.NET跨平台实践：再谈用C#开发Linux守护进程 — 完整篇

  1 using System;
  2 using System.Threading;
  3 using System.Timers;
  4 using System.Runtime.InteropServices;
  5 using System.IO;
  6 using System.Text;
  7 
  8 
  9 /********************************************
 10  * 一个完整的linux daemon示例，作者宇内流云 *
 11  ********************************************/
 12 
 13 namespace daemon
 14 {
 15     class Program
 16     {
 17 
 18         const string DaemonTag = "--daemon.";
 19         static void Main(string[] args)
 20         {
 21             // 判断是否已经进入Daemon状态，如果是，就直接执行后台主函数
 22             if (string.IsNullOrEmpty(Environment.GetEnvironmentVariable(DaemonTag)) == false)
 23             {
 24                 Environment.SetEnvironmentVariable(DaemonTag, null);
 25                 DaemonMain(args);
 26                 return;
 27             }
 28 
 29 
 30             // 如果还没有进入daemon状态，就作daemon处理
 31             /////////////////////////////////////////////////////
 32 
 33             int pid = fork();
 34             if (pid != 0) exit(0);
 35             setsid();
 36             pid = fork();
 37             if (pid != 0) exit(0);
 38             umask(0);
 39 
 40 
 41             // 这儿已经进入“守护进程”工作状态了!
 42 
 43             // 关闭所有打开的文件描述符
 44             int max = open("/dev/null", 0);
 45             for (var i = 0; i <= max; i++) { close(i); }
 46 
 47 
 48             // 设置标记，防止重复运行进入
 49             Environment.SetEnvironmentVariable(DaemonTag,"yes");
 50 
 51 
 52             //为execp参数重组参数
 53             var args1 = args == null ? new string[2] : new string[args.Length + 2];
 54 
 55             args1[0] = "MyDaemon";
 56             args1[1] = Path.Combine(Environment.CurrentDirectory, Thread.GetDomain().FriendlyName);
 57 
 58             if (args1.Length > 2)
 59             {
 60                 for (var i = 0; i < args.Length; i++)
 61                 { args1[i + 2] = args[i]; }
 62             }
 63 
 64 
 65             //守护状态下重新加载和运行本程序
 66             execvp("mono", args1);
 67 
 68         }
 69 
 70 
 71         /// <summary>
 72         /// Daemon工作状态的主方法
 73         /// </summary>
 74         /// <param name="aargs"></param>
 75         static void DaemonMain(string[] aargs)
 76         {
 77             //启动一个线程去处理一些事情
 78             (new Thread(DaemonWorkFunct) { IsBackground = true }).Start();
 79 
 80 
 81             //daemon时，控制台输入、输出流已经关闭
 82             //请不要再用Console.Write/Read等方法
 83 
 84             //阻止daemon进程退出
 85             (new AutoResetEvent(false)).WaitOne();
 86 
 87         }
 88 
 89 
 90         static FileStream fs;
 91         static int count = 0;
 92         static void DaemonWorkFunct() {
 93             fs = File.Open("/tmp/daemon.txt", FileMode.OpenOrCreate);
 94             var t = new System.Timers.Timer() { Interval = 1000 };
 95             t.Elapsed += OnElapsed;
 96             t.Start();
 97         }
 98         private static void OnElapsed(object sender, ElapsedEventArgs e)
 99         {
100             var s = DateTime.Now.ToString("yyy-MM-dd HH:mm:ss") + "\n";
101             var b = Encoding.ASCII.GetBytes(s);
102             fs.Write(b, 0, b.Length);
103             fs.Flush();
104 
105             count++;
106             if (count > 100) {
107                 fs.Close();
108                 fs.Dispose();
109                 exit(0);
110             }
111 
112         }
113 
114 
115 
116         [DllImport("libc", SetLastError = true)]
117         static extern int fork();
118 
119         [DllImport("libc", SetLastError = true)]
120         static extern int setsid();
121 
122         [DllImport("libc", SetLastError = true)]
123         static extern int umask(int mask);
124 
125         [DllImport("libc", SetLastError = true)]
126         static extern int open([MarshalAs(UnmanagedType.LPStr)]string pathname, int flags);
127 
128         [DllImport("libc", SetLastError = true)]
129         static extern int close(int fd);
130 
131         [DllImport("libc", SetLastError = true)]
132         static extern int exit(int code);
133 
134         [DllImport("libc", SetLastError = true)]
135         static extern int execvp([MarshalAs(UnmanagedType.LPStr)]string file, string[] argv);
136 
137 
138     }
139 
140 }