Delete circular buffer zero-length file

src/MMALSharp.Processing/Handlers/CircularBufferCaptureHandler.cs

@@ -4,6 +4,7 @@
 // </copyright>
 
 using System;
+using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Logging;
@@ -85,6 +86,7 @@ public override void Process(ImageContext context)
                     if (this.CurrentStream != null && this.CurrentStream.CanWrite)
                     {
                         this.CurrentStream.Write(this.Buffer.ToArray(), 0, this.Buffer.Size);
+                        this.FileIsEmpty = false;
                     }
 
                     this.Processed += this.Buffer.Size;
@@ -94,6 +96,7 @@ public override void Process(ImageContext context)
                 if (this.CurrentStream != null && this.CurrentStream.CanWrite)
                 {
                     this.CurrentStream.Write(context.Data, 0, context.Data.Length);
+                    this.FileIsEmpty = false;
                 }
 
                 this.Processed += context.Data.Length;
@@ -154,12 +157,6 @@ public void StopRecording()
             _receivedIFrame = false;
         }
 
-        /// <inheritdoc />
-        public override void Dispose()
-        {
-            this.CurrentStream?.Dispose();
-        }
-
         /// <inheritdoc />
         public override string TotalProcessed()
         {

src/MMALSharp.Processing/Handlers/FileStreamCaptureHandler.cs

@@ -4,6 +4,7 @@
 // </copyright>
 
 using Microsoft.Extensions.Logging;
+using MMALSharp.Common;
 using MMALSharp.Common.Utility;
 using System;
 using System.Collections.Generic;
@@ -36,17 +37,26 @@ public class FileStreamCaptureHandler : StreamCaptureHandler<FileStream>, IFileS
         public string Extension { get; set; }
 
         /// <summary>
-        /// The name of the current file associated with the FileStream.
+        /// The name of the file associated with the FileStream (without a path or extension).
         /// </summary>
         public string CurrentFilename { get; set; }
 
+        /// <summary>
+        /// When true, the Dispose method will delete the zero-length file identified by CurrentStream.Name.
+        /// Inheriting classes should set this to false any time they write to the file stream.
+        /// </summary>
+        protected bool FileIsEmpty { get; set; }
+
         /// <summary>
         /// Creates a new instance of the <see cref="FileStreamCaptureHandler"/> class without provisions for writing to a file. Supports
         /// subclasses in which file output is optional.
         /// </summary>
         public FileStreamCaptureHandler()
         {
             MMALLog.Logger.LogDebug($"{nameof(FileStreamCaptureHandler)} empty ctor invoked, no file will be written");
+
+            // Prevent Dispose from attempting to delete a non-existent file.
+            this.FileIsEmpty = false;
         }
 
         /// <summary>
@@ -63,9 +73,9 @@ public FileStreamCaptureHandler(string directory, string extension)
             MMALLog.Logger.LogDebug($"{nameof(FileStreamCaptureHandler)} created for directory {this.Directory} and extension {this.Extension}");
 
             System.IO.Directory.CreateDirectory(this.Directory);
-            
+
             var now = DateTime.Now.ToString("dd-MMM-yy HH-mm-ss");
-            
+
             int i = 1;
 
             var fileName = $"{this.Directory}/{now}.{this.Extension}";
@@ -80,6 +90,7 @@ public FileStreamCaptureHandler(string directory, string extension)
 
             this.CurrentFilename = Path.GetFileNameWithoutExtension(fileInfo.Name);
             this.CurrentStream = File.Create(fileName);
+            this.FileIsEmpty = true;
         }
 
         /// <summary>
@@ -94,12 +105,12 @@ public FileStreamCaptureHandler(string fullPath)
             this.CurrentFilename = Path.GetFileNameWithoutExtension(fileInfo.Name);
 
             var ext = fullPath.Split('.').LastOrDefault();
-            
+
             if (string.IsNullOrEmpty(ext))
             {
                 throw new ArgumentNullException(nameof(ext), "Could not get file extension from path string.");
             }
-            
+
             this.Extension = ext;
 
             MMALLog.Logger.LogDebug($"{nameof(FileStreamCaptureHandler)} created for directory {this.Directory} and extension {this.Extension}");
@@ -109,17 +120,25 @@ public FileStreamCaptureHandler(string fullPath)
             System.IO.Directory.CreateDirectory(this.Directory);
 
             this.CurrentStream = File.Create(fullPath);
+            this.FileIsEmpty = true;
+        }
+
+        /// <inheritdoc />
+        public override void Process(ImageContext context)
+        {
+            base.Process(context);
+            this.FileIsEmpty = false;
         }
 
         /// <summary>
-        /// Gets the filename that a FileStream points to.
+        /// Gets the filename that a FileStream points to without a path or extension.
         /// </summary>
         /// <returns>The filename.</returns>
         public string GetFilename() => 
             (this.CurrentStream != null) ? Path.GetFileNameWithoutExtension(this.CurrentStream.Name) : string.Empty;
 
         /// <summary>
-        /// Gets the filepath that a FileStream points to.
+        /// Gets the full file pathname that a FileStream points to.
         /// </summary>
         /// <returns>The filepath.</returns>
         public string GetFilepath() => 
@@ -161,6 +180,7 @@ public virtual void NewFile()
             }
 
             this.CurrentStream = File.Create(newFilename);
+            this.FileIsEmpty = true;
         }
 
         /// <inheritdoc />
@@ -180,5 +200,23 @@ public override string TotalProcessed()
         {
             return $"{this.Processed}";
         }
+
+        /// <inheritdoc />
+        public override void Dispose()
+        {
+            base.Dispose();
+
+            // Disposing the stream can leave a zero-length file on disk if nothing
+            // was recorded into it -- but after recording has taken place, only
+            // calling NewFile (or Split for videos) will create a new empty file.
+            if (this.FileIsEmpty)
+            {
+                try
+                {
+                    File.Delete(this.CurrentStream.Name);
+                }
+                catch { }
+            }
+        }
     }
 }

src/MMALSharp.Processing/Handlers/VideoStreamCaptureHandler.cs

@@ -76,16 +76,17 @@ public override void Process(ImageContext context)
             if (this.StoreVideoTimestamps && context.Pts.HasValue)
             {
                 var str = $"{context.Pts / 1000}.{context.Pts % 1000:000}" + Environment.NewLine;
-               
+
                 File.AppendAllText($"{this.Directory}/{this.CurrentFilename}.pts", str);
+                this.FileIsEmpty = false;
             }
         }
 
         /// <summary>
         /// Splits the current file by closing the current stream and opening a new one.
         /// </summary>
         public virtual void Split() => this.NewFile();
-        
+
         /// <summary>
         /// Used to set the current working motion vector store.
         /// </summary>