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muduo封装MutexLock MutexLockGuard Condition

文章目录
  1. 1. MutexLock
  2. 2. MutexLockGuard
  3. 3. Condition
  4. 4. 参考资料

MutexLock

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class CAPABILITY("mutex") MutexLock : noncopyable
{
 public:
  MutexLock()
    : holder_(0)
  {
    MCHECK(pthread_mutex_init(&mutex_, NULL));
  }

  ~MutexLock()
  {
    assert(holder_ == 0);
    MCHECK(pthread_mutex_destroy(&mutex_));
  }

  // must be called when locked, i.e. for assertion
  bool isLockedByThisThread() const
  {
    return holder_ == CurrentThread::tid();
  }

  void assertLocked() const ASSERT_CAPABILITY(this)
  {
    assert(isLockedByThisThread());
  }

  // internal usage

  void lock() ACQUIRE()
  {
    MCHECK(pthread_mutex_lock(&mutex_));
    assignHolder();
  }

  void unlock() RELEASE()
  {
    unassignHolder();
    MCHECK(pthread_mutex_unlock(&mutex_));
  }

  pthread_mutex_t* getPthreadMutex() /* non-const */
  {
    return &mutex_;
  }

 private:
  friend class Condition;

  class UnassignGuard : noncopyable
  {
   public:
    explicit UnassignGuard(MutexLock& owner)
      : owner_(owner)
    {
      owner_.unassignHolder();
    }

    ~UnassignGuard()
    {
      owner_.assignHolder();
    }

   private:
    MutexLock& owner_;
  };

  void unassignHolder()
  {
    holder_ = 0;
  }

  void assignHolder()
  {
    holder_ = CurrentThread::tid();
  }

  pthread_mutex_t mutex_;
  pid_t holder_;
};

MutexLockGuard

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class SCOPED_CAPABILITY MutexLockGuard : noncopyable
{
 public:
  explicit MutexLockGuard(MutexLock& mutex) ACQUIRE(mutex)
    : mutex_(mutex)
  {
    mutex_.lock();
  }

  ~MutexLockGuard() RELEASE()
  {
    mutex_.unlock();
  }

 private:

  MutexLock& mutex_;
};

}  // namespace muduo

// Prevent misuse like:
// MutexLockGuard(mutex_);
// A tempory object doesn't hold the lock for long!
#define MutexLockGuard(x) error "Missing guard object name"

Condition

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// Use of this source code is governed by a BSD-style license
// that can be found in the License file.
//
// Author: Shuo Chen (chenshuo at chenshuo dot com)

#ifndef MUDUO_BASE_CONDITION_H
#define MUDUO_BASE_CONDITION_H

#include "muduo/base/Mutex.h"

#include <pthread.h>

namespace muduo
{

class Condition : noncopyable
{
 public:
  explicit Condition(MutexLock& mutex)
    : mutex_(mutex)
  {
    MCHECK(pthread_cond_init(&pcond_, NULL));
  }

  ~Condition()
  {
    MCHECK(pthread_cond_destroy(&pcond_));
  }

  void wait()
  {
    MutexLock::UnassignGuard ug(mutex_);
    MCHECK(pthread_cond_wait(&pcond_, mutex_.getPthreadMutex()));
  }

  // returns true if time out, false otherwise.
  bool waitForSeconds(double seconds);

  void notify()
  {
    MCHECK(pthread_cond_signal(&pcond_));
  }

  void notifyAll()
  {
    MCHECK(pthread_cond_broadcast(&pcond_));
  }

 private:
  MutexLock& mutex_;
  pthread_cond_t pcond_;
};

}  // namespace muduo

#endif  // MUDUO_BASE_CONDITION_H
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bool muduo::Condition::waitForSeconds(double seconds)
{
  struct timespec abstime;
  // FIXME: use CLOCK_MONOTONIC or CLOCK_MONOTONIC_RAW to prevent time rewind.
  clock_gettime(CLOCK_REALTIME, &abstime);

  const int64_t kNanoSecondsPerSecond = 1000000000;
  int64_t nanoseconds = static_cast<int64_t>(seconds * kNanoSecondsPerSecond);

  abstime.tv_sec += static_cast<time_t>((abstime.tv_nsec + nanoseconds) / kNanoSecondsPerSecond);
  abstime.tv_nsec = static_cast<long>((abstime.tv_nsec + nanoseconds) % kNanoSecondsPerSecond);

  MutexLock::UnassignGuard ug(mutex_);
  return ETIMEDOUT == pthread_cond_timedwait(&pcond_, mutex_.getPthreadMutex(), &abstime);
}

参考资料

  • muduo base
  • Linux 多线程服务端编程–使用 muduo C++ 网络库