TER computeReverseLiquidityForAccount (
RippleCalc& rippleCalc,
const unsigned int nodeIndex, PathState& pathState,
const bool bMultiQuality)
{
TER terResult = tesSUCCESS;
auto const lastNodeIndex = pathState.nodes().size () - 1;
auto const isFinalNode = (nodeIndex == lastNodeIndex);
// 0 quality means none has yet been determined.
std::uint64_t uRateMax = 0;
auto& previousNode = pathState.nodes()[nodeIndex ? nodeIndex - 1 : 0];
auto& node = pathState.nodes()[nodeIndex];
auto& nextNode = pathState.nodes()[isFinalNode ? lastNodeIndex : nodeIndex + 1];
// Current is allowed to redeem to next.
const bool previousNodeIsAccount = !nodeIndex || previousNode.isAccount();
const bool nextNodeIsAccount = isFinalNode || nextNode.isAccount();
Account const& previousAccountID = previousNodeIsAccount
? previousNode.account_ : node.account_;
Account const& nextAccountID = nextNodeIsAccount ? nextNode.account_
: node.account_; // Offers are always issue.
// This is the quality from from the previous node to this one.
const std::uint32_t uQualityIn
= (nodeIndex != 0)
? rippleCalc.mActiveLedger.rippleQualityIn (
node.account_, previousAccountID, node.currency_)
: QUALITY_ONE;
// And this is the quality from the next one to this one.
const std::uint32_t uQualityOut
= (nodeIndex != lastNodeIndex)
? rippleCalc.mActiveLedger.rippleQualityOut (
node.account_, nextAccountID, node.currency_)
: QUALITY_ONE;
// For previousNodeIsAccount:
// Previous account is already owed.
const STAmount saPrvOwed = (previousNodeIsAccount && nodeIndex != 0)
? rippleCalc.mActiveLedger.rippleOwed (
node.account_, previousAccountID, node.currency_)
: STAmount ({node.currency_, node.account_});
// The limit amount that the previous account may owe.
const STAmount saPrvLimit = (previousNodeIsAccount && nodeIndex != 0)
? rippleCalc.mActiveLedger.rippleLimit (
node.account_, previousAccountID, node.currency_)
: STAmount ({node.currency_, node.account_});
// Next account is owed.
const STAmount saNxtOwed = (nextNodeIsAccount && nodeIndex != lastNodeIndex)
? rippleCalc.mActiveLedger.rippleOwed (
node.account_, nextAccountID, node.currency_)
: STAmount ({node.currency_, node.account_});
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount>"
<< " nodeIndex=%d/%d" << nodeIndex << "/" << lastNodeIndex
<< " previousAccountID=" << previousAccountID
<< " node.account_=" << node.account_
<< " nextAccountID=" << nextAccountID
<< " currency_=" << node.currency_
<< " uQualityIn=" << uQualityIn
<< " uQualityOut=" << uQualityOut
<< " saPrvOwed=" << saPrvOwed
<< " saPrvLimit=" << saPrvLimit;
// Requests are computed to be the maximum flow possible.
// Previous can redeem the owed IOUs it holds.
const STAmount saPrvRedeemReq = (saPrvOwed > zero)
? saPrvOwed
: STAmount (saPrvOwed.issue ());
// This is the amount we're actually going to be setting for the previous
// node.
STAmount& saPrvRedeemAct = previousNode.saRevRedeem;
// Previous can issue up to limit minus whatever portion of limit already
// used (not including redeemable amount) - another "maximum flow".
const STAmount saPrvIssueReq = (saPrvOwed < zero)
? saPrvLimit + saPrvOwed : saPrvLimit;
STAmount& saPrvIssueAct = previousNode.saRevIssue;
// Precompute these values in case we have an order book.
auto deliverCurrency = previousNode.saRevDeliver.getCurrency ();
const STAmount saPrvDeliverReq (
{deliverCurrency, previousNode.saRevDeliver.getIssuer ()}, -1);
// Unlimited delivery.
STAmount& saPrvDeliverAct = previousNode.saRevDeliver;
// For nextNodeIsAccount
const STAmount& saCurRedeemReq = node.saRevRedeem;
// Set to zero, because we're trying to hit the previous node.
auto saCurRedeemAct = saCurRedeemReq.zeroed();
const STAmount& saCurIssueReq = node.saRevIssue;
// Track the amount we actually redeem.
auto saCurIssueAct = saCurIssueReq.zeroed();
// For !nextNodeIsAccount
const STAmount& saCurDeliverReq = node.saRevDeliver;
auto saCurDeliverAct = saCurDeliverReq.zeroed();
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount:"
<< " saPrvRedeemReq:" << saPrvRedeemReq
<< " saPrvIssueReq:" << saPrvIssueReq
<< " saPrvDeliverAct:" << saPrvDeliverAct
<< " saPrvDeliverReq:" << saPrvDeliverReq
<< " saCurRedeemReq:" << saCurRedeemReq
<< " saCurIssueReq:" << saCurIssueReq
<< " saNxtOwed:" << saNxtOwed;
WriteLog (lsTRACE, RippleCalc) << pathState.getJson ();
// Current redeem req can't be more than IOUs on hand.
assert (!saCurRedeemReq || (-saNxtOwed) >= saCurRedeemReq);
assert (!saCurIssueReq // If not issuing, fine.
|| saNxtOwed >= zero
// saNxtOwed >= 0: Sender not holding next IOUs, saNxtOwed < 0:
// Sender holding next IOUs.
|| -saNxtOwed == saCurRedeemReq);
// If issue req, then redeem req must consume all owed.
if (nodeIndex == 0)
{
// ^ --> ACCOUNT --> account|offer
// Nothing to do, there is no previous to adjust.
//
// TODO(tom): we could have skipped all that setup and just left
// or even just never call this whole routine on nodeIndex = 0!
}
// The next four cases correspond to the table at the bottom of this Wiki
// page section: https://ripple.com/wiki/Transit_Fees#Implementation
else if (previousNodeIsAccount && nextNodeIsAccount)
{
if (isFinalNode)
{
// account --> ACCOUNT --> $
// Overall deliverable.
const STAmount saCurWantedReq = std::min (
pathState.outReq() - pathState.outAct(),
saPrvLimit + saPrvOwed);
auto saCurWantedAct = saCurWantedReq.zeroed ();
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: account --> ACCOUNT --> $ :"
<< " saCurWantedReq=" << saCurWantedReq;
// Calculate redeem
if (saPrvRedeemReq) // Previous has IOUs to redeem.
{
// Redeem your own IOUs at 1:1
saCurWantedAct = std::min (saPrvRedeemReq, saCurWantedReq);
saPrvRedeemAct = saCurWantedAct;
uRateMax = STAmount::uRateOne;
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: Redeem at 1:1"
<< " saPrvRedeemReq=" << saPrvRedeemReq
<< " (available) saPrvRedeemAct=" << saPrvRedeemAct
<< " uRateMax="
<< STAmount::saFromRate (uRateMax).getText ();
}
else
{
saPrvRedeemAct.clear (saPrvRedeemReq);
}
// Calculate issuing.
saPrvIssueAct.clear (saPrvIssueReq);
if (saCurWantedReq != saCurWantedAct // Need more.
&& saPrvIssueReq) // Will accept IOUs from previous.
{
// Rate: quality in : 1.0
// If we previously redeemed and this has a poorer rate, this
// won't be included the current increment.
computeRippleLiquidity (
rippleCalc,
uQualityIn, QUALITY_ONE,
saPrvIssueReq, saCurWantedReq,
saPrvIssueAct, saCurWantedAct, uRateMax);
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: Issuing: Rate: quality in : 1.0"
<< " saPrvIssueAct:" << saPrvIssueAct
<< " saCurWantedAct:" << saCurWantedAct;
}
if (!saCurWantedAct)
{
// Must have processed something.
terResult = tecPATH_DRY;
}
}
else
{
// Not final node.
// account --> ACCOUNT --> account
saPrvRedeemAct.clear (saPrvRedeemReq);
saPrvIssueAct.clear (saPrvIssueReq);
// redeem (part 1) -> redeem
if (saCurRedeemReq
// Next wants IOUs redeemed from current account.
&& saPrvRedeemReq)
// Previous has IOUs to redeem to the current account.
{
// TODO(tom): add English.
// Rate : 1.0 : quality out - we must accept our own IOUs as 1:1.
computeRippleLiquidity (
rippleCalc,
QUALITY_ONE, uQualityOut,
saPrvRedeemReq, saCurRedeemReq,
saPrvRedeemAct, saCurRedeemAct, uRateMax);
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "Rate : 1.0 : quality out"
<< " saPrvRedeemAct:" << saPrvRedeemAct
<< " saCurRedeemAct:" << saCurRedeemAct;
}
// issue (part 1) -> redeem
if (saCurRedeemReq != saCurRedeemAct
// The current node has more IOUs to redeem.
&& saPrvRedeemAct == saPrvRedeemReq)
// The previous node has no IOUs to redeem remaining, so issues.
{
// Rate: quality in : quality out
computeRippleLiquidity (
rippleCalc,
uQualityIn, uQualityOut,
saPrvIssueReq, saCurRedeemReq,
saPrvIssueAct, saCurRedeemAct, uRateMax);
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "Rate: quality in : quality out:"
<< " saPrvIssueAct:" << saPrvIssueAct
<< " saCurRedeemAct:" << saCurRedeemAct;
}
// redeem (part 2) -> issue.
if (saCurIssueReq // Next wants IOUs issued.
// TODO(tom): this condition seems redundant.
&& saCurRedeemAct == saCurRedeemReq
// Can only issue if completed redeeming.
&& saPrvRedeemAct != saPrvRedeemReq)
// Did not complete redeeming previous IOUs.
{
// Rate : 1.0 : transfer_rate
computeRippleLiquidity (
rippleCalc,
QUALITY_ONE,
rippleCalc.mActiveLedger.rippleTransferRate (node.account_),
saPrvRedeemReq, saCurIssueReq,
saPrvRedeemAct, saCurIssueAct, uRateMax);
WriteLog (lsDEBUG, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "Rate : 1.0 : transfer_rate:"
<< " saPrvRedeemAct:" << saPrvRedeemAct
<< " saCurIssueAct:" << saCurIssueAct;
}
// issue (part 2) -> issue
if (saCurIssueReq != saCurIssueAct
// Need wants more IOUs issued.
&& saCurRedeemAct == saCurRedeemReq
// Can only issue if completed redeeming.
&& saPrvRedeemReq == saPrvRedeemAct
// Previously redeemed all owed IOUs.
&& saPrvIssueReq)
// Previous can issue.
{
// Rate: quality in : 1.0
computeRippleLiquidity (
rippleCalc,
uQualityIn, QUALITY_ONE,
saPrvIssueReq, saCurIssueReq,
saPrvIssueAct, saCurIssueAct, uRateMax);
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "Rate: quality in : 1.0:"
<< " saPrvIssueAct:" << saPrvIssueAct
<< " saCurIssueAct:" << saCurIssueAct;
}
if (!saCurRedeemAct && !saCurIssueAct)
{
// Did not make progress.
terResult = tecPATH_DRY;
}
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "^|account --> ACCOUNT --> account :"
<< " saCurRedeemReq:" << saCurRedeemReq
<< " saCurIssueReq:" << saCurIssueReq
<< " saPrvOwed:" << saPrvOwed
<< " saCurRedeemAct:" << saCurRedeemAct
<< " saCurIssueAct:" << saCurIssueAct;
}
}
else if (previousNodeIsAccount && !nextNodeIsAccount)
{
// account --> ACCOUNT --> offer
// Note: deliver is always issue as ACCOUNT is the issuer for the offer
// input.
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "account --> ACCOUNT --> offer";
saPrvRedeemAct.clear (saPrvRedeemReq);
saPrvIssueAct.clear (saPrvIssueReq);
// We have three cases: the nxt offer can be owned by current account,
// previous account or some third party account.
//
// Also, the current account may or may not have a redeemable balance
// with the account for the next offer, so we don't yet know if we're
// redeeming or issuing.
//
// TODO(tom): Make sure deliver was cleared, or check actual is zero.
// redeem -> deliver/issue.
if (saPrvOwed > zero // Previous has IOUs to redeem.
&& saCurDeliverReq) // Need some issued.
{
// Rate : 1.0 : transfer_rate
computeRippleLiquidity (
rippleCalc, QUALITY_ONE,
rippleCalc.mActiveLedger.rippleTransferRate (node.account_),
saPrvRedeemReq, saCurDeliverReq,
saPrvRedeemAct, saCurDeliverAct, uRateMax);
}
// issue -> deliver/issue
if (saPrvRedeemReq == saPrvRedeemAct // Previously redeemed all owed.
&& saCurDeliverReq != saCurDeliverAct) // Still need some issued.
{
// Rate: quality in : 1.0
computeRippleLiquidity (
rippleCalc,
uQualityIn, QUALITY_ONE,
saPrvIssueReq, saCurDeliverReq,
saPrvIssueAct, saCurDeliverAct, uRateMax);
}
if (!saCurDeliverAct)
{
// Must want something.
terResult = tecPATH_DRY;
}
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< " saCurDeliverReq:" << saCurDeliverReq
<< " saCurDeliverAct:" << saCurDeliverAct
<< " saPrvOwed:" << saPrvOwed;
}
else if (!previousNodeIsAccount && nextNodeIsAccount)
{
if (isFinalNode)
{
// offer --> ACCOUNT --> $
// Previous is an offer, no limit: redeem own IOUs.
//
// This is the final node; we can't look to the right to get values;
// we have to go up to get the out value for the entire path state.
const STAmount& saCurWantedReq =
pathState.outReq() - pathState.outAct();
STAmount saCurWantedAct = saCurWantedReq.zeroed();
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "offer --> ACCOUNT --> $ :"
<< " saCurWantedReq:" << saCurWantedReq
<< " saOutAct:" << pathState.outAct()
<< " saOutReq:" << pathState.outReq();
if (saCurWantedReq <= zero)
{
// TEMPORARY emergency fix
//
// TODO(tom): why can't saCurWantedReq be -1 if you want to
// compute maximum liquidity? This might be unimplemented
// functionality. TODO(tom): should the same check appear in
// other paths or even be pulled up?
WriteLog (lsFATAL, RippleCalc) << "CurWantReq was not positive";
return tefEXCEPTION;
}
assert (saCurWantedReq > zero); // FIXME: We got one of these
// The previous node is an offer; we are receiving our own currency;
// The previous order book's entries might hold our issuances; might
// not hold our issuances; might be our own offer.
//
// Assume the worst case, the case which costs the most to go
// through, which is that it is not our own offer or our own
// issuances. Later on the forward pass we may be able to do
// better.
//
// TODO: this comment applies generally to this section - move it up
// to a document.
// Rate: quality in : 1.0
computeRippleLiquidity (
rippleCalc,
uQualityIn, QUALITY_ONE,
saPrvDeliverReq, saCurWantedReq,
saPrvDeliverAct, saCurWantedAct, uRateMax);
if (!saCurWantedAct)
{
// Must have processed something.
terResult = tecPATH_DRY;
}
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount:"
<< " saPrvDeliverAct:" << saPrvDeliverAct
<< " saPrvDeliverReq:" << saPrvDeliverReq
<< " saCurWantedAct:" << saCurWantedAct
<< " saCurWantedReq:" << saCurWantedReq;
}
else
{
// offer --> ACCOUNT --> account
// Note: offer is always delivering(redeeming) as account is issuer.
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: "
<< "offer --> ACCOUNT --> account :"
<< " saCurRedeemReq:" << saCurRedeemReq
<< " saCurIssueReq:" << saCurIssueReq;
// deliver -> redeem
// TODO(tom): now we have more checking in nodeRipple, these checks
// might be redundant.
if (saCurRedeemReq) // Next wants us to redeem.
{
// cur holds IOUs from the account to the right, the nxt
// account. If someone is making the current account get rid of
// the nxt account's IOUs, then charge the input for quality out.
//
// Rate : 1.0 : quality out
computeRippleLiquidity (
rippleCalc,
QUALITY_ONE, uQualityOut,
saPrvDeliverReq, saCurRedeemReq,
saPrvDeliverAct, saCurRedeemAct, uRateMax);
}
// deliver -> issue.
if (saCurRedeemReq == saCurRedeemAct
// Can only issue if previously redeemed all.
&& saCurIssueReq)
// Need some issued.
{
// Rate : 1.0 : transfer_rate
computeRippleLiquidity (
rippleCalc,
QUALITY_ONE,
rippleCalc.mActiveLedger.rippleTransferRate (node.account_),
saPrvDeliverReq, saCurIssueReq, saPrvDeliverAct,
saCurIssueAct, uRateMax);
}
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount:"
<< " saCurRedeemAct:" << saCurRedeemAct
<< " saCurRedeemReq:" << saCurRedeemReq
<< " saPrvDeliverAct:" << saPrvDeliverAct
<< " saCurIssueReq:" << saCurIssueReq;
if (!saPrvDeliverAct)
{
// Must want something.
terResult = tecPATH_DRY;
}
}
}
else
{
// offer --> ACCOUNT --> offer
// deliver/redeem -> deliver/issue.
WriteLog (lsTRACE, RippleCalc)
<< "computeReverseLiquidityForAccount: offer --> ACCOUNT --> offer";
// Rate : 1.0 : transfer_rate
computeRippleLiquidity (
rippleCalc,
QUALITY_ONE,
rippleCalc.mActiveLedger.rippleTransferRate (node.account_),
saPrvDeliverReq, saCurDeliverReq, saPrvDeliverAct,
saCurDeliverAct, uRateMax);
if (!saCurDeliverAct)
{
// Must want something.
terResult = tecPATH_DRY;
}
}
return terResult;
}
void pathNext (
RippleCalc& rippleCalc,
PathState& pathState, const bool bMultiQuality,
const LedgerEntrySet& lesCheckpoint, LedgerEntrySet& lesCurrent)
{
// The next state is what is available in preference order.
// This is calculated when referenced accounts changed.
pathState.clear();
WriteLog (lsTRACE, RippleCalc)
<< "pathNext: Path In: " << pathState.getJson ();
assert (pathState.nodes().size () >= 2);
lesCurrent = lesCheckpoint.duplicate (); // Restore from checkpoint.
for (unsigned int uIndex = pathState.nodes().size (); uIndex--;)
{
auto& node = pathState.nodes()[uIndex];
node.saRevRedeem.clear ();
node.saRevIssue.clear ();
node.saRevDeliver.clear ();
node.saFwdDeliver.clear ();
}
pathState.setStatus(computeReverseLiquidity (
rippleCalc, pathState, bMultiQuality));
WriteLog (lsTRACE, RippleCalc)
<< "pathNext: Path after reverse: " << pathState.getJson ();
if (tesSUCCESS == pathState.status())
{
// Do forward.
lesCurrent = lesCheckpoint.duplicate (); // Restore from checkpoint.
pathState.setStatus(computeForwardLiquidity (
rippleCalc, pathState, bMultiQuality));
}
if (tesSUCCESS == pathState.status())
{
CondLog (!pathState.inPass() || !pathState.outPass(), lsDEBUG, RippleCalc)
<< "pathNext: Error computeForwardLiquidity reported success for nothing:"
<< " saOutPass="******" inPass()=" << pathState.inPass();
if (!pathState.outPass() || !pathState.inPass())
throw std::runtime_error ("Made no progress.");
// Calculate relative quality.
pathState.setQuality(STAmount::getRate (
pathState.outPass(), pathState.inPass()));
WriteLog (lsTRACE, RippleCalc)
<< "pathNext: Path after forward: " << pathState.getJson ();
}
else
{
pathState.setQuality(0);
}
}
