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   /// @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:
MutexGuard(sys::Mutex & m)32     MutexGuard(sys::Mutex &m) : M(m) { M.lock(); }
~MutexGuard()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.
holds(const sys::Mutex & lock)37     bool holds(const sys::Mutex& lock) const { return &M == &lock; }
38   };
39 }
40 
41 #endif // LLVM_SUPPORT_MUTEXGUARD_H
42