include/llvm/Support/MutexGuard.h

   1 //===-- Support/MutexGuard.h - Acquire/Release Mutex In Scope ---*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines a guard for a block of code that ensures a Mutex is locked
  10 // upon construction and released upon destruction.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_SUPPORT_MUTEXGUARD_H
  15 #define LLVM_SUPPORT_MUTEXGUARD_H
  16
  17 #include "llvm/Support/Mutex.h"
  18
  19 namespace llvm {
  20   /// Instances of this class acquire a given Mutex Lock when constructed and
  21   /// hold that lock until destruction. The intention is to instantiate one of
  22   /// these on the stack at the top of some scope to be assured that C++
  23   /// destruction of the object will always release the Mutex and thus avoid
  24   /// a host of nasty multi-threading problems in the face of exceptions, etc.
  25   /// Guard a section of code with a Mutex.
  26   class MutexGuard {
  27     sys::Mutex &M;
  28     MutexGuard(const MutexGuard &) = delete;
  29     void operator=(const MutexGuard &) = delete;
  30   public:
  31     MutexGuard(sys::Mutex &m) : M(m) { M.lock(); }
  32     ~MutexGuard() { M.unlock(); }
  33     /// holds - Returns true if this locker instance holds the specified lock.
  34     /// This is mostly used in assertions to validate that the correct mutex
  35     /// is held.
  36     bool holds(const sys::Mutex& lock) const { return &M == &lock; }
  37   };
  38 }
  39
  40 #endif // LLVM_SUPPORT_MUTEXGUARD_H