rocksdb/util/mutexlock.h

//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
//  This source code is licensed under the BSD-style license found in the
//  LICENSE file in the root directory of this source tree. An additional grant
//  of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#pragma once
#include "port/port.h"

namespace rocksdb {

// Helper class that locks a mutex on construction and unlocks the mutex when
// the destructor of the MutexLock object is invoked.
//
// Typical usage:
//
//   void MyClass::MyMethod() {
//     MutexLock l(&mu_);       // mu_ is an instance variable
//     ... some complex code, possibly with multiple return paths ...
//   }

class MutexLock {
 public:
  explicit MutexLock(port::Mutex *mu) : mu_(mu) {
    this->mu_->Lock();
  }
  ~MutexLock() { this->mu_->Unlock(); }

 private:
  port::Mutex *const mu_;
  // No copying allowed
  MutexLock(const MutexLock&);
  void operator=(const MutexLock&);
};

//
// Acquire a ReadLock on the specified RWMutex.
// The Lock will be automatically released then the
// object goes out of scope.
//
class ReadLock {
 public:
  explicit ReadLock(port::RWMutex *mu) : mu_(mu) {
    this->mu_->ReadLock();
  }
  ~ReadLock() { this->mu_->ReadUnlock(); }

 private:
  port::RWMutex *const mu_;
  // No copying allowed
  ReadLock(const ReadLock&);
  void operator=(const ReadLock&);
};


//
// Acquire a WriteLock on the specified RWMutex.
// The Lock will be automatically released then the
// object goes out of scope.
//
class WriteLock {
 public:
  explicit WriteLock(port::RWMutex *mu) : mu_(mu) {
    this->mu_->WriteLock();
  }
  ~WriteLock() { this->mu_->WriteUnlock(); }

 private:
  port::RWMutex *const mu_;
  // No copying allowed
  WriteLock(const WriteLock&);
  void operator=(const WriteLock&);
};

}  // namespace rocksdb