1  // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
 2  // Use of this source code is governed by a BSD-style license that can be
 3  // found in the LICENSE file. See the AUTHORS file for names of contributors.
 4  
 5  #ifndef STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_
 6  #define STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_
 7  
 8  #include "port/port.h"
 9  #include "port/thread_annotations.h"
10  
11  namespace leveldb {
12  
13  // Helper class that locks a mutex on construction and unlocks the mutex when
14  // the destructor of the MutexLock object is invoked.
15  //
16  // Typical usage:
17  //
18  //   void MyClass::MyMethod() {
19  //     MutexLock l(&mu_);       // mu_ is an instance variable
20  //     ... some complex code, possibly with multiple return paths ...
21  //   }
22  
23  class SCOPED_LOCKABLE MutexLock {
24   public:
25    explicit MutexLock(port::Mutex* mu) EXCLUSIVE_LOCK_FUNCTION(mu) : mu_(mu) {
26      this->mu_->Lock();
27    }
28    ~MutexLock() UNLOCK_FUNCTION() { this->mu_->Unlock(); }
29  
30    MutexLock(const MutexLock&) = delete;
31    MutexLock& operator=(const MutexLock&) = delete;
32  
33   private:
34    port::Mutex* const mu_;
35  };
36  
37  }  // namespace leveldb
38  
39  #endif  // STORAGE_LEVELDB_UTIL_MUTEXLOCK_H_