MultiThreadingStudy/Docs/Jupyter笔记.2.5.原子操作.ipynb

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   "source": [
    "原子操作\n",
    "======="
   ]
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   "metadata": {},
   "source": [
    "在多线程环境中，因为多个线程可能会同时访问同一个资源，我们需要使用一些方式保证访问不发生冲突，其中最基础的方式就是原子操作。  \n",
    "原子操作是利用 CPU 提供的特性，所以不会阻塞线程。 \n",
    "线程安全方式有：  \n",
    "+ 使用设计，避免多线程中的资源共享\n",
    "+ 利用线程本地存储，使资源复制到线程本地，实现互相独立、互不干扰\n",
    "+ 使用原子操作\n",
    "+ 使用锁\n",
    "+ 使用信号量\n",
    "+ 综合使用"
   ]
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   "metadata": {},
   "source": [
    "## 全局设置，语言设置、Nuget包引用、空间引用等"
   ]
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    "//全局设置\n",
    "#!csharp\n",
    "using System.Threading;\n",
    "using System.Threading.Channels;\n",
    "using System.Threading.Tasks;\n",
    "\n",
    "//全局变量\n",
    "var noteBookThreadDesc = \"NoteBook线程\";\n",
    "\n",
    "//全局方法\n",
    "//显示线程信息\n",
    "public void ShowThreadInfo(Thread showThread=null, string describe = null)\n",
    "{\n",
    "    if(showThread == null)\n",
    "    {\n",
    "        showThread = Thread.CurrentThread;\n",
    "    }\n",
    "\n",
    "    if(string.IsNullOrWhiteSpace(describe))\n",
    "    {\n",
    "        describe = showThread.Name == null ? \"无名\" : showThread.Name;\n",
    "    }\n",
    "\n",
    "    Console.WriteLine($\"{describe}线程ID：{showThread.ManagedThreadId} \");\n",
    "    Console.WriteLine($\"{describe}线程名：{showThread.Name} \");\n",
    "    Console.WriteLine($\"{describe}线程状态：{showThread.ThreadState} \");\n",
    "    Console.WriteLine($\"{describe}线程模式：{showThread.GetApartmentState()} \");\n",
    "    Console.WriteLine($\"{describe}激活：{(showThread.IsAlive ? \"活动\" : \"非活动\")} \");\n",
    "    Console.WriteLine($\"{describe}线程池线程：{(showThread.IsThreadPoolThread ? \"是的\" : \"否\")} \");\n",
    "    Console.WriteLine($\"{describe}后台线：{(showThread.IsBackground ? \"是的\" : \"不是\")} \");\n",
    "    Console.WriteLine($\"{describe}区域：{showThread.CurrentCulture}\");\n",
    "    Console.WriteLine($\"{describe}UI区域：{showThread.CurrentUICulture}\");\n",
    "    Console.WriteLine($\"{describe}优先级：{showThread.Priority}\");\n",
    "}\n",
    "\n",
    "//显示线程状态\n",
    "public void ShowThreadState(Thread showThread=null, string describe = null)\n",
    "{\n",
    "    if(showThread == null)\n",
    "    {\n",
    "        showThread = Thread.CurrentThread;\n",
    "    }\n",
    "\n",
    "    if(string.IsNullOrWhiteSpace(describe))\n",
    "    {\n",
    "        describe = showThread.Name == null ? \"无名\" : showThread.Name;\n",
    "    }\n",
    "    Console.WriteLine($\"{describe}线程状态：{showThread.ThreadState} \");\n",
    "}"
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   "source": [
    "## .Net中的原子操作类"
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    ".Net中， System.Threading.Interlocked 类提供了用于执行原子操作的函数，这些函数接收引用参数(ref),也就是变量内存地址，然后针对该内存地址的值执行原子操作。"
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   "source": [
    "### Increment\n",
    "Interlocked.Increment 函数执行的原子操作属于 “获取-添加”分类，执行后变量的值增加1，返回的值是增加后的值，即增加前的值加1"
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    "//计数器类\n",
    "public class Counter\n",
    "{\n",
    "    //总次数\n",
    "    public static int TotalNumber = 0;\n",
    "    \n",
    "    //方法循环次数\n",
    "    public static readonly int LoopNumber = 100;\n",
    "\n",
    "    //执行\n",
    "    public static void Execute()\n",
    "    {\n",
    "        for (int i = 1; i <= LoopNumber; i++)\n",
    "        {\n",
    "            //原子操作\n",
    "            System.Threading.Interlocked.Increment(ref TotalNumber);\n",
    "        }\n",
    "        Console.WriteLine($\"线程[{Thread.CurrentThread.ManagedThreadId.ToString(\"000\")}] 执行了累加 {LoopNumber} 次，结束时 TotalNumber = {TotalNumber}\");\n",
    "    }\n",
    "}\n",
    "\n",
    "//使用域隔离和代码折叠\n",
    "{\n",
    "    var threads =  new List<Thread>()\n",
    "    {\n",
    "        new Thread(Counter.Execute){Name=\"thread_a\"},\n",
    "        new Thread(Counter.Execute){Name=\"thread_b\"}\n",
    "    };\n",
    "\n",
    "    threads.ForEach(t => t.Start());\n",
    "    threads.ForEach(t => t.Join());\n",
    "\n",
    "    //主线程信息\n",
    "    Console.WriteLine($\"主(执行)线程[{Thread.CurrentThread.ManagedThreadId.ToString(\"000\")}] 结束时，TotalLoopNumber = {Counter.TotalNumber}\");\n",
    "}\n",
    "\n",
    "//原子操作，多线程下多次执行结果相同"
   ]
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