// Copyright (c) 2019-2022, The Monero Project
//
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#pragma once
#include <boost/uuid/uuid.hpp>
#include <cstddef>
#include <memory>
#include <utility>
#include <vector>
#include "span.h"
namespace net
{
namespace dandelionpp
{
//! Assists with mapping source -> stem and tracking connections for stem.
class connection_map
{
// Make sure to update clone method if changing members
std::vector<boost::uuids::uuid> out_mapping_; //<! Current outgoing uuid connection at index.
std::vector<std::pair<boost::uuids::uuid, std::size_t>> in_mapping_; //<! uuid source to an `out_mapping_` index.
std::vector<std::size_t> usage_count_;
// Use clone method to prevent "hidden" copies.
connection_map(const connection_map&) = default;
public:
using value_type = boost::uuids::uuid;
using size_type = std::vector<boost::uuids::uuid>::size_type;
using difference_type = std::vector<boost::uuids::uuid>::difference_type;
using reference = const boost::uuids::uuid&;
using const_reference = reference;
using iterator = std::vector<boost::uuids::uuid>::const_iterator;
using const_iterator = iterator;
//! Initialized with zero stem connections.
explicit connection_map()
: connection_map(std::vector<boost::uuids::uuid>{}, 0)
{}
//! Initialized with `out_connections` and `stem_count`.
explicit connection_map(std::vector<boost::uuids::uuid> out_connections, std::size_t stems);
connection_map(connection_map&&) = default;
~connection_map() noexcept;
connection_map& operator=(connection_map&&) = default;
connection_map& operator=(const connection_map&) = delete;
//! \return An exact duplicate of `this` map.
connection_map clone() const;
//! \return First stem connection.
const_iterator begin() const noexcept
{
return out_mapping_.begin();
}
//! \return One-past the last stem connection.
const_iterator end() const noexcept
{
return out_mapping_.end();
}
/*! Merges in current connections with the previous set of connections.
If a connection died, a new one will take its place in the stem or
the stem is marked as dead.
\param connections Current outbound connection ids.
\return True if any updates to `get_connections()` was made. */
bool update(std::vector<boost::uuids::uuid> current);
//! \return Number of outgoing connections in use.
std::size_t size() const noexcept;
//! \return Current stem mapping for `source` or `nil_uuid()` if none is possible.
boost::uuids::uuid get_stem(const boost::uuids::uuid& source);
};
} // dandelionpp
} // net
