LLVM  10.0.0svn
MutexGuard.h
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1 //===-- Support/MutexGuard.h - Acquire/Release Mutex In Scope ---*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines a guard for a block of code that ensures a Mutex is locked
10 // upon construction and released upon destruction.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_SUPPORT_MUTEXGUARD_H
15 #define LLVM_SUPPORT_MUTEXGUARD_H
16 
17 #include "llvm/Support/Mutex.h"
18 
19 namespace llvm {
20  /// Instances of this class acquire a given Mutex Lock when constructed and
21  /// hold that lock until destruction. The intention is to instantiate one of
22  /// these on the stack at the top of some scope to be assured that C++
23  /// destruction of the object will always release the Mutex and thus avoid
24  /// a host of nasty multi-threading problems in the face of exceptions, etc.
25  /// Guard a section of code with a Mutex.
26  class MutexGuard {
27  sys::Mutex &M;
28  MutexGuard(const MutexGuard &) = delete;
29  void operator=(const MutexGuard &) = delete;
30  public:
31  MutexGuard(sys::Mutex &m) : M(m) { M.lock(); }
32  ~MutexGuard() { M.unlock(); }
33  /// holds - Returns true if this locker instance holds the specified lock.
34  /// This is mostly used in assertions to validate that the correct mutex
35  /// is held.
36  bool holds(const sys::Mutex& lock) const { return &M == &lock; }
37  };
38 }
39 
40 #endif // LLVM_SUPPORT_MUTEXGUARD_H
This class represents lattice values for constants.
Definition: AllocatorList.h:23
MutexGuard(sys::Mutex &m)
Definition: MutexGuard.h:31
Instances of this class acquire a given Mutex Lock when constructed and hold that lock until destruct...
Definition: MutexGuard.h:26
bool holds(const sys::Mutex &lock) const
holds - Returns true if this locker instance holds the specified lock.
Definition: MutexGuard.h:36