Respect System.Transactions IsolationLevel. Fixes #605

Author: bgrainger

src/MySqlConnector/Core/StandardImplicitTransaction.cs

@@ -12,7 +12,33 @@ public StandardImplicitTransaction(MySqlConnection connection) : base(connection
 
 		protected override void OnStart()
 		{
-			m_transaction = Connection.BeginTransaction();
+			System.Data.IsolationLevel isolationLevel;
+			switch (Transaction.IsolationLevel)
+			{
+			case IsolationLevel.Serializable:
+				isolationLevel = System.Data.IsolationLevel.Serializable;
+				break;
+			case IsolationLevel.RepeatableRead:
+				isolationLevel = System.Data.IsolationLevel.RepeatableRead;
+				break;
+			case IsolationLevel.ReadCommitted:
+				isolationLevel = System.Data.IsolationLevel.ReadCommitted;
+				break;
+			case IsolationLevel.ReadUncommitted:
+				isolationLevel = System.Data.IsolationLevel.ReadUncommitted;
+				break;
+			case IsolationLevel.Snapshot:
+				isolationLevel = System.Data.IsolationLevel.Snapshot;
+				break;
+			case IsolationLevel.Chaos:
+				isolationLevel = System.Data.IsolationLevel.Chaos;
+				break;
+			case IsolationLevel.Unspecified:
+			default:
+				isolationLevel = System.Data.IsolationLevel.Unspecified;
+				break;
+			}
+			m_transaction = Connection.BeginTransaction(isolationLevel);
 		}
 
 		protected override void OnPrepare(PreparingEnlistment enlistment)

tests/SideBySide/TransactionScopeTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using System.Transactions;
 using Dapper;
 using MySql.Data.MySqlClient;
@@ -533,6 +534,58 @@ public void TwoSimultaneousConnectionsThrowsWithNonXaTransactions()
 			}
 		}
 
+		[Fact]
+		public void SimultaneousConnectionsWithTransactionScopeReadCommittedWithNonXaTransactions()
+		{
+			var connectionString = AppConfig.ConnectionString;
+#if !BASELINE
+			connectionString += ";UseXaTransactions=False";
+#endif
+
+			// from https://github.com/mysql-net/MySqlConnector/issues/605
+			using (var connection = new MySqlConnection(connectionString))
+			{
+				connection.Open();
+				connection.Execute(@"DROP TABLE IF EXISTS orders;
+					CREATE TABLE `orders`(  
+						`id` BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
+						`description` VARCHAR(50),
+						PRIMARY KEY (`id`)
+					);");
+			}
+
+			var task = Task.Run(() => UseTransaction());
+			UseTransaction();
+			task.Wait();
+
+			void UseTransaction()
+			{
+				// This TransactionScope may be overly configured, but let's stick with the one I am actually using
+				using (var transactionScope = new TransactionScope(TransactionScopeOption.Required,
+					new TransactionOptions { IsolationLevel = IsolationLevel.ReadCommitted },
+					TransactionScopeAsyncFlowOption.Enabled))
+				{
+					using (var connection = new MySqlConnection(connectionString))
+					using (var command = connection.CreateCommand())
+					{
+						command.CommandText = @"SELECT MAX(id) FROM orders FOR UPDATE;";
+						connection.Open();
+						command.ExecuteScalar();
+					}
+
+					using (var connection = new MySqlConnection(connectionString))
+					using (var command = connection.CreateCommand())
+					{
+						command.CommandText = @"INSERT INTO orders (description) VALUES ('blabla'), ('blablabla');";
+						connection.Open();
+						command.ExecuteNonQuery();
+					}
+
+					transactionScope.Complete();
+				}
+			}
+		}
+
 		[Fact]
 		public void TwoDifferentConnectionStringsThrowsWithNonXaTransactions()
 		{
@@ -594,3 +647,4 @@ public void CannotMixNonXaAndXaTransactions()
 		DatabaseFixture m_database;
 	}
 }
+