rippled/include/xrpl/server/detail/ServerImpl.h

#pragma once

#include <xrpl/basics/chrono.h>
#include <xrpl/beast/core/List.h>
#include <xrpl/server/detail/Door.h>
#include <xrpl/server/detail/io_list.h>

#include <boost/asio.hpp>
#include <boost/asio/executor_work_guard.hpp>
#include <boost/asio/io_context.hpp>

#include <array>
#include <chrono>
#include <mutex>
#include <optional>
#include <unordered_map>

namespace xrpl {

using Endpoints = std::unordered_map<std::string, boost::asio::ip::tcp::endpoint>;

/** A multi-protocol server.

    This server maintains multiple configured listening ports,
    with each listening port allows for multiple protocols including
    HTTP, HTTP/S, WebSocket, Secure WebSocket, and the Peer protocol.
*/
class Server
{
public:
    /** Destroy the server.
        The server is closed if it is not already closed. This call
        blocks until the server has stopped.
    */
    virtual ~Server() = default;

    /** Returns the Journal associated with the server. */
    virtual beast::Journal
    journal() = 0;

    /** Set the listening port settings.
        This may only be called once.
    */
    virtual Endpoints
    ports(std::vector<Port> const& v) = 0;

    /** Close the server.
        The close is performed asynchronously. The handler will be notified
        when the server has stopped. The server is considered stopped when
        there are no pending I/O completion handlers and all connections
        have closed.
        Thread safety:
            Safe to call concurrently from any thread.
    */
    virtual void
    close() = 0;
};

template <class Handler>
class ServerImpl : public Server
{
private:
    using clock_type = std::chrono::system_clock;

    static constexpr auto kHistorySize = 100;

    Handler& handler_;
    beast::Journal const j_;
    boost::asio::io_context& ioContext_;
    boost::asio::strand<boost::asio::io_context::executor_type> strand_;
    std::optional<boost::asio::executor_work_guard<boost::asio::io_context::executor_type>> work_;

    std::mutex m_;
    std::vector<Port> ports_;
    std::vector<std::weak_ptr<Door<Handler>>> list_;
    int high_ = 0;
    std::array<std::size_t, 64> hist_{};

    IOList ios_;

public:
    ServerImpl(Handler& handler, boost::asio::io_context& ioContext, beast::Journal journal);

    ~ServerImpl() override;

    beast::Journal
    journal() override
    {
        return j_;
    }

    Endpoints
    ports(std::vector<Port> const& ports) override;

    void
    close() override;

    IOList&
    ios()
    {
        return ios_;
    }

    boost::asio::io_context&
    getIoContext()
    {
        return ioContext_;
    }

    bool
    closed();

private:
    static int
    ceilLog2(unsigned long long x);
};

template <class Handler>
ServerImpl<Handler>::ServerImpl(
    Handler& handler,
    boost::asio::io_context& ioContext,
    beast::Journal journal)
    : handler_(handler)
    , j_(journal)
    , ioContext_(ioContext)
    , strand_(boost::asio::make_strand(ioContext_))
    , work_(std::in_place, boost::asio::make_work_guard(ioContext_))
{
}

template <class Handler>
ServerImpl<Handler>::~ServerImpl()
{
    // Handler::onStopped will not be called
    work_ = std::nullopt;
    ios_.close();
    ios_.join();
}

template <class Handler>
Endpoints
ServerImpl<Handler>::ports(std::vector<Port> const& ports)
{
    if (closed())
        Throw<std::logic_error>("ports() on closed Server");
    ports_.reserve(ports.size());
    Endpoints eps;
    eps.reserve(ports.size());
    for (auto const& port : ports)
    {
        ports_.push_back(port);
        auto& internalPort = ports_.back();
        if (auto sp = ios_.emplace<Door<Handler>>(handler_, ioContext_, internalPort, j_))
        {
            list_.push_back(sp);

            auto ep = sp->getEndpoint();
            if (internalPort.port == 0u)
                internalPort.port = ep.port();
            eps.emplace(port.name, std::move(ep));

            sp->run();
        }
    }
    return eps;
}

template <class Handler>
void
ServerImpl<Handler>::close()
{
    ios_.close([&] {
        work_ = std::nullopt;
        handler_.onStopped(*this);
    });
}

template <class Handler>
bool
ServerImpl<Handler>::closed()
{
    return ios_.closed();
}
}  // namespace xrpl