Indexing / Updated image

Source/TailBlazer.Domain/FileHandling/SparseIndexer.cs

@@ -5,9 +5,7 @@
 using System.Reactive.Concurrency;
 using System.Reactive.Disposables;
 using System.Reactive.Linq;
-using System.Reactive.Subjects;
 using System.Text;
-using System.Threading.Tasks;
 using DynamicData;
 using DynamicData.Binding;
 using TailBlazer.Domain.Annotations;
@@ -17,16 +15,13 @@ namespace TailBlazer.Domain.FileHandling
     public class SparseIndexer: IDisposable
     {
         private readonly IDisposable _cleanUp;
+        private int _endOfFile;
+        private readonly ISourceList<SparseIndex> _indicies = new SourceList<SparseIndex>();
 
         public Encoding Encoding { get; }
         public FileInfo Info { get; }
-        public int Compression { get; set; }
+        public int Compression { get;  }
         public int TailSize { get;  }
-
-
-        private int _endOfFile;
-
-        private readonly ISourceList<SparseIndex> _indicies= new SourceList<SparseIndex>();
 
         public IObservable<SparseIndicies> Result { get; }
 
@@ -47,15 +42,12 @@ public SparseIndexer([NotNull] FileInfo info,
             TailSize = tailSize;
             Encoding = encoding ?? info.GetEncoding();
 
-            //create  a resulting index object from the collection of index fragments
+            //0. create  a resulting index object from the collection of index fragments
             Result = _indicies
                 .Connect()
                 .Sort(SortExpressionComparer<SparseIndex>.Ascending(si => si.Start))
                 .ToCollection()
-                .Scan((SparseIndicies)null, (previous, notification) =>
-                {
-                    return new SparseIndicies(notification, previous, Encoding);
-                });
+                .Scan((SparseIndicies)null, (previous, notification) => new SparseIndicies(notification, previous, Encoding));
 
 
             //1. Get  full length of file
@@ -88,13 +80,8 @@ public SparseIndexer([NotNull] FileInfo info,
                     });
                 });
 
-            ////3. Scan the remainder of the file when the first one has started
-           //scheduler.Schedule(() =>
-           //{
-
-           //})
-
-            var xxx = tailScanner.FirstAsync()
+            ////3. Scan the remainder of the file when the tail has been scanned
+            var headSubscriber = tailScanner.FirstAsync()
                 .Subscribe(head =>
                 {
                     var estimateLines = EstimateNumberOfLines(head, info);
@@ -112,35 +99,17 @@ public SparseIndexer([NotNull] FileInfo info,
                     });
                 });
 
-
-
-
             _cleanUp = new CompositeDisposable(_indicies,
                 tailSubscriber,
+                headSubscriber,
                 tailScanner.Connect());
         }
 
-        private  IObservable<SparseIndex> ScanHead(SparseIndex head,FileInfo info, int compression)
-        {
-            return Observable.Create<SparseIndex>(observer =>
-            {
-                var estimateLines = EstimateNumberOfLines(head, info);
-                var estimate = new SparseIndex(0, head.Start, compression, estimateLines, SpareIndexType.Page);
-                observer.OnNext(estimate);
-
-                var scan = Scan(0, head.Start, compression);
-                observer.OnNext(estimate);
-
-                return Observable.StartAsync( () =>  ScanAsync(0, head.Start, compression))
-                        .SubscribeSafe(observer);
-            });
-        }
-
         private int EstimateNumberOfLines(SparseIndex tail, FileInfo info)
         {
             //Calculate estimate line count
             var averageLineLength = tail.Size/tail.LineCount;
-            var estimatedLines = info.Length/averageLineLength;
+            var estimatedLines = (info.Length - tail.Size) /averageLineLength;
             return (int) estimatedLines;
         }
 
@@ -149,11 +118,6 @@ private SparseIndex ScanTail(int start)
             return Scan(start,-1, 1);
         }
 
-        private async Task<SparseIndex> ScanAsync(int start, int end, int compression)
-        {
-            return  await Task.Run(()=> Scan( start,  end,  compression));
-        }
-
         private SparseIndex Scan(int start, int end, int compression)
         {
             int count = 0;