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llvm-mirror/include/llvm/Support/MutexGuard.h
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

41 lines
1.6 KiB
C++

//===-- Support/MutexGuard.h - Acquire/Release Mutex In Scope ---*- 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 defines a guard for a block of code that ensures a Mutex is locked
// upon construction and released upon destruction.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_MUTEXGUARD_H
#define LLVM_SUPPORT_MUTEXGUARD_H
#include "llvm/Support/Mutex.h"
namespace llvm {
/// Instances of this class acquire a given Mutex Lock when constructed and
/// hold that lock until destruction. The intention is to instantiate one of
/// these on the stack at the top of some scope to be assured that C++
/// destruction of the object will always release the Mutex and thus avoid
/// a host of nasty multi-threading problems in the face of exceptions, etc.
/// Guard a section of code with a Mutex.
class MutexGuard {
sys::Mutex &M;
MutexGuard(const MutexGuard &) = delete;
void operator=(const MutexGuard &) = delete;
public:
MutexGuard(sys::Mutex &m) : M(m) { M.lock(); }
~MutexGuard() { M.unlock(); }
/// holds - Returns true if this locker instance holds the specified lock.
/// This is mostly used in assertions to validate that the correct mutex
/// is held.
bool holds(const sys::Mutex& lock) const { return &M == &lock; }
};
}
#endif // LLVM_SUPPORT_MUTEXGUARD_H