System.IO.FileSentry

FileSentry is a improved System.IO.FileSystemWatcher, which can be used to suppress duplicate events that fire on a single change to the file and remove event handlers during disposal.

This project is based on:

• Enhanced-FileSystemWatcher which was written by Vipul Prashar.
• System.IO.EnhancedFileSystemWatcher which was written by Stef Heyenrath.

NuGet

Frameworks

The following frameworks are supported:

• net 4.5 and up
• netstandard 2.0

Information

Introduction

This project describes an improved System.IO.FileSystemWatcher class which can be used to suppress duplicate events that fire on a single change to the file and remove event handlers during disposal.

Background

The System.IO.FileSystemWatcher class helps the user to monitor a directory and multiple or single file within a directory. Whenever a change (Creation, Modification, Deletion or Renaming) is detected, an appropriate event is raised. However, duplicate events fire depending on the software that is being used to modify the file.

Observation

Using Notepad, modifying the contents of a file results in 2 Changed events being fired. Doing the same using Textpad results in 4 Changed events being fired.

Using Textpad, creating a file in a directory that was being watched resulted in 1 Created and 3 Changed events being fired. In case of Notepad, Created followed by Deleted!!, followed by Created and 3 Changed Events were observed.

Proposed Solution

We need to keep track of the event as they get fired and suppress subsequent events that occur within pre-determined interval.

Example

class Program
{
    static void Main(string[] args)
    {
        using (var fsw = new FileSentry(@"C:\temp", "*.txt"))
        {
            fsw.Created += fsw_Created;
            fsw.Changed += fsw_Changed;
            fsw.Deleted += fsw_Deleted;
            fsw.Renamed += fsw_Renamed;
            fsw.EnableRaisingEvents = true;
            Console.ReadLine();
        }
    }

    static void fsw_Renamed(object sender, RenamedEventArgs e)
    {
        Console.WriteLine("Renamed: FileName - {0}, ChangeType - {1}, Old FileName - {2}", e.Name, e.ChangeType, e.OldName);
    }

    static void fsw_Deleted(object sender, FileSystemEventArgs e)
    {
        Console.WriteLine("Deleted: FileName - {0}, ChangeType - {1}", e.Name, e.ChangeType);
    }

    static void fsw_Changed(object sender, FileSystemEventArgs e)
    {
        Console.WriteLine("Changed: FileName - {0}, ChangeType - {1}", e.Name, e.ChangeType);
    }

    static void fsw_Created(object sender, FileSystemEventArgs e)
    {
        Console.WriteLine("Created: FileName - {0}, ChangeType - {1}", e.Name, e.ChangeType);
    }
}