//

// buffered_write_stream.hpp

// ~~~~~~~~~~~~~~~~~~~~~~~~~

//

// Copyright (c) 2003-2008 Christopher M. Kohlhoff (chris at kohlhoff dot com)

//

// Distributed under the Boost Software License, Version 1.0. (See accompanying

// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

//



#ifndef BOOST_ASIO_BUFFERED_WRITE_STREAM_HPP

#define BOOST_ASIO_BUFFERED_WRITE_STREAM_HPP



#if defined(_MSC_VER) && (_MSC_VER >= 1200)

# pragma once

#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)



#include <boost/asio/detail/push_options.hpp>



#include <boost/asio/detail/push_options.hpp>

#include <cstddef>

#include <cstring>

#include <boost/config.hpp>

#include <boost/type_traits.hpp>

#include <boost/asio/detail/pop_options.hpp>



#include <boost/asio/buffered_write_stream_fwd.hpp>

#include <boost/asio/buffer.hpp>

#include <boost/asio/completion_condition.hpp>

#include <boost/asio/error.hpp>

#include <boost/asio/io_service.hpp>

#include <boost/asio/write.hpp>

#include <boost/asio/detail/bind_handler.hpp>

#include <boost/asio/detail/buffered_stream_storage.hpp>

#include <boost/asio/detail/noncopyable.hpp>



namespace boost {

namespace asio {



/// Adds buffering to the write-related operations of a stream.

/**

 * The buffered_write_stream class template can be used to add buffering to the

 * synchronous and asynchronous write operations of a stream.

 *

 * @par Thread Safety

 * @e Distinct @e objects: Safe.@n

 * @e Shared @e objects: Unsafe.

 *

 * @par Concepts:

 * AsyncReadStream, AsyncWriteStream, Stream, SyncReadStream, SyncWriteStream.

 */

template <typename Stream>

class buffered_write_stream

  : private noncopyable

{

public:

  /// The type of the next layer.

  typedef typename boost::remove_reference<Stream>::type next_layer_type;



  /// The type of the lowest layer.

  typedef typename next_layer_type::lowest_layer_type lowest_layer_type;



#if defined(GENERATING_DOCUMENTATION)

  /// The default buffer size.

  static const std::size_t default_buffer_size = implementation_defined;

#else

  BOOST_STATIC_CONSTANT(std::size_t, default_buffer_size = 1024);

#endif



  /// Construct, passing the specified argument to initialise the next layer.

  template <typename Arg>

  explicit buffered_write_stream(Arg& a)

    : next_layer_(a),

      storage_(default_buffer_size)

  {

  }



  /// Construct, passing the specified argument to initialise the next layer.

  template <typename Arg>

  buffered_write_stream(Arg& a, std::size_t buffer_size)

    : next_layer_(a),

      storage_(buffer_size)

  {

  }



  /// Get a reference to the next layer.

  next_layer_type& next_layer()

  {

    return next_layer_;

  }



  /// Get a reference to the lowest layer.

  lowest_layer_type& lowest_layer()

  {

    return next_layer_.lowest_layer();

  }



  /// (Deprecated: use get_io_service().) Get the io_service associated with

  /// the object.

  boost::asio::io_service& io_service()

  {

    return next_layer_.get_io_service();

  }



  /// Get the io_service associated with the object.

  boost::asio::io_service& get_io_service()

  {

    return next_layer_.get_io_service();

  }



  /// Close the stream.

  void close()

  {

    next_layer_.close();

  }



  /// Close the stream.

  boost::system::error_code close(boost::system::error_code& ec)

  {

    return next_layer_.close(ec);

  }



  /// Flush all data from the buffer to the next layer. Returns the number of

  /// bytes written to the next layer on the last write operation. Throws an

  /// exception on failure.

  std::size_t flush()

  {

    std::size_t bytes_written = write(next_layer_,

        buffer(storage_.data(), storage_.size()));

    storage_.consume(bytes_written);

    return bytes_written;

  }



  /// Flush all data from the buffer to the next layer. Returns the number of

  /// bytes written to the next layer on the last write operation, or 0 if an

  /// error occurred.

  std::size_t flush(boost::system::error_code& ec)

  {

    std::size_t bytes_written = write(next_layer_,

        buffer(storage_.data(), storage_.size()),

        transfer_all(), ec);

    storage_.consume(bytes_written);

    return bytes_written;

  }



  template <typename WriteHandler>

  class flush_handler

  {

  public:

    flush_handler(boost::asio::io_service& io_service,

        detail::buffered_stream_storage& storage, WriteHandler handler)

      : io_service_(io_service),

        storage_(storage),

        handler_(handler)

    {

    }



    void operator()(const boost::system::error_code& ec,

        std::size_t bytes_written)

    {

      storage_.consume(bytes_written);

      io_service_.dispatch(detail::bind_handler(handler_, ec, bytes_written));

    }



  private:

    boost::asio::io_service& io_service_;

    detail::buffered_stream_storage& storage_;

    WriteHandler handler_;

  };



  /// Start an asynchronous flush.

  template <typename WriteHandler>

  void async_flush(WriteHandler handler)

  {

    async_write(next_layer_, buffer(storage_.data(), storage_.size()),

        flush_handler<WriteHandler>(get_io_service(), storage_, handler));

  }



  /// Write the given data to the stream. Returns the number of bytes written.

  /// Throws an exception on failure.

  template <typename ConstBufferSequence>

  std::size_t write_some(const ConstBufferSequence& buffers)

  {

    if (storage_.size() == storage_.capacity())

      flush();

    return copy(buffers);

  }



  /// Write the given data to the stream. Returns the number of bytes written,

  /// or 0 if an error occurred and the error handler did not throw.

  template <typename ConstBufferSequence>

  std::size_t write_some(const ConstBufferSequence& buffers,

      boost::system::error_code& ec)

  {

    ec = boost::system::error_code();

    if (storage_.size() == storage_.capacity() && !flush(ec))

      return 0;

    return copy(buffers);

  }



  template <typename ConstBufferSequence, typename WriteHandler>

  class write_some_handler

  {

  public:

    write_some_handler(boost::asio::io_service& io_service,

        detail::buffered_stream_storage& storage,

        const ConstBufferSequence& buffers, WriteHandler handler)

      : io_service_(io_service),

        storage_(storage),

        buffers_(buffers),

        handler_(handler)

    {

    }



    void operator()(const boost::system::error_code& ec, std::size_t)

    {

      if (ec)

      {

        std::size_t length = 0;

        io_service_.dispatch(detail::bind_handler(handler_, ec, length));

      }

      else

      {

        using namespace std; // For memcpy.



        std::size_t orig_size = storage_.size();

        std::size_t space_avail = storage_.capacity() - orig_size;

        std::size_t bytes_copied = 0;



        typename ConstBufferSequence::const_iterator iter = buffers_.begin();

        typename ConstBufferSequence::const_iterator end = buffers_.end();

        for (; iter != end && space_avail > 0; ++iter)

        {

          std::size_t bytes_avail = buffer_size(*iter);

          std::size_t length = (bytes_avail < space_avail)

            ? bytes_avail : space_avail;

          storage_.resize(orig_size + bytes_copied + length);

          memcpy(storage_.data() + orig_size + bytes_copied,

              buffer_cast<const void*>(*iter), length);

          bytes_copied += length;

          space_avail -= length;

        }



        io_service_.dispatch(detail::bind_handler(handler_, ec, bytes_copied));

      }

    }



  private:

    boost::asio::io_service& io_service_;

    detail::buffered_stream_storage& storage_;

    ConstBufferSequence buffers_;

    WriteHandler handler_;

  };



  /// Start an asynchronous write. The data being written must be valid for the

  /// lifetime of the asynchronous operation.

  template <typename ConstBufferSequence, typename WriteHandler>

  void async_write_some(const ConstBufferSequence& buffers,

      WriteHandler handler)

  {

    if (storage_.size() == storage_.capacity())

    {

      async_flush(write_some_handler<ConstBufferSequence, WriteHandler>(

            get_io_service(), storage_, buffers, handler));

    }

    else

    {

      std::size_t bytes_copied = copy(buffers);

      get_io_service().post(detail::bind_handler(

            handler, boost::system::error_code(), bytes_copied));

    }

  }



  /// Read some data from the stream. Returns the number of bytes read. Throws

  /// an exception on failure.

  template <typename MutableBufferSequence>

  std::size_t read_some(const MutableBufferSequence& buffers)

  {

    return next_layer_.read_some(buffers);

  }



  /// Read some data from the stream. Returns the number of bytes read or 0 if

  /// an error occurred.

  template <typename MutableBufferSequence>

  std::size_t read_some(const MutableBufferSequence& buffers,

      boost::system::error_code& ec)

  {

    return next_layer_.read_some(buffers, ec);

  }



  /// Start an asynchronous read. The buffer into which the data will be read

  /// must be valid for the lifetime of the asynchronous operation.

  template <typename MutableBufferSequence, typename ReadHandler>

  void async_read_some(const MutableBufferSequence& buffers,

      ReadHandler handler)

  {

    next_layer_.async_read_some(buffers, handler);

  }



  /// Peek at the incoming data on the stream. Returns the number of bytes read.

  /// Throws an exception on failure.

  template <typename MutableBufferSequence>

  std::size_t peek(const MutableBufferSequence& buffers)

  {

    return next_layer_.peek(buffers);

  }



  /// Peek at the incoming data on the stream. Returns the number of bytes read,

  /// or 0 if an error occurred.

  template <typename MutableBufferSequence>

  std::size_t peek(const MutableBufferSequence& buffers,

      boost::system::error_code& ec)

  {

    return next_layer_.peek(buffers, ec);

  }



  /// Determine the amount of data that may be read without blocking.

  std::size_t in_avail()

  {

    return next_layer_.in_avail();

  }



  /// Determine the amount of data that may be read without blocking.

  std::size_t in_avail(boost::system::error_code& ec)

  {

    return next_layer_.in_avail(ec);

  }



private:

  /// Copy data into the internal buffer from the specified source buffer.

  /// Returns the number of bytes copied.

  template <typename ConstBufferSequence>

  std::size_t copy(const ConstBufferSequence& buffers)

  {

    using namespace std; // For memcpy.



    std::size_t orig_size = storage_.size();

    std::size_t space_avail = storage_.capacity() - orig_size;

    std::size_t bytes_copied = 0;



    typename ConstBufferSequence::const_iterator iter = buffers.begin();

    typename ConstBufferSequence::const_iterator end = buffers.end();

    for (; iter != end && space_avail > 0; ++iter)

    {

      std::size_t bytes_avail = buffer_size(*iter);

      std::size_t length = (bytes_avail < space_avail)

        ? bytes_avail : space_avail;

      storage_.resize(orig_size + bytes_copied + length);

      memcpy(storage_.data() + orig_size + bytes_copied,

          buffer_cast<const void*>(*iter), length);

      bytes_copied += length;

      space_avail -= length;

    }



    return bytes_copied;

  }



  /// The next layer.

  Stream next_layer_;



  // The data in the buffer.

  detail::buffered_stream_storage storage_;

};



} // namespace asio

} // namespace boost



#include <boost/asio/detail/pop_options.hpp>



#endif // BOOST_ASIO_BUFFERED_WRITE_STREAM_HPP

