Add ReadByteArraySegment.

This allows part of the response to be read without allocating a temporary byte array.

Author: bgrainger

src/MySqlConnector/Core/ServerSession.cs

@@ -924,10 +924,10 @@ private async Task GetRealServerDetailsAsync(IOBehavior ioBehavior, Cancellation
 				var reader = new ByteArrayReader(payload.ArraySegment);
 				var length = reader.ReadLengthEncodedIntegerOrNull();
 				if (length != -1)
-					connectionId = int.Parse(Encoding.UTF8.GetString(reader.ReadByteArray(length)), CultureInfo.InvariantCulture);
+					connectionId = int.Parse(Encoding.UTF8.GetString(reader.ReadByteArraySegment(length)), CultureInfo.InvariantCulture);
 				length = reader.ReadLengthEncodedIntegerOrNull();
 				if (length != -1)
-					serverVersion = Encoding.UTF8.GetString(reader.ReadByteArray(length));
+					serverVersion = Encoding.UTF8.GetString(reader.ReadByteArraySegment(length));
 
 				// OK/EOF payload
 				payload = await ReceiveReplyAsync(ioBehavior, CancellationToken.None).ConfigureAwait(false);

src/MySqlConnector/Protocol/Payloads/ErrorPayload.cs

@@ -1,6 +1,7 @@
 using System.Text;
 using MySql.Data.MySqlClient;
 using MySqlConnector.Protocol.Serialization;
+using MySqlConnector.Utilities;
 
 namespace MySqlConnector.Protocol.Payloads
 {
@@ -19,17 +20,17 @@ public static ErrorPayload Create(PayloadData payload)
 			reader.ReadByte(Signature);
 
 			var errorCode = reader.ReadUInt16();
-			var stateMarker = Encoding.ASCII.GetString(reader.ReadByteArray(1));
+			var stateMarker = Encoding.ASCII.GetString(reader.ReadByteArraySegment(1));
 			string state, message;
 			if (stateMarker == "#")
 			{
-				state = Encoding.ASCII.GetString(reader.ReadByteArray(5));
-				message = Encoding.UTF8.GetString(reader.ReadByteArray(payload.ArraySegment.Count - 9));
+				state = Encoding.ASCII.GetString(reader.ReadByteArraySegment(5));
+				message = Encoding.UTF8.GetString(reader.ReadByteArraySegment(payload.ArraySegment.Count - 9));
 			}
 			else
 			{
 				state = "HY000";
-				message = stateMarker + Encoding.UTF8.GetString(reader.ReadByteArray(payload.ArraySegment.Count - 4));
+				message = stateMarker + Encoding.UTF8.GetString(reader.ReadByteArraySegment(payload.ArraySegment.Count - 4));
 			}
 			return new ErrorPayload(errorCode, state, message);
 		}

src/MySqlConnector/Protocol/Payloads/InitialHandshakePayload.cs

@@ -18,7 +18,8 @@ public static InitialHandshakePayload Create(PayloadData payload)
 			reader.ReadByte(c_protocolVersion);
 			var serverVersion = reader.ReadNullTerminatedByteString();
 			var connectionId = reader.ReadInt32();
-			var authPluginData = reader.ReadByteArray(8);
+			byte[] authPluginData = null;
+			var authPluginData1 = reader.ReadByteArraySegment(8);
 			string authPluginName = null;
 			reader.ReadByte(0);
 			var protocolCapabilities = (ProtocolCapabilities) reader.ReadUInt16();
@@ -29,18 +30,23 @@ public static InitialHandshakePayload Create(PayloadData payload)
 				var capabilityFlagsHigh = reader.ReadUInt16();
 				protocolCapabilities |= (ProtocolCapabilities) (capabilityFlagsHigh << 16);
 				var authPluginDataLength = reader.ReadByte();
-				var unused = reader.ReadByteArray(10);
+				var unused = reader.ReadByteArraySegment(10);
 				if ((protocolCapabilities & ProtocolCapabilities.SecureConnection) != 0)
 				{
-					var authPluginData2 = reader.ReadByteArray(Math.Max(13, authPluginDataLength - 8));
-					var concatenated = new byte[authPluginData.Length + authPluginData2.Length];
-					Buffer.BlockCopy(authPluginData, 0, concatenated, 0, authPluginData.Length);
-					Buffer.BlockCopy(authPluginData2, 0, concatenated,authPluginData.Length, authPluginData2.Length);
+					var authPluginData2 = reader.ReadByteArraySegment(Math.Max(13, authPluginDataLength - 8));
+					var concatenated = new byte[authPluginData1.Count + authPluginData2.Count];
+					Buffer.BlockCopy(authPluginData1.Array, authPluginData1.Offset, concatenated, 0, authPluginData1.Count);
+					Buffer.BlockCopy(authPluginData2.Array, authPluginData2.Offset, concatenated, authPluginData1.Count, authPluginData2.Count);
 					authPluginData = concatenated;
 				}
 				if ((protocolCapabilities & ProtocolCapabilities.PluginAuth) != 0)
 					authPluginName = Encoding.UTF8.GetString(reader.ReadNullOrEofTerminatedByteString());
 			}
+			if (authPluginData == null)
+			{
+				authPluginData = new byte[authPluginData1.Count];
+				Buffer.BlockCopy(authPluginData1.Array, authPluginData1.Offset, authPluginData, 0, authPluginData1.Count);
+			}
 
 			if (reader.BytesRemaining != 0)
 				throw new FormatException("Extra bytes at end of payload.");

src/MySqlConnector/Protocol/Payloads/LocalInfilePayload.cs

@@ -1,5 +1,6 @@
 using System.Text;
 using MySqlConnector.Protocol.Serialization;
+using MySqlConnector.Utilities;
 
 namespace MySqlConnector.Protocol.Payloads
 {
@@ -14,7 +15,7 @@ public static LocalInfilePayload Create(PayloadData payload)
 		{
 			var reader = new ByteArrayReader(payload.ArraySegment);
 			reader.ReadByte(Signature);
-			var fileName = Encoding.UTF8.GetString(reader.ReadByteArray(reader.BytesRemaining));
+			var fileName = Encoding.UTF8.GetString(reader.ReadByteArraySegment(reader.BytesRemaining));
 			return new LocalInfilePayload(fileName);
 		}
 

src/MySqlConnector/Protocol/Serialization/ByteArrayReader.cs

@@ -127,6 +127,14 @@ public byte[] ReadByteArray(int length)
 			return result;
 		}
 
+		public ArraySegment<byte> ReadByteArraySegment(int length)
+		{
+			VerifyRead(length);
+			var result = new ArraySegment<byte>(m_buffer, m_offset, length);
+			m_offset += length;
+			return result;
+		}
+
 		public ulong ReadLengthEncodedInteger()
 		{
 			byte encodedLength = m_buffer[m_offset++];