[libc-commits] [libc] [libc] rework mutex (PR #92168)

[Nick Desaulniers via libc-commits]

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@@ -0,0 +1,121 @@
+//===--- Implementation of a Linux RawMutex class ---------------*- 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_RAW_MUTEX_H
+#define LLVM_LIBC_SRC___SUPPORT_THREADS_LINUX_RAW_MUTEX_H
+
+#include "futex_word.h"
+#include "src/__support/CPP/optional.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/attributes.h"
+#include "src/__support/threads/linux/futex_utils.h"
+#include "src/__support/threads/sleep.h"
+#include "src/__support/time/linux/abs_timeout.h"
+#ifdef LIBC_COPT_TIMEOUT_ENSURE_MONOTONICITY
+#include "src/__support/time/linux/monotonicity.h"
+#endif
+
+#ifndef LIBC_COPT_RAW_MUTEX_DEFAULT_SPIN_COUNT
+#define LIBC_COPT_RAW_MUTEX_DEFAULT_SPIN_COUNT 100
+#endif
+
+namespace LIBC_NAMESPACE {
+struct CndVar;
+namespace internal {
+// Lock is a simple timable lock for internal usage.
+// This is separated from Mutex because this one does not need to consider
+// robustness and reentrancy. Also, this one has spin optimization for shorter
+// critical sections.
+class RawMutex {
+protected:
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nickdesaulniers wrote:

Do all of these need to be protected? Can more be private?

https://github.com/llvm/llvm-project/pull/92168