Amounts
BasicTaker::remaining_offer (STAmountCalcSwitchovers const& amountCalcSwitchovers) const
{
// If the taker is done, then there's no offer to place.
if (done ())
return Amounts (remaining_.in.zeroed(), remaining_.out.zeroed());
// Avoid math altogether if we didn't cross.
if (original_ == remaining_)
return original_;
if (sell_)
{
assert (remaining_.in > zero);
// We scale the output based on the remaining input:
return Amounts (remaining_.in, divRound (
remaining_.in, quality_.rate (), issue_out_, true,
amountCalcSwitchovers));
}
assert (remaining_.out > zero);
// We scale the input based on the remaining output:
return Amounts (mulRound (
remaining_.out, quality_.rate (), issue_in_, true, amountCalcSwitchovers),
remaining_.out);
}
Amounts
Taker::remaining_offer () const
{
// If the taker is done, then there's no offer to place.
if (done ())
return Amounts (m_amount.in.zeroed(), m_amount.out.zeroed());
// Avoid math altogether if we didn't cross.
if (m_amount == m_remain)
return m_amount;
if (m_options.sell)
{
assert (m_remain.in > zero);
// We scale the output based on the remaining input:
return Amounts (m_remain.in, divRound (
m_remain.in, m_quality.rate (), m_remain.out.issue (), true));
}
assert (m_remain.out > zero);
// We scale the input based on the remaining output:
return Amounts (mulRound (
m_remain.out, m_quality.rate (), m_remain.in.issue (), true), m_remain.out);
}
Amounts
Quality::ceil_out (Amounts const& amount, STAmount const& limit) const
{
if (amount.out > limit)
{
Amounts result (mulRound (
limit, rate(), amount.in.issue (), true), limit);
// Clamp in
if (result.in > amount.in)
result.in = amount.in;
assert (result.out == limit);
return result;
}
assert (amount.out <= limit);
return amount;
}
Quality
composed_quality (Quality const& lhs, Quality const& rhs)
{
STAmount const lhs_rate (lhs.rate ());
assert (lhs_rate != zero);
STAmount const rhs_rate (rhs.rate ());
assert (rhs_rate != zero);
STAmount const rate (mulRound (
lhs_rate, rhs_rate, lhs_rate.issue (), true));
std::uint64_t const stored_exponent (rate.exponent () + 100);
std::uint64_t const stored_mantissa (rate.mantissa());
assert ((stored_exponent > 0) && (stored_exponent <= 255));
return Quality ((stored_exponent << (64 - 8)) | stored_mantissa);
}
TER PathCursor::deliverNodeForward (
AccountID const& uInAccountID, // --> Input owner's account.
STAmount const& saInReq, // --> Amount to deliver.
STAmount& saInAct, // <-- Amount delivered, this invocation.
STAmount& saInFees, // <-- Fees charged, this invocation.
bool callerHasLiquidity) const
{
TER resultCode = tesSUCCESS;
// Don't deliver more than wanted.
// Zeroed in reverse pass.
node().directory.restart(multiQuality_);
saInAct.clear (saInReq);
saInFees.clear (saInReq);
int loopCount = 0;
auto viewJ = rippleCalc_.logs_.journal ("View");
// XXX Perhaps make sure do not exceed node().saRevDeliver as another way to
// stop?
while (resultCode == tesSUCCESS && saInAct + saInFees < saInReq)
{
// Did not spend all inbound deliver funds.
if (++loopCount >
(multiQuality_ ?
CALC_NODE_DELIVER_MAX_LOOPS_MQ :
CALC_NODE_DELIVER_MAX_LOOPS))
{
JLOG (j_.warn())
<< "deliverNodeForward: max loops cndf";
return telFAILED_PROCESSING;
}
// Determine values for pass to adjust saInAct, saInFees, and
// node().saFwdDeliver.
advanceNode (saInAct, false, callerHasLiquidity);
// If needed, advance to next funded offer.
if (resultCode != tesSUCCESS)
{
}
else if (!node().offerIndex_)
{
JLOG (j_.warn())
<< "deliverNodeForward: INTERNAL ERROR: Ran out of offers.";
return telFAILED_PROCESSING;
}
else if (resultCode == tesSUCCESS)
{
auto const xferRate = effectiveRate (
previousNode().issue_,
uInAccountID,
node().offerOwnerAccount_,
previousNode().transferRate_);
// First calculate assuming no output fees: saInPassAct,
// saInPassFees, saOutPassAct.
// Offer maximum out - limited by funds with out fees.
auto saOutFunded = std::min (
node().saOfferFunds, node().saTakerGets);
// Offer maximum out - limit by most to deliver.
auto saOutPassFunded = std::min (
saOutFunded,
node().saRevDeliver - node().saFwdDeliver);
// Offer maximum in - Limited by by payout.
auto saInFunded = mulRound (
saOutPassFunded,
node().saOfrRate,
node().saTakerPays.issue (),
true);
// Offer maximum in with fees.
auto saInTotal = multiplyRound (
saInFunded, xferRate, true);
auto saInRemaining = saInReq - saInAct - saInFees;
if (saInRemaining < beast::zero)
saInRemaining.clear();
// In limited by remaining.
auto saInSum = std::min (saInTotal, saInRemaining);
// In without fees.
auto saInPassAct = std::min (
node().saTakerPays,
divideRound (saInSum, xferRate, true));
// Out limited by in remaining.
auto outPass = divRound (
saInPassAct, node().saOfrRate, node().saTakerGets.issue (), true);
STAmount saOutPassMax = std::min (saOutPassFunded, outPass);
STAmount saInPassFeesMax = saInSum - saInPassAct;
// Will be determined by next node().
STAmount saOutPassAct;
// Will be determined by adjusted saInPassAct.
STAmount saInPassFees;
JLOG (j_.trace())
<< "deliverNodeForward:"
<< " nodeIndex_=" << nodeIndex_
<< " saOutFunded=" << saOutFunded
<< " saOutPassFunded=" << saOutPassFunded
<< " node().saOfferFunds=" << node().saOfferFunds
<< " node().saTakerGets=" << node().saTakerGets
<< " saInReq=" << saInReq
<< " saInAct=" << saInAct
<< " saInFees=" << saInFees
<< " saInFunded=" << saInFunded
<< " saInTotal=" << saInTotal
<< " saInSum=" << saInSum
<< " saInPassAct=" << saInPassAct
<< " saOutPassMax=" << saOutPassMax;
// FIXME: We remove an offer if WE didn't want anything out of it?
if (!node().saTakerPays || saInSum <= beast::zero)
{
JLOG (j_.debug())
<< "deliverNodeForward: Microscopic offer unfunded.";
// After math offer is effectively unfunded.
pathState_.unfundedOffers().push_back (node().offerIndex_);
node().bEntryAdvance = true;
continue;
}
if (!saInFunded)
{
// Previous check should catch this.
JLOG (j_.warn())
<< "deliverNodeForward: UNREACHABLE REACHED";
// After math offer is effectively unfunded.
pathState_.unfundedOffers().push_back (node().offerIndex_);
node().bEntryAdvance = true;
continue;
}
if (!isXRP(nextNode().account_))
{
// ? --> OFFER --> account
// Input fees: vary based upon the consumed offer's owner.
// Output fees: none as XRP or the destination account is the
// issuer.
saOutPassAct = saOutPassMax;
saInPassFees = saInPassFeesMax;
JLOG (j_.trace())
<< "deliverNodeForward: ? --> OFFER --> account:"
<< " offerOwnerAccount_="
<< node().offerOwnerAccount_
<< " nextNode().account_="
<< nextNode().account_
<< " saOutPassAct=" << saOutPassAct
<< " saOutFunded=" << saOutFunded;
// Output: Debit offer owner, send XRP or non-XPR to next
// account.
resultCode = accountSend(view(),
node().offerOwnerAccount_,
nextNode().account_,
saOutPassAct, viewJ);
if (resultCode != tesSUCCESS)
break;
}
else
{
// ? --> OFFER --> offer
//
// Offer to offer means current order book's output currency and
// issuer match next order book's input current and issuer.
//
// Output fees: possible if issuer has fees and is not on either
// side.
STAmount saOutPassFees;
// Output fees vary as the next nodes offer owners may vary.
// Therefore, immediately push through output for current offer.
resultCode = increment().deliverNodeForward (
node().offerOwnerAccount_, // --> Current holder.
saOutPassMax, // --> Amount available.
saOutPassAct, // <-- Amount delivered.
saOutPassFees, // <-- Fees charged.
saInAct > beast::zero);
if (resultCode != tesSUCCESS)
break;
if (saOutPassAct == saOutPassMax)
{
// No fees and entire output amount.
saInPassFees = saInPassFeesMax;
}
else
{
// Fraction of output amount.
// Output fees are paid by offer owner and not passed to
// previous.
assert (saOutPassAct < saOutPassMax);
auto inPassAct = mulRound (
saOutPassAct, node().saOfrRate, saInReq.issue (), true);
saInPassAct = std::min (node().saTakerPays, inPassAct);
auto inPassFees = multiplyRound (
saInPassAct, xferRate, true);
saInPassFees = std::min (saInPassFeesMax, inPassFees);
}
// Do outbound debiting.
// Send to issuer/limbo total amount including fees (issuer gets
// fees).
auto const& id = isXRP(node().issue_) ?
xrpAccount() : node().issue_.account;
auto outPassTotal = saOutPassAct + saOutPassFees;
accountSend(view(),
node().offerOwnerAccount_,
id,
outPassTotal,
viewJ);
JLOG (j_.trace())
<< "deliverNodeForward: ? --> OFFER --> offer:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutPassFees=" << saOutPassFees;
}
JLOG (j_.trace())
<< "deliverNodeForward: "
<< " nodeIndex_=" << nodeIndex_
<< " node().saTakerGets=" << node().saTakerGets
<< " node().saTakerPays=" << node().saTakerPays
<< " saInPassAct=" << saInPassAct
<< " saInPassFees=" << saInPassFees
<< " saOutPassAct=" << saOutPassAct
<< " saOutFunded=" << saOutFunded;
// Funds were spent.
node().bFundsDirty = true;
// Do inbound crediting.
//
// Credit offer owner from in issuer/limbo (input transfer fees left
// with owner). Don't attempt to have someone credit themselves, it
// is redundant.
if (isXRP (previousNode().issue_.currency)
|| uInAccountID != node().offerOwnerAccount_)
{
auto id = !isXRP(previousNode().issue_.currency) ?
uInAccountID : xrpAccount();
resultCode = accountSend(view(),
id,
node().offerOwnerAccount_,
saInPassAct,
viewJ);
if (resultCode != tesSUCCESS)
break;
}
// Adjust offer.
//
// Fees are considered paid from a seperate budget and are not named
// in the offer.
STAmount saTakerGetsNew = node().saTakerGets - saOutPassAct;
STAmount saTakerPaysNew = node().saTakerPays - saInPassAct;
if (saTakerPaysNew < beast::zero || saTakerGetsNew < beast::zero)
{
JLOG (j_.warn())
<< "deliverNodeForward: NEGATIVE:"
<< " saTakerPaysNew=" << saTakerPaysNew
<< " saTakerGetsNew=" << saTakerGetsNew;
resultCode = telFAILED_PROCESSING;
break;
}
node().sleOffer->setFieldAmount (sfTakerGets, saTakerGetsNew);
node().sleOffer->setFieldAmount (sfTakerPays, saTakerPaysNew);
view().update (node().sleOffer);
if (saOutPassAct == saOutFunded || saTakerGetsNew == beast::zero)
{
// Offer became unfunded.
JLOG (j_.debug())
<< "deliverNodeForward: unfunded:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutFunded=" << saOutFunded;
pathState_.unfundedOffers().push_back (node().offerIndex_);
node().bEntryAdvance = true;
}
else
{
if (saOutPassAct >= saOutFunded)
{
JLOG (j_.warn())
<< "deliverNodeForward: TOO MUCH:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutFunded=" << saOutFunded;
}
assert (saOutPassAct < saOutFunded);
}
saInAct += saInPassAct;
saInFees += saInPassFees;
// Adjust amount available to next node().
node().saFwdDeliver = std::min (node().saRevDeliver,
node().saFwdDeliver + saOutPassAct);
}
}
JLOG (j_.trace())
<< "deliverNodeForward<"
<< " nodeIndex_=" << nodeIndex_
<< " saInAct=" << saInAct
<< " saInFees=" << saInFees;
return resultCode;
}
// To deliver from an order book, when computing
TER PathCursor::deliverNodeReverseImpl (
AccountID const& uOutAccountID, // --> Output owner's account.
STAmount const& saOutReq, // --> Funds requested to be
// delivered for an increment.
STAmount& saOutAct, // <-- Funds actually delivered for an
// increment
bool callerHasLiquidity
) const
{
TER resultCode = tesSUCCESS;
// Accumulation of what the previous node must deliver.
// Possible optimization: Note this gets zeroed on each increment, ideally
// only on first increment, then it could be a limit on the forward pass.
saOutAct.clear (saOutReq);
JLOG (j_.trace())
<< "deliverNodeReverse>"
<< " saOutAct=" << saOutAct
<< " saOutReq=" << saOutReq
<< " saPrvDlvReq=" << previousNode().saRevDeliver;
assert (saOutReq != zero);
int loopCount = 0;
auto viewJ = rippleCalc_.logs_.journal ("View");
// While we did not deliver as much as requested:
while (saOutAct < saOutReq)
{
if (++loopCount >
(multiQuality_ ?
CALC_NODE_DELIVER_MAX_LOOPS_MQ :
CALC_NODE_DELIVER_MAX_LOOPS))
{
JLOG (j_.warn()) << "loop count exceeded";
return telFAILED_PROCESSING;
}
resultCode = advanceNode (saOutAct, true, callerHasLiquidity);
// If needed, advance to next funded offer.
if (resultCode != tesSUCCESS || !node().offerIndex_)
// Error or out of offers.
break;
auto const xferRate = effectiveRate (
node().issue_,
uOutAccountID,
node().offerOwnerAccount_,
node().transferRate_);
JLOG (j_.trace())
<< "deliverNodeReverse:"
<< " offerOwnerAccount_=" << node().offerOwnerAccount_
<< " uOutAccountID=" << uOutAccountID
<< " node().issue_.account=" << node().issue_.account
<< " xferRate=" << xferRate;
// Only use rate when not in multi-quality mode
if (!multiQuality_)
{
if (!node().rateMax)
{
// Set initial rate.
JLOG (j_.trace())
<< "Set initial rate";
node().rateMax = xferRate;
}
else if (xferRate > node().rateMax)
{
// Offer exceeds initial rate.
JLOG (j_.trace())
<< "Offer exceeds initial rate: " << *node().rateMax;
break; // Done. Don't bother looking for smaller transferRates.
}
else if (xferRate < node().rateMax)
{
// Reducing rate. Additional offers will only
// be considered for this increment if they
// are at least this good.
//
// At this point, the overall rate is reducing,
// while the overall rate is not xferRate, it
// would be wrong to add anything with a rate
// above xferRate.
//
// The rate would be reduced if the current
// offer was from the issuer and the previous
// offer wasn't.
JLOG (j_.trace())
<< "Reducing rate: " << *node().rateMax;
node().rateMax = xferRate;
}
}
// Amount that goes to the taker.
STAmount saOutPassReq = std::min (
std::min (node().saOfferFunds, node().saTakerGets),
saOutReq - saOutAct);
// Maximum out - assuming no out fees.
STAmount saOutPassAct = saOutPassReq;
// Amount charged to the offer owner.
//
// The fee goes to issuer. The fee is paid by offer owner and not passed
// as a cost to taker.
//
// Round down: prefer liquidity rather than microscopic fees.
STAmount saOutPlusFees = multiplyRound (
saOutPassAct, xferRate, false);
// Offer out with fees.
JLOG (j_.trace())
<< "deliverNodeReverse:"
<< " saOutReq=" << saOutReq
<< " saOutAct=" << saOutAct
<< " node().saTakerGets=" << node().saTakerGets
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees
<< " node().saOfferFunds=" << node().saOfferFunds;
if (saOutPlusFees > node().saOfferFunds)
{
// Offer owner can not cover all fees, compute saOutPassAct based on
// node().saOfferFunds.
saOutPlusFees = node().saOfferFunds;
// Round up: prefer liquidity rather than microscopic fees. But,
// limit by requested.
auto fee = divideRound (saOutPlusFees, xferRate, true);
saOutPassAct = std::min (saOutPassReq, fee);
JLOG (j_.trace())
<< "deliverNodeReverse: Total exceeds fees:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees
<< " node().saOfferFunds=" << node().saOfferFunds;
}
// Compute portion of input needed to cover actual output.
auto outputFee = mulRound (
saOutPassAct, node().saOfrRate, node().saTakerPays.issue (), true);
if (*stAmountCalcSwitchover == false && ! outputFee)
{
JLOG (j_.fatal())
<< "underflow computing outputFee "
<< "saOutPassAct: " << saOutPassAct
<< " saOfrRate: " << node ().saOfrRate;
return telFAILED_PROCESSING;
}
STAmount saInPassReq = std::min (node().saTakerPays, outputFee);
STAmount saInPassAct;
JLOG (j_.trace())
<< "deliverNodeReverse:"
<< " outputFee=" << outputFee
<< " saInPassReq=" << saInPassReq
<< " node().saOfrRate=" << node().saOfrRate
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees;
if (!saInPassReq) // FIXME: This is bogus
{
// After rounding did not want anything.
JLOG (j_.debug())
<< "deliverNodeReverse: micro offer is unfunded.";
node().bEntryAdvance = true;
continue;
}
// Find out input amount actually available at current rate.
else if (!isXRP(previousNode().account_))
{
// account --> OFFER --> ?
// Due to node expansion, previous is guaranteed to be the issuer.
//
// Previous is the issuer and receiver is an offer, so no fee or
// quality.
//
// Previous is the issuer and has unlimited funds.
//
// Offer owner is obtaining IOUs via an offer, so credit line limits
// are ignored. As limits are ignored, don't need to adjust
// previous account's balance.
saInPassAct = saInPassReq;
JLOG (j_.trace())
<< "deliverNodeReverse: account --> OFFER --> ? :"
<< " saInPassAct=" << saInPassAct;
}
else
{
// offer --> OFFER --> ?
// Compute in previous offer node how much could come in.
// TODO(tom): Fix nasty recursion here!
resultCode = increment(-1).deliverNodeReverseImpl(
node().offerOwnerAccount_,
saInPassReq,
saInPassAct,
saOutAct > zero);
if (amendmentRIPD1141(view().info().parentCloseTime))
{
// The recursive call is dry this time, but we have liquidity
// from previous calls
if (resultCode == tecPATH_DRY && saOutAct > zero)
{
resultCode = tesSUCCESS;
break;
}
}
JLOG (j_.trace())
<< "deliverNodeReverse: offer --> OFFER --> ? :"
<< " saInPassAct=" << saInPassAct;
}
if (resultCode != tesSUCCESS)
break;
if (saInPassAct < saInPassReq)
{
// Adjust output to conform to limited input.
auto outputRequirements = divRound (saInPassAct, node ().saOfrRate,
node ().saTakerGets.issue (), true);
saOutPassAct = std::min (saOutPassReq, outputRequirements);
auto outputFees = multiplyRound (saOutPassAct, xferRate, true);
saOutPlusFees = std::min (node().saOfferFunds, outputFees);
JLOG (j_.trace())
<< "deliverNodeReverse: adjusted:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees;
}
else
{
// TODO(tom): more logging here.
assert (saInPassAct == saInPassReq);
}
// Funds were spent.
node().bFundsDirty = true;
// Want to deduct output to limit calculations while computing reverse.
// Don't actually need to send.
//
// Sending could be complicated: could fund a previous offer not yet
// visited. However, these deductions and adjustments are tenative.
//
// Must reset balances when going forward to perform actual transfers.
resultCode = accountSend(view(),
node().offerOwnerAccount_, node().issue_.account, saOutPassAct, viewJ);
if (resultCode != tesSUCCESS)
break;
// Adjust offer
STAmount saTakerGetsNew = node().saTakerGets - saOutPassAct;
STAmount saTakerPaysNew = node().saTakerPays - saInPassAct;
if (saTakerPaysNew < zero || saTakerGetsNew < zero)
{
JLOG (j_.warn())
<< "deliverNodeReverse: NEGATIVE:"
<< " node().saTakerPaysNew=" << saTakerPaysNew
<< " node().saTakerGetsNew=" << saTakerGetsNew;
resultCode = telFAILED_PROCESSING;
break;
}
node().sleOffer->setFieldAmount (sfTakerGets, saTakerGetsNew);
node().sleOffer->setFieldAmount (sfTakerPays, saTakerPaysNew);
view().update (node().sleOffer);
if (saOutPassAct == node().saTakerGets)
{
// Offer became unfunded.
JLOG (j_.debug())
<< "deliverNodeReverse: offer became unfunded.";
node().bEntryAdvance = true;
// XXX When don't we want to set advance?
}
else
{
assert (saOutPassAct < node().saTakerGets);
}
saOutAct += saOutPassAct;
// Accumulate what is to be delivered from previous node.
previousNode().saRevDeliver += saInPassAct;
}
if (saOutAct > saOutReq)
{
JLOG (j_.warn())
<< "deliverNodeReverse: TOO MUCH:"
<< " saOutAct=" << saOutAct
<< " saOutReq=" << saOutReq;
}
assert(saOutAct <= saOutReq);
if (resultCode == tesSUCCESS && !saOutAct)
resultCode = tecPATH_DRY;
// Unable to meet request, consider path dry.
// Design invariant: if nothing was actually delivered, return tecPATH_DRY.
JLOG (j_.trace())
<< "deliverNodeReverse<"
<< " saOutAct=" << saOutAct
<< " saOutReq=" << saOutReq
<< " saPrvDlvReq=" << previousNode().saRevDeliver;
return resultCode;
}
// To deliver from an order book, when computing
TER PathCursor::deliverNodeReverse (
Account const& uOutAccountID, // --> Output owner's account.
STAmount const& saOutReq, // --> Funds requested to be
// delivered for an increment.
STAmount& saOutAct) const // <-- Funds actually delivered for an
// increment.
{
TER resultCode = tesSUCCESS;
node().directory.restart(multiQuality_);
// Accumulation of what the previous node must deliver.
// Possible optimization: Note this gets zeroed on each increment, ideally
// only on first increment, then it could be a limit on the forward pass.
saOutAct.clear (saOutReq);
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse>"
<< " saOutAct=" << saOutAct
<< " saOutReq=" << saOutReq
<< " saPrvDlvReq=" << previousNode().saRevDeliver;
assert (saOutReq != zero);
int loopCount = 0;
// While we did not deliver as much as requested:
while (saOutAct < saOutReq)
{
if (++loopCount > CALC_NODE_DELIVER_MAX_LOOPS)
{
WriteLog (lsFATAL, RippleCalc) << "loop count exceeded";
return telFAILED_PROCESSING;
}
resultCode = advanceNode (saOutAct, true);
// If needed, advance to next funded offer.
if (resultCode != tesSUCCESS || !node().offerIndex_)
// Error or out of offers.
break;
auto const hasFee = node().offerOwnerAccount_ == node().issue_.account
|| uOutAccountID == node().issue_.account;
// Issuer sending or receiving.
const STAmount saOutFeeRate = hasFee
? saOne // No fee.
: node().transferRate_; // Transfer rate of issuer.
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse:"
<< " offerOwnerAccount_="
<< node().offerOwnerAccount_
<< " uOutAccountID="
<< uOutAccountID
<< " node().issue_.account="
<< node().issue_.account
<< " node().transferRate_=" << node().transferRate_
<< " saOutFeeRate=" << saOutFeeRate;
if (multiQuality_)
{
// In multi-quality mode, ignore rate.
}
else if (!node().saRateMax)
{
// Set initial rate.
node().saRateMax = saOutFeeRate;
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: Set initial rate:"
<< " node().saRateMax=" << node().saRateMax
<< " saOutFeeRate=" << saOutFeeRate;
}
else if (saOutFeeRate > node().saRateMax)
{
// Offer exceeds initial rate.
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: Offer exceeds initial rate:"
<< " node().saRateMax=" << node().saRateMax
<< " saOutFeeRate=" << saOutFeeRate;
break; // Done. Don't bother looking for smaller transferRates.
}
else if (saOutFeeRate < node().saRateMax)
{
// Reducing rate. Additional offers will only considered for this
// increment if they are at least this good.
//
// At this point, the overall rate is reducing, while the overall
// rate is not saOutFeeRate, it would be wrong to add anything with
// a rate above saOutFeeRate.
//
// The rate would be reduced if the current offer was from the
// issuer and the previous offer wasn't.
node().saRateMax = saOutFeeRate;
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: Reducing rate:"
<< " node().saRateMax=" << node().saRateMax;
}
// Amount that goes to the taker.
STAmount saOutPassReq = std::min (
std::min (node().saOfferFunds, node().saTakerGets),
saOutReq - saOutAct);
// Maximum out - assuming no out fees.
STAmount saOutPassAct = saOutPassReq;
// Amount charged to the offer owner.
//
// The fee goes to issuer. The fee is paid by offer owner and not passed
// as a cost to taker.
//
// Round down: prefer liquidity rather than microscopic fees.
STAmount saOutPlusFees = mulRound (
saOutPassAct, saOutFeeRate, saOutPassAct.issue (), false);
// Offer out with fees.
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse:"
<< " saOutReq=" << saOutReq
<< " saOutAct=" << saOutAct
<< " node().saTakerGets=" << node().saTakerGets
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees
<< " node().saOfferFunds=" << node().saOfferFunds;
if (saOutPlusFees > node().saOfferFunds)
{
// Offer owner can not cover all fees, compute saOutPassAct based on
// node().saOfferFunds.
saOutPlusFees = node().saOfferFunds;
// Round up: prefer liquidity rather than microscopic fees. But,
// limit by requested.
auto fee = divRound (saOutPlusFees, saOutFeeRate,
saOutPlusFees.issue (), true);
saOutPassAct = std::min (saOutPassReq, fee);
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: Total exceeds fees:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees
<< " node().saOfferFunds=" << node().saOfferFunds;
}
// Compute portion of input needed to cover actual output.
auto outputFee = mulRound (
saOutPassAct, node().saOfrRate, node().saTakerPays.issue (), true);
STAmount saInPassReq = std::min (node().saTakerPays, outputFee);
STAmount saInPassAct;
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse:"
<< " outputFee=" << outputFee
<< " saInPassReq=" << saInPassReq
<< " node().saOfrRate=" << node().saOfrRate
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees;
if (!saInPassReq) // FIXME: This is bogus
{
// After rounding did not want anything.
WriteLog (lsDEBUG, RippleCalc)
<< "deliverNodeReverse: micro offer is unfunded.";
node().bEntryAdvance = true;
continue;
}
// Find out input amount actually available at current rate.
else if (!isXRP(previousNode().account_))
{
// account --> OFFER --> ?
// Due to node expansion, previous is guaranteed to be the issuer.
//
// Previous is the issuer and receiver is an offer, so no fee or
// quality.
//
// Previous is the issuer and has unlimited funds.
//
// Offer owner is obtaining IOUs via an offer, so credit line limits
// are ignored. As limits are ignored, don't need to adjust
// previous account's balance.
saInPassAct = saInPassReq;
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: account --> OFFER --> ? :"
<< " saInPassAct=" << saInPassAct;
}
else
{
// offer --> OFFER --> ?
// Compute in previous offer node how much could come in.
// TODO(tom): Fix nasty recursion here!
resultCode = increment(-1).deliverNodeReverse(
node().offerOwnerAccount_,
saInPassReq,
saInPassAct);
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: offer --> OFFER --> ? :"
<< " saInPassAct=" << saInPassAct;
}
if (resultCode != tesSUCCESS)
break;
if (saInPassAct < saInPassReq)
{
// Adjust output to conform to limited input.
auto outputRequirements = divRound (
saInPassAct, node().saOfrRate, node().saTakerGets.issue (), true);
saOutPassAct = std::min (saOutPassReq, outputRequirements);
auto outputFees = mulRound (
saOutPassAct, saOutFeeRate, saOutPassAct.issue (), true);
saOutPlusFees = std::min (node().saOfferFunds, outputFees);
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse: adjusted:"
<< " saOutPassAct=" << saOutPassAct
<< " saOutPlusFees=" << saOutPlusFees;
}
else
{
// TODO(tom): more logging here.
assert (saInPassAct == saInPassReq);
}
// Funds were spent.
node().bFundsDirty = true;
// Want to deduct output to limit calculations while computing reverse.
// Don't actually need to send.
//
// Sending could be complicated: could fund a previous offer not yet
// visited. However, these deductions and adjustments are tenative.
//
// Must reset balances when going forward to perform actual transfers.
resultCode = ledger().accountSend (
node().offerOwnerAccount_, node().issue_.account, saOutPassAct);
if (resultCode != tesSUCCESS)
break;
// Adjust offer
STAmount saTakerGetsNew = node().saTakerGets - saOutPassAct;
STAmount saTakerPaysNew = node().saTakerPays - saInPassAct;
if (saTakerPaysNew < zero || saTakerGetsNew < zero)
{
WriteLog (lsWARNING, RippleCalc)
<< "deliverNodeReverse: NEGATIVE:"
<< " node().saTakerPaysNew=" << saTakerPaysNew
<< " node().saTakerGetsNew=" << saTakerGetsNew;
resultCode = telFAILED_PROCESSING;
break;
}
node().sleOffer->setFieldAmount (sfTakerGets, saTakerGetsNew);
node().sleOffer->setFieldAmount (sfTakerPays, saTakerPaysNew);
ledger().entryModify (node().sleOffer);
if (saOutPassAct == node().saTakerGets)
{
// Offer became unfunded.
WriteLog (lsDEBUG, RippleCalc)
<< "deliverNodeReverse: offer became unfunded.";
node().bEntryAdvance = true;
// XXX When don't we want to set advance?
}
else
{
assert (saOutPassAct < node().saTakerGets);
}
saOutAct += saOutPassAct;
// Accumulate what is to be delivered from previous node.
previousNode().saRevDeliver += saInPassAct;
}
CondLog (saOutAct > saOutReq, lsWARNING, RippleCalc)
<< "deliverNodeReverse: TOO MUCH:"
<< " saOutAct=" << saOutAct
<< " saOutReq=" << saOutReq;
assert (saOutAct <= saOutReq);
if (resultCode == tesSUCCESS && !saOutAct)
resultCode = tecPATH_DRY;
// Unable to meet request, consider path dry.
// Design invariant: if nothing was actually delivered, return tecPATH_DRY.
WriteLog (lsTRACE, RippleCalc)
<< "deliverNodeReverse<"
<< " saOutAct=" << saOutAct
<< " saOutReq=" << saOutReq
<< " saPrvDlvReq=" << previousNode().saRevDeliver;
return resultCode;
}
// The reverse pass has been narrowing by credit available and inflating by fees
// as it worked backwards. Now, for the current account node, take the actual
// amount from previous and adjust forward balances.
//
// Perform balance adjustments between previous and current node.
// - The previous node: specifies what to push through to current.
// - All of previous output is consumed.
//
// Then, compute current node's output for next node.
// - Current node: specify what to push through to next.
// - Output to next node is computed as input minus quality or transfer fee.
// - If next node is an offer and output is non-XRP then we are the issuer and
// do not need to push funds.
// - If next node is an offer and output is XRP then we need to deliver funds to
// limbo.
TER PathCursor::forwardLiquidityForAccount () const
{
TER resultCode = tesSUCCESS;
auto const lastNodeIndex = pathState_.nodes().size () - 1;
auto viewJ = rippleCalc_.logs_.journal ("View");
std::uint64_t uRateMax = 0;
AccountID const& previousAccountID =
previousNode().isAccount() ? previousNode().account_ :
node().account_;
// Offers are always issue.
AccountID const& nextAccountID =
nextNode().isAccount() ? nextNode().account_ : node().account_;
std::uint32_t uQualityIn = nodeIndex_
? quality_in (view(),
node().account_,
previousAccountID,
node().issue_.currency)
: QUALITY_ONE;
std::uint32_t uQualityOut = (nodeIndex_ == lastNodeIndex)
? quality_out (view(),
node().account_,
nextAccountID,
node().issue_.currency)
: QUALITY_ONE;
// When looking backward (prv) for req we care about what we just
// calculated: use fwd.
// When looking forward (cur) for req we care about what was desired: use
// rev.
// For nextNode().isAccount()
auto saPrvRedeemAct = previousNode().saFwdRedeem.zeroed();
auto saPrvIssueAct = previousNode().saFwdIssue.zeroed();
// For !previousNode().isAccount()
auto saPrvDeliverAct = previousNode().saFwdDeliver.zeroed ();
JLOG (j_.trace)
<< "forwardLiquidityForAccount> "
<< "nodeIndex_=" << nodeIndex_ << "/" << lastNodeIndex
<< " previousNode.saFwdRedeem:" << previousNode().saFwdRedeem
<< " saPrvIssueReq:" << previousNode().saFwdIssue
<< " previousNode.saFwdDeliver:" << previousNode().saFwdDeliver
<< " node.saRevRedeem:" << node().saRevRedeem
<< " node.saRevIssue:" << node().saRevIssue
<< " node.saRevDeliver:" << node().saRevDeliver;
// Ripple through account.
if (previousNode().isAccount() && nextNode().isAccount())
{
// Next is an account, must be rippling.
if (!nodeIndex_)
{
// ^ --> ACCOUNT --> account
// For the first node, calculate amount to ripple based on what is
// available.
node().saFwdRedeem = node().saRevRedeem;
if (pathState_.inReq() >= zero)
{
// Limit by send max.
node().saFwdRedeem = std::min (
node().saFwdRedeem, pathState_.inReq() - pathState_.inAct());
}
pathState_.setInPass (node().saFwdRedeem);
node().saFwdIssue = node().saFwdRedeem == node().saRevRedeem
// Fully redeemed.
? node().saRevIssue : STAmount (node().saRevIssue);
if (node().saFwdIssue && pathState_.inReq() >= zero)
{
// Limit by send max.
node().saFwdIssue = std::min (
node().saFwdIssue,
pathState_.inReq() - pathState_.inAct() - node().saFwdRedeem);
}
pathState_.setInPass (pathState_.inPass() + node().saFwdIssue);
JLOG (j_.trace)
<< "forwardLiquidityForAccount: ^ --> "
<< "ACCOUNT --> account :"
<< " saInReq=" << pathState_.inReq()
<< " saInAct=" << pathState_.inAct()
<< " node.saFwdRedeem:" << node().saFwdRedeem
<< " node.saRevIssue:" << node().saRevIssue
<< " node.saFwdIssue:" << node().saFwdIssue
<< " pathState_.saInPass:"******"forwardLiquidityForAccount: account --> "
<< "ACCOUNT --> $ :"
<< " previousAccountID="
<< to_string (previousAccountID)
<< " node.account_="
<< to_string (node().account_)
<< " previousNode.saFwdRedeem:" << previousNode().saFwdRedeem
<< " previousNode.saFwdIssue:" << previousNode().saFwdIssue;
// Last node. Accept all funds. Calculate amount actually to credit.
auto& saCurReceive = pathState_.outPass();
STAmount saIssueCrd = uQualityIn >= QUALITY_ONE
? previousNode().saFwdIssue // No fee.
: mulRound (
previousNode().saFwdIssue,
amountFromRate (uQualityIn),
previousNode().saFwdIssue.issue (),
true); // Amount to credit.
// Amount to credit. Credit for less than received as a surcharge.
pathState_.setOutPass (previousNode().saFwdRedeem + saIssueCrd);
if (saCurReceive)
{
// Actually receive.
resultCode = rippleCredit(view(),
previousAccountID,
node().account_,
previousNode().saFwdRedeem + previousNode().saFwdIssue,
false, viewJ);
}
else
{
// After applying quality, total payment was microscopic.
resultCode = tecPATH_DRY;
}
}
else
{
// account --> ACCOUNT --> account
JLOG (j_.trace)
<< "forwardLiquidityForAccount: account --> "
<< "ACCOUNT --> account";
node().saFwdRedeem.clear (node().saRevRedeem);
node().saFwdIssue.clear (node().saRevIssue);
// Previous redeem part 1: redeem -> redeem
if (previousNode().saFwdRedeem && node().saRevRedeem)
// Previous wants to redeem.
{
// Rate : 1.0 : quality out
rippleLiquidity (
rippleCalc_,
QUALITY_ONE,
uQualityOut,
previousNode().saFwdRedeem,
node().saRevRedeem,
saPrvRedeemAct,
node().saFwdRedeem,
uRateMax);
}
// Previous issue part 1: issue -> redeem
if (previousNode().saFwdIssue != saPrvIssueAct
// Previous wants to issue.
&& node().saRevRedeem != node().saFwdRedeem)
// Current has more to redeem to next.
{
// Rate: quality in : quality out
rippleLiquidity (
rippleCalc_,
uQualityIn,
uQualityOut,
previousNode().saFwdIssue,
node().saRevRedeem,
saPrvIssueAct,
node().saFwdRedeem,
uRateMax);
}
// Previous redeem part 2: redeem -> issue.
if (previousNode().saFwdRedeem != saPrvRedeemAct
// Previous still wants to redeem.
&& node().saRevRedeem == node().saFwdRedeem
// Current redeeming is done can issue.
&& node().saRevIssue)
// Current wants to issue.
{
// Rate : 1.0 : transfer_rate
rippleLiquidity (
rippleCalc_,
QUALITY_ONE,
rippleTransferRate (view(), node().account_),
previousNode().saFwdRedeem,
node().saRevIssue,
saPrvRedeemAct,
node().saFwdIssue,
uRateMax);
}
// Previous issue part 2 : issue -> issue
if (previousNode().saFwdIssue != saPrvIssueAct
// Previous wants to issue.
&& node().saRevRedeem == node().saFwdRedeem
// Current redeeming is done can issue.
&& node().saRevIssue)
// Current wants to issue.
{
// Rate: quality in : 1.0
rippleLiquidity (
rippleCalc_,
uQualityIn,
QUALITY_ONE,
previousNode().saFwdIssue,
node().saRevIssue,
saPrvIssueAct,
node().saFwdIssue,
uRateMax);
}
STAmount saProvide = node().saFwdRedeem + node().saFwdIssue;
// Adjust prv --> cur balance : take all inbound
resultCode = saProvide
? rippleCredit(view(),
previousAccountID,
node().account_,
previousNode().saFwdRedeem + previousNode().saFwdIssue,
false, viewJ)
: tecPATH_DRY;
}
}
else if (previousNode().isAccount() && !nextNode().isAccount())
{
// Current account is issuer to next offer.
// Determine deliver to offer amount.
// Don't adjust outbound balances- keep funds with issuer as limbo.
// If issuer hold's an offer owners inbound IOUs, there is no fee and
// redeem/issue will transparently happen.
if (nodeIndex_)
{
// Non-XRP, current node is the issuer.
JLOG (j_.trace)
<< "forwardLiquidityForAccount: account --> "
<< "ACCOUNT --> offer";
node().saFwdDeliver.clear (node().saRevDeliver);
// redeem -> issue/deliver.
// Previous wants to redeem.
// Current is issuing to an offer so leave funds in account as
// "limbo".
if (previousNode().saFwdRedeem)
// Previous wants to redeem.
{
// Rate : 1.0 : transfer_rate
// XXX Is having the transfer rate here correct?
rippleLiquidity (
rippleCalc_,
QUALITY_ONE,
rippleTransferRate (view(), node().account_),
previousNode().saFwdRedeem,
node().saRevDeliver,
saPrvRedeemAct,
node().saFwdDeliver,
uRateMax);
}
// issue -> issue/deliver
if (previousNode().saFwdRedeem == saPrvRedeemAct
// Previous done redeeming: Previous has no IOUs.
&& previousNode().saFwdIssue)
// Previous wants to issue. To next must be ok.
{
// Rate: quality in : 1.0
rippleLiquidity (
rippleCalc_,
uQualityIn,
QUALITY_ONE,
previousNode().saFwdIssue,
node().saRevDeliver,
saPrvIssueAct,
node().saFwdDeliver,
uRateMax);
}
// Adjust prv --> cur balance : take all inbound
resultCode = node().saFwdDeliver
? rippleCredit(view(),
previousAccountID, node().account_,
previousNode().saFwdRedeem + previousNode().saFwdIssue,
false, viewJ)
: tecPATH_DRY; // Didn't actually deliver anything.
}
else
{
// Delivering amount requested from downstream.
node().saFwdDeliver = node().saRevDeliver;
// If limited, then limit by send max and available.
if (pathState_.inReq() >= zero)
{
// Limit by send max.
node().saFwdDeliver = std::min (
node().saFwdDeliver, pathState_.inReq() - pathState_.inAct());
// Limit XRP by available. No limit for non-XRP as issuer.
if (isXRP (node().issue_))
node().saFwdDeliver = std::min (
node().saFwdDeliver,
accountHolds(view(),
node().account_,
xrpCurrency(),
xrpAccount(),
fhIGNORE_FREEZE, viewJ)); // XRP can't be frozen
}
// Record amount sent for pass.
pathState_.setInPass (node().saFwdDeliver);
if (!node().saFwdDeliver)
{
resultCode = tecPATH_DRY;
}
else if (!isXRP (node().issue_))
{
// Non-XRP, current node is the issuer.
// We could be delivering to multiple accounts, so we don't know
// which ripple balance will be adjusted. Assume just issuing.
JLOG (j_.trace)
<< "forwardLiquidityForAccount: ^ --> "
<< "ACCOUNT -- !XRP --> offer";
// As the issuer, would only issue.
// Don't need to actually deliver. As from delivering leave in
// the issuer as limbo.
}
else
{
JLOG (j_.trace)
<< "forwardLiquidityForAccount: ^ --> "
<< "ACCOUNT -- XRP --> offer";
// Deliver XRP to limbo.
resultCode = accountSend(view(),
node().account_, xrpAccount(), node().saFwdDeliver, viewJ);
}
}
}
else if (!previousNode().isAccount() && nextNode().isAccount())
{
if (nodeIndex_ == lastNodeIndex)
{
// offer --> ACCOUNT --> $
JLOG (j_.trace)
<< "forwardLiquidityForAccount: offer --> "
<< "ACCOUNT --> $ : "
<< previousNode().saFwdDeliver;
// Amount to credit.
pathState_.setOutPass (previousNode().saFwdDeliver);
// No income balance adjustments necessary. The paying side inside
// the offer paid to this account.
}
else
{
// offer --> ACCOUNT --> account
JLOG (j_.trace)
<< "forwardLiquidityForAccount: offer --> "
<< "ACCOUNT --> account";
node().saFwdRedeem.clear (node().saRevRedeem);
node().saFwdIssue.clear (node().saRevIssue);
// deliver -> redeem
if (previousNode().saFwdDeliver && node().saRevRedeem)
// Previous wants to deliver and can current redeem.
{
// Rate : 1.0 : quality out
rippleLiquidity (
rippleCalc_,
QUALITY_ONE,
uQualityOut,
previousNode().saFwdDeliver,
node().saRevRedeem,
saPrvDeliverAct,
node().saFwdRedeem,
uRateMax);
}
// deliver -> issue
// Wants to redeem and current would and can issue.
if (previousNode().saFwdDeliver != saPrvDeliverAct
// Previous still wants to deliver.
&& node().saRevRedeem == node().saFwdRedeem
// Current has more to redeem to next.
&& node().saRevIssue)
// Current wants issue.
{
// Rate : 1.0 : transfer_rate
rippleLiquidity (
rippleCalc_,
QUALITY_ONE,
rippleTransferRate (view(), node().account_),
previousNode().saFwdDeliver,
node().saRevIssue,
saPrvDeliverAct,
node().saFwdIssue,
uRateMax);
}
// No income balance adjustments necessary. The paying side inside
// the offer paid and the next link will receive.
STAmount saProvide = node().saFwdRedeem + node().saFwdIssue;
if (!saProvide)
resultCode = tecPATH_DRY;
}
}
else
{
// offer --> ACCOUNT --> offer
// deliver/redeem -> deliver/issue.
JLOG (j_.trace)
<< "forwardLiquidityForAccount: offer --> ACCOUNT --> offer";
node().saFwdDeliver.clear (node().saRevDeliver);
if (previousNode().saFwdDeliver && node().saRevDeliver)
{
// Rate : 1.0 : transfer_rate
rippleLiquidity (
rippleCalc_,
QUALITY_ONE,
rippleTransferRate (view(), node().account_),
previousNode().saFwdDeliver,
node().saRevDeliver,
saPrvDeliverAct,
node().saFwdDeliver,
uRateMax);
}
// No income balance adjustments necessary. The paying side inside the
// offer paid and the next link will receive.
if (!node().saFwdDeliver)
resultCode = tecPATH_DRY;
}
return resultCode;
}
void rippleLiquidity (
RippleCalc& rippleCalc,
std::uint32_t const uQualityIn,
std::uint32_t const uQualityOut,
STAmount const& saPrvReq, // --> in limit including fees, <0 = unlimited
STAmount const& saCurReq, // --> out limit
STAmount& saPrvAct, // <-> in limit including achieved so far: <-- <= -->
STAmount& saCurAct, // <-> out limit including achieved so far: <-- <= -->
std::uint64_t& uRateMax)
{
WriteLog (lsTRACE, RippleCalc)
<< "rippleLiquidity>"
<< " uQualityIn=" << uQualityIn
<< " uQualityOut=" << uQualityOut
<< " saPrvReq=" << saPrvReq
<< " saCurReq=" << saCurReq
<< " saPrvAct=" << saPrvAct
<< " saCurAct=" << saCurAct;
// saCurAct was once zero in a production server.
assert (saCurReq != zero);
assert (saCurReq > zero);
assert (saPrvReq.getCurrency () == saCurReq.getCurrency ());
assert (saPrvReq.getCurrency () == saPrvAct.getCurrency ());
assert (saPrvReq.getIssuer () == saPrvAct.getIssuer ());
const bool bPrvUnlimited = (saPrvReq < zero); // -1 means unlimited.
// Unlimited stays unlimited - don't do calculations.
// How much could possibly flow through the previous node?
const STAmount saPrv = bPrvUnlimited ? saPrvReq : saPrvReq - saPrvAct;
// How much could possibly flow through the current node?
const STAmount saCur = saCurReq - saCurAct;
WriteLog (lsTRACE, RippleCalc)
<< "rippleLiquidity: "
<< " bPrvUnlimited=" << bPrvUnlimited
<< " saPrv=" << saPrv
<< " saCur=" << saCur;
// If nothing can flow, we might as well not do any work.
if (saPrv == zero || saCur == zero)
return;
if (uQualityIn >= uQualityOut)
{
// You're getting better quality than you asked for, so no fee.
WriteLog (lsTRACE, RippleCalc) << "rippleLiquidity: No fees";
// Only process if the current rate, 1:1, is not worse than the previous
// rate, uRateMax - otherwise there is no flow.
if (!uRateMax || STAmount::uRateOne <= uRateMax)
{
// Limit amount to transfer if need - the minimum of amount being
// paid and the amount that's wanted.
STAmount saTransfer = bPrvUnlimited ? saCur
: std::min (saPrv, saCur);
// In reverse, we want to propagate the limited cur to prv and set
// actual cur.
//
// In forward, we want to propagate the limited prv to cur and set
// actual prv.
//
// This is the actual flow.
saPrvAct += saTransfer;
saCurAct += saTransfer;
// If no rate limit, set rate limit to avoid combining with
// something with a worse rate.
if (uRateMax == 0)
uRateMax = STAmount::uRateOne;
}
}
else
{
// If the quality is worse than the previous
WriteLog (lsTRACE, RippleCalc) << "rippleLiquidity: Fee";
std::uint64_t uRate = getRate (
STAmount (uQualityOut), STAmount (uQualityIn));
// If the next rate is at least as good as the current rate, process.
if (!uRateMax || uRate <= uRateMax)
{
auto currency = saCur.getCurrency ();
auto uCurIssuerID = saCur.getIssuer ();
// current actual = current request * (quality out / quality in).
auto numerator = mulRound (
saCur, uQualityOut, {currency, uCurIssuerID}, true);
// True means "round up" to get best flow.
STAmount saCurIn = divRound (
numerator, uQualityIn, {currency, uCurIssuerID}, true);
WriteLog (lsTRACE, RippleCalc)
<< "rippleLiquidity:"
<< " bPrvUnlimited=" << bPrvUnlimited
<< " saPrv=" << saPrv
<< " saCurIn=" << saCurIn;
if (bPrvUnlimited || saCurIn <= saPrv)
{
// All of current. Some amount of previous.
saCurAct += saCur;
saPrvAct += saCurIn;
WriteLog (lsTRACE, RippleCalc)
<< "rippleLiquidity:3c:"
<< " saCurReq=" << saCurReq
<< " saPrvAct=" << saPrvAct;
}
else
{
// There wasn't enough money to start with - so given the
// limited input, how much could we deliver?
// current actual = previous request
// * (quality in / quality out).
// This is inverted compared to the code above because we're
// going the other way
Issue issue{currency, uCurIssuerID};
auto numerator = mulRound (
saPrv, uQualityIn, issue, true);
// A part of current. All of previous. (Cur is the driver
// variable.)
STAmount saCurOut = divRound (
numerator, uQualityOut, issue, true);
WriteLog (lsTRACE, RippleCalc)
<< "rippleLiquidity:4: saCurReq=" << saCurReq;
saCurAct += saCurOut;
saPrvAct = saPrvReq;
}
if (!uRateMax)
uRateMax = uRate;
}
}
WriteLog (lsTRACE, RippleCalc)
<< "rippleLiquidity<"
<< " uQualityIn=" << uQualityIn
<< " uQualityOut=" << uQualityOut
<< " saPrvReq=" << saPrvReq
<< " saCurReq=" << saCurReq
<< " saPrvAct=" << saPrvAct
<< " saCurAct=" << saCurAct;
}