TemporaryFile.cs

using System;
using System.IO;
using System.Threading.Tasks;
using Waher.Events;

namespace Waher.Runtime.Temporary
{
	/// <summary>
	/// Class managing the contents of a temporary file. When the class is disposed, the temporary file is deleted.
	/// </summary>
	public class TemporaryFile : FileStream
	{
		/// <summary>
		/// Default buffer size, in bytes.
		/// </summary>
		public const int DefaultBufferSize = 16384;

		private string fileName;
		private bool deleteWhenDisposed = true;

		/// <summary>
		/// Class managing the contents of a temporary file. When the class is disposed, the temporary file is deleted.
		/// </summary>
		public TemporaryFile()
			: this(Path.GetTempFileName(), DefaultBufferSize)
		{
		}

		/// <summary>
		/// Class managing the contents of a temporary file. When the class is disposed, the temporary file is deleted.
		/// </summary>
		/// <param name="FileName">Name of temporary file. Call <see cref="Path.GetTempFileName()"/> to get a new temporary file name.</param>
		public TemporaryFile(string FileName)
			: this(FileName, DefaultBufferSize)
		{
		}

		/// <summary>
		/// Class managing the contents of a temporary file. When the class is disposed, the temporary file is deleted.
		/// </summary>
		/// <param name="FileName">Name of temporary file. Call <see cref="Path.GetTempFileName()"/> to get a new temporary file name.</param>
		/// <param name="BufferSize">Buffer size.</param>
		public TemporaryFile(string FileName, int BufferSize)
			: base(FileName, FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.Read, BufferSize, FileOptions.RandomAccess)
		{
			this.fileName = FileName;
		}

		/// <summary>
		/// File Name.
		/// </summary>
		public string FileName => this.fileName;

		/// <summary>
		/// Delete file when object is disposed.
		/// </summary>
		public bool DeleteWhenDisposed
		{
			get => this.deleteWhenDisposed;
			set => this.deleteWhenDisposed = value;
		}

		/// <summary>
		/// Disposes of the object, and deletes the temporary file.
		/// </summary>
		protected override void Dispose(bool disposing)
		{
			base.Dispose(disposing);

			if (!(this.fileName is null))
			{
				if (this.deleteWhenDisposed)
					DeleteFile(FileName);

				this.fileName = null;
			}
		}

		private static void DeleteFile(string FileName)
		{
			try
			{
				if (File.Exists(FileName))
					File.Delete(FileName);
			}
			catch (IOException)		// File locked. Wait a while and try again.
			{
				Task.Delay(10000).ContinueWith((T) => DeleteFile(FileName));
			}
			catch (Exception ex)
			{
				Log.Exception(ex);
			}
		}
	}
}