asio/detail/eventfd_select_interrupter.hpp

0001 //
0002 // detail/eventfd_select_interrupter.hpp
0003 // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0004 //
0005 // Copyright (c) 2003-2023 Christopher M. Kohlhoff (chris at kohlhoff dot com)
0006 // Copyright (c) 2008 Roelof Naude (roelof.naude at gmail dot com)
0007 //
0008 // Distributed under the Boost Software License, Version 1.0. (See accompanying
0009 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0010 //
0011
0012 #ifndef BOOST_ASIO_DETAIL_EVENTFD_SELECT_INTERRUPTER_HPP
0013 #define BOOST_ASIO_DETAIL_EVENTFD_SELECT_INTERRUPTER_HPP
0014
0015 #if defined(_MSC_VER) && (_MSC_VER >= 1200)
0016 # pragma once
0017 #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
0018
0019 #include <boost/asio/detail/config.hpp>
0020
0021 #if defined(BOOST_ASIO_HAS_EVENTFD)
0022
0023 #include <boost/asio/detail/push_options.hpp>
0024
0025 namespace boost {
0026 namespace asio {
0027 namespace detail {
0028
0029 class eventfd_select_interrupter
0030 {
0031 public:
0032   // Constructor.
0033   BOOST_ASIO_DECL eventfd_select_interrupter();
0034
0035   // Destructor.
0036   BOOST_ASIO_DECL ~eventfd_select_interrupter();
0037
0038   // Recreate the interrupter's descriptors. Used after a fork.
0039   BOOST_ASIO_DECL void recreate();
0040
0041   // Interrupt the select call.
0042   BOOST_ASIO_DECL void interrupt();
0043
0044   // Reset the select interrupter. Returns true if the reset was successful.
0045   BOOST_ASIO_DECL bool reset();
0046
0047   // Get the read descriptor to be passed to select.
0048   int read_descriptor() const
0049   {
0050     return read_descriptor_;
0051   }
0052
0053 private:
0054   // Open the descriptors. Throws on error.
0055   BOOST_ASIO_DECL void open_descriptors();
0056
0057   // Close the descriptors.
0058   BOOST_ASIO_DECL void close_descriptors();
0059
0060   // The read end of a connection used to interrupt the select call. This file
0061   // descriptor is passed to select such that when it is time to stop, a single
0062   // 64bit value will be written on the other end of the connection and this
0063   // descriptor will become readable.
0064   int read_descriptor_;
0065
0066   // The write end of a connection used to interrupt the select call. A single
0067   // 64bit non-zero value may be written to this to wake up the select which is
0068   // waiting for the other end to become readable. This descriptor will only
0069   // differ from the read descriptor when a pipe is used.
0070   int write_descriptor_;
0071 };
0072
0073 } // namespace detail
0074 } // namespace asio
0075 } // namespace boost
0076
0077 #include <boost/asio/detail/pop_options.hpp>
0078
0079 #if defined(BOOST_ASIO_HEADER_ONLY)
0080 # include <boost/asio/detail/impl/eventfd_select_interrupter.ipp>
0081 #endif // defined(BOOST_ASIO_HEADER_ONLY)
0082
0083 #endif // defined(BOOST_ASIO_HAS_EVENTFD)
0084
0085 #endif // BOOST_ASIO_DETAIL_EVENTFD_SELECT_INTERRUPTER_HPP