table: DeadNonceList code cleanup/modernization

Change-Id: I7d2bb8982b60b138c979470406b0a607301f2768
diff --git a/daemon/table/dead-nonce-list.cpp b/daemon/table/dead-nonce-list.cpp
index 142ddea..c89e9cc 100644
--- a/daemon/table/dead-nonce-list.cpp
+++ b/daemon/table/dead-nonce-list.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2020,  Regents of the University of California,
+ * Copyright (c) 2014-2021,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -32,16 +32,16 @@
 
 NFD_LOG_INIT(DeadNonceList);
 
-const time::nanoseconds DeadNonceList::DEFAULT_LIFETIME = 6_s;
-const time::nanoseconds DeadNonceList::MIN_LIFETIME = 1_ms;
-const size_t DeadNonceList::INITIAL_CAPACITY = 1 << 7;
-const size_t DeadNonceList::MIN_CAPACITY = 1 << 3;
-const size_t DeadNonceList::MAX_CAPACITY = 1 << 24;
-const DeadNonceList::Entry DeadNonceList::MARK = 0;
-const size_t DeadNonceList::EXPECTED_MARK_COUNT = 5;
-const double DeadNonceList::CAPACITY_UP = 1.2;
-const double DeadNonceList::CAPACITY_DOWN = 0.9;
-const size_t DeadNonceList::EVICT_LIMIT = 1 << 6;
+const time::nanoseconds DeadNonceList::DEFAULT_LIFETIME;
+const time::nanoseconds DeadNonceList::MIN_LIFETIME;
+const size_t DeadNonceList::INITIAL_CAPACITY;
+const size_t DeadNonceList::MIN_CAPACITY;
+const size_t DeadNonceList::MAX_CAPACITY;
+const DeadNonceList::Entry DeadNonceList::MARK;
+const size_t DeadNonceList::EXPECTED_MARK_COUNT;
+const double DeadNonceList::CAPACITY_UP;
+const double DeadNonceList::CAPACITY_DOWN;
+const size_t DeadNonceList::EVICT_LIMIT;
 
 DeadNonceList::DeadNonceList(time::nanoseconds lifetime)
   : m_lifetime(lifetime)
@@ -61,12 +61,6 @@
 
   m_markEvent = getScheduler().schedule(m_markInterval, [this] { mark(); });
   m_adjustCapacityEvent = getScheduler().schedule(m_adjustCapacityInterval, [this] { adjustCapacity(); });
-}
-
-DeadNonceList::~DeadNonceList()
-{
-  m_markEvent.cancel();
-  m_adjustCapacityEvent.cancel();
 
   BOOST_ASSERT_MSG(DEFAULT_LIFETIME >= MIN_LIFETIME, "DEFAULT_LIFETIME is too small");
   static_assert(INITIAL_CAPACITY >= MIN_CAPACITY, "INITIAL_CAPACITY is too small");
@@ -83,7 +77,7 @@
 size_t
 DeadNonceList::size() const
 {
-  return m_queue.size() - this->countMarks();
+  return m_queue.size() - countMarks();
 }
 
 bool
@@ -99,13 +93,13 @@
   Entry entry = DeadNonceList::makeEntry(name, nonce);
   m_queue.push_back(entry);
 
-  this->evictEntries();
+  evictEntries();
 }
 
 DeadNonceList::Entry
 DeadNonceList::makeEntry(const Name& name, Interest::Nonce nonce)
 {
-  Block nameWire = name.wireEncode();
+  const auto& nameWire = name.wireEncode();
   uint32_t n;
   std::memcpy(&n, nonce.data(), sizeof(n));
   return CityHash64WithSeed(reinterpret_cast<const char*>(nameWire.wire()), nameWire.size(), n);
@@ -121,7 +115,7 @@
 DeadNonceList::mark()
 {
   m_queue.push_back(MARK);
-  size_t nMarks = this->countMarks();
+  size_t nMarks = countMarks();
   m_actualMarkCounts.insert(nMarks);
 
   NFD_LOG_TRACE("mark nMarks=" << nMarks);
@@ -145,7 +139,7 @@
   }
 
   m_actualMarkCounts.clear();
-  this->evictEntries();
+  evictEntries();
 
   m_adjustCapacityEvent = getScheduler().schedule(m_adjustCapacityInterval, [this] { adjustCapacity(); });
 }
@@ -153,11 +147,11 @@
 void
 DeadNonceList::evictEntries()
 {
-  ssize_t nOverCapacity = m_queue.size() - m_capacity;
-  if (nOverCapacity <= 0) // not over capacity
+  if (m_queue.size() <= m_capacity) // not over capacity
     return;
 
-  for (ssize_t nEvict = std::min<ssize_t>(nOverCapacity, EVICT_LIMIT); nEvict > 0; --nEvict) {
+  auto nEvict = std::min(m_queue.size() - m_capacity, EVICT_LIMIT);
+  for (; nEvict > 0; --nEvict) {
     m_queue.erase(m_queue.begin());
   }
   BOOST_ASSERT(m_queue.size() >= m_capacity);
diff --git a/daemon/table/dead-nonce-list.hpp b/daemon/table/dead-nonce-list.hpp
index 5322dd4..ff9dfcd 100644
--- a/daemon/table/dead-nonce-list.hpp
+++ b/daemon/table/dead-nonce-list.hpp
@@ -34,56 +34,58 @@
 
 namespace nfd {
 
-/** \brief Represents the Dead Nonce List
+/**
+ * \brief Represents the Dead Nonce List.
  *
- *  The Dead Nonce List is a global table that supplements PIT for loop detection.
- *  When a Nonce is erased (dead) from PIT entry, the Nonce and the Interest Name is added to
- *  Dead Nonce List, and kept for a duration in which most loops are expected to have occured.
+ * The Dead Nonce List is a global table that supplements the PIT for loop detection.
+ * When a Nonce is erased (dead) from a PIT entry, the Nonce and the Interest Name are added to
+ * the Dead Nonce List and kept for a duration in which most loops are expected to have occured.
  *
- *  To reduce memory usage, the Interest Name and Nonce are stored as a 64-bit hash.
- *  There could be false positives (non-looping Interest could be considered looping),
- *  but the probability is small, and the error is recoverable when consumer retransmits
- *  with a different Nonce.
+ * To reduce memory usage, the Interest Name and Nonce are stored as a 64-bit hash.
+ * The probability of false positives (a non-looping Interest considered as looping) is small
+ * and a collision is recoverable when the consumer retransmits with a different Nonce.
  *
- *  To reduce memory usage, entries do not have associated timestamps. Instead,
- *  lifetime of entries is controlled by dynamically adjusting the capacity of the container.
- *  At fixed intervals, the MARK, an entry with a special value, is inserted into the container.
- *  The number of MARKs stored in the container reflects the lifetime of entries,
- *  because MARKs are inserted at fixed intervals.
+ * To reduce memory usage, entries do not have associated timestamps. Instead, the lifetime
+ * of the entries is controlled by dynamically adjusting the capacity of the container.
+ * At fixed intervals, a MARK (an entry with a special value) is inserted into the container.
+ * The number of MARKs stored in the container reflects the lifetime of the entries,
+ * because MARKs are inserted at fixed intervals.
  */
 class DeadNonceList : noncopyable
 {
 public:
-  /** \brief Constructs the Dead Nonce List
-   *  \param lifetime duration of the expected lifetime of each nonce,
-   *         must be no less than MIN_LIFETIME.
-   *         This should be set to the duration in which most loops would have occured.
-   *         A loop cannot be detected if delay of the cycle is greater than lifetime.
-   *  \throw std::invalid_argument if lifetime is less than MIN_LIFETIME
+  /**
+   * \brief Constructs the Dead Nonce List
+   * \param lifetime expected lifetime of each nonce, must be no less than #MIN_LIFETIME.
+   *        This should be set to a duration over which most loops would have occured.
+   *        A loop cannot be detected if the total delay of the cycle is greater than lifetime.
+   * \throw std::invalid_argument if lifetime is less than #MIN_LIFETIME
    */
   explicit
   DeadNonceList(time::nanoseconds lifetime = DEFAULT_LIFETIME);
 
-  ~DeadNonceList();
-
-  /** \brief Determines if name+nonce exists
-   *  \return true if name+nonce exists, false otherwise
+  /**
+   * \brief Determines if name+nonce is in the list
+   * \return true if name+nonce exists, false otherwise
    */
   bool
   has(const Name& name, Interest::Nonce nonce) const;
 
-  /** \brief Records name+nonce
+  /**
+   * \brief Adds name+nonce to the list
    */
   void
   add(const Name& name, Interest::Nonce nonce);
 
-  /** \return number of stored Nonces
-   *  \note The return value does not contain non-Nonce entries in the index, if any.
+  /**
+   * \brief Returns the number of stored nonces
+   * \note The return value does not contain non-Nonce entries in the index, if any.
    */
   size_t
   size() const;
 
-  /** \return expected lifetime
+  /**
+   * \brief Returns the expected nonce lifetime
    */
   time::nanoseconds
   getLifetime() const
@@ -91,26 +93,12 @@
     return m_lifetime;
   }
 
-private: // Entry and Index
-  typedef uint64_t Entry;
+private:
+  using Entry = uint64_t;
 
   static Entry
   makeEntry(const Name& name, Interest::Nonce nonce);
 
-  typedef boost::multi_index_container<
-    Entry,
-    boost::multi_index::indexed_by<
-      boost::multi_index::sequenced<>,
-      boost::multi_index::hashed_non_unique<
-        boost::multi_index::identity<Entry>
-      >
-    >
-  > Index;
-
-  typedef Index::nth_index<0>::type Queue;
-  typedef Index::nth_index<1>::type Hashtable;
-
-private: // actual lifetime estimation and capacity control
   /** \brief Return the number of MARKs in the index
    */
   size_t
@@ -136,17 +124,28 @@
 
 public:
   /// Default entry lifetime
-  static const time::nanoseconds DEFAULT_LIFETIME;
+  static constexpr time::nanoseconds DEFAULT_LIFETIME = 6_s;
   /// Minimum entry lifetime
-  static const time::nanoseconds MIN_LIFETIME;
+  static constexpr time::nanoseconds MIN_LIFETIME = 1_ms;
 
 private:
-  time::nanoseconds m_lifetime;
+  const time::nanoseconds m_lifetime;
+
+  using Index = boost::multi_index_container<
+    Entry,
+    boost::multi_index::indexed_by<
+      boost::multi_index::sequenced<>,
+      boost::multi_index::hashed_non_unique<boost::multi_index::identity<Entry>>
+    >
+  >;
+  using Queue = Index::nth_index<0>::type;
+  using Hashtable = Index::nth_index<1>::type;
+
   Index m_index;
   Queue& m_queue;
   Hashtable& m_ht;
 
-NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE: // actual lifetime estimation and capacity control
+NFD_PUBLIC_WITH_TESTS_ELSE_PRIVATE:
 
   // ---- current capacity and hard limits
 
@@ -159,33 +158,32 @@
    */
   size_t m_capacity;
 
-  static const size_t INITIAL_CAPACITY;
+  static constexpr size_t INITIAL_CAPACITY = 1 << 7;
 
   /** \brief Minimum capacity
    *
    *  This is to ensure correct algorithm operations.
    */
-  static const size_t MIN_CAPACITY;
+  static constexpr size_t MIN_CAPACITY = 1 << 3;
 
   /** \brief Maximum capacity
    *
    *  This is to limit memory usage.
    */
-  static const size_t MAX_CAPACITY;
+  static constexpr size_t MAX_CAPACITY = 1 << 24;
 
   // ---- actual entry lifetime estimation
 
   /** \brief The MARK for capacity
    *
    *  The MARK doesn't have a distinct type.
-   *  Entry is a hash. The hash function should have non-invertible property,
-   *  so it's unlikely for a usual Entry to have collision with the MARK.
+   *  Entry is a hash. The hash function should be non-invertible, so that
+   *  it's infeasible to craft a "normal" Entry that collides with the MARK.
    */
-  static const Entry MARK;
+  static constexpr Entry MARK = 0;
 
-  /** \brief Expected number of MARKs in the index
-   */
-  static const size_t EXPECTED_MARK_COUNT;
+  /// Expected number of MARKs in the index
+  static constexpr size_t EXPECTED_MARK_COUNT = 5;
 
   /** \brief Number of MARKs in the index after each MARK insertion
    *
@@ -194,18 +192,18 @@
    */
   std::multiset<size_t> m_actualMarkCounts;
 
-  time::nanoseconds m_markInterval;
-  scheduler::EventId m_markEvent;
+  const time::nanoseconds m_markInterval;
+  scheduler::ScopedEventId m_markEvent;
 
   // ---- capacity adjustments
 
-  static const double CAPACITY_UP;
-  static const double CAPACITY_DOWN;
-  time::nanoseconds m_adjustCapacityInterval;
-  scheduler::EventId m_adjustCapacityEvent;
+  static constexpr double CAPACITY_UP = 1.2;
+  static constexpr double CAPACITY_DOWN = 0.9;
+  const time::nanoseconds m_adjustCapacityInterval;
+  scheduler::ScopedEventId m_adjustCapacityEvent;
 
-  /// Maximum number of entries to evict at each operation if index is over capacity
-  static const size_t EVICT_LIMIT;
+  /// Maximum number of entries to evict at each operation if the index is over capacity
+  static constexpr size_t EVICT_LIMIT = 64;
 };
 
 } // namespace nfd
diff --git a/docs/doxygen.conf.in b/docs/doxygen.conf.in
index d68d7c6..edc9da7 100644
--- a/docs/doxygen.conf.in
+++ b/docs/doxygen.conf.in
@@ -1041,13 +1041,6 @@
 
 ALPHABETICAL_INDEX     = YES
 
-# The COLS_IN_ALPHA_INDEX tag can be used to specify the number of columns in
-# which the alphabetical index list will be split.
-# Minimum value: 1, maximum value: 20, default value: 5.
-# This tag requires that the tag ALPHABETICAL_INDEX is set to YES.
-
-COLS_IN_ALPHA_INDEX    = 5
-
 # In case all classes in a project start with a common prefix, all classes will
 # be put under the same header in the alphabetical index. The IGNORE_PREFIX tag
 # can be used to specify a prefix (or a list of prefixes) that should be ignored
diff --git a/tests/daemon/table/dead-nonce-list.t.cpp b/tests/daemon/table/dead-nonce-list.t.cpp
index a5a537e..fb3ab90 100644
--- a/tests/daemon/table/dead-nonce-list.t.cpp
+++ b/tests/daemon/table/dead-nonce-list.t.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2020,  Regents of the University of California,
+ * Copyright (c) 2014-2021,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -55,15 +55,14 @@
 
 BOOST_AUTO_TEST_CASE(MinLifetime)
 {
-  BOOST_CHECK_THROW(DeadNonceList dnl(time::milliseconds::zero()), std::invalid_argument);
+  BOOST_CHECK_THROW(DeadNonceList(0_ms), std::invalid_argument);
 }
 
-/// A Fixture that periodically inserts Nonces
+/// A fixture that periodically inserts Nonces
 class PeriodicalInsertionFixture : public GlobalIoTimeFixture
 {
 protected:
   PeriodicalInsertionFixture()
-    : dnl(LIFETIME)
   {
     addNonce();
   }
@@ -81,31 +80,30 @@
       dnl.add(name, ++lastNonce);
     }
 
-    if (addNonceInterval > 0_ns) {
-      addNonceEvent = getScheduler().schedule(addNonceInterval, [this] { addNonce(); });
-    }
+    addNonceEvent = getScheduler().schedule(ADD_INTERVAL, [this] { addNonce(); });
   }
 
   /** \brief advance clocks by LIFETIME*t
    */
   void
-  advanceClocksByLifetime(float t)
+  advanceClocksByLifetime(double t)
   {
-    advanceClocks(timeUnit, time::duration_cast<time::nanoseconds>(LIFETIME * t));
+    advanceClocks(ADD_INTERVAL / 2, time::duration_cast<time::nanoseconds>(LIFETIME * t));
   }
 
 protected:
-  static const time::nanoseconds LIFETIME;
-  DeadNonceList dnl;
+  static constexpr time::nanoseconds LIFETIME = 200_ms;
+  static constexpr time::nanoseconds ADD_INTERVAL = LIFETIME / DeadNonceList::EXPECTED_MARK_COUNT;
+
+  DeadNonceList dnl{LIFETIME};
   Name name = "/N";
   uint32_t lastNonce = 0;
   size_t addNonceBatch = 0;
-  const time::nanoseconds addNonceInterval = LIFETIME / DeadNonceList::EXPECTED_MARK_COUNT;
-  const time::nanoseconds timeUnit = addNonceInterval / 2;
   scheduler::ScopedEventId addNonceEvent;
 };
 
-const time::nanoseconds PeriodicalInsertionFixture::LIFETIME = 200_ms;
+const time::nanoseconds PeriodicalInsertionFixture::LIFETIME;
+const time::nanoseconds PeriodicalInsertionFixture::ADD_INTERVAL;
 
 BOOST_FIXTURE_TEST_CASE(Lifetime, PeriodicalInsertionFixture)
 {