reactive_socket_service.hpp

这是国外的resip协议栈

    asio::io_service& io_service_;
    asio::io_service::work work_;
    ConstBufferSequence buffers_;
    endpoint_type destination_;
    socket_base::message_flags flags_;
    Handler handler_;
  };

  // Start an asynchronous send. The data being sent must be valid for the
  // lifetime of the asynchronous operation.
  template <typename ConstBufferSequence, typename Handler>
  void async_send_to(implementation_type& impl,
      const ConstBufferSequence& buffers,
      const endpoint_type& destination, socket_base::message_flags flags,
      Handler handler)
  {
    if (!is_open(impl))
    {
      this->get_io_service().post(bind_handler(handler,
            asio::error::bad_descriptor, 0));
    }
    else
    {
      // Make socket non-blocking.
      if (!(impl.flags_ & implementation_type::internal_non_blocking))
      {
        ioctl_arg_type non_blocking = 1;
        asio::error_code ec;
        if (socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec))
        {
          this->get_io_service().post(bind_handler(handler, ec, 0));
          return;
        }
        impl.flags_ |= implementation_type::internal_non_blocking;
      }

      reactor_.start_write_op(impl.socket_,
          send_to_handler<ConstBufferSequence, Handler>(
            impl.socket_, this->get_io_service(), buffers,
            destination, flags, handler));
    }
  }

  // Receive some data from the peer. Returns the number of bytes received.
  template <typename MutableBufferSequence>
  size_t receive(implementation_type& impl,
      const MutableBufferSequence& buffers,
      socket_base::message_flags flags, asio::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = asio::error::bad_descriptor;
      return 0;
    }

    // Copy buffers into array.
    socket_ops::buf bufs[max_buffers];
    typename MutableBufferSequence::const_iterator iter = buffers.begin();
    typename MutableBufferSequence::const_iterator end = buffers.end();
    size_t i = 0;
    size_t total_buffer_size = 0;
    for (; iter != end && i < max_buffers; ++iter, ++i)
    {
      asio::mutable_buffer buffer(*iter);
      socket_ops::init_buf(bufs[i],
          asio::buffer_cast<void*>(buffer),
          asio::buffer_size(buffer));
      total_buffer_size += asio::buffer_size(buffer);
    }

    // A request to receive 0 bytes on a stream socket is a no-op.
    if (impl.protocol_.type() == SOCK_STREAM && total_buffer_size == 0)
    {
      ec = asio::error_code();
      return 0;
    }

    // Make socket non-blocking if user wants non-blocking.
    if (impl.flags_ & implementation_type::user_set_non_blocking)
    {
      if (!(impl.flags_ & implementation_type::internal_non_blocking))
      {
        ioctl_arg_type non_blocking = 1;
        if (socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec))
          return 0;
        impl.flags_ |= implementation_type::internal_non_blocking;
      }
    }

    // Receive some data.
    for (;;)
    {
      // Try to complete the operation without blocking.
      int bytes_recvd = socket_ops::recv(impl.socket_, bufs, i, flags, ec);

      // Check if operation succeeded.
      if (bytes_recvd > 0)
        return bytes_recvd;

      // Check for EOF.
      if (bytes_recvd == 0)
      {
        ec = asio::error::eof;
        return 0;
      }

      // Operation failed.
      if ((impl.flags_ & implementation_type::user_set_non_blocking)
          || (ec != asio::error::would_block
            && ec != asio::error::try_again))
        return 0;

      // Wait for socket to become ready.
      if (socket_ops::poll_read(impl.socket_, ec) < 0)
        return 0;
    }
  }

  template <typename MutableBufferSequence, typename Handler>
  class receive_handler
  {
  public:
    receive_handler(socket_type socket, asio::io_service& io_service,
        const MutableBufferSequence& buffers, socket_base::message_flags flags,
        Handler handler)
      : socket_(socket),
        io_service_(io_service),
        work_(io_service),
        buffers_(buffers),
        flags_(flags),
        handler_(handler)
    {
    }

    bool operator()(const asio::error_code& result)
    {
      // Check whether the operation was successful.
      if (result)
      {
        io_service_.post(bind_handler(handler_, result, 0));
        return true;
      }

      // Copy buffers into array.
      socket_ops::buf bufs[max_buffers];
      typename MutableBufferSequence::const_iterator iter = buffers_.begin();
      typename MutableBufferSequence::const_iterator end = buffers_.end();
      size_t i = 0;
      for (; iter != end && i < max_buffers; ++iter, ++i)
      {
        asio::mutable_buffer buffer(*iter);
        socket_ops::init_buf(bufs[i],
            asio::buffer_cast<void*>(buffer),
            asio::buffer_size(buffer));
      }

      // Receive some data.
      asio::error_code ec;
      int bytes = socket_ops::recv(socket_, bufs, i, flags_, ec);
      if (bytes == 0)
        ec = asio::error::eof;

      // Check if we need to run the operation again.
      if (ec == asio::error::would_block
          || ec == asio::error::try_again)
        return false;

      io_service_.post(bind_handler(handler_, ec, bytes < 0 ? 0 : bytes));
      return true;
    }

  private:
    socket_type socket_;
    asio::io_service& io_service_;
    asio::io_service::work work_;
    MutableBufferSequence buffers_;
    socket_base::message_flags flags_;
    Handler handler_;
  };

  // Start an asynchronous receive. The buffer for the data being received
  // must be valid for the lifetime of the asynchronous operation.
  template <typename MutableBufferSequence, typename Handler>
  void async_receive(implementation_type& impl,
      const MutableBufferSequence& buffers,
      socket_base::message_flags flags, Handler handler)
  {
    if (!is_open(impl))
    {
      this->get_io_service().post(bind_handler(handler,
            asio::error::bad_descriptor, 0));
    }
    else
    {
      if (impl.protocol_.type() == SOCK_STREAM)
      {
        // Determine total size of buffers.
        typename MutableBufferSequence::const_iterator iter = buffers.begin();
        typename MutableBufferSequence::const_iterator end = buffers.end();
        size_t i = 0;
        size_t total_buffer_size = 0;
        for (; iter != end && i < max_buffers; ++iter, ++i)
        {
          asio::mutable_buffer buffer(*iter);
          total_buffer_size += asio::buffer_size(buffer);
        }

        // A request to receive 0 bytes on a stream socket is a no-op.
        if (total_buffer_size == 0)
        {
          this->get_io_service().post(bind_handler(handler,
                asio::error_code(), 0));
          return;
        }
      }

      // Make socket non-blocking.
      if (!(impl.flags_ & implementation_type::internal_non_blocking))
      {
        ioctl_arg_type non_blocking = 1;
        asio::error_code ec;
        if (socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec))
        {
          this->get_io_service().post(bind_handler(handler, ec, 0));
          return;
        }
        impl.flags_ |= implementation_type::internal_non_blocking;
      }

      if (flags & socket_base::message_out_of_band)
      {
        reactor_.start_except_op(impl.socket_,
            receive_handler<MutableBufferSequence, Handler>(
              impl.socket_, this->get_io_service(), buffers, flags, handler));
      }
      else
      {
        reactor_.start_read_op(impl.socket_,
            receive_handler<MutableBufferSequence, Handler>(
              impl.socket_, this->get_io_service(), buffers, flags, handler));
      }
    }
  }

  // Receive a datagram with the endpoint of the sender. Returns the number of
  // bytes received.
  template <typename MutableBufferSequence>
  size_t receive_from(implementation_type& impl,
      const MutableBufferSequence& buffers,
      endpoint_type& sender_endpoint, socket_base::message_flags flags,
      asio::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = asio::error::bad_descriptor;
      return 0;
    }

    // Copy buffers into array.
    socket_ops::buf bufs[max_buffers];
    typename MutableBufferSequence::const_iterator iter = buffers.begin();
    typename MutableBufferSequence::const_iterator end = buffers.end();
    size_t i = 0;
    for (; iter != end && i < max_buffers; ++iter, ++i)
    {
      asio::mutable_buffer buffer(*iter);
      socket_ops::init_buf(bufs[i],
          asio::buffer_cast<void*>(buffer),
          asio::buffer_size(buffer));
    }

    // Make socket non-blocking if user wants non-blocking.
    if (impl.flags_ & implementation_type::user_set_non_blocking)
    {
      if (!(impl.flags_ & implementation_type::internal_non_blocking))
      {
        ioctl_arg_type non_blocking = 1;
        if (socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec))
          return 0;
        impl.flags_ |= implementation_type::internal_non_blocking;
      }
    }

    // Receive some data.
    for (;;)
    {
      // Try to complete the operation without blocking.
      std::size_t addr_len = sender_endpoint.capacity();
      int bytes_recvd = socket_ops::recvfrom(impl.socket_, bufs, i, flags,
          sender_endpoint.data(), &addr_len, ec);

      // Check if operation succeeded.
      if (bytes_recvd > 0)
      {
        sender_endpoint.resize(addr_len);
        return bytes_recvd;
      }

      // Check for EOF.
      if (bytes_recvd == 0)
      {
        ec = asio::error::eof;
        return 0;
      }

      // Operation failed.
      if ((impl.flags_ & implementation_type::user_set_non_blocking)
          || (ec != asio::error::would_block
            && ec != asio::error::try_again))
        return 0;

      // Wait for socket to become ready.
      if (socket_ops::poll_read(impl.socket_, ec) < 0)
        return 0;
    }
  }

  template <typename MutableBufferSequence, typename Handler>
  class receive_from_handler
  {
  public:
    receive_from_handler(socket_type socket,
        asio::io_service& io_service,
        const MutableBufferSequence& buffers, endpoint_type& endpoint,
        socket_base::message_flags flags, Handler handler)
      : socket_(socket),
        io_service_(io_service),
        work_(io_service),
        buffers_(buffers),
        sender_endpoint_(endpoint),
        flags_(flags),
        handler_(handler)
    {
    }

    bool operator()(const asio::error_code& result)
    {
      // Check whether the operation was successful.
      if (result)
      {
        io_service_.post(bind_handler(handler_, result, 0));
        return true;
      }

      // Copy buffers into array.
      socket_ops::buf bufs[max_buffers];
      typename MutableBufferSequence::const_iterator iter = buffers_.begin();
      typename MutableBufferSequence::const_iterator end = buffers_.end();
      size_t i = 0;
      for (; iter != end && i < max_buffers; ++iter, ++i)
      {
        asio::mutable_buffer buffer(*iter);
        socket_ops::init_buf(bufs[i],
            asio::buffer_cast<void*>(buffer),
            asio::buffer_size(buffer));
      }

      // Receive some data.
      std::size_t addr_len = sender_endpoint_.capacity();
      asio::error_code ec;
      int bytes = socket_ops::recvfrom(socket_, bufs, i, flags_,
          sender_endpoint_.data(), &addr_len, ec);
      if (bytes == 0)
        ec = asio::error::eof;

      // Check if we need to run the operation again.
      if (ec == asio::error::would_block
          || ec == asio::error::try_again)
        return false;

      sender_endpoint_.resize(addr_len);
      io_service_.post(bind_handler(handler_, ec, bytes < 0 ? 0 : bytes));
      return true;
    }

  private:
    socket_type socket_;
    asio::io_service& io_service_;
    asio::io_service::work work_;
    MutableBufferSequence buffers_;
    endpoint_type& sender_endpoint_;
    socket_base::message_flags flags_;
    Handler handler_;
  };

  // Start an asynchronous receive. The buffer for the data being received and
  // the sender_endpoint object must both be valid for the lifetime of the
  // asynchronous operation.
  template <typename MutableBufferSequence, typename Handler>
  void async_receive_from(implementation_type& impl,
      const MutableBufferSequence& buffers, endpoint_type& sender_endpoint,
      socket_base::message_flags flags, Handler handler)
  {
    if (!is_open(impl))
    {