src/llvm/include/llvm/Support/MutexGuard.h

   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 &) LLVM_DELETED_FUNCTION;
  30     void operator=(const MutexGuard &) LLVM_DELETED_FUNCTION;
  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