多线程

#include <iostream>#include <thread>#include <vector>#include <memory>#include <chrono>#include <mutex> //独占互斥量 using namespace std;void say_hello(){cout << "Hi!\n";}void say_hello1(){_sleep(3000);cout << "hello\n";}void ca_time(int *arr,int &len_){cout << "You only got five seconds to type the number 1~5,,ready go,,\n";_sleep(5000);cout << "Sorry time out!!\n";cout << "Ok, here is your greads:\n";for(int i = 0; i < len_; i ++){cout << arr[i] << " ";}cout << endl;cout <<"-->" << len_ << endl;return;}void fun_type(int *arr,int &len_){memset(arr,'\0',sizeof(arr));for(; len_ < 5; len_ ++){cin >> arr[len_];}}//将线程放在容器里面vector<thread> g_list;vector<shared_ptr<thread>> g_list2; //智能指针void CreateThread(){thread t(say_hello);g_list.push_back(move(t));g_list2.push_back(make_shared<thread>(say_hello)); //make_shared作用和new差不多(速度比new快)}//获得线程得IDthread::id GetThreadId(thread& t){return t.get_id();}//获得CPU的核心数(返回0获取失败)int GetCPU_concurrency(){return thread::hardware_concurrency();}void ThreadSleep(){this_thread::sleep_for(chrono::seconds(6));}int main(){////非阻塞线程//thread t1(say_hello);//t1.detach();////阻塞线程//thread t2([](void){cout << "hello,阻塞\n";}); //lambda表达式//非阻塞的线程//thread t3(say_hello1);//t3.detach();//阻塞的线程//thread t5(say_hello);//t5.join();//线程t5 会先于t3执行完,因为t3是非阻塞的 如果t3 换成t3.join()的话就会等待t3 返回以后t5才会执行(子线程与子线程之间没有等待关系)//thread t4(move(t3));//t4.join();//计时输入词语:/*int arr[100];int len = 0;thread time(ca_time,arr,ref(len));time.detach();fun_type(arr,len);*/////将线程保存于容器中//CreateThread();//for(auto& thread : g_list)//{//thread.join();//}//for(auto& thread : g_list2)//{//thread->join();//}////获取线程信息(线程ID,CPU核心数)//cout << "你的CPU核心数为:" << GetCPU_concurrency() << endl;//thread t1(say_hello);//thread t2(say_hello1);//thread t3(say_hello);//thread t4_sleep(ThreadSleep);//t1.join();//t2.join();//t3.join();//t4_sleep.join();//cout << "他们的线程id分别为:" << GetThreadId(t1)<< " "<< GetThreadId(t2)<< " " << GetThreadId(t3) << endl;return 0;}

//互斥量:

--保护多线程同时访问的共享数据

1)普通的互斥量

#include <iostream>#include <thread>#include <mutex>int a = 0;int b = 0;std::mutex lock;void fun1(){std::lock_guard<std::mutex>locker(lock); //上锁,只能允许使用此函数的进程访问共享变量a = 1;std::cout <<"fun1 a: " << a << std::endl;b = 1;std::cout <<"fun1 b: " << b << std::endl;std::cout <<"fun1 a: " << a << std::endl;std::cout <<"fun1 b: " << b << std::endl;}void fun2(){std::lock_guard<std::mutex>locker(lock);//同上a = 5;std::cout <<"fun2 a: " << a << std::endl;b = 5;std::cout <<"fun2 b: " << b << std::endl;std::cout <<"fun2 a: " << a << std::endl;std::cout <<"fun2 b: " << b << std::endl;}int main(){std::thread t1(fun1);std::thread t2(fun2);t1.join();t2.join();system("pause");return 1;}

//不使用上面两句std::lock_guard<std::mutex>locker(lock)的结果 如图(出现混乱)

2)递归互斥量

//死锁示例(普通不支持递归互斥量)struct Complex{mutex mutex;int i;Complex():i(1) {}void mul(int x){lock_guard<std::mutex>lock(mutex);i *= x;cout << "--" << i <<endl;}void div(int x){lock_guard<std::mutex>lock(mutex);i /= x;cout << "==" << i <<endl;}void both(int x, int y){lock_guard<std::mutex>lock(mutex);mul(x);div(y);}};//用递归锁改进上面的死锁struct Complex_recursion{<span style="white-space:pre"></span>std::recursive_mutex mutex;<span style="white-space:pre"></span>int i;<span style="white-space:pre"></span>Complex_recursion():i(1){}<span style="white-space:pre"></span>void mul(int x)<span style="white-space:pre"></span>{<span style="white-space:pre"></span>lock_guard<std::recursive_mutex>lock(mutex);<span style="white-space:pre"></span>i *= x;<span style="white-space:pre"></span>cout << "--" << i <<endl;<span style="white-space:pre"></span>}<span style="white-space:pre"></span>void div(int x)<span style="white-space:pre"></span>{<span style="white-space:pre"></span>std::lock_guard<std::recursive_mutex>lock(mutex);<span style="white-space:pre"></span>i /= x;<span style="white-space:pre"></span>cout << "==" << i <<endl;<span style="white-space:pre"></span>}<span style="white-space:pre"></span>void both(int x, int y)<span style="white-space:pre"></span>{<span style="white-space:pre"></span>std::lock_guard<std::recursive_mutex>lock(mutex);<span style="white-space:pre"></span>mul(x);<span style="white-space:pre"></span>div(y);<span style="white-space:pre"></span>}};<pre name="code" class="cpp">void main(){//死锁示范://Complex complex;//complex.both(32,23);//递归互斥量改进死锁//Complex_recursion complex_re;//complex_re.both(32,23);}

//带超时的互斥量tsd::timed_mutex

#include <iostream>#include <thread>#include <mutex>#include <ctime>//带超时的锁//std::timed_mutex //带超时//std::recursive_timed_mutex //带超时+递归std::timed_mutex timedMutex;void get_mutex(){std::chrono::seconds times(8); //设置时间 chrono boost的时间库 现已加入c++11豪华标准套餐//timedMutex.try_lock(); //如果已获取锁，则为值 true；否则为值 false。while(!timedMutex.try_lock_for(times)){std::cout << "001 Wait for get...\n";}//timedMutex.try_lock_until;std::cout << "001 function get_mutex have got it!\n";std::this_thread::sleep_for(std::chrono::seconds(8));timedMutex.unlock();}void try_to_get_mutex(){std::chrono::seconds times(1);while(!timedMutex.try_lock_for(times)){std::cout << "002 Wait for get...\n";}std::cout << "002 function try_to_get_mutex have got it!\n";timedMutex.unlock();}void try_to_get_mutex1(){std::chrono::seconds times(1);while(!timedMutex.try_lock_for(times)){std::cout << "003 Wait for get...\n";} std::cout << "003 function try_to_get_mutex1 have got it!\n";timedMutex.unlock();}int mian(){//std::thread t1(get_mutex);//std::thread t2(try_to_get_mutex);//t1.join();//t2.join();//通过运行可以发现当线程t1获得互斥量以后,线程t2经过8次循环获得了互斥量,因为线程t1休眠8秒,线程t2用try_lock_for(1秒)每次获取时常1秒}