hierarchical mutex-优快云博客

本文链接：https://blog.youkuaiyun.com/wangzhicheng1983/article/details/63682941

本文介绍了一种基于层级概念的互斥锁实现方法，通过维护每个线程的层级值来确保正确的锁定顺序，防止死锁发生。代码示例展示了如何使用此类互斥锁并提供了简单的应用程序验证其功能。

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/****************************************************************************
@File Name: hierarchical_mutex.h
@Author: 
@mail: 
@Created Time: Sun 19 Mar 2017 09:17:24 AM CST
****************************************************************************/
#ifndef HIERARCHICAL_MUTEX_H
#define HIERARCHICAL_MUTEX_H
#include <thread>
#include <mutex>
#include <stdexcept>
#include <climits>
namespace hierarchical_mutex
{
using namespace std;
class HierarchicalMutex
{
private:
	mutex m_lock;
	unsigned long const m_current_value;		// current hierarchical value
	unsigned long m_previous_value;				// previous hierarchical value
	static thread_local unsigned long m_thisthread_value;
private:
	inline void check_hierarchy_violation()
	{
		if(m_thisthread_value <= m_current_value)
		{
			throw logic_error("mutex hierarchy violation...!\n");
		}
	}
	inline void update_hierarchy_value()
	{
		m_previous_value = m_thisthread_value;
		m_thisthread_value = m_current_value;
	}
public:
	explicit HierarchicalMutex(unsigned long value):m_current_value(value), m_previous_value(0)
	{
	}
	void lock();
	void unlock();
	bool try_lock();
};
}
#endif

/****************************************************************************
@File Name: hierarchical_mutex.h
@Author: 
@mail: 
@Created Time: Sun 19 Mar 2017 09:17:24 AM CST
****************************************************************************/
#include "hierarchical_mutex.h"
namespace hierarchical_mutex
{
thread_local unsigned long HierarchicalMutex::m_thisthread_value(ULONG_MAX);
void HierarchicalMutex::lock()
{
	check_hierarchy_violation();
	m_lock.lock();
	update_hierarchy_value();
}
void HierarchicalMutex::unlock()
{
	m_thisthread_value = m_previous_value;
	m_lock.unlock();
}
bool HierarchicalMutex::try_lock()
{
	check_hierarchy_violation();
	if(!m_lock.try_lock()) return false;
	update_hierarchy_value();
	return true;
}
}

/****************************************************************************
@File Name: main.cpp
@Author: 
@mail: 
@Created Time: Sun 19 Mar 2017 09:50:25 AM CST
****************************************************************************/
#include "hierarchical_mutex.h"
#include <iostream>
using namespace hierarchical_mutex;
HierarchicalMutex hm0(10);
HierarchicalMutex hm1(8);
void do_low_level()
{
	cout << "do_low_level()...!" << endl;
}
void do_high_level()
{
	cout << "do_high_level()...!" << endl;
}
void low_level_func()
{
	lock_guard<HierarchicalMutex>lk(hm1);
	do_low_level();
}
void high_level_func()
{
	lock_guard<HierarchicalMutex>lk(hm1);
	try
	{
		low_level_func();
	}
	catch(exception &e)
	{
		cerr << e.what();
	}
}
int main()
{
	thread th0(high_level_func);
	th0.join();

	return 0;
}

CC=g++
all:
	$(CC) -std=c++11 -g -o hierarchical_mutexTest main.cpp hierarchical_mutex.cpp hierarchical_mutex.h -pthread