custom file stream implementation

Docker/run/config/standalone/files-standalone.json

@@ -4,12 +4,12 @@
     },
     "Logging": {
         "LogLevel": {
-            "Default": "Debug",
-            "Microsoft": "Debug",
+            "Default": "Warning",
+            "Microsoft": "Warning",
             "Microsoft.Hosting.Lifetime": "Information",
             "MareSynchronosStaticFilesServer": "Debug",
             "MareSynchronosShared": "Debug",
-            "System.IO": "Information"
+            "System.IO": "Information",
         },
         "File": {
             "BasePath": "logs",

MareSynchronosServer/MareSynchronosStaticFilesServer/Controllers/CacheController.cs

@@ -2,8 +2,6 @@
 using MareSynchronosStaticFilesServer.Services;
 using MareSynchronosStaticFilesServer.Utils;
 using Microsoft.AspNetCore.Mvc;
-using System.Globalization;
-using System.Text;
 
 namespace MareSynchronosStaticFilesServer.Controllers;
 
@@ -34,27 +32,22 @@ public class CacheController : ControllerBase
         _requestQueue.ActivateRequest(requestId);
 
         Response.ContentType = "application/octet-stream";
-        var memoryStream = new MemoryStream();
-        var streamWriter = new BinaryWriter(memoryStream);
 
         long requestSize = 0;
+        List<BlockFileDataSubstream> substreams = new();
 
         foreach (var file in request.FileIds)
         {
             var fs = await _cachedFileProvider.GetAndDownloadFileStream(file);
             if (fs == null) continue;
-            streamWriter.Write(Encoding.ASCII.GetBytes("#" + file + ":" + fs.Length.ToString(CultureInfo.InvariantCulture) + "#"));
-            byte[] buffer = new byte[fs.Length];
-            _ = await fs.ReadAsync(buffer, HttpContext.RequestAborted);
-            streamWriter.Write(buffer);
+
+            substreams.Add(new(fs));
+
             requestSize += fs.Length;
         }
 
-        streamWriter.Flush();
-        memoryStream.Position = 0;
-
         _fileStatisticsService.LogRequest(requestSize);
 
-        return _requestFileStreamResultFactory.Create(requestId, memoryStream);
+        return _requestFileStreamResultFactory.Create(requestId, new BlockFileDataStream(substreams.ToArray()));
     }
 }

MareSynchronosServer/MareSynchronosStaticFilesServer/Utils/BlockFileDataStream.cs

@@ -0,0 +1,70 @@
+namespace MareSynchronosStaticFilesServer.Utils;
+
+public sealed class BlockFileDataStream : Stream
+{
+    private readonly BlockFileDataSubstream[] _substreams;
+    private int _currentStreamIndex = 0;
+
+    public BlockFileDataStream(BlockFileDataSubstream[] substreams)
+    {
+        _substreams = substreams;
+    }
+
+    public override bool CanRead => true;
+    public override bool CanSeek => false;
+    public override bool CanWrite => false;
+    public override long Length => throw new NotSupportedException();
+    public override long Position { get => throw new NotSupportedException(); set => throw new NotSupportedException(); }
+
+    public override int Read(byte[] buffer, int offset, int count)
+    {
+        int totalRead = 0;
+        int currentOffset = 0;
+        int remainingCount = count;
+        while (totalRead < count && _currentStreamIndex < _substreams.Length)
+        {
+            var lastReadBytes = _substreams[_currentStreamIndex].Read(buffer, currentOffset, remainingCount);
+            if (lastReadBytes < remainingCount)
+            {
+                _substreams[_currentStreamIndex].Dispose();
+                _currentStreamIndex++;
+            }
+
+            totalRead += lastReadBytes;
+            currentOffset += lastReadBytes;
+            remainingCount -= lastReadBytes;
+        }
+
+        return totalRead;
+    }
+
+    protected override void Dispose(bool disposing)
+    {
+        base.Dispose(disposing);
+        foreach (var substream in _substreams)
+        {
+            // probably unnecessary but better safe than sorry
+            substream.Dispose();
+        }
+    }
+
+    public override void Flush()
+    {
+        throw new NotSupportedException();
+    }
+
+    public override long Seek(long offset, SeekOrigin origin)
+    {
+        throw new NotSupportedException();
+    }
+
+    public override void SetLength(long value)
+    {
+        throw new NotSupportedException();
+    }
+
+    public override void Write(byte[] buffer, int offset, int count)
+    {
+        throw new NotSupportedException();
+    }
+}

MareSynchronosServer/MareSynchronosStaticFilesServer/Utils/BlockFileDataSubstream.cs

@@ -0,0 +1,73 @@
+using System.Globalization;
+using System.Text;
+
+namespace MareSynchronosStaticFilesServer.Utils;
+
+public sealed class BlockFileDataSubstream : IDisposable
+{
+    private readonly MemoryStream _headerStream;
+    private readonly FileStream _dataStream;
+    private int _headerPosition = 0;
+    private long _dataPosition = 0;
+    private bool _disposed = false;
+
+    private long RemainingHeaderLength => _headerStream.Length - _headerPosition;
+    private long RemainingDataLength => _dataStream.Length - _dataPosition;
+
+    public BlockFileDataSubstream(FileStream dataStream)
+    {
+        _headerStream = new MemoryStream();
+        var headerStreamWriter = new BinaryWriter(_headerStream);
+        headerStreamWriter.Write(Encoding.ASCII.GetBytes("#" + new FileInfo(dataStream.Name).Name + ":" + dataStream.Length.ToString(CultureInfo.InvariantCulture) + "#"));
+        headerStreamWriter.Flush();
+        _headerStream.Position = 0;
+        _dataStream = dataStream;
+    }
+
+    public int Read(byte[] inputBuffer, int offset, int count)
+    {
+        int currentOffset = offset;
+        int currentCount = count;
+        int readHeaderBytes = 0;
+
+        if (RemainingHeaderLength > 0)
+        {
+            bool readOnlyHeader = currentCount <= RemainingHeaderLength;
+            byte[] readHeaderBuffer = new byte[Math.Min(currentCount, RemainingHeaderLength)];
+
+            readHeaderBytes = _headerStream.Read(readHeaderBuffer, 0, readHeaderBuffer.Length);
+            _headerPosition += readHeaderBytes;
+
+            Buffer.BlockCopy(readHeaderBuffer, 0, inputBuffer, currentOffset, readHeaderBytes);
+
+            if (readOnlyHeader)
+            {
+                return readHeaderBytes;
+            }
+
+            currentOffset += readHeaderBytes;
+            currentCount -= readHeaderBytes;
+        }
+
+        if (RemainingDataLength > 0)
+        {
+            byte[] readDataBuffer = new byte[currentCount];
+            var readDataBytes = _dataStream.Read(readDataBuffer, 0, readDataBuffer.Length);
+            _dataPosition += readDataBytes;
+
+            Buffer.BlockCopy(readDataBuffer, 0, inputBuffer, currentOffset, readDataBytes);
+
+            return readDataBytes + readHeaderBytes;
+        }
+
+        return 0;
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _headerStream.Dispose();
+        _dataStream.Dispose();
+        _disposed = true;
+    }
+}

MareSynchronosServer/MareSynchronosStaticFilesServer/Utils/RequestFileStreamResultFactory.cs

@@ -17,9 +17,9 @@ public class RequestFileStreamResultFactory
         _configurationService = configurationService;
     }
 
-    public RequestFileStreamResult Create(Guid requestId, MemoryStream ms)
+    public RequestFileStreamResult Create(Guid requestId, Stream stream)
     {
         return new RequestFileStreamResult(requestId, _requestQueueService,
-            _metrics, ms, "application/octet-stream");
+            _metrics, stream, "application/octet-stream");
     }
 }