Context.hpp

/* Copyright 2020, Ableton AG, Berlin. All rights reserved.
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *  If you would like to incorporate Link into a proprietary software application,
 *  please contact <link-devs@ableton.com>.
 */

#pragma once

#include <ableton/discovery/AsioTypes.hpp>
#include <ableton/discovery/IpInterface.hpp>
#include <ableton/platforms/asio/AsioTimer.hpp>
#include <ableton/platforms/asio/Socket.hpp>
#include <ableton/platforms/esp32/LockFreeCallbackDispatcher.hpp>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>

namespace ableton
{
namespace platforms
{
namespace esp32
{

template <typename ScanIpIfAddrs, typename LogT>
class Context
{
  class ServiceRunner
  {
    // This task used to exclusively poll ASIO with `poll_one()`, with an
    // interval of 100 microseconds. Since ASIO uses `select()` internally to
    // implement `poll_one()`, we might as well use an event based approach and
    // save some CPU cycles by using `io_service::run()` instead.
    static void run(void* userParams)
    {
      auto runner = static_cast<ServiceRunner*>(userParams);
      for (;;)
      {
        try
        {
          runner->mpService->run();
        }
        catch (...)
        {
        }
      }
    }

  public:
    ServiceRunner()
      : mpService(new ::asio::io_service())
      , mpWork(new ::asio::io_service::work(*mpService))
    {
      xTaskCreatePinnedToCore(run,
                              "link",
                              8192,
                              this,
                              2 | portPRIVILEGE_BIT,
                              &mTaskHandle,
                              LINK_ESP_TASK_CORE_ID);
    }

    ~ServiceRunner() { vTaskDelete(mTaskHandle); }

    template <typename Handler>
    void async(Handler handler)
    {
      mpService->post(std::move(handler));
    }

    ::asio::io_service& service() const { return *mpService; }

  private:
    TaskHandle_t mTaskHandle;
    std::unique_ptr<::asio::io_service> mpService;
    std::unique_ptr<::asio::io_service::work> mpWork;
  };

public:
  using Timer = ::ableton::platforms::asio::AsioTimer;
  using Log = LogT;

  template <typename Handler, typename Duration>
  using LockFreeCallbackDispatcher = LockFreeCallbackDispatcher<Handler, Duration>;

  template <std::size_t BufferSize>
  using Socket = asio::Socket<BufferSize>;

  Context()
    : Context(DefaultHandler{})
  {
  }

  template <typename ExceptionHandler>
  explicit Context(ExceptionHandler exceptHandler)
  {
  }

  Context(const Context&) = delete;

  Context(Context&& rhs)
    : mLog(std::move(rhs.mLog))
    , mScanIpIfAddrs(std::move(rhs.mScanIpIfAddrs))
  {
  }

  void stop() {}

  template <std::size_t BufferSize>
  Socket<BufferSize> openUnicastSocket(const ::asio::ip::address& addr)
  {
    auto socket =
      addr.is_v4() ? Socket<BufferSize>{serviceRunner().service(), ::asio::ip::udp::v4()}
                   : Socket<BufferSize>{serviceRunner().service(), ::asio::ip::udp::v6()};
    socket.mpImpl->mSocket.set_option(
      ::asio::ip::multicast::enable_loopback(addr.is_loopback()));
    if (addr.is_v4())
    {
      socket.mpImpl->mSocket.set_option(
        ::asio::ip::multicast::outbound_interface(addr.to_v4()));
      socket.mpImpl->mSocket.bind(
        ::LINK_ASIO_NAMESPACE::ip::udp::endpoint{addr.to_v4(), 0});
    }
    else if (addr.is_v6())
    {
      const auto scopeId = addr.to_v6().scope_id();
      socket.mpImpl->mSocket.set_option(
        ::asio::ip::multicast::outbound_interface(static_cast<unsigned int>(scopeId)));
      socket.mpImpl->mSocket.bind(
        ::LINK_ASIO_NAMESPACE::ip::udp::endpoint{addr.to_v6(), 0});
    }
    else
    {
      throw(std::runtime_error("Unknown Protocol"));
    }
    return socket;
  }

  template <std::size_t BufferSize>
  Socket<BufferSize> openMulticastSocket(const ::asio::ip::address& addr)
  {
    auto socket =
      addr.is_v4() ? Socket<BufferSize>{serviceRunner().service(), ::asio::ip::udp::v4()}
                   : Socket<BufferSize>{serviceRunner().service(), ::asio::ip::udp::v6()};

    socket.mpImpl->mSocket.set_option(::asio::ip::udp::socket::reuse_address(true));
    socket.mpImpl->mSocket.set_option(
      ::asio::socket_base::broadcast(!addr.is_loopback()));
    socket.mpImpl->mSocket.set_option(
      ::asio::ip::multicast::enable_loopback(addr.is_loopback()));

    if (addr.is_v4())
    {
      socket.mpImpl->mSocket.set_option(
        ::asio::ip::multicast::outbound_interface(addr.to_v4()));
      socket.mpImpl->mSocket.bind(
        {::asio::ip::address_v4::any(), discovery::multicastEndpointV4().port()});
      socket.mpImpl->mSocket.set_option(::asio::ip::multicast::join_group(
        discovery::multicastEndpointV4().address().to_v4(), addr.to_v4()));
    }
    else if (addr.is_v6())
    {
      const auto scopeId = addr.to_v6().scope_id();
      socket.mpImpl->mSocket.set_option(
        ::asio::ip::multicast::outbound_interface(static_cast<unsigned int>(scopeId)));
      const auto multicastEndpoint = discovery::multicastEndpointV6(scopeId);
      socket.mpImpl->mSocket.bind(
        {::asio::ip::address_v6::any(), multicastEndpoint.port()});
      socket.mpImpl->mSocket.set_option(
        ::asio::ip::multicast::join_group(multicastEndpoint.address().to_v6(), scopeId));
    }
    else
    {
      throw(std::runtime_error("Unknown Protocol"));
    }
    return socket;
  }

  std::vector<::asio::ip::address> scanNetworkInterfaces() { return mScanIpIfAddrs(); }

  Timer makeTimer() const { return {serviceRunner().service()}; }

  Log& log() { return mLog; }

  template <typename Handler>
  void async(Handler handler)
  {
    serviceRunner().service().post(std::move(handler));
  }

private:
  // Default handler is hidden and defines a hidden exception type
  // that will never be thrown by other code, so it effectively does
  // not catch.
  struct DefaultHandler
  {
    struct Exception
    {
    };

    void operator()(const Exception&) {}
  };

  static ServiceRunner& serviceRunner()
  {
    static ServiceRunner runner;
    return runner;
  }

  Log mLog;
  ScanIpIfAddrs mScanIpIfAddrs;
};

} // namespace esp32
} // namespace platforms
} // namespace ableton