lokinet/llarp/dht/txholder.hpp

#ifndef LLARP_DHT_TXHOLDER
#define LLARP_DHT_TXHOLDER

#include "tx.hpp"
#include "txowner.hpp"
#include <llarp/util/time.hpp>
#include <llarp/util/status.hpp>

#include <memory>
#include <unordered_map>

namespace llarp
{
  namespace dht
  {
    template <typename K, typename V>
    struct TXHolder
    {
      using TXPtr = std::unique_ptr<TX<K, V>>;
      // tx who are waiting for a reply for each key
      std::unordered_multimap<K, TXOwner> waiting;
      // tx timesouts by key
      std::unordered_map<K, llarp_time_t> timeouts;
      // maps remote peer with tx to handle reply from them
      std::unordered_map<TXOwner, TXPtr> tx;

      const TX<K, V>*
      GetPendingLookupFrom(const TXOwner& owner) const;

      util::StatusObject
      ExtractStatus() const
      {
        util::StatusObject obj{};
        std::vector<util::StatusObject> txObjs, timeoutsObjs, waitingObjs;
        std::transform(
            tx.begin(),
            tx.end(),
            std::back_inserter(txObjs),
            [](const auto& item) -> util::StatusObject {
              return util::StatusObject{
                  {"owner", item.first.ExtractStatus()}, {"tx", item.second->ExtractStatus()}};
            });
        obj["tx"] = txObjs;
        std::transform(
            timeouts.begin(),
            timeouts.end(),
            std::back_inserter(timeoutsObjs),
            [](const auto& item) -> util::StatusObject {
              return util::StatusObject{
                  {"time", to_json(item.second)}, {"target", item.first.ExtractStatus()}};
            });
        obj["timeouts"] = timeoutsObjs;
        std::transform(
            waiting.begin(),
            waiting.end(),
            std::back_inserter(waitingObjs),
            [](const auto& item) -> util::StatusObject {
              return util::StatusObject{
                  {"target", item.first.ExtractStatus()},
                  {"whoasked", item.second.ExtractStatus()}};
            });
        obj["waiting"] = waitingObjs;
        return obj;
      }

      bool
      HasLookupFor(const K& target) const
      {
        return timeouts.find(target) != timeouts.end();
      }

      bool
      HasPendingLookupFrom(const TXOwner& owner) const
      {
        return GetPendingLookupFrom(owner) != nullptr;
      }

      void
      NewTX(
          const TXOwner& askpeer,
          const TXOwner& whoasked,
          const K& k,
          TX<K, V>* t,
          llarp_time_t requestTimeoutMS = 15s);

      /// mark tx as not fond
      void
      NotFound(const TXOwner& from, const std::unique_ptr<Key_t>& next);

      void
      Found(const TXOwner& from, const K& k, const std::vector<V>& values)
      {
        Inform(from, k, values, true);
      }

      /// inform all watches for key of values found
      void
      Inform(
          TXOwner from,
          K key,
          std::vector<V> values,
          bool sendreply = false,
          bool removeTimeouts = true);

      void
      Expire(llarp_time_t now);
    };

    template <typename K, typename V>
    const TX<K, V>*
    TXHolder<K, V>::GetPendingLookupFrom(const TXOwner& owner) const
    {
      auto itr = tx.find(owner);
      if (itr == tx.end())
      {
        return nullptr;
      }

      return itr->second.get();
    }

    template <typename K, typename V>
    void
    TXHolder<K, V>::NewTX(
        const TXOwner& askpeer,
        const TXOwner& whoasked,
        const K& k,
        TX<K, V>* t,
        llarp_time_t requestTimeoutMS)
    {
      (void)whoasked;
      tx.emplace(askpeer, std::unique_ptr<TX<K, V>>(t));
      auto count = waiting.count(k);
      waiting.emplace(k, askpeer);

      auto itr = timeouts.find(k);
      if (itr == timeouts.end())
      {
        timeouts.emplace(k, time_now_ms() + requestTimeoutMS);
      }
      if (count == 0)
      {
        t->Start(askpeer);
      }
    }

    template <typename K, typename V>
    void
    TXHolder<K, V>::NotFound(const TXOwner& from, const std::unique_ptr<Key_t>&)
    {
      auto txitr = tx.find(from);
      if (txitr == tx.end())
      {
        return;
      }
      Inform(from, txitr->second->target, {}, true, true);
    }

    template <typename K, typename V>
    void
    TXHolder<K, V>::Inform(
        TXOwner from, K key, std::vector<V> values, bool sendreply, bool removeTimeouts)
    {
      auto range = waiting.equal_range(key);
      auto itr = range.first;
      while (itr != range.second)
      {
        auto txitr = tx.find(itr->second);
        if (txitr != tx.end())
        {
          for (const auto& value : values)
          {
            txitr->second->OnFound(from.node, value);
          }
          if (sendreply)
          {
            txitr->second->SendReply();
            tx.erase(txitr);
          }
        }
        ++itr;
      }

      if (sendreply)
      {
        waiting.erase(key);
      }

      if (removeTimeouts)
      {
        timeouts.erase(key);
      }
    }

    template <typename K, typename V>
    void
    TXHolder<K, V>::Expire(llarp_time_t now)
    {
      auto itr = timeouts.begin();
      while (itr != timeouts.end())
      {
        if (now >= itr->second)
        {
          Inform(TXOwner{}, itr->first, {}, true, false);
          itr = timeouts.erase(itr);
        }
        else
        {
          ++itr;
        }
      }
    }
  }  // namespace dht
}  // namespace llarp

#endif