Support CLIENT_SESSION_TRACK. Fixes #323

Author: bgrainger

.ci/config/config.compression.json

@@ -3,7 +3,7 @@
       "ConnectionString": "server=127.0.0.1;user id=mysqltest;password='test;key=\"val';port=3306;database=mysqltest;ssl mode=none;UseCompression=true;DefaultCommandTimeout=3600",
       "PasswordlessUser": "no_password",
       "SecondaryDatabase": "testdb2",
-      "SupportedFeatures": "Json,StoredProcedures,Sha256Password,LargePackets",
+      "SupportedFeatures": "Json,StoredProcedures,Sha256Password,LargePackets,SessionTrack",
       "MySqlBulkLoaderLocalCsvFile": "../../../../TestData/LoadData_UTF8_BOM_Unix.CSV",
       "MySqlBulkLoaderLocalTsvFile": "../../../../TestData/LoadData_UTF8_BOM_Unix.TSV"
     }

.ci/config/config.json

@@ -3,7 +3,7 @@
       "ConnectionString": "server=127.0.0.1;user id=mysqltest;password='test;key=\"val';port=3306;database=mysqltest;ssl mode=none;Use Affected Rows=true;DefaultCommandTimeout=3600",
       "PasswordlessUser": "no_password",
       "SecondaryDatabase": "testdb2",
-      "SupportedFeatures": "Json,StoredProcedures,Sha256Password,LargePackets",
+      "SupportedFeatures": "Json,StoredProcedures,Sha256Password,LargePackets,SessionTrack",
       "MySqlBulkLoaderLocalCsvFile": "../../../../TestData/LoadData_UTF8_BOM_Unix.CSV",
       "MySqlBulkLoaderLocalTsvFile": "../../../../TestData/LoadData_UTF8_BOM_Unix.TSV"
     }

.travis.yml

@@ -8,16 +8,16 @@ env:
     FEATURES=StoredProcedures
   - IMAGE=mysql:5.7
     NAME=mysql
-    FEATURES=Json,StoredProcedures,Sha256Password,LargePackets
+    FEATURES=Json,StoredProcedures,Sha256Password,LargePackets,SessionTrack
   - IMAGE=mysql:8.0
     NAME=mysql
-    FEATURES=Json,StoredProcedures,Sha256Password,LargePackets,CachingSha2Password
+    FEATURES=Json,StoredProcedures,Sha256Password,LargePackets,CachingSha2Password,SessionTrack
   - IMAGE=percona:5.7
     NAME=percona
-    FEATURES=Json,StoredProcedures,Sha256Password,OpenSsl,LargePackets
+    FEATURES=Json,StoredProcedures,Sha256Password,OpenSsl,LargePackets,SessionTrack
   - IMAGE=mariadb:10.2
     NAME=mariadb
-    FEATURES=StoredProcedures,OpenSsl,LargePackets
+    FEATURES=StoredProcedures,OpenSsl,LargePackets,SessionTrack
 
 before_install:
 - .ci/docker-run.sh $IMAGE $NAME 3307 $FEATURES

src/MySqlConnector/Core/ResultSet.cs

@@ -48,6 +48,8 @@ public async Task<ResultSet> ReadResultSetHeaderAsync(IOBehavior ioBehavior)
 						var ok = OkPayload.Create(payload);
 						RecordsAffected = (RecordsAffected ?? 0) + ok.AffectedRowCount;
 						LastInsertId = ok.LastInsertId;
+						if (ok.NewSchema != null)
+							Connection.Session.DatabaseOverride = ok.NewSchema;
 						ColumnDefinitions = null;
 						ColumnTypes = null;
 						State = (ok.ServerStatus & ServerStatus.MoreResultsExist) == 0

src/MySqlConnector/Protocol/Payloads/HandshakeResponse41Payload.cs

@@ -22,6 +22,7 @@ private static PayloadWriter CreateCapabilitiesPayload(ProtocolCapabilities serv
 				(cs.UseAffectedRows ? 0 : ProtocolCapabilities.FoundRows) |
 				(useCompression ? ProtocolCapabilities.Compress : ProtocolCapabilities.None) |
 				(serverCapabilities & ProtocolCapabilities.ConnectionAttributes) |
+				(serverCapabilities & ProtocolCapabilities.SessionTrack) |
 				(serverCapabilities & ProtocolCapabilities.DeprecateEof) |
 				additionalCapabilities));
 			writer.WriteInt32(0x4000_0000);

src/MySqlConnector/Protocol/Payloads/OkPayload.cs

@@ -1,15 +1,17 @@
 using System;
+using System.Text;
 using MySqlConnector.Protocol.Serialization;
 using MySqlConnector.Utilities;
 
 namespace MySqlConnector.Protocol.Payloads
 {
 	internal sealed class OkPayload
 	{
-		public int AffectedRowCount { get; set; }
-		public long LastInsertId { get; set; }
-		public ServerStatus ServerStatus { get; set; }
-		public int WarningCount { get; set; }
+		public int AffectedRowCount { get; }
+		public long LastInsertId { get; }
+		public ServerStatus ServerStatus { get; }
+		public int WarningCount { get; }
+		public string NewSchema { get; }
 
 		public const byte Signature = 0x00;
 
@@ -35,16 +37,47 @@ public static OkPayload Create(PayloadData payload, bool deprecateEof)
 			var lastInsertId = checked((long) reader.ReadLengthEncodedInteger());
 			var serverStatus = (ServerStatus) reader.ReadUInt16();
 			var warningCount = (int) reader.ReadUInt16();
+			string newSchema = null;
 
-			return new OkPayload(affectedRowCount, lastInsertId, serverStatus, warningCount);
+			if ((serverStatus & ServerStatus.SessionStateChanged) == ServerStatus.SessionStateChanged)
+			{
+				reader.ReadLengthEncodedByteString(); // human-readable info
+
+				// implies ProtocolCapabilities.SessionTrack
+				var sessionStateChangeDataLength = checked((int) reader.ReadLengthEncodedInteger());
+				var endOffset = reader.Offset + sessionStateChangeDataLength;
+				while (reader.Offset < endOffset)
+				{
+					var kind = (SessionTrackKind) reader.ReadByte();
+					var dataLength = (int) reader.ReadLengthEncodedInteger();
+					switch (kind)
+					{
+					case SessionTrackKind.Schema:
+						newSchema = Encoding.UTF8.GetString(reader.ReadLengthEncodedByteString());
+						break;
+
+					default:
+						reader.Offset += dataLength;
+						break;
+					}
+				}
+			}
+			else
+			{
+				// either "string<EOF> info" or "string<lenenc> info" (followed by no session change info)
+				// ignore human-readable string in both cases
+			}
+
+			return new OkPayload(affectedRowCount, lastInsertId, serverStatus, warningCount, newSchema);
 		}
 
-		private OkPayload(int affectedRowCount, long lastInsertId, ServerStatus serverStatus, int warningCount)
+		private OkPayload(int affectedRowCount, long lastInsertId, ServerStatus serverStatus, int warningCount, string newSchema)
 		{
 			AffectedRowCount = affectedRowCount;
 			LastInsertId = lastInsertId;
 			ServerStatus = serverStatus;
 			WarningCount = warningCount;
+			NewSchema = newSchema;
 		}
 	}
 }

src/MySqlConnector/Protocol/SessionTrackKind.cs

@@ -0,0 +1,25 @@
+namespace MySqlConnector.Protocol
+{
+	internal enum SessionTrackKind : byte
+	{
+		/// <summary>
+		/// SESSION_TRACK_SYSTEM_VARIABLES: one or more system variables changed
+		/// </summary>
+		SystemVariables = 0,
+
+		/// <summary>
+		/// SESSION_TRACK_SCHEMA: schema changed
+		/// </summary>
+		Schema = 1,
+
+		/// <summary>
+		/// SESSION_TRACK_STATE_CHANGE: "track state change" changed
+		/// </summary>
+		StateChange = 2,
+
+		/// <summary>
+		/// SESSION_TRACK_GTIDS: "track GTIDs" changed
+		/// </summary>
+		Gtids = 3,
+	}
+}

tests/SideBySide/ConnectAsync.cs

@@ -226,6 +226,28 @@ public async Task ChangeDatabaseConnectionPooling()
 			}
 		}
 
+		[SkippableFact(ServerFeatures.SessionTrack, ConfigSettings.SecondaryDatabase, Baseline = "https://bugs.mysql.com/bug.php?id=89085")]
+		public async Task UseDatabase()
+		{
+			var csb = AppConfig.CreateConnectionStringBuilder();
+			using (var connection = new MySqlConnection(csb.ConnectionString))
+			{
+				connection.Open();
+
+				Assert.Equal(csb.Database, connection.Database);
+				Assert.Equal(csb.Database, await QueryCurrentDatabaseAsync(connection));
+
+				using (var cmd = connection.CreateCommand())
+				{
+					cmd.CommandText = $"USE {AppConfig.SecondaryDatabase};";
+					await cmd.ExecuteNonQueryAsync();
+				}
+
+				Assert.Equal(AppConfig.SecondaryDatabase, connection.Database);
+				Assert.Equal(AppConfig.SecondaryDatabase, await QueryCurrentDatabaseAsync(connection));
+			}
+		}
+
 		private static async Task<string> QueryCurrentDatabaseAsync(MySqlConnection connection)
 		{
 			using (var cmd = connection.CreateCommand())

tests/SideBySide/ConnectSync.cs

@@ -307,6 +307,28 @@ public void ChangeDatabaseConnectionPooling()
 			}
 		}
 
+		[SkippableFact(ServerFeatures.SessionTrack, ConfigSettings.SecondaryDatabase, Baseline = "https://bugs.mysql.com/bug.php?id=89085")]
+		public void UseDatabase()
+		{
+			var csb = AppConfig.CreateConnectionStringBuilder();
+			using (var connection = new MySqlConnection(csb.ConnectionString))
+			{
+				connection.Open();
+
+				Assert.Equal(csb.Database, connection.Database);
+				Assert.Equal(csb.Database, QueryCurrentDatabase(connection));
+
+				using (var cmd = connection.CreateCommand())
+				{
+					cmd.CommandText = $"USE {AppConfig.SecondaryDatabase};";
+					cmd.ExecuteNonQuery();
+				}
+
+				Assert.Equal(AppConfig.SecondaryDatabase, connection.Database);
+				Assert.Equal(AppConfig.SecondaryDatabase, QueryCurrentDatabase(connection));
+			}
+		}
+
 		private static string QueryCurrentDatabase(MySqlConnection connection)
 		{
 			using (var cmd = connection.CreateCommand())

tests/SideBySide/ServerFeatures.cs

@@ -11,6 +11,7 @@ public enum ServerFeatures
 		Sha256Password = 4,
 		OpenSsl = 8,
 		LargePackets = 16,
-		CachingSha2Password = 32
+		CachingSha2Password = 32,
+		SessionTrack = 64,
 	}
 }