std::pair<TER, core::Amounts>
CreateOffer::crossOffersDirect (
core::LedgerView& view,
core::Amounts const& taker_amount)
{
core::Taker::Options const options (mTxn.getFlags());
core::Clock::time_point const when (
mEngine->getLedger ()->getParentCloseTimeNC ());
core::LedgerView view_cancel (view.duplicate());
core::OfferStream offers (
view, view_cancel,
Book (taker_amount.in.issue(), taker_amount.out.issue()),
when, m_journal);
core::Taker taker (offers.view(), mTxnAccountID, taker_amount, options);
TER cross_result (tesSUCCESS);
while (true)
{
// Modifying the order or logic of these
// operations causes a protocol breaking change.
// Checks which remove offers are performed early so we
// can reduce the size of the order book as much as possible
// before terminating the loop.
if (taker.done())
{
m_journal.debug << "The taker reports he's done during crossing!";
break;
}
if (! offers.step ())
{
// Place the order since there are no
// more offers and the order has a balance.
m_journal.debug << "No more offers to consider during crossing!";
break;
}
auto const& offer (offers.tip());
if (taker.reject (offer.quality()))
{
// Place the order since there are no more offers
// at the desired quality, and the order has a balance.
break;
}
if (offer.account() == taker.account())
{
// Skip offer from self. The offer will be considered expired and
// will get deleted.
continue;
}
if (m_journal.debug) m_journal.debug <<
" Offer: " << offer.entry()->getIndex() << std::endl <<
" " << offer.amount().in << " : " << offer.amount().out;
cross_result = taker.cross (offer);
if (cross_result != tesSUCCESS)
{
cross_result = tecFAILED_PROCESSING;
break;
}
}
return std::make_pair(cross_result, taker.remaining_offer ());
}
bool
OfferStream::step ()
{
// Modifying the order or logic of these
// operations causes a protocol breaking change.
for(;;)
{
// BookTip::step deletes the current offer from the view before
// advancing to the next (unless the ledger entry is missing).
if (! m_tip.step())
return false;
SLE::pointer const& entry (m_tip.entry());
// Remove if missing
if (! entry)
{
erase (view());
erase (view_cancel());
continue;
}
// Remove if expired
if (entry->isFieldPresent (sfExpiration) &&
entry->getFieldU32 (sfExpiration) <= m_when)
{
view_cancel().offerDelete (entry->getIndex());
if (m_journal.trace) m_journal.trace <<
"Removing expired offer " << entry->getIndex();
continue;
}
m_offer = Offer (entry, m_tip.quality());
Amounts const amount (m_offer.amount());
// Remove if either amount is zero
if (amount.empty())
{
view_cancel().offerDelete (entry->getIndex());
if (m_journal.warning) m_journal.warning <<
"Removing bad offer " << entry->getIndex();
m_offer = Offer{};
continue;
}
// Calculate owner funds
// NIKB NOTE The calling code also checks the funds, how expensive is
// looking up the funds twice?
Amount const owner_funds (view().accountFunds (
m_offer.account(), m_offer.amount().out, fhZERO_IF_FROZEN));
// Check for unfunded offer
if (owner_funds <= zero)
{
// If the owner's balance in the pristine view is the same,
// we haven't modified the balance and therefore the
// offer is "found unfunded" versus "became unfunded"
if (view_cancel().accountFunds (m_offer.account(),
m_offer.amount().out, fhZERO_IF_FROZEN) == owner_funds)
{
view_cancel().offerDelete (entry->getIndex());
if (m_journal.trace) m_journal.trace <<
"Removing unfunded offer " << entry->getIndex();
}
else
{
if (m_journal.trace) m_journal.trace <<
"Removing became unfunded offer " << entry->getIndex();
}
m_offer = Offer{};
continue;
}
break;
}
return true;
}