ReadBuffer implementation (DNET-748, pull#65).

Author: cincuranet

Provider/src/FirebirdSql.Data.FirebirdClient/Client/Managed/XdrStream.cs

@@ -23,7 +23,6 @@
 using System.Net;
 using System.Text;
 using System.Globalization;
-using System.Linq;
 using FirebirdSql.Data.Common;
 using System.Collections.Generic;
 
@@ -79,7 +78,7 @@ private static byte[] Pad
 
 		private long _position;
 		private List<byte> _outputBuffer;
-		private List<byte> _inputBuffer;
+		private ReadBuffer _inputBuffer;
 		private Ionic.Zlib.ZlibCodec _deflate;
 		private Ionic.Zlib.ZlibCodec _inflate;
 		private byte[] _compressionBuffer;
@@ -142,7 +141,7 @@ public XdrStream(Stream innerStream, Charset charset, bool compression, bool own
 
 			_position = 0;
 			_outputBuffer = new List<byte>(PreferredBufferSize);
-			_inputBuffer = new List<byte>(PreferredBufferSize);
+			_inputBuffer = new ReadBuffer(PreferredBufferSize);
 			if (_compression)
 			{
 				_deflate = new Ionic.Zlib.ZlibCodec(Ionic.Zlib.CompressionMode.Compress);
@@ -224,7 +223,7 @@ public override int Read(byte[] buffer, int offset, int count)
 			CheckDisposed();
 			EnsureReadable();
 
-			if (_inputBuffer.Count < count)
+			if (_inputBuffer.Length < count)
 			{
 				var readBuffer = new byte[PreferredBufferSize];
 				var read = _innerStream.Read(readBuffer, 0, readBuffer.Length);
@@ -246,14 +245,12 @@ public override int Read(byte[] buffer, int offset, int count)
 						readBuffer = _compressionBuffer;
 						read = _inflate.NextOut;
 					}
-					_inputBuffer.AddRange(readBuffer.Take(read));
+					_inputBuffer.AddRange(readBuffer, read);
 				}
 			}
-			var data = _inputBuffer.Take(count).ToArray();
-			_inputBuffer.RemoveRange(0, data.Length);
-			Array.Copy(data, 0, buffer, offset, data.Length);
-			_position += data.Length;
-			return data.Length;
+			var dataLength = _inputBuffer.ReadInto(ref buffer, offset, count);
+			_position += dataLength;
+			return dataLength;
 		}
 
 		public override void WriteByte(byte value)
@@ -269,7 +266,7 @@ public override void Write(byte[] buffer, int offset, int count)
 			CheckDisposed();
 			EnsureWritable();
 
-			_outputBuffer.AddRange(buffer.Skip(offset).Take(count));
+			_outputBuffer.AddRange(new ArraySegment<byte>(buffer, offset, count));
 		}
 
 		public byte[] ToArray()

Provider/src/FirebirdSql.Data.FirebirdClient/Common/ReadBuffer.cs

@@ -0,0 +1,73 @@
+/*
+ *	Firebird ADO.NET Data provider for .NET and Mono
+ *
+ *	   The contents of this file are subject to the Initial
+ *	   Developer's Public License Version 1.0 (the "License");
+ *	   you may not use this file except in compliance with the
+ *	   License. You may obtain a copy of the License at
+ *	   http://www.firebirdsql.org/index.php?op=doc&id=idpl
+ *
+ *	   Software distributed under the License is distributed on
+ *	   an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either
+ *	   express or implied. See the License for the specific
+ *	   language governing rights and limitations under the License.
+ *
+ *	Copyright (c) 2017 Gerdus van Zyl
+ *	Copyright (c) 2017 Jiri Cincura (jiri@cincura.net)
+ *	All Rights Reserved.
+ */
+
+using System;
+
+namespace FirebirdSql.Data.Common
+{
+	class ReadBuffer
+	{
+		byte[] _buffer;
+		int _readPosition;
+		int _writePosition;
+		int _length;
+
+		public int Length => _length;
+
+		public ReadBuffer(int bufferSize)
+		{
+			_buffer = new byte[bufferSize];
+			_readPosition = 0;
+			_writePosition = 0;
+			_length = 0;
+		}
+
+		public void AddRange(byte[] source, int count)
+		{
+			if ((_length + count) >= _buffer.Length)
+			{
+				var newBuffer = new byte[_buffer.Length * 2];
+				Array.Copy(_buffer, newBuffer, _buffer.Length);
+				_buffer = newBuffer;
+			}
+			for (var i = 0; i < count; i++)
+			{
+				if (_writePosition == _buffer.Length)
+					_writePosition = 0;
+				_buffer[_writePosition] = source[i];
+				_writePosition++;
+			}
+			_length += count;
+		}
+
+		public int ReadInto(ref byte[] destination, int offset, int count)
+        {
+			count = Math.Min(count, Length);
+			for (var i = 0; i < count; i++)
+			{
+				if (_readPosition == _buffer.Length)
+					_readPosition = 0;
+				destination[offset + i] = _buffer[_readPosition];
+				_readPosition++;
+			}
+			_length -= count;
+			return count;
+		}
+	}
+}

Provider/src/FirebirdSql.Data.FirebirdClient/FirebirdSql.Data.FirebirdClient_NET40.csproj

@@ -80,6 +80,7 @@
     <Compile Include="Common\IscErrorMessages.cs" />
     <Compile Include="Common\Marshal2.cs" />
     <Compile Include="Common\PageSizeHelper.cs" />
+    <Compile Include="Common\ReadBuffer.cs" />
     <Compile Include="Common\SqlStateMapping.cs" />
     <Compile Include="Common\TimeoutHelper.cs" />
     <Compile Include="Common\TraceHelper.cs" />

Provider/src/FirebirdSql.Data.FirebirdClient/FirebirdSql.Data.FirebirdClient_NET45.csproj

@@ -80,6 +80,7 @@
     <Compile Include="Common\IscErrorMessages.cs" />
     <Compile Include="Common\Marshal2.cs" />
     <Compile Include="Common\PageSizeHelper.cs" />
+    <Compile Include="Common\ReadBuffer.cs" />
     <Compile Include="Common\SqlStateMapping.cs" />
     <Compile Include="Common\TimeoutHelper.cs" />
     <Compile Include="Common\TraceHelper.cs" />