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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             :   /// @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     2140336 :     MutexGuard(sys::Mutex &m) : M(m) { M.lock(); }
      33     2140336 :     ~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