liuxiaolong
2021-07-20 58d904a328c0d849769b483e901a0be9426b8209
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//
// detail/impl/pipe_select_interrupter.ipp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2020 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_IMPL_PIPE_SELECT_INTERRUPTER_IPP
#define BOOST_ASIO_DETAIL_IMPL_PIPE_SELECT_INTERRUPTER_IPP
 
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
 
#include <boost/asio/detail/config.hpp>
 
#if !defined(BOOST_ASIO_WINDOWS_RUNTIME)
#if !defined(BOOST_ASIO_WINDOWS)
#if !defined(__CYGWIN__)
#if !defined(__SYMBIAN32__)
#if !defined(BOOST_ASIO_HAS_EVENTFD)
 
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <boost/asio/detail/pipe_select_interrupter.hpp>
#include <boost/asio/detail/socket_types.hpp>
#include <boost/asio/detail/throw_error.hpp>
#include <boost/asio/error.hpp>
 
#include <boost/asio/detail/push_options.hpp>
 
namespace boost {
namespace asio {
namespace detail {
 
pipe_select_interrupter::pipe_select_interrupter()
{
  open_descriptors();
}
 
void pipe_select_interrupter::open_descriptors()
{
  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);
 
#if defined(FD_CLOEXEC)
    ::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
    ::fcntl(write_descriptor_, F_SETFD, FD_CLOEXEC);
#endif // defined(FD_CLOEXEC)
  }
  else
  {
    boost::system::error_code ec(errno,
        boost::asio::error::get_system_category());
    boost::asio::detail::throw_error(ec, "pipe_select_interrupter");
  }
}
 
pipe_select_interrupter::~pipe_select_interrupter()
{
  close_descriptors();
}
 
void pipe_select_interrupter::close_descriptors()
{
  if (read_descriptor_ != -1)
    ::close(read_descriptor_);
  if (write_descriptor_ != -1)
    ::close(write_descriptor_);
}
 
void pipe_select_interrupter::recreate()
{
  close_descriptors();
 
  write_descriptor_ = -1;
  read_descriptor_ = -1;
 
  open_descriptors();
}
 
void pipe_select_interrupter::interrupt()
{
  char byte = 0;
  signed_size_type result = ::write(write_descriptor_, &byte, 1);
  (void)result;
}
 
bool pipe_select_interrupter::reset()
{
  for (;;)
  {
    char data[1024];
    signed_size_type bytes_read = ::read(read_descriptor_, data, sizeof(data));
    if (bytes_read == sizeof(data))
      continue;
    if (bytes_read > 0)
      return true;
    if (bytes_read == 0)
      return false;
    if (errno == EINTR)
      continue;
    if (errno == EWOULDBLOCK || errno == EAGAIN)
      return true;
    return false;
  }
}
 
} // namespace detail
} // namespace asio
} // namespace boost
 
#include <boost/asio/detail/pop_options.hpp>
 
#endif // !defined(BOOST_ASIO_HAS_EVENTFD)
#endif // !defined(__SYMBIAN32__)
#endif // !defined(__CYGWIN__)
#endif // !defined(BOOST_ASIO_WINDOWS)
#endif // !defined(BOOST_ASIO_WINDOWS_RUNTIME)
 
#endif // BOOST_ASIO_DETAIL_IMPL_PIPE_SELECT_INTERRUPTER_IPP