lokinet/include/llarp/codel.hpp

#ifndef LLARP_CODEL_QUEUE_HPP
#define LLARP_CODEL_QUEUE_HPP
#ifdef _MSC_VER
#define NOMINMAX
#endif
#include <llarp/time.h>
#include <llarp/logger.hpp>
#include <llarp/threading.hpp>

#include <algorithm>
#include <cmath>
#include <functional>

#include <queue>
#include <string>

namespace llarp
{
  namespace util
  {
    struct DummyMutex
    {
    };

    struct DummyLock
    {
      DummyLock(const DummyMutex& mtx){};

      ~DummyLock()
      {
      }
    };
    template < typename T, typename GetTime >
    struct CoDelCompareTime
    {
      bool
      operator()(const T& left, const T& right) const
      {
        return GetTime()(left) < GetTime()(right);
      }
    };

    template < typename T >
    struct CoDelComparePriority
    {
      bool
      operator()(const T& left, const T& right) const
      {
        return left < right;
      }
    };

    template < typename T, typename GetTime, typename PutTime, typename Compare,
               typename Mutex_t = util::Mutex, typename Lock_t = util::Lock,
               llarp_time_t dropMs = 5, llarp_time_t initialIntervalMs = 100 >
    struct CoDelQueue
    {
      CoDelQueue(const std::string& name) : m_name(name)
      {
      }

      size_t
      Size()
      {
        Lock_t lock(m_QueueMutex);
        return m_Queue.size();
      }

      void
      Put(std::unique_ptr< T >& ptr)
      {
        Lock_t lock(m_QueueMutex);
        PutTime()(ptr.get());
        if(firstPut == 0)
          firstPut = GetTime()(ptr.get());
        m_Queue.push(std::move(ptr));
      }

      template < typename Func >
      void
      Process(Func visitor)
      {
        llarp_time_t lowest = 0xFFFFFFFFFFFFFFFFUL;
        // auto start          = llarp_time_now_ms();
        // llarp::LogInfo("CoDelQueue::Process - start at ", start);
        Lock_t lock(m_QueueMutex);
        auto start = firstPut;
        while(m_Queue.size())
        {
          // llarp::LogInfo("CoDelQueue::Process - queue has ", m_Queue.size());
          auto& item = m_Queue.top();
          auto dlt   = start - GetTime()(item.get());
          // llarp::LogInfo("CoDelQueue::Process - dlt ", dlt);
          lowest = std::min(dlt, lowest);
          if(m_Queue.size() == 1)
          {
            // llarp::LogInfo("CoDelQueue::Process - single item: lowest ",
            // lowest, " dropMs: ", dropMs);
            if(lowest > dropMs)
            {
              nextTickInterval += initialIntervalMs / std::sqrt(++dropNum);
              m_Queue.pop();
              break;
            }
            else
            {
              nextTickInterval = initialIntervalMs;
              dropNum          = 0;
            }
          }
          // llarp::LogInfo("CoDelQueue::Process - passing");
          visitor(item);
          m_Queue.pop();
        }
        firstPut = 0;
      }

      llarp_time_t firstPut         = 0;
      size_t dropNum                = 0;
      llarp_time_t nextTickInterval = initialIntervalMs;
      Mutex_t m_QueueMutex;
      std::priority_queue< std::unique_ptr< T >,
                           std::vector< std::unique_ptr< T > >, Compare >
          m_Queue;
      std::string m_name;
    };
  }  // namespace util
}  // namespace llarp

#endif