Remove COM_MULTI implementation. Fixes #946

The only server that supported this capability bit was MariaDB prior to version 10.6. Additionally, this code is never regularly tested because CI only runs against MariaDB 10.6 and later.

src/MySqlConnector/Core/ServerSession.cs

@@ -62,7 +62,6 @@ public ServerSession(ILogger logger, ConnectionPool? pool, int poolGeneration, i
 	public IPEndPoint? IPEndPoint => m_tcpClient?.Client.RemoteEndPoint as IPEndPoint;
 	public string? UserID { get; private set; }
 	public WeakReference<MySqlConnection>? OwningConnection { get; set; }
-	public bool SupportsComMulti => m_supportsComMulti;
 	public bool SupportsDeprecateEof => m_supportsDeprecateEof;
 	public bool SupportsCachedPreparedMetadata { get; private set; }
 	public bool SupportsQueryAttributes { get; private set; }
@@ -485,7 +484,6 @@ public async Task DisposeAsync(IOBehavior ioBehavior, CancellationToken cancella
 						activity.SetTag(ActivitySourceHelper.DatabaseConnectionIdTagName, connectionId);
 				}
 
-				m_supportsComMulti = (initialHandshake.ProtocolCapabilities & ProtocolCapabilities.MariaDbComMulti) != 0;
 				m_supportsConnectionAttributes = (initialHandshake.ProtocolCapabilities & ProtocolCapabilities.ConnectionAttributes) != 0;
 				m_supportsDeprecateEof = (initialHandshake.ProtocolCapabilities & ProtocolCapabilities.DeprecateEof) != 0;
 				SupportsCachedPreparedMetadata = (initialHandshake.ProtocolCapabilities & ProtocolCapabilities.MariaDbCacheMetadata) != 0;
@@ -1933,7 +1931,6 @@ protected override void OnStatementBegin(int index)
 	private IPayloadHandler? m_payloadHandler;
 	private bool m_useCompression;
 	private bool m_isSecureConnection;
-	private bool m_supportsComMulti;
 	private bool m_supportsConnectionAttributes;
 	private bool m_supportsDeprecateEof;
 	private bool m_supportsSessionTrack;

src/MySqlConnector/MySqlBatch.cs

@@ -160,8 +160,7 @@ private ValueTask<MySqlDataReader> ExecuteReaderAsync(CommandBehavior behavior,
 		foreach (MySqlBatchCommand batchCommand in BatchCommands)
 			batchCommand.Batch = this;
 
-		var payloadCreator = Connection!.Session.SupportsComMulti ? BatchedCommandPayloadCreator.Instance :
-			IsPrepared ? SingleCommandPayloadCreator.Instance :
+		var payloadCreator = IsPrepared ? SingleCommandPayloadCreator.Instance :
 			ConcatenatedCommandPayloadCreator.Instance;
 		return CommandExecutor.ExecuteReaderAsync(new(BatchCommands!.Commands), payloadCreator, behavior, default, ioBehavior, cancellationToken);
 	}

src/MySqlConnector/Protocol/CommandKind.cs

@@ -10,5 +10,4 @@ internal enum CommandKind
 	StatementPrepare = 22,
 	StatementExecute = 23,
 	ResetConnection = 31,
-	Multi = 254,
 }

src/MySqlConnector/Protocol/Payloads/HandshakeResponse41Payload.cs

@@ -28,7 +28,6 @@ private static ByteBufferWriter CreateCapabilitiesPayload(ProtocolCapabilities s
 			ProtocolCapabilities.SessionTrack |
 			ProtocolCapabilities.DeprecateEof |
 			ProtocolCapabilities.QueryAttributes |
-			ProtocolCapabilities.MariaDbComMulti |
 			ProtocolCapabilities.MariaDbCacheMetadata |
 			additionalCapabilities) & serverCapabilities;
 

tests/IntegrationTests/BatchTests.cs

@@ -223,29 +223,6 @@ public void ExecuteBatch(string suffix)
 		Assert.Equal(16, total);
 	}
 
-	[Fact(Skip = "COM_MULTI")]
-	public void ExecuteInvalidSqlBatch()
-	{
-		using var connection = new MySqlConnection(AppConfig.ConnectionString);
-		connection.Open();
-		using var batch = new MySqlBatch(connection)
-		{
-			BatchCommands =
-			{
-				new MySqlBatchCommand("SELECT 1;"),
-				new MySqlBatchCommand("SELECT 2 /* incomplete"),
-				new MySqlBatchCommand("SELECT 3;"),
-			},
-		};
-		using var reader = batch.ExecuteReader();
-		Assert.True(reader.Read());
-		Assert.Equal(1, reader.GetInt32(0));
-		Assert.False(reader.Read());
-
-		var ex = Assert.Throws<MySqlException>(() => reader.NextResult());
-		Assert.Equal(MySqlErrorCode.ParseError, ex.ErrorCode);
-	}
-
 	[Theory]
 	[InlineData(false)]
 	[InlineData(true)]

tests/IntegrationTests/CancelTests.cs

@@ -519,50 +519,6 @@ public void CancelBatchBeforeRead()
 		Assert.InRange(rows, 0, 10000000);
 	}
 
-	[SkippableFact(ServerFeatures.StreamingResults | ServerFeatures.Timeout, Skip = "COM_MULTI")]
-	public void CancelMultiCommandBatchReader()
-	{
-		using var barrier = new Barrier(2);
-		using var batch = new MySqlBatch(m_database.Connection)
-		{
-			BatchCommands =
-			{
-				new MySqlBatchCommand(c_hugeQuery),
-				new MySqlBatchCommand(c_hugeQuery),
-				new MySqlBatchCommand(c_hugeQuery),
-			},
-		};
-		var task = Task.Run(() =>
-		{
-			barrier.SignalAndWait();
-			batch.Cancel();
-		});
-
-		int rows = 0;
-		using (var reader = batch.ExecuteReader())
-		{
-			Assert.True(reader.Read());
-
-			barrier.SignalAndWait();
-			try
-			{
-				while (reader.Read())
-					rows++;
-			}
-			catch (MySqlException ex)
-			{
-				Assert.Equal(MySqlErrorCode.QueryInterrupted, ex.ErrorCode);
-			}
-
-			// query returns 25 billion rows; we shouldn't have read many of them
-			Assert.InRange(rows, 0, 10000000);
-
-			Assert.False(reader.NextResult());
-		}
-
-		task.Wait(); // shouldn't throw
-	}
-
 	[Fact]
 	public async Task CancelBatchWithTokenBeforeExecuteScalar()
 	{
@@ -688,41 +644,6 @@ public async Task CancelHugeQueryBatchWithTokenAfterExecuteReader()
 		Assert.False(reader.NextResult());
 	}
 
-	[SkippableFact(ServerFeatures.StreamingResults | ServerFeatures.Timeout, Skip = "COM_MULTI")]
-	public async Task CancelHugeQueryBatchWithTokenInNextResult()
-	{
-		using var batch = new MySqlBatch(m_database.Connection)
-		{
-			BatchCommands =
-			{
-				new MySqlBatchCommand(c_hugeQuery),
-				new MySqlBatchCommand("select 1, 2, 3;"),
-			},
-		};
-		using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(0.5));
-		using var reader = await batch.ExecuteReaderAsync(cts.Token);
-
-		// read first result set
-		Assert.True(await reader.ReadAsync(cts.Token));
-
-		try
-		{
-			// skip to the next result set
-			Assert.True(await reader.NextResultAsync(cts.Token));
-
-			// shouldn't get here
-			Assert.True(false);
-		}
-		catch (OperationCanceledException ex)
-		{
-			Assert.Equal(cts.Token, ex.CancellationToken);
-		}
-
-		// no more result sets
-		Assert.False(reader.Read());
-		Assert.False(reader.NextResult());
-	}
-
 	[SkippableFact(ServerFeatures.Timeout)]
 	public async Task CancelSlowQueryBatchWithTokenAfterExecuteReader()
 	{
@@ -796,39 +717,6 @@ public async Task CancelSlowQueryBatchWithTokenAfterNextResult()
 
 		Assert.False(await reader.NextResultAsync());
 	}
-
-	[SkippableFact(ServerFeatures.StreamingResults | ServerFeatures.Timeout, Skip = "COM_MULTI")]
-	public async Task CancelMultiStatementBatchInRead()
-	{
-		using var batch = new MySqlBatch(m_database.Connection)
-		{
-			BatchCommands =
-			{
-				new MySqlBatchCommand(c_hugeQuery),
-				new MySqlBatchCommand(c_hugeQuery),
-				new MySqlBatchCommand(c_hugeQuery),
-			},
-		};
-		using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(0.5));
-		using var reader = await batch.ExecuteReaderAsync();
-		var rows = 0;
-		try
-		{
-			while (await reader.ReadAsync(cts.Token))
-				rows++;
-
-			Assert.True(false);
-		}
-		catch (OperationCanceledException ex)
-		{
-			Assert.Equal(cts.Token, ex.CancellationToken);
-			Assert.InRange(rows, 0, 10000000);
-		}
-
-		// no more result sets; the whole command was cancelled
-		Assert.False(reader.Read());
-		Assert.False(reader.NextResult());
-	}
 #endif
 
 	private static CancellationToken GetCanceledToken()