fw: add processing for afterNewNextHop signal

Refs: #4931
Change-Id: I08bddc0ae3ceca0ddb777392ea656876ad6fe701
diff --git a/daemon/fw/forwarder.cpp b/daemon/fw/forwarder.cpp
index f59963e..5c529a8 100644
--- a/daemon/fw/forwarder.cpp
+++ b/daemon/fw/forwarder.cpp
@@ -75,6 +75,10 @@
     cleanupOnFaceRemoval(m_nameTree, m_fib, m_pit, face);
   });
 
+  m_fib.afterNewNextHop.connect([&] (const Name& prefix, const fib::NextHop& nextHop) {
+    this->startProcessNewNextHop(prefix, nextHop);
+  });
+
   m_strategyChoice.setDefaultStrategy(getDefaultStrategyName());
 }
 
@@ -504,6 +508,46 @@
 }
 
 void
+Forwarder::onNewNextHop(const Name& prefix, const fib::NextHop& nextHop)
+{
+  const auto affectedEntries = this->getNameTree().partialEnumerate(prefix,
+    [&] (const name_tree::Entry& nte) -> std::pair<bool, bool> {
+      const fib::Entry* fibEntry = nte.getFibEntry();
+      const fw::Strategy* strategy = nullptr;
+      if (nte.getStrategyChoiceEntry() != nullptr) {
+        strategy = &nte.getStrategyChoiceEntry()->getStrategy();
+      }
+      // current nte has buffered Interests but no fibEntry (except for the root nte) and the strategy
+      // enables new nexthop behavior, we enumerate the current nte and keep visiting its children.
+      if (nte.getName().size() == 0 ||
+          (strategy != nullptr && strategy->wantNewNextHopTrigger() &&
+          fibEntry == nullptr && nte.hasPitEntries())) {
+        return {true, true};
+      }
+      // we don't need the current nte (no pitEntry or strategy doesn't support new nexthop), but
+      // if the current nte has no fibEntry, it's still possible that its children are affected by
+      // the new nexthop.
+      else if (fibEntry == nullptr) {
+        return {false, true};
+      }
+      // if the current nte has a fibEntry, we ignore the current nte and don't visit its
+      // children because they are already covered by the current nte's fibEntry.
+      else {
+        return {false, false};
+      }
+    });
+
+  for (const auto& nte : affectedEntries) {
+    for (const auto& pitEntry : nte.getPitEntries()) {
+      this->dispatchToStrategy(*pitEntry,
+        [&] (fw::Strategy& strategy) {
+          strategy.afterNewNextHop(nextHop, pitEntry);
+        });
+    }
+  }
+}
+
+void
 Forwarder::setExpiryTimer(const shared_ptr<pit::Entry>& pitEntry, time::milliseconds duration)
 {
   BOOST_ASSERT(pitEntry);
diff --git a/daemon/fw/forwarder.hpp b/daemon/fw/forwarder.hpp
index 3b14a61..2da7c87 100644
--- a/daemon/fw/forwarder.hpp
+++ b/daemon/fw/forwarder.hpp
@@ -107,6 +107,16 @@
     this->onIncomingNack(ingress, nack);
   }
 
+  /** \brief start new nexthop processing
+   *  \param prefix the prefix of the FibEntry containing the new nexthop
+   *  \param nextHop the new NextHop
+   */
+  void
+  startProcessNewNextHop(const Name& prefix, const fib::NextHop& nextHop)
+  {
+    this->onNewNextHop(prefix, nextHop);
+  }
+
   NameTree&
   getNameTree()
   {
@@ -218,6 +228,9 @@
   VIRTUAL_WITH_TESTS void
   onDroppedInterest(const FaceEndpoint& egress, const Interest& interest);
 
+  VIRTUAL_WITH_TESTS void
+  onNewNextHop(const Name& prefix, const fib::NextHop& nextHop);
+
 PROTECTED_WITH_TESTS_ELSE_PRIVATE:
   /** \brief set a new expiry timer (now + \p duration) on a PIT entry
    */
diff --git a/daemon/fw/strategy.cpp b/daemon/fw/strategy.cpp
index f9f4106..d33ad9a 100644
--- a/daemon/fw/strategy.cpp
+++ b/daemon/fw/strategy.cpp
@@ -207,6 +207,13 @@
 }
 
 void
+Strategy::afterNewNextHop(const fib::NextHop& nextHop, const shared_ptr<pit::Entry>& pitEntry)
+{
+  NFD_LOG_DEBUG("afterNewNextHop pitEntry=" << pitEntry->getName()
+                << " nexthop=" << nextHop.getFace().getId());
+}
+
+void
 Strategy::sendData(const shared_ptr<pit::Entry>& pitEntry, const Data& data,
                    const FaceEndpoint& egress)
 {
diff --git a/daemon/fw/strategy.hpp b/daemon/fw/strategy.hpp
index 99e4826..37d98bb 100644
--- a/daemon/fw/strategy.hpp
+++ b/daemon/fw/strategy.hpp
@@ -82,7 +82,7 @@
   static std::set<Name>
   listRegistered();
 
-public: // constructor, destructor, strategy name
+public: // constructor, destructor, strategy info
   /** \brief Construct a strategy instance.
    *  \param forwarder a reference to the forwarder, used to enable actions and accessors.
    *  \note Strategy subclass constructor must not retain a reference to \p forwarder.
@@ -114,6 +114,14 @@
     return m_name;
   }
 
+  /** \return whether the afterNewNextHop trigger should be invoked for this strategy.
+   */
+  bool
+  wantNewNextHopTrigger() const
+  {
+    return m_wantNewNextHopTrigger;
+  }
+
 public: // triggers
   /** \brief trigger after Interest is received
    *
@@ -233,6 +241,14 @@
   virtual void
   onDroppedInterest(const FaceEndpoint& egress, const Interest& interest);
 
+  /** \brief trigger after new nexthop is added
+   *
+   *  The strategy should decide whether to send the buffered Interests to the new nexthop.
+   *  In the base class, this method does nothing.
+   */
+  virtual void
+  afterNewNextHop(const fib::NextHop& nextHop, const shared_ptr<pit::Entry>& pitEntry);
+
 protected: // actions
   /** \brief send Interest to egress
    *  \param pitEntry PIT entry
@@ -368,6 +384,15 @@
     m_name = name;
   }
 
+PUBLIC_WITH_TESTS_ELSE_PROTECTED: // setter
+  /** \brief set whether the afterNewNextHop trigger should be invoked for this strategy
+   */
+  void
+  enableNewNextHopTrigger(bool enabled)
+  {
+    m_wantNewNextHopTrigger = enabled;
+  }
+
 private: // registry
   typedef std::function<unique_ptr<Strategy>(Forwarder& forwarder, const Name& strategyName)> CreateFunc;
   typedef std::map<Name, CreateFunc> Registry; // indexed by strategy name
@@ -392,6 +417,8 @@
   Forwarder& m_forwarder;
 
   MeasurementsAccessor m_measurements;
+
+  bool m_wantNewNextHopTrigger = false;
 };
 
 } // namespace fw
diff --git a/tests/daemon/fw/dummy-strategy.cpp b/tests/daemon/fw/dummy-strategy.cpp
index 4497ede..84038c7 100644
--- a/tests/daemon/fw/dummy-strategy.cpp
+++ b/tests/daemon/fw/dummy-strategy.cpp
@@ -72,6 +72,8 @@
                                      const FaceEndpoint& ingress, const Data& data)
 {
   ++beforeSatisfyInterest_count;
+
+  Strategy::beforeSatisfyInterest(pitEntry, ingress, data);
 }
 
 void
@@ -97,6 +99,16 @@
                                 const shared_ptr<pit::Entry>& pitEntry)
 {
   ++afterReceiveNack_count;
+
+  Strategy::afterReceiveNack(ingress, nack, pitEntry);
+}
+
+void
+DummyStrategy::afterNewNextHop(const fib::NextHop& nextHop, const shared_ptr<pit::Entry>& pitEntry)
+{
+  afterNewNextHopCalls.push_back(pitEntry->getName());
+
+  Strategy::afterNewNextHop(nextHop, pitEntry);
 }
 
 } // namespace tests
diff --git a/tests/daemon/fw/dummy-strategy.hpp b/tests/daemon/fw/dummy-strategy.hpp
index 9a2445b..04a5d9d 100644
--- a/tests/daemon/fw/dummy-strategy.hpp
+++ b/tests/daemon/fw/dummy-strategy.hpp
@@ -82,6 +82,9 @@
   afterReceiveNack(const FaceEndpoint& ingress, const lp::Nack& nack,
                    const shared_ptr<pit::Entry>& pitEntry) override;
 
+  void
+  afterNewNextHop(const fib::NextHop& nextHop, const shared_ptr<pit::Entry>& pitEntry) override;
+
 protected:
   /** \brief register an alias
    *  \tparam S subclass of DummyStrategy
@@ -102,6 +105,9 @@
   int afterReceiveData_count;
   int afterReceiveNack_count;
 
+  // a collection of names of PIT entries that afterNewNextHop() was called on
+  std::vector<Name> afterNewNextHopCalls;
+
   shared_ptr<Face> interestOutFace;
 };
 
diff --git a/tests/daemon/fw/strategy-newnexthop.t.cpp b/tests/daemon/fw/strategy-newnexthop.t.cpp
new file mode 100644
index 0000000..282e74f
--- /dev/null
+++ b/tests/daemon/fw/strategy-newnexthop.t.cpp
@@ -0,0 +1,163 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/*
+ * Copyright (c) 2014-2019,  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 "fw/forwarder.hpp"
+#include "common/global.hpp"
+
+#include "tests/test-common.hpp"
+#include "tests/daemon/global-io-fixture.hpp"
+#include "tests/daemon/face/dummy-face.hpp"
+#include "choose-strategy.hpp"
+#include "dummy-strategy.hpp"
+
+namespace nfd {
+namespace tests {
+
+class StrategyNewNextHopFixture : public GlobalIoTimeFixture
+{
+protected:
+  template<typename ...Args>
+  shared_ptr<DummyFace>
+  addFace(Args&&... args)
+  {
+    auto face = make_shared<DummyFace>(std::forward<Args>(args)...);
+    faceTable.add(face);
+    return face;
+  }
+
+protected:
+  FaceTable faceTable;
+  Forwarder forwarder{faceTable};
+};
+
+BOOST_AUTO_TEST_SUITE(Fw)
+BOOST_FIXTURE_TEST_SUITE(TestStrategyNewNextHop, StrategyNewNextHopFixture)
+
+BOOST_AUTO_TEST_CASE(AfterNewNextHop1)
+{
+  auto face1 = addFace();
+  auto face2 = addFace();
+  auto face3 = addFace();
+
+  DummyStrategy& strategy = choose<DummyStrategy>(forwarder, "/A", DummyStrategy::getStrategyName());
+  StrategyChoice& sc = forwarder.getStrategyChoice();
+  sc.insert(Name("/A/B"), strategy.getStrategyName());
+  sc.insert(Name("/A/B/C"), strategy.getStrategyName());
+
+  strategy.enableNewNextHopTrigger(true);
+
+  Fib& fib = forwarder.getFib();
+  Pit& pit = forwarder.getPit();
+
+  // fib: "/", "/A/B"
+  fib::Entry* entry = fib.insert("/").first;
+  fib.addOrUpdateNextHop(*entry, *face1, 0);
+  entry = fib.insert("/A/B").first;
+  fib.addOrUpdateNextHop(*entry, *face1, 0);
+
+  // pit: "/A", "/A/B/C"
+  auto interest1 = makeInterest("/A");
+  shared_ptr<pit::Entry> pit1 = pit.insert(*interest1).first;
+  pit1->insertOrUpdateInRecord(*face3, *interest1);
+  auto interest2 = makeInterest("/A/B/C");
+  shared_ptr<pit::Entry> pit2 = pit.insert(*interest2).first;
+  pit2->insertOrUpdateInRecord(*face3, *interest2);
+  // new nexthop for "/"
+  entry = fib.insert("/").first;
+  fib.addOrUpdateNextHop(*entry, *face2, 0);
+
+  // /A --> triggered, /A/B --> not triggered, /A/B/C --> not triggered
+  BOOST_REQUIRE_EQUAL(strategy.afterNewNextHopCalls.size(), 1);
+  BOOST_CHECK_EQUAL(strategy.afterNewNextHopCalls[0], Name("/A"));
+}
+
+BOOST_AUTO_TEST_CASE(AfterNewNextHop2)
+{
+  auto face1 = addFace();
+  auto face2 = addFace();
+  auto face3 = addFace();
+
+  DummyStrategy& strategy = choose<DummyStrategy>(forwarder, "/A", DummyStrategy::getStrategyName());
+  StrategyChoice& sc = forwarder.getStrategyChoice();
+  sc.insert(Name("/A/B"), strategy.getStrategyName());
+  sc.insert(Name("/A/B/C"), strategy.getStrategyName());
+
+  strategy.enableNewNextHopTrigger(true);
+
+  Fib& fib = forwarder.getFib();
+  Pit& pit = forwarder.getPit();
+
+  // fib: "/", "/A/B"
+  fib::Entry* entry = fib.insert("/").first;
+  fib.addOrUpdateNextHop(*entry, *face1, 0);
+  entry = fib.insert("/A/B").first;
+  fib.addOrUpdateNextHop(*entry, *face1, 0);
+
+  // pit: "/A", "/A/B/C"
+  auto interest1 = makeInterest("/A");
+  shared_ptr<pit::Entry> pit1 = pit.insert(*interest1).first;
+  pit1->insertOrUpdateInRecord(*face3, *interest1);
+  auto interest2 = makeInterest("/A/B");
+  shared_ptr<pit::Entry> pit2 = pit.insert(*interest2).first;
+  pit2->insertOrUpdateInRecord(*face3, *interest2);
+  // new nexthop for "/"
+  entry = fib.insert("/").first;
+  fib.addOrUpdateNextHop(*entry, *face2, 0);
+
+  // /A --> triggered, /A/B --> not triggered, /A/B/C --> not triggered
+  BOOST_REQUIRE_EQUAL(strategy.afterNewNextHopCalls.size(), 1);
+  BOOST_CHECK_EQUAL(strategy.afterNewNextHopCalls[0], Name("/A"));
+}
+
+BOOST_AUTO_TEST_CASE(DisableTrigger)
+{
+  auto face1 = addFace();
+  auto face2 = addFace();
+  auto face3 = addFace();
+
+  DummyStrategy& strategy = choose<DummyStrategy>(forwarder, "/A", DummyStrategy::getStrategyName());
+  strategy.enableNewNextHopTrigger(false);
+
+  Fib& fib = forwarder.getFib();
+  Pit& pit = forwarder.getPit();
+
+  fib::Entry* entry = fib.insert("/").first;
+  fib.addOrUpdateNextHop(*entry, *face1, 0);
+
+  auto interest1 = makeInterest("/A");
+  shared_ptr<pit::Entry> pit1 = pit.insert(*interest1).first;
+  pit1->insertOrUpdateInRecord(*face3, *interest1);
+  // new nexthop for "/A"
+  entry = fib.insert("/A").first;
+  fib.addOrUpdateNextHop(*entry, *face2, 0);
+
+  BOOST_CHECK_EQUAL(strategy.afterNewNextHopCalls.size(), 0);
+}
+
+BOOST_AUTO_TEST_SUITE_END() // TestStrategyNewNextHop
+BOOST_AUTO_TEST_SUITE_END() // Fw
+
+} // namespace tests
+} // namespace nfd