DirectoryInfoExtensions.cs

ディレクトリのサイズを素早く返す

// >= .NET 5.0 
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
public static class DirectoryInfoExtensions
{
	/// <summary>
	/// ディレクトリのサイズを返します。
	/// </summary>
	public static long GetDirectorySize(this DirectoryInfo directoryInfo)
	{
		long startDirectorySize = 0L;
		if (directoryInfo == null || !directoryInfo.Exists)
		{
			return startDirectorySize;
		}
		var eo = new EnumerationOptions
		{
			AttributesToSkip = FileAttributes.ReparsePoint | FileAttributes.Offline | FileAttributes.Device,
			ReturnSpecialDirectories = false,
			RecurseSubdirectories = false,
		};
		foreach (var fileInfo in directoryInfo.EnumerateFiles("*", eo))
		{
			Interlocked.Add(ref startDirectorySize, fileInfo.Length);
		}
		Parallel.ForEach(directoryInfo.EnumerateDirectories("*", eo),
			subDirectory => Interlocked.Add(ref startDirectorySize, GetDirectorySize(subDirectory)));
		return startDirectorySize;
	}
}
/*
class Program
{
	static void Main()
	{
		var di = new System.IO.DirectoryInfo(@"C:\Program Files");
		Console.WriteLine(di.FullName);
		Console.WriteLine($"{di.GetDirectorySize():N0} Bytes");
		Console.ReadLine();
	}
}
*/