NonBlockingSender.h

/*
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * NonBlockingSender.h
 * Copyright (C) 2013 Simon Newton
 *
 * Explanation:
 *  If we just write IOStacks directly to ConnectedDescriptors, we may not be
 *  able to write the entire message. This can happen if the remote end is slow
 *  to ack and data builds up in the kernel socket buffer.
 *
 *  This class abstracts the caller from having to deal with this situation. At
 *  construction time we specify the maximum number of message bytes we want to
 *  buffer. Once the buffer reaches this size subsequent calls to SendMessage
 *  will return false.
 */

#ifndef INCLUDE_OLA_IO_NONBLOCKINGSENDER_H_
#define INCLUDE_OLA_IO_NONBLOCKINGSENDER_H_

#include <ola/io/Descriptor.h>
#include <ola/io/IOQueue.h>
#include <ola/io/MemoryBlockPool.h>
#include <ola/io/OutputBuffer.h>
#include <ola/io/SelectServerInterface.h>

namespace ola {
namespace io {

class NonBlockingSender {
 public:
  NonBlockingSender(ola::io::ConnectedDescriptor *descriptor,
                    ola::io::SelectServerInterface *ss,
                    ola::io::MemoryBlockPool *memory_pool,
                    unsigned int max_buffer_size = DEFAULT_MAX_BUFFER_SIZE);

  ~NonBlockingSender();

  bool LimitReached() const;

  bool SendMessage(class IOStack *stack);

  bool SendMessage(IOQueue *queue);

  static const unsigned int DEFAULT_MAX_BUFFER_SIZE;

 private:
  ola::io::ConnectedDescriptor *m_descriptor;
  ola::io::SelectServerInterface *m_ss;
  ola::io::IOQueue m_output_buffer;
  bool m_associated;
  unsigned int m_max_buffer_size;

  void PerformWrite();
  void AssociateIfRequired();

  DISALLOW_COPY_AND_ASSIGN(NonBlockingSender);
};
}  // namespace io
}  // namespace ola
#endif  // INCLUDE_OLA_IO_NONBLOCKINGSENDER_H_