boost/asio/buffered_read_stream.hpp
//
// buffered_read_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_READ_STREAM_HPP
#define BOOST_ASIO_BUFFERED_READ_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_read_stream_fwd.hpp>
#include <boost/asio/buffer.hpp>
#include <boost/asio/error.hpp>
#include <boost/asio/io_service.hpp>
#include <boost/asio/detail/bind_handler.hpp>
#include <boost/asio/detail/buffer_resize_guard.hpp>
#include <boost/asio/detail/buffered_stream_storage.hpp>
#include <boost/asio/detail/noncopyable.hpp>
namespace boost {
namespace asio {
/// Adds buffering to the read-related operations of a stream.
/**
* The buffered_read_stream class template can be used to add buffering to the
* synchronous and asynchronous read operations of a stream.
*
* @par Thread Safety
* @e Distinct @e objects: Safe.@n
* @e Shared @e objects: Unsafe.
*
* @par Concepts:
* AsyncReadStream, AsyncWriteStream, Stream, Sync_Read_Stream, SyncWriteStream.
*/
template <typename Stream>
class buffered_read_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_read_stream(Arg& a)
: next_layer_(a),
storage_(default_buffer_size)
{
}
/// Construct, passing the specified argument to initialise the next layer.
template <typename Arg>
buffered_read_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();
}
/// Get a const reference to the lowest layer.
const lowest_layer_type& lowest_layer() const
{
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);
}
/// 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)
{
return next_layer_.write_some(buffers);
}
/// Write the given data to the stream. Returns the number of bytes written,
/// or 0 if an error occurred.
template <typename ConstBufferSequence>
std::size_t write_some(const ConstBufferSequence& buffers,
boost::system::error_code& ec)
{
return next_layer_.write_some(buffers, ec);
}
/// 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)
{
next_layer_.async_write_some(buffers, handler);
}
/// Fill the buffer with some data. Returns the number of bytes placed in the
/// buffer as a result of the operation. Throws an exception on failure.
std::size_t fill()
{
detail::buffer_resize_guard<detail::buffered_stream_storage>
resize_guard(storage_);
std::size_t previous_size = storage_.size();
storage_.resize(storage_.capacity());
storage_.resize(previous_size + next_layer_.read_some(buffer(
storage_.data() + previous_size,
storage_.size() - previous_size)));
resize_guard.commit();
return storage_.size() - previous_size;
}
/// Fill the buffer with some data. Returns the number of bytes placed in the
/// buffer as a result of the operation, or 0 if an error occurred.
std::size_t fill(boost::system::error_code& ec)
{
detail::buffer_resize_guard<detail::buffered_stream_storage>
resize_guard(storage_);
std::size_t previous_size = storage_.size();
storage_.resize(storage_.capacity());
storage_.resize(previous_size + next_layer_.read_some(buffer(
storage_.data() + previous_size,
storage_.size() - previous_size),
ec));
resize_guard.commit();
return storage_.size() - previous_size;
}
template <typename ReadHandler>
class fill_handler
{
public:
fill_handler(boost::asio::io_service& io_service,
detail::buffered_stream_storage& storage,
std::size_t previous_size, ReadHandler handler)
: io_service_(io_service),
storage_(storage),
previous_size_(previous_size),
handler_(handler)
{
}
void operator()(const boost::system::error_code& ec,
std::size_t bytes_transferred)
{
storage_.resize(previous_size_ + bytes_transferred);
io_service_.dispatch(detail::bind_handler(
handler_, ec, bytes_transferred));
}
private:
boost::asio::io_service& io_service_;
detail::buffered_stream_storage& storage_;
std::size_t previous_size_;
ReadHandler handler_;
};
/// Start an asynchronous fill.
template <typename ReadHandler>
void async_fill(ReadHandler handler)
{
std::size_t previous_size = storage_.size();
storage_.resize(storage_.capacity());
next_layer_.async_read_some(
buffer(
storage_.data() + previous_size,
storage_.size() - previous_size),
fill_handler<ReadHandler>(get_io_service(),
storage_, previous_size, handler));
}
/// 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)
{
if (storage_.empty())
fill();
return copy(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)
{
ec = boost::system::error_code();
if (storage_.empty() && !fill(ec))
return 0;
return copy(buffers);
}
template <typename MutableBufferSequence, typename ReadHandler>
class read_some_handler
{
public:
read_some_handler(boost::asio::io_service& io_service,
detail::buffered_stream_storage& storage,
const MutableBufferSequence& buffers, ReadHandler handler)
: io_service_(io_service),
storage_(storage),
buffers_(buffers),
handler_(handler)
{
}
void operator()(const boost::system::error_code& ec, std::size_t)
{
if (ec || storage_.empty())
{
std::size_t length = 0;
io_service_.dispatch(detail::bind_handler(handler_, ec, length));
}
else
{
using namespace std; // For memcpy.
std::size_t bytes_avail = storage_.size();
std::size_t bytes_copied = 0;
typename MutableBufferSequence::const_iterator iter = buffers_.begin();
typename MutableBufferSequence::const_iterator end = buffers_.end();
for (; iter != end && bytes_avail > 0; ++iter)
{
std::size_t max_length = buffer_size(*iter);
std::size_t length = (max_length < bytes_avail)
? max_length : bytes_avail;
memcpy(buffer_cast<void*>(*iter),
storage_.data() + bytes_copied, length);
bytes_copied += length;
bytes_avail -= length;
}
storage_.consume(bytes_copied);
io_service_.dispatch(detail::bind_handler(handler_, ec, bytes_copied));
}
}
private:
boost::asio::io_service& io_service_;
detail::buffered_stream_storage& storage_;
MutableBufferSequence buffers_;
ReadHandler handler_;
};
/// 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)
{
if (storage_.empty())
{
async_fill(read_some_handler<MutableBufferSequence, ReadHandler>(
get_io_service(), storage_, buffers, handler));
}
else
{
std::size_t length = copy(buffers);
get_io_service().post(detail::bind_handler(
handler, boost::system::error_code(), length));
}
}
/// 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)
{
if (storage_.empty())
fill();
return peek_copy(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)
{
ec = boost::system::error_code();
if (storage_.empty() && !fill(ec))
return 0;
return peek_copy(buffers);
}
/// Determine the amount of data that may be read without blocking.
std::size_t in_avail()
{
return storage_.size();
}
/// Determine the amount of data that may be read without blocking.
std::size_t in_avail(boost::system::error_code& ec)
{
ec = boost::system::error_code();
return storage_.size();
}
private:
/// Copy data out of the internal buffer to the specified target buffer.
/// Returns the number of bytes copied.
template <typename MutableBufferSequence>
std::size_t copy(const MutableBufferSequence& buffers)
{
using namespace std; // For memcpy.
std::size_t bytes_avail = storage_.size();
std::size_t bytes_copied = 0;
typename MutableBufferSequence::const_iterator iter = buffers.begin();
typename MutableBufferSequence::const_iterator end = buffers.end();
for (; iter != end && bytes_avail > 0; ++iter)
{
std::size_t max_length = buffer_size(*iter);
std::size_t length = (max_length < bytes_avail)
? max_length : bytes_avail;
memcpy(buffer_cast<void*>(*iter), storage_.data() + bytes_copied, length);
bytes_copied += length;
bytes_avail -= length;
}
storage_.consume(bytes_copied);
return bytes_copied;
}
/// Copy data from the internal buffer to the specified target buffer, without
/// removing the data from the internal buffer. Returns the number of bytes
/// copied.
template <typename MutableBufferSequence>
std::size_t peek_copy(const MutableBufferSequence& buffers)
{
using namespace std; // For memcpy.
std::size_t bytes_avail = storage_.size();
std::size_t bytes_copied = 0;
typename MutableBufferSequence::const_iterator iter = buffers.begin();
typename MutableBufferSequence::const_iterator end = buffers.end();
for (; iter != end && bytes_avail > 0; ++iter)
{
std::size_t max_length = buffer_size(*iter);
std::size_t length = (max_length < bytes_avail)
? max_length : bytes_avail;
memcpy(buffer_cast<void*>(*iter), storage_.data() + bytes_copied, length);
bytes_copied += length;
bytes_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_READ_STREAM_HPP