fw: Best Route Strategy version 2
refs #1871
Change-Id: I196a5ff0839f72caf9210af61ad54066242ba9c2
diff --git a/daemon/fw/best-route-strategy2.cpp b/daemon/fw/best-route-strategy2.cpp
new file mode 100644
index 0000000..58300fe
--- /dev/null
+++ b/daemon/fw/best-route-strategy2.cpp
@@ -0,0 +1,175 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (c) 2014, Regents of the University of California,
+ * Arizona Board of Regents,
+ * Colorado State University,
+ * University Pierre & Marie Curie, Sorbonne University,
+ * Washington University in St. Louis,
+ * Beijing Institute of Technology,
+ * The University of Memphis
+ *
+ * This file is part of NFD (Named Data Networking Forwarding Daemon).
+ * See AUTHORS.md for complete list of NFD authors and contributors.
+ *
+ * NFD is free software: you can redistribute it and/or modify it under the terms
+ * of the GNU General Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ *
+ * NFD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+ * PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "best-route-strategy2.hpp"
+#include "core/logger.hpp"
+
+namespace nfd {
+namespace fw {
+
+NFD_LOG_INIT("BestRouteStrategy2");
+
+/// \todo set to ndn:/localhost/nfd/strategy/best-route/%FD%02 after #1893 completion
+const Name BestRouteStrategy2::STRATEGY_NAME("ndn:/localhost/nfd/strategy/best-route");
+/// \todo don't use fixed interval; make it adaptive or use exponential back-off #1913
+const time::milliseconds BestRouteStrategy2::MIN_RETRANSMISSION_INTERVAL(100);
+
+BestRouteStrategy2::BestRouteStrategy2(Forwarder& forwarder, const Name& name)
+ : Strategy(forwarder, name)
+{
+}
+
+/** \brief determines whether a NextHop is eligible
+ * \param currentDownstream incoming FaceId of current Interest
+ * \param wantUnused if true, NextHop must not have unexpired OutRecord
+ * \param now time::steady_clock::now(), ignored if !wantUnused
+ */
+static inline bool
+predicate_NextHop_eligible(const shared_ptr<pit::Entry>& pitEntry,
+ const fib::NextHop& nexthop, FaceId currentDownstream,
+ bool wantUnused = false,
+ time::steady_clock::TimePoint now = time::steady_clock::TimePoint::min())
+{
+ shared_ptr<Face> upstream = nexthop.getFace();
+
+ // upstream is current downstream
+ if (upstream->getId() == currentDownstream)
+ return false;
+
+ // forwarding would violate scope
+ if (pitEntry->violatesScope(*upstream))
+ return false;
+
+ if (wantUnused) {
+ // NextHop must not have unexpired OutRecord
+ pit::OutRecordCollection::const_iterator outRecord = pitEntry->getOutRecord(upstream);
+ if (outRecord != pitEntry->getOutRecords().end() &&
+ outRecord->getExpiry() > now) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static inline bool
+compare_OutRecord_lastRenewed(const pit::OutRecord& a, const pit::OutRecord& b)
+{
+ return a.getLastRenewed() < b.getLastRenewed();
+}
+
+/** \brief pick an eligible NextHop with earliest OutRecord
+ * \note It is assumed that every nexthop has an OutRecord
+ */
+static inline fib::NextHopList::const_iterator
+findEligibleNextHopWithEarliestOutRecord(const shared_ptr<pit::Entry>& pitEntry,
+ const fib::NextHopList& nexthops,
+ FaceId currentDownstream)
+{
+ fib::NextHopList::const_iterator found = nexthops.end();
+ time::steady_clock::TimePoint earliestRenewed = time::steady_clock::TimePoint::max();
+ for (fib::NextHopList::const_iterator it = nexthops.begin(); it != nexthops.end(); ++it) {
+ if (!predicate_NextHop_eligible(pitEntry, *it, currentDownstream))
+ continue;
+ pit::OutRecordCollection::const_iterator outRecord = pitEntry->getOutRecord(it->getFace());
+ BOOST_ASSERT(outRecord != pitEntry->getOutRecords().end());
+ if (outRecord->getLastRenewed() < earliestRenewed) {
+ found = it;
+ earliestRenewed = outRecord->getLastRenewed();
+ }
+ }
+ return found;
+}
+
+void
+BestRouteStrategy2::afterReceiveInterest(const Face& inFace,
+ const Interest& interest,
+ shared_ptr<fib::Entry> fibEntry,
+ shared_ptr<pit::Entry> pitEntry)
+{
+ const fib::NextHopList& nexthops = fibEntry->getNextHops();
+ fib::NextHopList::const_iterator it = nexthops.end();
+
+ bool isNewPitEntry = !pitEntry->hasUnexpiredOutRecords();
+ if (isNewPitEntry) {
+ // forward to nexthop with lowest cost except downstream
+ it = std::find_if(nexthops.begin(), nexthops.end(),
+ bind(&predicate_NextHop_eligible, pitEntry, _1, inFace.getId(),
+ false, time::steady_clock::TimePoint::min()));
+
+ if (it == nexthops.end()) {
+ NFD_LOG_DEBUG(interest << " from=" << inFace.getId() << " noNextHop");
+ this->rejectPendingInterest(pitEntry);
+ return;
+ }
+
+ shared_ptr<Face> outFace = it->getFace();
+ this->sendInterest(pitEntry, outFace);
+ NFD_LOG_DEBUG(interest << " from=" << inFace.getId()
+ << " newPitEntry-to=" << outFace->getId());
+ return;
+ }
+
+ // when was the last outgoing Interest?
+ const pit::OutRecordCollection& outRecords = pitEntry->getOutRecords();
+ pit::OutRecordCollection::const_iterator lastOutgoing = std::max_element(
+ outRecords.begin(), outRecords.end(), &compare_OutRecord_lastRenewed);
+ BOOST_ASSERT(lastOutgoing != outRecords.end()); // otherwise it's new PIT entry
+
+ time::steady_clock::TimePoint now = time::steady_clock::now();
+ time::steady_clock::Duration sinceLastOutgoing = now - lastOutgoing->getLastRenewed();
+ bool shouldRetransmit = sinceLastOutgoing >= MIN_RETRANSMISSION_INTERVAL;
+ if (!shouldRetransmit) {
+ NFD_LOG_DEBUG(interest << " from=" << inFace.getId()
+ << " dontRetransmit sinceLastOutgoing=" << sinceLastOutgoing.count());
+ return;
+ }
+
+ // find an unused upstream with lowest cost except downstream
+ it = std::find_if(nexthops.begin(), nexthops.end(),
+ bind(&predicate_NextHop_eligible, pitEntry, _1, inFace.getId(), true, now));
+ if (it != nexthops.end()) {
+ shared_ptr<Face> outFace = it->getFace();
+ this->sendInterest(pitEntry, outFace);
+ NFD_LOG_DEBUG(interest << " from=" << inFace.getId()
+ << " retransmit-unused-to=" << outFace->getId());
+ return;
+ }
+
+ // find an eligible upstream that is used earliest
+ it = findEligibleNextHopWithEarliestOutRecord(pitEntry, nexthops, inFace.getId());
+ if (it == nexthops.end()) {
+ NFD_LOG_DEBUG(interest << " from=" << inFace.getId() << " retransmitNoNextHop");
+ }
+ else {
+ shared_ptr<Face> outFace = it->getFace();
+ this->sendInterest(pitEntry, outFace);
+ NFD_LOG_DEBUG(interest << " from=" << inFace.getId()
+ << " retransmit-retry-to=" << outFace->getId());
+ }
+}
+
+} // namespace fw
+} // namespace nfd