add 并发编程

并发编程/joinable_join_detach.cpp

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+/*
+ * @Author: your name
+ * @Date: 2020-04-10 17:55:46
+ * @LastEditTime: 2020-04-10 19:04:08
+ * @LastEditors: Please set LastEditors
+ * @Description: In User Settings Edit
+ * @FilePath: /C++课程学习记录/thread多线程/test.cpp
+ */
+
+// join()
+/**
+ * 一旦线程开始，我们要想等待线程完成，需要在该对象上调用join()
+ * 双重join将导致程序终止
+ * 在join之前我们应该检查显示是否可以被join,通过使用joinable()
+*/
+
+// detach()
+/**
+ * 这用于从父线程分离新创建的线程
+ * 在分离线程之前，请务必检查它是否可以joinable，
+ * 否则可能会导致两次分离，并且双重detach()将导致程序终止
+ * 如果我们有分离的线程并且main函数正在返回，那么分离的线程执行将被挂起
+*/
+
+#include <iostream>
+#include <thread>
+#include <chrono>
+#include <mutex>
+
+using namespace std;
+
+void run(int count) {
+    while (count-- > 0) {
+        cout << count << endl;
+    }
+    std::this_thread::sleep_for(chrono::seconds(3));
+}
+
+int main() {
+    thread t1(run, 10);
+    cout << "main()" << endl;
+    if(t1.joinable()) t1.join();
+    // t1.detach(); // erroe 必须检查是否可以joinable()
+    if(t1.joinable()) t1.detach();
+    cout << "main() after" << endl;
+    return 0;
+}

并发编程/mutex并发编程.cpp

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+/*
+ * @Author: your name
+ * @Date: 2020-04-10 19:05:51
+ * @LastEditTime: 2020-04-10 19:18:25
+ * @LastEditors: Please set LastEditors
+ * @Description: In User Settings Edit
+ * @FilePath: /C++课程学习记录/thread多线程/test.cpp
+ */
+
+#include <iostream>
+#include <mutex>
+#include <thread>
+
+using namespace std;
+
+int sum = 0; //shared
+
+mutex m; // 与 lock unlock 成对使用
+
+/*
+mutex对象是一个lockable的对象，当关键区域需要被互斥访问的时候被用来当作信号
+调用该函数后，调用函数会锁定mutex，在有些情况下调用函数会阻塞。
+1、如果mutex当前没有被任何其他线程locked，则调用线程lock这个mutex对象（从此刻到直到其成员函数unlock被调用，当前线程拥有mutex对象）。
+2、如果mutex目前被其他线程locked，则当前线程阻塞直到mutex被其他线程unlock。
+3、如果mutex目前被当前线程lock，则会产生死锁错误。大部分情况会崩溃，因为mutex不支持递归。
+*/
+
+void *countgold() {
+    int i; //local to each thread
+    for (i = 0; i < 10000000; i++) {
+        m.lock();
+        sum += 1;
+        m.unlock();
+    }
+    return NULL;
+}
+
+int main() {
+    thread t1(countgold);
+    thread t2(countgold);
+
+    //Wait for both threads to finish
+    t1.join();
+    cout << "1\n";
+    t2.join();
+    cout << "2\n";
+
+    cout << "sum = " << sum << endl;
+    return 0;
+}

并发编程/多线程在函数和lambda算子中.cpp

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+/*
+ * @Author: your name
+ * @Date: 2020-04-10 17:28:24
+ * @LastEditTime: 2020-04-10 18:50:14
+ * @LastEditors: Please set LastEditors
+ * @Description: In User Settings Edit
+ * @FilePath: /C++课程学习记录/thread多线程/intro.cpp
+ */
+
+#include <iostream>
+#include <thread> // 线程库 编译时要加 -pthread 参数
+#include <chrono> // hrono 时钟库，以各种精度跟踪时间的类型的灵活汇集
+
+using namespace std::chrono;
+using namespace std;
+
+using ull = unsigned long long;
+ull OddSum = 0;
+ull EvenSum = 0;
+
+void findEven(ull start, ull end) {
+    for (ull i = start; i <= end; ++i)
+        if ((i & 1) == 0)
+            EvenSum += i;
+}
+
+void findOdd(ull start, ull end) {
+    for (ull i = start; i <= end; ++i)
+        if ((i & 1) == 1)
+            OddSum += i;
+}
+
+int main() {
+
+    ull start = 0, end = 1900000000;
+
+    // 引入线程t1, t2
+    auto startTime = high_resolution_clock::now(); // 高分辨率时钟
+    // findOdd(start, end); // 寻找奇数
+    // findEven(start, end); // 寻找偶数
+
+    // std::thread t1(findOdd, start, end);
+    // 或者将t1线程的 定义语句和函数 利用lambda算子合并
+    std::thread t1([](int start, int end){int i = 0; for(int i = start; i < end; i ++) { if(i & 1 == 1) OddSum += 1; }}, start, end);
+    t1.join();
+
+    std::thread t2(findEven, start, end);
+    t2.join();
+
+    auto stopTime = high_resolution_clock::now();
+    auto duration = duration_cast<microseconds>(stopTime - startTime);
+
+    cout << "EvenSum = " << EvenSum << endl;
+    cout << "OddSum = " << OddSum << endl;
+    cout << "duration = " << duration.count() / 1000000 << endl;
+    return 0;
+}

并发编程/多线程在类中.cpp

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+/*
+ * @Author: your name
+ * @Date: 2020-04-10 18:02:41
+ * @LastEditTime: 2020-04-10 18:58:01
+ * @LastEditors: Please set LastEditors
+ * @Description: In User Settings Edit
+ * @FilePath: /C++课程学习记录/thread多线程/point.cpp
+ */
+
+#include <iostream>
+#include <thread>
+
+using namespace std;
+
+// 3.functor (Funciton Object)
+class Base {
+   public:
+   // 重载operator ()
+    void operator()(int x) {
+        while (x-- > 0) {
+            cout << x << endl;
+        }
+    }
+    // 非静态成员
+    void fun1(int x) {
+        while (x-- > 0) {
+            cout << x << endl;
+        }
+    }
+    // 静态成员
+    static void fun2(int x) {
+        while (x-- > 0) {
+            cout << x << endl;
+        }
+    }
+};
+
+int main() {
+    thread t(Base(), 10);
+    // Base b;
+    // thread t(&Base::fun1, &b, 10);
+    // thread t(&Base::fun2, 10);
+    t.join();
+    return 0;
+}