[libc-commits] [libc] [libc] refactor futex and remove dependency cycle (PR #117923)

[Nick Desaulniers via libc-commits]

================
@@ -0,0 +1,62 @@
+//===--- Futex Wrapper ------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_THREADS_LINUX_FUTEX_TIMEOUT_H
+#define LLVM_LIBC_SRC___SUPPORT_THREADS_LINUX_FUTEX_TIMEOUT_H
+
+#include "src/__support/CPP/atomic.h"
+#include "src/__support/CPP/limits.h"
+#include "src/__support/CPP/optional.h"
+#include "src/__support/OSUtil/syscall.h"
+#include "src/__support/macros/attributes.h"
+#include "src/__support/macros/config.h"
+#include "src/__support/threads/linux/futex_utils.h"
+#include "src/__support/time/linux/abs_timeout.h"
+
+namespace LIBC_NAMESPACE_DECL {
+class TimedFutex : public Futex {
+public:
+  using Timeout = internal::AbsTimeout;
+  using Futex::Futex;
+  using Futex::operator=;
+  LIBC_INLINE long wait(FutexWordType expected,
+                        cpp::optional<Timeout> timeout = cpp::nullopt,
+                        bool is_shared = false) {
+    // use bitset variants to enforce abs_time
+    uint32_t op = is_shared ? FUTEX_WAIT_BITSET : FUTEX_WAIT_BITSET_PRIVATE;
+    if (timeout && timeout->is_realtime()) {
+      op |= FUTEX_CLOCK_REALTIME;
+    }
----------------
nickdesaulniers wrote:

```suggestion
    if (timeout && timeout->is_realtime())
      op |= FUTEX_CLOCK_REALTIME;
```

https://github.com/llvm/llvm-project/pull/117923