cs-policy-lru.cpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
#include "cs-policy-lru.hpp"
#include "cs.hpp"

namespace nfd {
namespace cs {
namespace lru {

const std::string LruPolicy::POLICY_NAME = "lru";
NFD_REGISTER_CS_POLICY(LruPolicy);

LruPolicy::LruPolicy()
  : Policy(POLICY_NAME)
{
}

void
LruPolicy::doAfterInsert(iterator i)
{
  this->insertToQueue(i, true);
  this->evictEntries();
}

void
LruPolicy::doAfterRefresh(iterator i)
{
  this->insertToQueue(i, false);
}

void
LruPolicy::doBeforeErase(iterator i)
{
  m_queue.get<1>().erase(i);
}

void
LruPolicy::doBeforeUse(iterator i)
{
  this->insertToQueue(i, false);
}

void
LruPolicy::evictEntries()
{
  BOOST_ASSERT(this->getCs() != nullptr);
  while (this->getCs()->size() > this->getLimit()) {
    BOOST_ASSERT(!m_queue.empty());
    iterator i = m_queue.front();
    m_queue.pop_front();
    this->emitSignal(beforeEvict, i);
  }
}

void
LruPolicy::insertToQueue(iterator i, bool isNewEntry)
{
  Queue::iterator it;
  bool isNew = false;
  // push_back only if iterator i does not exist
  std::tie(it, isNew) = m_queue.push_back(i);

  BOOST_ASSERT(isNew == isNewEntry);
  if (!isNewEntry) {
    m_queue.relocate(m_queue.end(), it);
  }
}

} // namespace lru
} // namespace cs
} // namespace nfd