table: Strategy Choice table

refs #1309

Change-Id: I6fd8efdfc98175a1cc39fdc3aa7175671596f470
diff --git a/daemon/table/strategy-choice.cpp b/daemon/table/strategy-choice.cpp
new file mode 100644
index 0000000..9e5cb37
--- /dev/null
+++ b/daemon/table/strategy-choice.cpp
@@ -0,0 +1,178 @@
+/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
+/**
+ * Copyright (C) 2014 Named Data Networking Project
+ * See COPYING for copyright and distribution information.
+ */
+
+#include "strategy-choice.hpp"
+#include "fw/strategy.hpp"
+#include "pit-entry.hpp"
+
+namespace nfd {
+
+using strategy_choice::Entry;
+using fw::Strategy;
+
+NFD_LOG_INIT("StrategyChoice");
+
+StrategyChoice::StrategyChoice(NameTree& nameTree, shared_ptr<Strategy> defaultStrategy)
+  : m_nameTree(nameTree)
+{
+  this->setDefaultStrategy(defaultStrategy);
+}
+
+bool
+StrategyChoice::hasStrategy(const Name& strategyName) const
+{
+  return m_strategyInstances.count(strategyName) > 0;
+}
+
+bool
+StrategyChoice::install(shared_ptr<Strategy> strategy)
+{
+  BOOST_ASSERT(static_cast<bool>(strategy));
+  const Name& strategyName = strategy->getName();
+
+  if (this->hasStrategy(strategyName)) {
+    NFD_LOG_ERROR("install(" << strategyName << ") duplicate strategyName");
+    return false;
+  }
+
+  m_strategyInstances[strategyName] = strategy;
+  return true;
+}
+
+bool
+StrategyChoice::insert(const Name& prefix, const Name& strategyName)
+{
+  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.lookup(prefix);
+  shared_ptr<Entry> entry = nameTreeEntry->getStrategyChoiceEntry();
+  shared_ptr<Strategy> oldStrategy;
+
+  if (static_cast<bool>(entry)) {
+    if (entry->getStrategy().getName() == strategyName) {
+      NFD_LOG_INFO("insert(" << prefix << "," << strategyName << ") not changing");
+      return true;
+    }
+    oldStrategy = entry->getStrategy().shared_from_this();
+    NFD_LOG_INFO("insert(" << prefix << "," << strategyName << ") "
+                 "changing from " << oldStrategy->getName());
+  }
+
+  shared_ptr<Strategy> strategy = this->getStrategy(strategyName);
+  if (!static_cast<bool>(strategy)) {
+    NFD_LOG_ERROR("insert(" << prefix << "," << strategyName << ") strategy not installed");
+    return false;
+  }
+
+  if (!static_cast<bool>(entry)) {
+    oldStrategy = this->findEffectiveStrategy(prefix).shared_from_this();
+    entry = make_shared<Entry>(prefix);
+    nameTreeEntry->setStrategyChoiceEntry(entry);
+    ++m_nItems;
+    NFD_LOG_INFO("insert(" << prefix << "," << strategyName << ") new entry");
+  }
+
+  this->changeStrategy(entry, oldStrategy, strategy);
+  return true;
+}
+
+void
+StrategyChoice::erase(const Name& prefix)
+{
+  BOOST_ASSERT(prefix.size() > 0);
+
+  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.findExactMatch(prefix);
+  if (!static_cast<bool>(nameTreeEntry)) {
+    return;
+  }
+
+  shared_ptr<Entry> entry = nameTreeEntry->getStrategyChoiceEntry();
+  if (!static_cast<bool>(entry)) {
+    return;
+  }
+
+  Strategy& oldStrategy = entry->getStrategy();
+  nameTreeEntry->setStrategyChoiceEntry(shared_ptr<Entry>());
+  --m_nItems;
+
+  Strategy& parentStrategy = this->findEffectiveStrategy(prefix);
+  this->changeStrategy(entry, oldStrategy.shared_from_this(), parentStrategy.shared_from_this());
+}
+
+shared_ptr<const Name>
+StrategyChoice::get(const Name& prefix) const
+{
+  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.findExactMatch(prefix);
+  if (!static_cast<bool>(nameTreeEntry)) {
+    return shared_ptr<const Name>();
+  }
+
+  shared_ptr<Entry> entry = nameTreeEntry->getStrategyChoiceEntry();
+  if (!static_cast<bool>(entry)) {
+    return shared_ptr<const Name>();
+  }
+
+  return entry->getStrategy().getName().shared_from_this();
+}
+
+static inline bool
+predicate_NameTreeEntry_hasStrategyChoiceEntry(const name_tree::Entry& entry)
+{
+  return static_cast<bool>(entry.getStrategyChoiceEntry());
+}
+
+Strategy&
+StrategyChoice::findEffectiveStrategy(const Name& prefix) const
+{
+  shared_ptr<name_tree::Entry> nameTreeEntry =
+    m_nameTree.findLongestPrefixMatch(prefix, &predicate_NameTreeEntry_hasStrategyChoiceEntry);
+  BOOST_ASSERT(static_cast<bool>(nameTreeEntry));
+  return nameTreeEntry->getStrategyChoiceEntry()->getStrategy();
+}
+
+Strategy&
+StrategyChoice::findEffectiveStrategy(const pit::Entry& pitEntry) const
+{
+  return this->findEffectiveStrategy(pitEntry.getName());
+}
+
+shared_ptr<fw::Strategy>
+StrategyChoice::getStrategy(const Name& strategyName)
+{
+  StrategyInstanceTable::iterator it = m_strategyInstances.find(strategyName);
+  return it != m_strategyInstances.end() ? it->second : shared_ptr<fw::Strategy>();
+}
+
+void
+StrategyChoice::setDefaultStrategy(shared_ptr<Strategy> strategy)
+{
+  this->install(strategy);
+
+  // don't use .insert here, because it will invoke findEffectiveStrategy
+  // which expects an existing root entry
+  shared_ptr<name_tree::Entry> nameTreeEntry = m_nameTree.lookup(Name());
+  shared_ptr<Entry> entry = make_shared<Entry>(Name());
+  nameTreeEntry->setStrategyChoiceEntry(entry);
+  ++m_nItems;
+  NFD_LOG_INFO("setDefaultStrategy(" << strategy->getName() << ") new entry");
+
+  entry->setStrategy(strategy);
+}
+
+void
+StrategyChoice::changeStrategy(shared_ptr<strategy_choice::Entry> entry,
+                               shared_ptr<fw::Strategy> oldStrategy,
+                               shared_ptr<fw::Strategy> newStrategy)
+{
+  entry->setStrategy(newStrategy);
+  if (oldStrategy == newStrategy) {
+    return;
+  }
+
+  // TODO delete incompatible StrategyInfo
+  NFD_LOG_WARN("changeStrategy(" << entry->getPrefix() << ") " <<
+               "runtime strategy change not implemented");
+}
+
+} // namespace nfd