YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you under the Apache License, Version 2.0 (the

// "License"); you may not use this file except in compliance

// with the License.  You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing,

// software distributed under the License is distributed on an

// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

// KIND, either express or implied.  See the License for the

// specific language governing permissions and limitations

// under the License.

//

// The following only applies to changes made to this file as part of YugaByte development.

//

// Portions Copyright (c) YugaByte, Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License.  You may obtain a copy of the License at

//

// http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied.  See the License for the specific language governing permissions and limitations

// under the License.

//

#ifndef YB_UTIL_MUTEX_H

#define YB_UTIL_MUTEX_H

#include <pthread.h>

#include <sys/types.h>

#include <memory>

#include <glog/logging.h>

#include "yb/gutil/macros.h"

namespace yb {

class StackTrace;

// A lock built around pthread_mutex_t. Does not allow recursion.

//

// The following checks will be performed in DEBUG mode:

//   Acquire(), TryAcquire() - the lock isn't already held.

//   Release() - the lock is already held by this thread.

//

class Mutex {

 public:

  Mutex();

  ~Mutex();

  void Acquire();

  void Release();

  bool TryAcquire();

  void lock() { Acquire(); }

  void unlock() { Release(); }

  bool try_lock() { return TryAcquire(); }

#ifndef NDEBUG

  void AssertAcquired() const;

#else

  void AssertAcquired() const {}

#endif

 private:

  friend class ConditionVariable;

  pthread_mutex_t native_handle_;

#ifndef NDEBUG

  // Members and routines taking care of locks assertions.

  void CheckHeldAndUnmark();

  void CheckUnheldAndMark();

  // All private data is implicitly protected by native_handle_.

  // Be VERY careful to only access members under that lock.

  uint64_t owning_tid_;

  std::unique_ptr<StackTrace> stack_trace_;

#endif

  DISALLOW_COPY_AND_ASSIGN(Mutex);

};

// A helper class that acquires the given Lock while the MutexLock is in scope.

class MutexLock {

 public:

  struct AlreadyAcquired {};

  // Acquires 'lock' (must be unheld) and wraps around it.

  //

  // Sample usage:

  // {

  //   MutexLock l(lock_); // acquired

  //   ...

  // } // released

  explicit MutexLock(Mutex& lock) // NOLINT

    : lock_(&lock),

      owned_(true) {

    lock_->Acquire();

  }

  // Wraps around 'lock' (must already be held by this thread).

  //

  // Sample usage:

  // {

  //   lock_.Acquire(); // acquired

  //   ...

  //   MutexLock l(lock_, AlreadyAcquired());

  //   ...

  // } // released

  MutexLock(Mutex& lock, const AlreadyAcquired&) // NOLINT

    : lock_(&lock),

      owned_(true) {

    lock_->AssertAcquired();

  }

  void Lock() {

    DCHECK(!owned_);

    lock_->Acquire();

    owned_ = true;

  }

  void Unlock() {

    DCHECK(owned_);

    lock_->AssertAcquired();

    lock_->Release();

    owned_ = false;

  }

  ~MutexLock() {

    if (owned_) {

      Unlock();

    }

  }

  bool OwnsLock() const {

    return owned_;

  }

 private:

  Mutex* lock_;

  bool owned_;

  DISALLOW_COPY_AND_ASSIGN(MutexLock);

};

} // namespace yb

#endif /* YB_UTIL_MUTEX_H */