使数据可用于FileSystemWatcher事件处理程序

Question

I have C# 5.0 application that involves using a FileSystemWatcher on a number of different directories.

This application contains a List<> of objects. Each object describes the directory being monitored, as well as a lot of other data that needs to be accessed by the FileSystemWatcher event handler. These objects are of type CustomDirectorySetting .

This is a server application, and I expect that the FileSystemWatcher 's event handlers will be called quite often. I must ensure that they can keep up with their work and not fall behind responding to file change events. It may be worth adding that the directories that are being monitored are local to the machine running the application.

How can I make the FileSystemWatcher 's CustomDirectorySetting object available quickly to the event handler of each FileSystemWatcher , and should I be looking at using the Task Parallel Library for this implementation? I'm a novice at TPL, so I'd appreciate your thoughts on what aspects would be most appropriate.

Answer 1

由于FileSystemWatcher似乎可用作基类，因此您可以从中派生自己的类并添加CustomDirectorySetting类型的属性。

Answer 2

Contrary to what nvoigt said, I think creating a type derived from FileSystemWatcher is an overkill.

A better option would be to have the event handler on your CustomDirectorySetting type, which means it will be able to access the data you need through this .

class CustomDirectorySetting
{
    public string Directory { get; set; }

    public void OnChanged(object sender, FileSystemEventArgs e)
    {
        // your code here
    }
}

…

List<CustomDirectorySetting> list = …;
foreach (var setting in list)
{
    var fsw = new FileSystemWatcher(setting.Directory);
    fsw.Changed += setting.OnChanged;
    fsw.EnableRaisingEvents = true;
}

Another option is to use a lambda:

private static void OnChanged(
    CustomDirectorySetting setting, FileSystemEventArgs eventArgs)
{
    // your code here
}

…

foreach (var setting in list)
{
    var fsw = new FileSystemWatcher(setting.Directory);
    CustomDirectorySetting settingCopy = setting;
    fsw.Changed += (sender, eventArgs) => OnChanged(settingCopy, eventArgs);
    fsw.EnableRaisingEvents = true;
}

In this case, it's probably a good idea not to use the loop variable directly in the lambda, because it wouldn't work correctly in older versions of C#.