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//
// detail/impl/eventfd_select_interrupter.ipp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2018 Christopher M. Kohlhoff (chris at kohlhoff dot com)
// Copyright (c) 2008 Roelof Naude (roelof.naude at gmail 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 ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP
#define ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include "asio/detail/config.hpp"
#if defined(ASIO_HAS_EVENTFD)
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#if __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
# include <asm/unistd.h>
#else // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
# include <sys/eventfd.h>
#endif // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
#include "asio/detail/cstdint.hpp"
#include "asio/detail/eventfd_select_interrupter.hpp"
#include "asio/detail/throw_error.hpp"
#include "asio/error.hpp"
#include "asio/detail/push_options.hpp"
namespace asio {
namespace detail {
eventfd_select_interrupter::eventfd_select_interrupter()
{
open_descriptors();
}
void eventfd_select_interrupter::open_descriptors()
{
#if __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
write_descriptor_ = read_descriptor_ = syscall(__NR_eventfd, 0);
if (read_descriptor_ != -1)
{
::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
}
#else // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
# if defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK)
write_descriptor_ = read_descriptor_ =
::eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
# else // defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK)
errno = EINVAL;
write_descriptor_ = read_descriptor_ = -1;
# endif // defined(EFD_CLOEXEC) && defined(EFD_NONBLOCK)
if (read_descriptor_ == -1 && errno == EINVAL)
{
write_descriptor_ = read_descriptor_ = ::eventfd(0, 0);
if (read_descriptor_ != -1)
{
::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
}
}
#endif // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8
if (read_descriptor_ == -1)
{
int pipe_fds[2];
if (pipe(pipe_fds) == 0)
{
read_descriptor_ = pipe_fds[0];
::fcntl(read_descriptor_, F_SETFL, O_NONBLOCK);
::fcntl(read_descriptor_, F_SETFD, FD_CLOEXEC);
write_descriptor_ = pipe_fds[1];
::fcntl(write_descriptor_, F_SETFL, O_NONBLOCK);
::fcntl(write_descriptor_, F_SETFD, FD_CLOEXEC);
}
else
{
asio::error_code ec(errno,
asio::error::get_system_category());
asio::detail::throw_error(ec, "eventfd_select_interrupter");
}
}
}
eventfd_select_interrupter::~eventfd_select_interrupter()
{
close_descriptors();
}
void eventfd_select_interrupter::close_descriptors()
{
if (write_descriptor_ != -1 && write_descriptor_ != read_descriptor_)
::close(write_descriptor_);
if (read_descriptor_ != -1)
::close(read_descriptor_);
}
void eventfd_select_interrupter::recreate()
{
close_descriptors();
write_descriptor_ = -1;
read_descriptor_ = -1;
open_descriptors();
}
void eventfd_select_interrupter::interrupt()
{
uint64_t counter(1UL);
int result = ::write(write_descriptor_, &counter, sizeof(uint64_t));
(void)result;
}
bool eventfd_select_interrupter::reset()
{
if (write_descriptor_ == read_descriptor_)
{
for (;;)
{
// Only perform one read. The kernel maintains an atomic counter.
uint64_t counter(0);
errno = 0;
int bytes_read = ::read(read_descriptor_, &counter, sizeof(uint64_t));
if (bytes_read < 0 && errno == EINTR)
continue;
bool was_interrupted = (bytes_read > 0);
return was_interrupted;
}
}
else
{
for (;;)
{
// Clear all data from the pipe.
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;
}
}
}
} // namespace detail
} // namespace asio
#include "asio/detail/pop_options.hpp"
#endif // defined(ASIO_HAS_EVENTFD)
#endif // ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP
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