LLVM  8.0.0svn
MutexGuard.h
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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 
20 namespace 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  /// 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
This class represents lattice values for constants.
Definition: AllocatorList.h:24
MutexGuard(sys::Mutex &m)
Definition: MutexGuard.h:32
Instances of this class acquire a given Mutex Lock when constructed and hold that lock until destruct...
Definition: MutexGuard.h:27
bool holds(const sys::Mutex &lock) const
holds - Returns true if this locker instance holds the specified lock.
Definition: MutexGuard.h:37