Initial Commit

include/asio/detail/impl/eventfd_select_interrupter.ipp

@@ -0,0 +1,171 @@
+//
+// detail/impl/eventfd_select_interrupter.ipp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2025 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 && !defined(__UCLIBC__)
+# include <asm/unistd.h>
+#else // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8 && !defined(__UCLIBC__)
+# include <sys/eventfd.h>
+#endif // __GLIBC__ == 2 && __GLIBC_MINOR__ < 8 && !defined(__UCLIBC__)
+#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 && !defined(__UCLIBC__)
+  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 && !defined(__UCLIBC__)
+# 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 && !defined(__UCLIBC__)
+
+  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;
+      return true;
+    }
+  }
+  else
+  {
+    for (;;)
+    {
+      // Clear all data from the pipe.
+      char data[1024];
+      int 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)
+        return true;
+      if (errno == EAGAIN)
+        return true;
+      return false;
+    }
+  }
+}
+
+} // namespace detail
+} // namespace asio
+
+#include "asio/detail/pop_options.hpp"
+
+#endif // defined(ASIO_HAS_EVENTFD)
+
+#endif // ASIO_DETAIL_IMPL_EVENTFD_SELECT_INTERRUPTER_IPP