Question

我正在开发一个database file system。它包含一个多目录观察程序，它是一个Windows服务，它使用来自.net的file system watcher类。

我想在单独的线程上运行每个观察者类。线程无法在.net中扩展，因为它是“密封”的。我想要的是，在相关的线程中运行我的观察者类的所有方法。我怎样才能做到这一点？

编辑 -

以下是我的基础守望者课程。

 public abstract class WatcherBase
  {
    private IWatchObject _watchObject;

    public WatcherBase() { }

    public WatcherBase(IWatchObject watchObject, bool canPauseAndContinue)
    {
        _watchObject = watchObject;
        CanPauseAndContinue = canPauseAndContinue;
    }

    public bool CanPauseAndContinue { get; set; }

    public IWatchObject ObjectToWatch
    {
        get
        { 
            return _watchObject; 
        }
    }

    public abstract void Start();
    public abstract void Pause();
    public abstract void Continue();
    public abstract void Stop();
}

以下是我从WatcherBase类扩展的目录监视器类

  namespace RankFs.WatcherService
  {
    public class DirectoryWatcher : WatcherBase
    {
    private WatchDirectory _directoryToWatch;
    private FileSystemWatcher _watcher;

    public DirectoryWatcher(WatchDirectory directory, bool CanPauseAndContinue)
        :base(directory ,CanPauseAndContinue)
    {
        _directoryToWatch = directory;
        _watcher = new FileSystemWatcher(_directoryToWatch.Path);
        _watcher.IncludeSubdirectories = _directoryToWatch.WatchSubDirectories;
        _watcher.Created +=new FileSystemEventHandler(Watcher_Created);
        //_watcher.Changed +=new FileSystemEventHandler(Watcher_Changed);
        _watcher.Deleted +=new FileSystemEventHandler(Watcher_Deleted);
        _watcher.Renamed +=new RenamedEventHandler(Watcher_Renamed);
    }

    public WatchDirectory DirectoryToWatch
    {
        get 
        {
            return _directoryToWatch;
        }
    }

    public override void Start()
    {
        _watcher.EnableRaisingEvents = true;
    }

    public override void Pause()
    {
        _watcher.EnableRaisingEvents = false;
    }

    public override void Continue()
    {
        _watcher.EnableRaisingEvents = true;
    }

    public override void Stop()
    {
        _watcher.EnableRaisingEvents = false;
    }

    private void Watcher_Created(object sender, FileSystemEventArgs e)
    {
       // adds a new file entry to database 
    }

    private void Watcher_Deleted(object sender, FileSystemEventArgs e)
    {
       //updates the database(deleted file)
    }

    private void Watcher_Renamed(object sender, RenamedEventArgs e)
    {
   //updates the database(renamed file)
    }
} }

我现在陷入困境。请帮助我。

Answer 1

FileSystemWatcher将在单独的线程中触发事件。事件处理程序内部的逻辑需要考虑这一事实并执行所需的任何同步。

如果运行以下示例，您将看到Changed事件处理程序将在另一个线程中运行。

public static void Main(string[] args)
{
    Directory.CreateDirectory("dir1");
    Directory.CreateDirectory("dir2");
    Directory.CreateDirectory("dir3");

    Console.WriteLine("Main Thread Id: {0}", 
        Thread.CurrentThread.ManagedThreadId);

    const int watcherCount = 3;
    string[] dirs = new string[] { "dir1", "dir2", "dir3" };

    for (int i = 0; i < watcherCount; i++)
    {
        var watcher = new FileSystemWatcher();
        watcher.Path = dirs[i];
        watcher.Changed += (sender, e) =>
        {
            Console.WriteLine("File: {0} | Thread: {1}", e.Name,
                Thread.CurrentThread.ManagedThreadId);

            Thread.Sleep(2000); // Simulate long operation
        };
        watcher.EnableRaisingEvents = true;
    }

    File.WriteAllText(@"dir1\test1", "hello");
    File.WriteAllText(@"dir2\test2", "hello");
    File.WriteAllText(@"dir3\test3", "hello");

    Thread.Sleep(10000);
}

运行此示例时，我获得了以下输出：

// Main Thread Id: 1
// File: test1 | Thread: 3
// File: test2 | Thread: 4
// File: test3 | Thread: 5
// File: test1 | Thread: 3
// File: test2 | Thread: 4
// File: test3 | Thread: 5

<强>更新由于您在FileSystemWatcher中使用事件方法，因此您已经在使用多线程方法，因为每个FileSystemWatcher实例的事件处理程序将以异步方式在单独的线程中触发。

Answer 2

我会编写一个wraps or adapts FileSystemWatcher的新类，然后在新线程上启动我的新类。适配器类将处理来自FSW类的通知，然后您可以找出将这些通知广播或中继到某种编组功能的最佳方法。

有几种不同的方式来发布新线程和数十亿关于如何做的教程，所以我不打算在这里回答这个问题。

如何为每个文件系统观察程序分配单独的线程？

2 个答案: