From 919e5f28b77de620845846f9f74e9583e7f3d436 Mon Sep 17 00:00:00 2001
From: frsama <108132842+frsama@users.noreply.github.com>
Date: Tue, 9 Aug 2022 15:52:14 +0800
Subject: [PATCH] Update main.cpp
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1.将和用户相关的若干变量、结构体和函数封装成了类。
2.给用户类的几个哈希表上了锁。
3.将线程池改为类实现，丰富了功能。线程池改为常驻固定个数的工作线程，使用了条件变量，任务队列中无任务时工作线程会一直wait。
---
 main.cpp | 164 +++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 118 insertions(+), 46 deletions(-)

diff --git a/main.cpp b/main.cpp
index f4ecab8..f3a33e9 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2,68 +2,139 @@
 #include <functional>
 #include <iostream>
 #include <sstream>
-#include <cstdlib>
 #include <string>
 #include <thread>
 #include <map>
+#include <chrono>
+#include <shared_mutex>
+#include <condition_variable>
+#include <queue>
 
+#define MAX_THREAD_N 8
 
-struct User {
-    std::string password;
-    std::string school;
-    std::string phone;
-};
+//改用类实现，原来的几个变量、数据结构和函数都是强耦合关系，应该封装在一起
+class Users {
+    struct User {
+        std::string password;
+        std::string school;
+        std::string phone;
+    };
 
-std::map<std::string, User> users;
-std::map<std::string, long> has_login;  // 换成 std::chrono::seconds 之类的
-
-// 作业要求1：把这些函数变成多线程安全的
-// 提示：能正确利用 shared_mutex 加分，用 lock_guard 系列加分
-std::string do_register(std::string username, std::string password, std::string school, std::string phone) {
-    User user = {password, school, phone};
-    if (users.emplace(username, user).second)
-        return "注册成功";
-    else
-        return "用户名已被注册";
-}
+    std::map<std::string, User> users;
+    std::map<std::string, std::chrono::_V2::steady_clock::time_point> has_login; // 换成 std::chrono::seconds 之类的
+    std::shared_mutex users_mtx;
+    std::shared_mutex has_login_mtx;
 
-std::string do_login(std::string username, std::string password) {
-    // 作业要求2：把这个登录计时器改成基于 chrono 的
-    long now = time(NULL);   // C 语言当前时间
-    if (has_login.find(username) != has_login.end()) {
-        int sec = now - has_login.at(username);  // C 语言算时间差
-        return std::to_string(sec) + "秒内登录过";
+public:
+    // 作业要求1：把这些函数变成多线程安全的
+    // 提示：能正确利用 shared_mutex 加分，用 lock_guard 系列加分
+    std::string do_register(std::string username, std::string password, std::string school, std::string phone) {
+        std::cout << "in do_register" << std::endl;
+        User user = {password, school, phone};
+        std::unique_lock lck(users_mtx);
+        if (users.emplace(username, user).second)
+            return "注册成功";
+        else
+            return "用户名已被注册";
     }
-    has_login[username] = now;
 
-    if (users.find(username) == users.end())
-        return "用户名错误";
-    if (users.at(username).password != password)
-        return "密码错误";
-    return "登录成功";
-}
+    std::string do_login(std::string username, std::string password) {
+        // 作业要求2：把这个登录计时器改成基于 chrono 的
+        std::cout<<"in do_login"<<std::endl;
+        auto now = std::chrono::steady_clock::now();
+        std::shared_lock s_lck1(has_login_mtx);
+        if (has_login.find(username) != has_login.end()) {
+            auto dt = now - has_login[username];
+            auto sec = std::chrono::duration_cast<std::chrono::seconds>(dt).count();  
+            return std::to_string(sec) + "秒内登录过";
+        }
+        s_lck1.unlock();
 
-std::string do_queryuser(std::string username) {
-    auto &user = users.at(username);
-    std::stringstream ss;
-    ss << "用户名: " << username << std::endl;
-    ss << "学校:" << user.school << std::endl;
-    ss << "电话: " << user.phone << std::endl;
-    return ss.str();
-}
+        std::unique_lock u_lck1(has_login_mtx);
+        has_login[username] = now;
+        u_lck1.unlock();
+
+        std::shared_lock s_lck2(users_mtx);
+        if (users.find(username) == users.end())
+            return "用户名错误";
+        if (users.at(username).password != password)
+            return "密码错误";
+        return "登录成功";
+    }
+
+    std::string do_queryuser(std::string username) {
+        std::cout<<"in do_queryuser"<<std::endl;
+        std::stringstream ss;
+        std::shared_lock lck(users_mtx);
+        if(users.find(username)==users.end()){
+            return ss.str();
+        }
+        auto &user = users.at(username);
+        ss << "用户名: " << username << std::endl;
+        ss << "学校:" << user.school << std::endl;
+        ss << "电话: " << user.phone << std::endl;
+        return ss.str();
+    }
 
+} users;
 
-struct ThreadPool {
-    void create(std::function<void()> start) {
+//改用类实现
+class ThreadPool {
+    int thread_num;
+    std::vector<std::thread> threads;
+    bool activate;//用来关闭工作线程
+
+    std::queue<std::function<void()>> missions_queue;
+    std::mutex mtx;//用来独占missions_queue
+    std::condition_variable cv;//用来控制工作线程等待任务队列
+
+public:
+    ThreadPool(int num = MAX_THREAD_N):thread_num(num), threads(num), activate(true){
+        for(int i = 0; i<thread_num; ++i){
+            //使用cv实现，每个工作线程常驻，避免重复构造和析构std::thread，没有任务就wait，
+            threads[i]=std::thread(&ThreadPool::working,this);
+        }
+    }
+    ~ThreadPool(){
+        while (missions_queue.size()){
+            std::this_thread::sleep_for(std::chrono::seconds(1));
+        }
+        activate=false;
+        cv.notify_all();
+        for(auto &t:threads){
+            t.join();
+        }
+    }
+    void create(std::function<void()> start)
+    {
         // 作业要求3：如何让这个线程保持在后台执行不要退出？
         // 提示：改成 async 和 future 且用法正确也可以加分
-        std::thread thr(start);
+        //用cv改成工作线程常驻，等待任务队列的形式。
+        std::unique_lock lck(mtx);
+        missions_queue.push(start);
+        lck.unlock();
+        cv.notify_one();
+    }
+
+    void working(){
+        std::unique_lock lck(mtx);
+        while(activate){
+            if(missions_queue.size()==0){
+                cv.wait(lck);
+                continue;
+            }
+            std::function<void()> f{[](){}};
+            f = missions_queue.front();
+            missions_queue.pop();
+            lck.unlock();
+            f();
+            lck.lock();
+        }
     }
 };
 
 ThreadPool tpool;
 
-
 namespace test {  // 测试用例？出水用力！
 std::string username[] = {"张心欣", "王鑫磊", "彭于斌", "胡原名"};
 std::string password[] = {"hellojob", "anti-job42", "cihou233", "reCihou_!"};
@@ -74,16 +145,17 @@ std::string phone[] = {"110", "119", "120", "12315"};
 int main() {
     for (int i = 0; i < 262144; i++) {
         tpool.create([&] {
-            std::cout << do_register(test::username[rand() % 4], test::password[rand() % 4], test::school[rand() % 4], test::phone[rand() % 4]) << std::endl;
+            std::cout << users.do_register(test::username[rand() % 4], test::password[rand() % 4], test::school[rand() % 4], test::phone[rand() % 4]) << std::endl;
         });
         tpool.create([&] {
-            std::cout << do_login(test::username[rand() % 4], test::password[rand() % 4]) << std::endl;
+            std::cout << users.do_login(test::username[rand() % 4], test::password[rand() % 4]) << std::endl;
         });
         tpool.create([&] {
-            std::cout << do_queryuser(test::username[rand() % 4]) << std::endl;
+            std::cout << users.do_queryuser(test::username[rand() % 4]) << std::endl;
         });
     }
 
     // 作业要求4：等待 tpool 中所有线程都结束后再退出
+    // 结束自动调用析构函数，析构函数会逐个join
     return 0;
 }