c++ 线程 单例模式

 

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <mutex>
#include <thread>
using namespace std;

#define ll long long

const int maxn=1e5+10;

class Singleton {
public:
    static Singleton* getInstance() {
        if (instance == nullptr) {
            lock_guard<mutex> lock(mtx);
            if (instance == nullptr)
                instance = new Singleton();
        }
        return instance;
    }

    void dosomething() {
    }

    static void destoryInstance() {
        if (instance != nullptr) {
            delete instance;
            instance = nullptr;
        }
    }
private:
    Sinleton(const Singleton&) = delete;
    Singleton& operator=(const Singleton&) = delete;

    static Singleton *instance;
    static mutex mtx;
};

void threadFunc(int id)
{
    cout << "thread " + to_string(id) << endl;
    Singleton *s = Singleton::getInstance();
    s -> dosomething();
}

Singleton * Singleton::instance = nullptr;
mutex Singleton::mtx;

int main()
{
    thread t1(threadFunc, 1);
    thread t2(threadFunc, 2);
    thread t3(threadFunc, 3);
    t1.join();
    t2.join();
    t3.join();
    Singleton::destoryInstance();
    return 0;
}