cut legacy eventfd shims for glibc 2.5

Summary: That is an old glibc. The shims are no longer required.

Reviewed By: Orvid

Differential Revision: D32632173

fbshipit-source-id: d6ce675c6f16b896a950363b411bec66cedca966

folly/io/async/EventBaseAtomicNotificationQueue.h

@@ -23,9 +23,9 @@
 #include <folly/portability/Sockets.h>
 #include <folly/portability/Unistd.h>
 
-#if defined(__linux__) && !defined(__ANDROID__)
+#if __has_include(<sys/eventfd.h>)
 #define FOLLY_HAVE_EVENTFD
-#include <folly/io/async/EventFDWrapper.h>
+#include <sys/eventfd.h>
 #endif
 
 namespace folly {

folly/io/async/EventFDWrapper.h

-/*
- * Copyright (c) Facebook, Inc. and its affiliates.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * Work around the lack of <sys/eventfd.h> on glibc 2.5.1 which we still
- * need to support, sigh.
- */
-
-#pragma once
-
-#include <folly/portability/Config.h>
-
-#if defined(__GLIBC__) && !defined(__APPLE__)
-#if __GLIBC_PREREQ(2, 9)
-#define FOLLY_GLIBC_2_9
-#endif
-#endif
-
-// <sys/eventfd.h> doesn't exist on older glibc versions
-#ifdef FOLLY_GLIBC_2_9
-#include <sys/eventfd.h>
-#else /* !def FOLLY_GLIBC_2_9 */
-
-#include <fcntl.h>
-#include <sys/syscall.h>
-#include <unistd.h>
-
-// Use existing __NR_eventfd2 if already defined
-// Values from the Linux kernel source:
-// arch/x86/include/asm/unistd_{32,64}.h
-#ifndef __NR_eventfd2
-#if FOLLY_X64
-/* nolint */
-#define __NR_eventfd2 290
-#elif defined(__i386__)
-/* nolint */
-#define __NR_eventfd2 328
-#else
-#error "Can't define __NR_eventfd2 for your architecture."
-#endif
-#endif
-
-enum {
-  EFD_SEMAPHORE = 1,
-#define EFD_SEMAPHORE EFD_SEMAPHORE
-  EFD_CLOEXEC = 02000000,
-#define EFD_CLOEXEC EFD_CLOEXEC
-  EFD_NONBLOCK = 04000
-#define EFD_NONBLOCK EFD_NONBLOCK
-};
-
-// http://www.kernel.org/doc/man-pages/online/pages/man2/eventfd.2.html
-// Use the eventfd2 system call, as in glibc 2.9+
-// (requires kernel 2.6.30+)
-#define eventfd(initval, flags) syscall(__NR_eventfd2, (initval), (flags))
-
-#endif /* !(defined(__GLIBC__) && __GLIBC_PREREQ(2, 9)) */

folly/io/async/NotificationQueue.h

@@ -41,9 +41,9 @@
 #include <folly/portability/Unistd.h>
 #include <folly/system/Pid.h>
 
-#if defined(__linux__) && !defined(__ANDROID__)
+#if __has_include(<sys/eventfd.h>)
 #define FOLLY_HAVE_EVENTFD
-#include <folly/io/async/EventFDWrapper.h>
+#include <sys/eventfd.h>
 #endif
 
 namespace folly {