comm.h

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#ifndef ASYNC_COMM_COMM_H
#define ASYNC_COMM_COMM_H

#include <condition_variable>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <list>
#include <mutex>
#include <thread>

#include <boost/asio.hpp>
#include <boost/function.hpp>

#include <async_comm/message_handler.h>

namespace async_comm
{

class CommListener
{
public:
  virtual void receive_callback(const uint8_t * buf, size_t size) = 0;
};

class Comm
{
public:
  Comm(MessageHandler& message_handler = default_message_handler_);
  virtual ~Comm();

  bool init();

  void close();

  void send_bytes(const uint8_t * src, size_t len);

  inline void send_byte(uint8_t data) { send_bytes(&data, 1); }

  void register_receive_callback(std::function<void(const uint8_t*, size_t)> fun);

  void register_listener(CommListener &listener);

protected:

  static constexpr size_t READ_BUFFER_SIZE = 1024;
  static constexpr size_t WRITE_BUFFER_SIZE = 1024;

  static DefaultMessageHandler default_message_handler_;

  virtual bool is_open() = 0;
  virtual bool do_init() = 0;
  virtual void do_close() = 0;
  virtual void do_async_read(const boost::asio::mutable_buffers_1 &buffer,
                             boost::function<void(const boost::system::error_code&, size_t)> handler) = 0;
  virtual void do_async_write(const boost::asio::const_buffers_1 &buffer,
                              boost::function<void(const boost::system::error_code&, size_t)> handler) = 0;

  MessageHandler& message_handler_;
  boost::asio::io_service io_service_;

private:

  struct ReadBuffer
  {
    uint8_t data[READ_BUFFER_SIZE];
    size_t len;

    ReadBuffer(const uint8_t * buf, size_t len) : len(len)
    {
      assert(len <= READ_BUFFER_SIZE); // only checks in debug mode
      memcpy(data, buf, len);
    }
  };

  struct WriteBuffer
  {
    uint8_t data[WRITE_BUFFER_SIZE];
    size_t len;
    size_t pos;

    WriteBuffer() : len(0), pos(0) {}

    WriteBuffer(const uint8_t * buf, size_t len) : len(len), pos(0)
    {
      assert(len <= WRITE_BUFFER_SIZE); // only checks in debug mode
      memcpy(data, buf, len);
    }

    const uint8_t * dpos() const { return data + pos; }

    size_t nbytes() const { return len - pos; }
  };

  typedef std::lock_guard<std::recursive_mutex> mutex_lock;

  void async_read();
  void async_read_end(const boost::system::error_code& error, size_t bytes_transferred);

  void async_write(bool check_write_state);
  void async_write_end(const boost::system::error_code& error, size_t bytes_transferred);

  void process_callbacks();

  std::thread io_thread_;
  std::thread callback_thread_;

  uint8_t read_buffer_[READ_BUFFER_SIZE];
  std::list<ReadBuffer> read_queue_;
  std::mutex callback_mutex_;
  std::condition_variable condition_variable_;
  bool new_data_;
  bool shutdown_requested_;

  std::list<WriteBuffer> write_queue_;
  std::recursive_mutex write_mutex_;
  bool write_in_progress_;

  std::function<void(const uint8_t *, size_t)> receive_callback_ = nullptr;
  std::vector<std::reference_wrapper<CommListener>> listeners_;
};

} // namespace async_comm

#endif // ASYNC_COMM_COMM_H