From 1d07cfede2d0153ebfa23543ffcc08faf55b4539 Mon Sep 17 00:00:00 2001
From: Abseil Team <absl-team@google.com>
Date: Tue, 28 Feb 2023 10:47:58 -0800
Subject: Rollback because of internal incompatibility.

PiperOrigin-RevId: 512979517
Change-Id: I7fe38ed246e42e6f8eb322e15c3b299215163168
---
 absl/synchronization/internal/futex.h | 70 ++++++++++++-----------------------
 1 file changed, 23 insertions(+), 47 deletions(-)

(limited to 'absl/synchronization/internal/futex.h')

diff --git a/absl/synchronization/internal/futex.h b/absl/synchronization/internal/futex.h
index 62bb40f7..9cf9841d 100644
--- a/absl/synchronization/internal/futex.h
+++ b/absl/synchronization/internal/futex.h
@@ -16,7 +16,9 @@
 
 #include "absl/base/config.h"
 
-#ifndef _WIN32
+#ifdef _WIN32
+#include <windows.h>
+#else
 #include <sys/time.h>
 #include <unistd.h>
 #endif
@@ -83,60 +85,34 @@ namespace synchronization_internal {
 
 class FutexImpl {
  public:
-  // Atomically check that `*v == val`, and if it is, then sleep until the
-  // timeout `t` has been reached, or until woken by `Wake()`.
-  static int WaitUntil(std::atomic<int32_t>* v, int32_t val,
+  static int WaitUntil(std::atomic<int32_t> *v, int32_t val,
                        KernelTimeout t) {
-    if (!t.has_timeout()) {
-      return Wait(v, val);
-    } else if (t.is_absolute_timeout()) {
-      auto abs_timespec = t.MakeAbsTimespec();
-      return WaitAbsoluteTimeout(v, val, &abs_timespec);
+    long err = 0;  // NOLINT(runtime/int)
+    if (t.has_timeout()) {
+      // https://locklessinc.com/articles/futex_cheat_sheet/
+      // Unlike FUTEX_WAIT, FUTEX_WAIT_BITSET uses absolute time.
+      struct timespec abs_timeout = t.MakeAbsTimespec();
+      // Atomically check that the futex value is still 0, and if it
+      // is, sleep until abs_timeout or until woken by FUTEX_WAKE.
+      err = syscall(
+          SYS_futex, reinterpret_cast<int32_t *>(v),
+          FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME, val,
+          &abs_timeout, nullptr, FUTEX_BITSET_MATCH_ANY);
     } else {
-      auto rel_timespec = t.MakeRelativeTimespec();
-      return WaitRelativeTimeout(v, val, &rel_timespec);
+      // Atomically check that the futex value is still 0, and if it
+      // is, sleep until woken by FUTEX_WAKE.
+      err = syscall(SYS_futex, reinterpret_cast<int32_t *>(v),
+                    FUTEX_WAIT | FUTEX_PRIVATE_FLAG, val, nullptr);
     }
-  }
-
-  // Atomically check that `*v == val`, and if it is, then sleep until the until
-  // woken by `Wake()`.
-  static int Wait(std::atomic<int32_t>* v, int32_t val) {
-    return WaitAbsoluteTimeout(v, val, nullptr);
-  }
-
-  // Atomically check that `*v == val`, and if it is, then sleep until
-  // CLOCK_REALTIME reaches `*abs_timeout`, or until woken by `Wake()`.
-  static int WaitAbsoluteTimeout(std::atomic<int32_t>* v, int32_t val,
-                                 const struct timespec* abs_timeout) {
-    // https://locklessinc.com/articles/futex_cheat_sheet/
-    // Unlike FUTEX_WAIT, FUTEX_WAIT_BITSET uses absolute time.
-    auto err =
-        syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
-                FUTEX_WAIT_BITSET | FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME,
-                val, abs_timeout, nullptr, FUTEX_BITSET_MATCH_ANY);
-    if (err != 0) {
-      return -errno;
-    }
-    return 0;
-  }
-
-  // Atomically check that `*v == val`, and if it is, then sleep until
-  // `*rel_timeout` has elapsed, or until woken by `Wake()`.
-  static int WaitRelativeTimeout(std::atomic<int32_t>* v, int32_t val,
-                                 const struct timespec* rel_timeout) {
-    // Atomically check that the futex value is still 0, and if it
-    // is, sleep until abs_timeout or until woken by FUTEX_WAKE.
-    auto err = syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
-                       FUTEX_PRIVATE_FLAG, val, rel_timeout);
-    if (err != 0) {
+    if (ABSL_PREDICT_FALSE(err != 0)) {
       return -errno;
     }
     return 0;
   }
 
-  // Wakes at most `count` waiters that have entered the sleep state on `v`.
-  static int Wake(std::atomic<int32_t>* v, int32_t count) {
-    auto err = syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
+  static int Wake(std::atomic<int32_t> *v, int32_t count) {
+    // NOLINTNEXTLINE(runtime/int)
+    long err = syscall(SYS_futex, reinterpret_cast<int32_t*>(v),
                        FUTEX_WAKE | FUTEX_PRIVATE_FLAG, count);
     if (ABSL_PREDICT_FALSE(err < 0)) {
       return -errno;
-- 
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