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//===- llvm/Support/Mutex.h - Mutex Operating System Concept -----*- 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
//
//===----------------------------------------------------------------------===//
//
// This file declares the llvm::sys::Mutex class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_MUTEX_H
#define LLVM_SUPPORT_MUTEX_H
#include "llvm/Support/Threading.h"
#include <cassert>
#include <mutex>
namespace llvm
{
namespace sys
{
/// SmartMutex - A mutex with a compile time constant parameter that
/// indicates whether this mutex should become a no-op when we're not
/// running in multithreaded mode.
template<bool mt_only>
class SmartMutex {
std::recursive_mutex impl;
unsigned acquired = 0;
public:
bool lock() {
if (!mt_only || llvm_is_multithreaded()) {
impl.lock();
return true;
} else {
// Single-threaded debugging code. This would be racy in
// multithreaded mode, but provides not sanity checks in single
// threaded mode.
++acquired;
return true;
}
}
bool unlock() {
if (!mt_only || llvm_is_multithreaded()) {
impl.unlock();
return true;
} else {
// Single-threaded debugging code. This would be racy in
// multithreaded mode, but provides not sanity checks in single
// threaded mode.
assert(acquired && "Lock not acquired before release!");
--acquired;
return true;
}
}
bool try_lock() {
if (!mt_only || llvm_is_multithreaded())
return impl.try_lock();
else return true;
}
};
/// Mutex - A standard, always enforced mutex.
typedef SmartMutex<false> Mutex;
template <bool mt_only>
using SmartScopedLock = std::lock_guard<SmartMutex<mt_only>>;
typedef SmartScopedLock<false> ScopedLock;
}
}
#endif
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