boost/asio/detail/pipe_select_interrupter.hpp
//
// pipe_select_interrupter.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2010 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_DETAIL_PIPE_SELECT_INTERRUPTER_HPP
#define BOOST_ASIO_DETAIL_PIPE_SELECT_INTERRUPTER_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 <boost/config.hpp>
#include <boost/throw_exception.hpp>
#include <boost/system/system_error.hpp>
#include <boost/asio/detail/pop_options.hpp>
#if !defined(BOOST_WINDOWS) && !defined(__CYGWIN__)
#include <boost/asio/detail/push_options.hpp>
#include <fcntl.h>
#include <boost/asio/detail/pop_options.hpp>
#include <boost/asio/error.hpp>
#include <boost/asio/detail/socket_types.hpp>
namespace boost {
namespace asio {
namespace detail {
class pipe_select_interrupter
{
public:
// Constructor.
pipe_select_interrupter()
{
int pipe_fds[2];
if (pipe(pipe_fds) == 0)
{
read_descriptor_ = pipe_fds[0];
::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
write_descriptor_ = pipe_fds[1];
::fcntl(write_descriptor_, F_SETFL, O_NONBLOCK);
}
else
{
boost::system::error_code ec(errno,
boost::asio::error::get_system_category());
boost::system::system_error e(ec, "pipe_select_interrupter");
boost::throw_exception(e);
}
}
// Destructor.
~pipe_select_interrupter()
{
if (read_descriptor_ != -1)
::close(read_descriptor_);
if (write_descriptor_ != -1)
::close(write_descriptor_);
}
// Interrupt the select call.
void interrupt()
{
char byte = 0;
int result = ::write(write_descriptor_, &byte, 1);
(void)result;
}
// Reset the select interrupt. Returns true if the call was interrupted.
bool reset()
{
for (;;)
{
char data[1024];
int bytes_read = ::read(read_descriptor_, data, sizeof(data));
if (bytes_read < 0 && errno == EINTR)
continue;
bool was_interrupted = (bytes_read > 0);
while (bytes_read == sizeof(data))
bytes_read = ::read(read_descriptor_, data, sizeof(data));
return was_interrupted;
}
}
// Get the read descriptor to be passed to select.
int read_descriptor() const
{
return read_descriptor_;
}
private:
// The read end of a connection used to interrupt the select call. This file
// descriptor is passed to select such that when it is time to stop, a single
// byte will be written on the other end of the connection and this
// descriptor will become readable.
int read_descriptor_;
// The write end of a connection used to interrupt the select call. A single
// byte may be written to this to wake up the select which is waiting for the
// other end to become readable.
int write_descriptor_;
};
} // namespace detail
} // namespace asio
} // namespace boost
#endif // !defined(BOOST_WINDOWS) && !defined(__CYGWIN__)
#include <boost/asio/detail/pop_options.hpp>
#endif // BOOST_ASIO_DETAIL_PIPE_SELECT_INTERRUPTER_HPP