mutex.h

Go to the documentation of this file.

/******************************************************************************
 * Copyright 2018 The Apollo Authors. All Rights Reserved.
 *
 * 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.
 *****************************************************************************/
#pragma once

#include <pthread.h>

namespace apollo {
namespace perception {
namespace lib {

class Mutex {
 public:
  Mutex() { pthread_mutex_init(&mu_, nullptr); }

  ~Mutex() { pthread_mutex_destroy(&mu_); }

  inline void Lock() { pthread_mutex_lock(&mu_); }

  inline void Unlock() { pthread_mutex_unlock(&mu_); }

  inline bool TryLock() { return pthread_mutex_trylock(&mu_) == 0; }

  Mutex(const Mutex &) = delete;
  Mutex &operator=(const Mutex &) = delete;

 private:
  friend class CondVar;
  pthread_mutex_t mu_;
};

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

  MutexLock(const MutexLock &) = delete;
  MutexLock &operator=(const MutexLock &) = delete;

 private:
  Mutex *const mu_;
};

// Wrapper for pthread_cond_t
class CondVar {
 public:
  CondVar() { pthread_cond_init(&cv_, nullptr); }
  ~CondVar() { pthread_cond_destroy(&cv_); }

  void Wait(Mutex *mu) { pthread_cond_wait(&cv_, &mu->mu_); }

  void Signal() { pthread_cond_signal(&cv_); }

  void Signalall() { pthread_cond_broadcast(&cv_); }

  CondVar(const CondVar &) = delete;
  CondVar &operator=(const CondVar &) = delete;

 private:
  pthread_cond_t cv_;
};

class BlockingCounter {
 public:
  explicit BlockingCounter(size_t cnt) : counter_(cnt) {}

  bool Decrement() {
    MutexLock lock(&mutex_);
    --counter_;

    if (counter_ == 0u) {
      cond_.Signalall();
    }

    return counter_ == 0u;
  }

  void Reset(size_t cnt) {
    MutexLock lock(&mutex_);
    counter_ = cnt;
  }

  void Wait() {
    MutexLock lock(&mutex_);

    while (counter_ != 0u) {
      cond_.Wait(&mutex_);
    }
  }

  BlockingCounter(const BlockingCounter &) = delete;
  BlockingCounter &operator=(const BlockingCounter &) = delete;

 private:
  Mutex mutex_;
  CondVar cond_;
  size_t counter_;
};

class RwMutex {
 public:
  RwMutex() { pthread_rwlock_init(&mu_, nullptr); }
  ~RwMutex() { pthread_rwlock_destroy(&mu_); }

  inline void ReaderLock() { pthread_rwlock_rdlock(&mu_); }
  inline void WriterLock() { pthread_rwlock_wrlock(&mu_); }

  inline void Unlock() { pthread_rwlock_unlock(&mu_); }

  RwMutex(const RwMutex &) = delete;
  RwMutex &operator=(const RwMutex &) = delete;

 private:
  pthread_rwlock_t mu_;
};

class ReaderMutexLock {
 public:
  explicit ReaderMutexLock(RwMutex *mu) : mu_(mu) { mu_->ReaderLock(); }
  ~ReaderMutexLock() { mu_->Unlock(); }

  ReaderMutexLock(const ReaderMutexLock &) = delete;
  ReaderMutexLock &operator=(const ReaderMutexLock &) = delete;

 private:
  RwMutex *mu_ = nullptr;
};

class WriterMutexLock {
 public:
  explicit WriterMutexLock(RwMutex *mu) : mu_(mu) { mu_->WriterLock(); }
  ~WriterMutexLock() { mu_->Unlock(); }

  WriterMutexLock(const WriterMutexLock &) = delete;
  WriterMutexLock &operator=(const WriterMutexLock &) = delete;

 private:
  RwMutex *mu_ = nullptr;
};

}  // namespace lib
}  // namespace perception
}  // namespace apollo