void epoll_reactor::start_op()

in demo_example/asio/asio/detail/impl/epoll_reactor.ipp [232:320]

• 82 lines of code
• 17 McCabe index (conditional complexity)

void epoll_reactor::start_op(int op_type, socket_type descriptor,
    epoll_reactor::per_descriptor_data& descriptor_data, reactor_op* op,
    bool is_continuation, bool allow_speculative)
{
  if (!descriptor_data)
  {
    op->ec_ = asio::error::bad_descriptor;
    post_immediate_completion(op, is_continuation);
    return;
  }

  mutex::scoped_lock descriptor_lock(descriptor_data->mutex_);

  if (descriptor_data->shutdown_)
  {
    post_immediate_completion(op, is_continuation);
    return;
  }

  if (descriptor_data->op_queue_[op_type].empty())
  {
    if (allow_speculative
        && (op_type != read_op
          || descriptor_data->op_queue_[except_op].empty()))
    {
      if (descriptor_data->try_speculative_[op_type])
      {
        if (reactor_op::status status = op->perform())
        {
          if (status == reactor_op::done_and_exhausted)
            if (descriptor_data->registered_events_ != 0)
              descriptor_data->try_speculative_[op_type] = false;
          descriptor_lock.unlock();
          scheduler_.post_immediate_completion(op, is_continuation);
          return;
        }
      }

      if (descriptor_data->registered_events_ == 0)
      {
        op->ec_ = asio::error::operation_not_supported;
        scheduler_.post_immediate_completion(op, is_continuation);
        return;
      }

      if (op_type == write_op)
      {
        if ((descriptor_data->registered_events_ & EPOLLOUT) == 0)
        {
          epoll_event ev = { 0, { 0 } };
          ev.events = descriptor_data->registered_events_ | EPOLLOUT;
          ev.data.ptr = descriptor_data;
          if (epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, descriptor, &ev) == 0)
          {
            descriptor_data->registered_events_ |= ev.events;
          }
          else
          {
            op->ec_ = asio::error_code(errno,
                asio::error::get_system_category());
            scheduler_.post_immediate_completion(op, is_continuation);
            return;
          }
        }
      }
    }
    else if (descriptor_data->registered_events_ == 0)
    {
      op->ec_ = asio::error::operation_not_supported;
      scheduler_.post_immediate_completion(op, is_continuation);
      return;
    }
    else
    {
      if (op_type == write_op)
      {
        descriptor_data->registered_events_ |= EPOLLOUT;
      }

      epoll_event ev = { 0, { 0 } };
      ev.events = descriptor_data->registered_events_;
      ev.data.ptr = descriptor_data;
      epoll_ctl(epoll_fd_, EPOLL_CTL_MOD, descriptor, &ev);
    }
  }

  descriptor_data->op_queue_[op_type].push(op);
  scheduler_.work_started();
}