paid is the reduction in interest due
.interestPaid =
deltas.interest + overpaymentComponents.untrackedInterest,
// Value change includes both the reduction from paying down principal
// (negative) and any untracked interest penalties (positive, e.g., if
// the overpayment itself incurs a fee)
.valueChange =
valueChange + overpaymentComponents.trackedInterestPart(),
// Fee paid includes both the reduction in tracked management fees and
// any untracked fees on the overpayment itself
.feePaid = deltas.managementFee +
overpaymentComponents.untrackedManagementFee};
return std::make_pair(
LoanPaymentParts{
// Principal paid is the reduction in principal outstanding
.principalPaid = deltas.principal,
// Interest paid is the reduction in interest due
.interestPaid =
deltas.interest + overpaymentComponents.untrackedInterest,
// Value change includes both the reduction from paying down
// principal (negative) and any untracked interest penalties
// (positive, e.g., if the overpayment itself incurs a fee)
.valueChange =
valueChange + overpaymentComponents.trackedInterestPart(),
// Fee paid includes both the reduction in tracked management fees
// and any untracked fees on the overpayment itself
.feePaid = deltas.managementFee +
overpaymentComponents.untrackedManagementFee +
overpaymentComponents.trackedManagementFeeDelta,
},
newLoanProperties);
}
/* Validates and applies an overpayment to the loan state.
@@ -585,23 +574,16 @@ doOverpayment(
NumberProxy& principalOutstandingProxy,
NumberProxy& managementFeeOutstandingProxy,
NumberProxy& periodicPaymentProxy,
TenthBips32 const interestRate,
std::uint32_t const paymentInterval,
Number const& periodicRate,
std::uint32_t const paymentRemaining,
std::uint32_t const prevPaymentDate,
std::optional<std::uint32_t> const nextDueDate,
TenthBips16 const managementFeeRate,
beast::Journal j)
{
// Create temporary copies of the loan state that can be safely modified
// and discarded if the overpayment doesn't work out. This prevents
// corrupting the actual ledger data if validation fails.
Number totalValueOutstanding = totalValueOutstandingProxy;
Number principalOutstanding = principalOutstandingProxy;
Number managementFeeOutstanding = managementFeeOutstandingProxy;
Number periodicPayment = periodicPaymentProxy;
auto const loanState = constructLoanState(
totalValueOutstandingProxy,
principalOutstandingProxy,
managementFeeOutstandingProxy);
auto const periodicPayment = periodicPaymentProxy;
JLOG(j.debug())
<< "overpayment components:"
<< ", totalValue before: " << *totalValueOutstandingProxy
@@ -620,33 +602,28 @@ doOverpayment(
asset,
loanScale,
overpaymentComponents,
totalValueOutstanding,
principalOutstanding,
managementFeeOutstanding,
loanState,
periodicPayment,
interestRate,
paymentInterval,
periodicRate,
paymentRemaining,
prevPaymentDate,
nextDueDate,
managementFeeRate,
j);
if (!ret)
return Unexpected(ret.error());
auto const& loanPaymentParts = *ret;
auto const& [loanPaymentParts, newLoanProperties] = *ret;
auto const newRoundedLoanState = newLoanProperties.loanState;
// Safety check: the principal must have decreased. If it didn't (or
// increased!), something went wrong in the calculation and we should
// reject the overpayment.
if (principalOutstandingProxy <= principalOutstanding)
if (principalOutstandingProxy <= newRoundedLoanState.principalOutstanding)
{
// LCOV_EXCL_START
JLOG(j.warn()) << "Overpayment not allowed: principal "
<< "outstanding did not decrease. Before: "
<< *principalOutstandingProxy
<< ". After: " << principalOutstanding;
<< *principalOutstandingProxy << ". After: "
<< newRoundedLoanState.principalOutstanding;
return Unexpected(tesSUCCESS);
// LCOV_EXCL_STOP
}
@@ -657,28 +634,29 @@ doOverpayment(
XRPL_ASSERT_PARTS(
overpaymentComponents.trackedPrincipalDelta ==
principalOutstandingProxy - principalOutstanding,
principalOutstandingProxy -
newRoundedLoanState.principalOutstanding,
"xrpl::detail::doOverpayment",
"principal change agrees");
// I'm not 100% sure the following asserts are correct. If in doubt, and
// everything else works, remove any that cause trouble.
JLOG(j.debug()) << "valueChange: " << loanPaymentParts.valueChange
<< ", totalValue before: " << *totalValueOutstandingProxy
<< ", totalValue after: " << totalValueOutstanding
<< ", totalValue delta: "
<< (totalValueOutstandingProxy - totalValueOutstanding)
<< ", principalDelta: "
<< overpaymentComponents.trackedPrincipalDelta
<< ", principalPaid: " << loanPaymentParts.principalPaid
<< ", Computed difference: "
<< overpaymentComponents.trackedPrincipalDelta -
(totalValueOutstandingProxy - totalValueOutstanding);
JLOG(j.debug())
<< "valueChange: " << loanPaymentParts.valueChange
<< ", totalValue before: " << *totalValueOutstandingProxy
<< ", totalValue after: " << newRoundedLoanState.valueOutstanding
<< ", totalValue delta: "
<< (totalValueOutstandingProxy - newRoundedLoanState.valueOutstanding)
<< ", principalDelta: " << overpaymentComponents.trackedPrincipalDelta
<< ", principalPaid: " << loanPaymentParts.principalPaid
<< ", Computed difference: "
<< overpaymentComponents.trackedPrincipalDelta -
(totalValueOutstandingProxy - newRoundedLoanState.valueOutstanding);
XRPL_ASSERT_PARTS(
loanPaymentParts.valueChange ==
totalValueOutstanding -
newRoundedLoanState.valueOutstanding -
(totalValueOutstandingProxy -
overpaymentComponents.trackedPrincipalDelta) +
overpaymentComponents.trackedInterestPart(),
@@ -693,10 +671,10 @@ doOverpayment(
// All validations passed, so update the proxy objects (which will
// modify the actual Loan ledger object)
totalValueOutstandingProxy = totalValueOutstanding;
principalOutstandingProxy = principalOutstanding;
managementFeeOutstandingProxy = managementFeeOutstanding;
periodicPaymentProxy = periodicPayment;
totalValueOutstandingProxy = newRoundedLoanState.valueOutstanding;
principalOutstandingProxy = newRoundedLoanState.principalOutstanding;
managementFeeOutstandingProxy = newRoundedLoanState.managementFeeDue;
periodicPaymentProxy = newLoanProperties.periodicPayment;
return loanPaymentParts;
}
@@ -1289,7 +1267,7 @@ checkLoanGuards(
beast::Journal j)
{
auto const totalInterestOutstanding =
properties.totalValueOutstanding - principalRequested;
properties.loanState.valueOutstanding - principalRequested;
// Guard 1: if there is no computed total interest over the life of the
// loan for a non-zero interest rate, we cannot properly amortize the
// loan
@@ -1344,13 +1322,13 @@ checkLoanGuards(
NumberRoundModeGuard mg(Number::upward);
if (std::int64_t const computedPayments{
properties.totalValueOutstanding / roundedPayment};
properties.loanState.valueOutstanding / roundedPayment};
computedPayments != paymentTotal)
{
JLOG(j.warn()) << "Loan Periodic payment ("
<< properties.periodicPayment << ") rounding ("
<< roundedPayment << ") on a total value of "
<< properties.totalValueOutstanding
<< properties.loanState.valueOutstanding
<< " can not complete the loan in the specified "
"number of payments ("
<< computedPayments << " != " << paymentTotal << ")";
@@ -1533,19 +1511,35 @@ computeManagementFee(
LoanProperties
computeLoanProperties(
Asset const& asset,
Number principalOutstanding,
Number const& principalOutstanding,
TenthBips32 interestRate,
std::uint32_t paymentInterval,
std::uint32_t paymentsRemaining,
TenthBips32 managementFeeRate,
std::int32_t minimumScale,
beast::Journal j)
std::int32_t minimumScale)
{
auto const periodicRate = loanPeriodicRate(interestRate, paymentInterval);
XRPL_ASSERT(
interestRate == 0 || periodicRate > 0,
"xrpl::computeLoanProperties : valid rate");
return computeLoanProperties(
asset,
principalOutstanding,
periodicRate,
paymentsRemaining,
managementFeeRate,
minimumScale);
}
LoanProperties
computeLoanProperties(
Asset const& asset,
Number const& principalOutstanding,
Number const& periodicRate,
std::uint32_t paymentsRemaining,
TenthBips32 managementFeeRate,
std::int32_t minimumScale)
{
auto const periodicPayment = detail::loanPeriodicPayment(
principalOutstanding, periodicRate, paymentsRemaining);
@@ -1559,13 +1553,6 @@ computeLoanProperties(
// Equation (30) from XLS-66 spec, Section A-2 Equation Glossary
STAmount amount{asset, periodicPayment * paymentsRemaining};
JLOG(j.debug()) << "computeLoanProperties:" << " Principal requested: "
<< principalOutstanding
<< ". Periodic payment: " << periodicPayment
<< ". Payments remaining: " << paymentsRemaining
<< ". Raw total value: "
<< periodicPayment * paymentsRemaining
<< ". Candidate total value: " << amount << std::endl;
// Base the loan scale on the total value, since that's going to be
// the biggest number involved (barring unusual parameters for late,
@@ -1582,21 +1569,18 @@ computeLoanProperties(
// scale
amount = roundToAsset(asset, amount, loanScale);
JLOG(j.debug()) << "computeLoanProperties: Loan scale:" << loanScale
<< ". Actual total value: " << amount << std::endl;
return std::make_pair(amount, loanScale);
}();
// Since we just figured out the loan scale, we haven't been able to
// validate that the principal fits in it, so to allow this function to
// succeed, round it here, and let the caller do the validation.
principalOutstanding = roundToAsset(
auto const roundedPrincipalOutstanding = roundToAsset(
asset, principalOutstanding, loanScale, Number::to_nearest);
// E<quation (31) from XLS-66 spec, Section A-2 Equation Glossary
auto const totalInterestOutstanding =
totalValueOutstanding - principalOutstanding;
totalValueOutstanding - roundedPrincipalOutstanding;
auto const feeOwedToBroker = computeManagementFee(
asset, totalInterestOutstanding, managementFeeRate, loanScale);
@@ -1626,10 +1610,13 @@ computeLoanProperties(
return LoanProperties{
.periodicPayment = periodicPayment,
.totalValueOutstanding = totalValueOutstanding,
.managementFeeOwedToBroker = feeOwedToBroker,
.loanState = constructLoanState(
totalValueOutstanding,
roundedPrincipalOutstanding,
feeOwedToBroker),
.loanScale = loanScale,
.firstPaymentPrincipal = firstPaymentPrincipal};
.firstPaymentPrincipal = firstPaymentPrincipal,
};
}
/*
@@ -1958,12 +1945,8 @@ loanMakePayment(
principalOutstandingProxy,
managementFeeOutstandingProxy,
periodicPaymentProxy,
interestRate,
paymentInterval,
periodicRate,
paymentRemainingProxy,
prevPaymentDateProxy,
nextDueDateProxy,
managementFeeRate,
j))
totalParts += *overResult;

24
src/xrpld/app/tx/detail/LoanSet.cpp
View File

@@ -404,13 +404,12 @@ LoanSet::doApply()
paymentInterval,
paymentTotal,
TenthBips16{brokerSle->at(sfManagementFeeRate)},
vaultScale,
j_);
vaultScale);
LoanState const state = constructLoanState(
properties.totalValueOutstanding,
properties.loanState.valueOutstanding,
principalRequested,
properties.managementFeeOwedToBroker);
properties.loanState.managementFeeDue);
if (vaultSle->at(sfAssetsMaximum) != 0 &&
vaultTotalProxy + state.interestDue > vaultSle->at(sfAssetsMaximum))
@@ -429,8 +428,8 @@ LoanSet::doApply()
JLOG(j_.warn())
<< field.f->getName() << " (" << *value
<< ") has too much precision. Total loan value is "
<< properties.totalValueOutstanding << " with a scale of "
<< properties.loanScale;
<< properties.loanState.valueOutstanding
<< " with a scale of " << properties.loanScale;
return tecPRECISION_LOSS;
}
}
@@ -446,15 +445,15 @@ LoanSet::doApply()
return ret;
// Check that the other computed values are valid
if (properties.managementFeeOwedToBroker < 0 ||
properties.totalValueOutstanding <= 0 ||
if (properties.loanState.managementFeeDue < 0 ||
properties.loanState.valueOutstanding <= 0 ||
properties.periodicPayment <= 0)
{
// LCOV_EXCL_START
JLOG(j_.warn())
<< "Computed loan properties are invalid. Does not compute."
<< " Management fee: " << properties.managementFeeOwedToBroker
<< ". Total Value: " << properties.totalValueOutstanding
<< " Management fee: " << properties.loanState.managementFeeDue
<< ". Total Value: " << properties.loanState.valueOutstanding
<< ". PeriodicPayment: " << properties.periodicPayment;
return tecINTERNAL;
// LCOV_EXCL_STOP
@@ -598,8 +597,9 @@ LoanSet::doApply()
// Set dynamic / computed fields to their initial values
loan->at(sfPrincipalOutstanding) = principalRequested;
loan->at(sfPeriodicPayment) = properties.periodicPayment;
loan->at(sfTotalValueOutstanding) = properties.totalValueOutstanding;
loan->at(sfManagementFeeOutstanding) = properties.managementFeeOwedToBroker;
loan->at(sfTotalValueOutstanding) = properties.loanState.valueOutstanding;
loan->at(sfManagementFeeOutstanding) =
properties.loanState.managementFeeDue;
loan->at(sfPreviousPaymentDate) = 0;
loan->at(sfNextPaymentDueDate) = startDate + paymentInterval;
loan->at(sfPaymentRemaining) = paymentTotal;