There is a new feature in Directory
and DirectoryInfo
in .NET 4 that allows them to return an IEnumerable
instead of an array, and start returning results before reading all the directory contents.
Directory.EnumerateFileSystemEntries
method overloadspublic bool IsDirectoryEmpty(string path)
{
IEnumerable<string> items = Directory.EnumerateFileSystemEntries(path);
using (IEnumerator<string> en = items.GetEnumerator())
{
return !en.MoveNext();
}
}
EDIT: seeing that answer again, I realize this code can be made much simpler...
public bool IsDirectoryEmpty(string path)
{
return !Directory.EnumerateFileSystemEntries(path).Any();
}
Here is the extra fast solution, that I finally implemented. Here I am using WinAPI and functions FindFirstFile, FindNextFile. It allows to avoid enumeration of all items in Folder and stops right after detecting the first object in the Folder. This approach is ~6(!!) times faster, than described above. 250 calls in 36ms!
private static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
private struct WIN32_FIND_DATA
{
public uint dwFileAttributes;
public System.Runtime.InteropServices.ComTypes.FILETIME ftCreationTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastAccessTime;
public System.Runtime.InteropServices.ComTypes.FILETIME ftLastWriteTime;
public uint nFileSizeHigh;
public uint nFileSizeLow;
public uint dwReserved0;
public uint dwReserved1;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
public string cFileName;
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 14)]
public string cAlternateFileName;
}
[DllImport("kernel32.dll", CharSet=CharSet.Auto)]
private static extern IntPtr FindFirstFile(string lpFileName, out WIN32_FIND_DATA lpFindFileData);
[DllImport("kernel32.dll", CharSet=CharSet.Auto)]
private static extern bool FindNextFile(IntPtr hFindFile, out WIN32_FIND_DATA lpFindFileData);
[DllImport("kernel32.dll")]
private static extern bool FindClose(IntPtr hFindFile);
public static bool CheckDirectoryEmpty_Fast(string path)
{
if (string.IsNullOrEmpty(path))
{
throw new ArgumentNullException(path);
}
if (Directory.Exists(path))
{
if (path.EndsWith(Path.DirectorySeparatorChar.ToString()))
path += "*";
else
path += Path.DirectorySeparatorChar + "*";
WIN32_FIND_DATA findData;
var findHandle = FindFirstFile(path, out findData);
if (findHandle != INVALID_HANDLE_VALUE)
{
try
{
bool empty = true;
do
{
if (findData.cFileName != "." && findData.cFileName != "..")
empty = false;
} while (empty && FindNextFile(findHandle, out findData));
return empty;
}
finally
{
FindClose(findHandle);
}
}
throw new Exception("Failed to get directory first file",
Marshal.GetExceptionForHR(Marshal.GetHRForLastWin32Error()));
}
throw new DirectoryNotFoundException();
}
I hope it will be useful for somebody in the future.
You could try Directory.Exists(path)
and Directory.GetFiles(path)
- probably less overhead (no objects - just strings etc).
private static void test()
{
System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
sw.Start();
string [] dirs = System.IO.Directory.GetDirectories("C:\\Test\\");
string[] files = System.IO.Directory.GetFiles("C:\\Test\\");
if (dirs.Length == 0 && files.Length == 0)
Console.WriteLine("Empty");
else
Console.WriteLine("Not Empty");
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
}
This quick test came back in 2 milliseconds for the folder when empty and when containing subfolders & files (5 folders with 5 files in each)
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