Revert "Optimise reset connection." Fixes #486

Pipelining the packets was not supported by Amazon Aurora.

This reverts commit be19393.

Author: bgrainger

src/MySqlConnector/Core/ServerSession.cs

@@ -362,31 +362,14 @@ public async Task<bool> TryResetConnectionAsync(ConnectionSettings cs, IOBehavio
 				{
 					m_logArguments[1] = ServerVersion.OriginalString;
 					Log.Debug("Session{0} ServerVersion={1} supports reset connection; sending reset connection request", m_logArguments);
-					if (m_payloadHandler is StandardPayloadHandler standardPayloadHandler)
-					{
-						// send both packets at once
-						await standardPayloadHandler.ByteHandler.WriteBytesAsync(s_resetConnectionPackets, ioBehavior).ConfigureAwait(false);
-
-						// read two OK replies
-						standardPayloadHandler.SetNextSequenceNumber(1);
-						var payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
-						OkPayload.Create(payload);
+					await SendAsync(ResetConnectionPayload.Instance, ioBehavior, cancellationToken).ConfigureAwait(false);
+					var payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
+					OkPayload.Create(payload);
 
-						standardPayloadHandler.SetNextSequenceNumber(1);
-						payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
-						OkPayload.Create(payload);
-					}
-					else
-					{
-						await SendAsync(ResetConnectionPayload.Instance, ioBehavior, cancellationToken).ConfigureAwait(false);
-						var payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
-						OkPayload.Create(payload);
-
-						// the "reset connection" packet also resets the connection charset, so we need to change that back to our default
-						await SendAsync(s_setNamesUtf8mb4Payload, ioBehavior, cancellationToken).ConfigureAwait(false);
-						payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
-						OkPayload.Create(payload);
-					}
+					// the "reset connection" packet also resets the connection charset, so we need to change that back to our default
+					await SendAsync(s_setNamesUtf8mb4Payload, ioBehavior, cancellationToken).ConfigureAwait(false);
+					payload = await ReceiveReplyAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
+					OkPayload.Create(payload);
 				}
 				else
 				{
@@ -1219,11 +1202,6 @@ private enum State
 		static byte[] s_connectionAttributes;
 		static readonly IMySqlConnectorLogger Log = MySqlConnectorLogManager.CreateLogger(nameof(ServerSession));
 		static readonly PayloadData s_setNamesUtf8mb4Payload = QueryPayload.Create("SET NAMES utf8mb4 COLLATE utf8mb4_bin;");
-		static readonly ArraySegment<byte> s_resetConnectionPackets = new ArraySegment<byte>(new byte[]
-		{
-			1, 0, 0, 0, (byte) CommandKind.ResetConnection,
-			39, 0, 0, 0, (byte) CommandKind.Query, 83, 69, 84, 32, 78, 65, 77, 69, 83, 32, 117, 116, 102, 56, 109, 98, 52, 32, 67, 79, 76, 76, 65, 84, 69, 32, 117, 116, 102, 56, 109, 98, 52, 95, 98, 105, 110, 59 // SET NAMES utf8mb4 COLLATE utf8mb4_bin;
-		});
 
 		readonly object m_lock;
 		readonly object[] m_logArguments;

src/MySqlConnector/Protocol/Serialization/StandardPayloadHandler.cs

@@ -23,8 +23,6 @@ public void StartNewConversation()
 			m_sequenceNumber = 0;
 		}
 
-		public void SetNextSequenceNumber(int sequenceNumber) => m_sequenceNumber = sequenceNumber;
-
 		public IByteHandler ByteHandler
 		{
 			get => m_byteHandler;