1//===-- Support/MutexGuard.h - Acquire/Release Mutex In Scope ---*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines a guard for a block of code that ensures a Mutex is locked
11// upon construction and released upon destruction.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_SUPPORT_MUTEXGUARD_H
16#define LLVM_SUPPORT_MUTEXGUARD_H
17
18#include "llvm/Support/Mutex.h"
19
20namespace llvm {
21  /// Instances of this class acquire a given Mutex Lock when constructed and
22  /// hold that lock until destruction. The intention is to instantiate one of
23  /// these on the stack at the top of some scope to be assured that C++
24  /// destruction of the object will always release the Mutex and thus avoid
25  /// a host of nasty multi-threading problems in the face of exceptions, etc.
26  /// @brief Guard a section of code with a Mutex.
27  class MutexGuard {
28    sys::Mutex &M;
29    MutexGuard(const MutexGuard &) = delete;
30    void operator=(const MutexGuard &) = delete;
31  public:
32    MutexGuard(sys::Mutex &m) : M(m) { M.lock(); }
33    ~MutexGuard() { M.unlock(); }
34    /// holds - Returns true if this locker instance holds the specified lock.
35    /// This is mostly used in assertions to validate that the correct mutex
36    /// is held.
37    bool holds(const sys::Mutex& lock) const { return &M == &lock; }
38  };
39}
40
41#endif // LLVM_SUPPORT_MUTEXGUARD_H
42