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Support System.Transactions. Fixes #13 
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‎docs/content/tutorials/migrating-from-connector-net.md

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@@ -39,8 +39,16 @@ MySqlConnector has some different default connection string options:
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Some command line options that are supported in Connector/NET are not supported in MySqlConnector. For a full list of options that are
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supported in MySqlConnector, see the [Connection Options](connection-options)
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### TransactionScope
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MySqlConnector adds full distributed transaction support (for client code using [`TransactionScope`](https://msdn.microsoft.com/en-us/library/system.transactions.transactionscope.aspx)),
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while Connector/NET uses regular database transactions. As a result, code that uses `TransactionScope`
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may execute differently with MySqlConnector. To get Connector/NET-compatible behavior, remove
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`TransactionScope` and use `BeginTransaction`/`Commit` directly.
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### Bugs present in Connector/NET that are fixed in MySqlConnector
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* [#37283](https://bugs.mysql.com/bug.php?id=37283), [#70587](https://bugs.mysql.com/bug.php?id=70587): Distributed transactions are not supported
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* [#66476](https://bugs.mysql.com/bug.php?id=66476): Connection pool uses queue instead of stack
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* [#70111](https://bugs.mysql.com/bug.php?id=70111): `Async` methods execute synchronously
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* [#70686](https://bugs.mysql.com/bug.php?id=70686): `TIME(3)` and `TIME(6)` fields serialize milliseconds incorrectly

‎src/MySqlConnector/MySqlClient/MySqlConnection.cs

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@@ -37,6 +37,10 @@ private async Task<MySqlTransaction> BeginDbTransactionAsync(IsolationLevel isol
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throw new InvalidOperationException("Connection is not open.");
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if (CurrentTransaction != null)
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throw new InvalidOperationException("Transactions may not be nested.");
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#if !NETSTANDARD1_3
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if (m_xaTransaction != null)
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throw new InvalidOperationException("Cannot begin a transaction when already enlisted in a transaction.");
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#endif
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string isolationLevelValue;
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switch (isolationLevel)
@@ -76,8 +80,32 @@ private async Task<MySqlTransaction> BeginDbTransactionAsync(IsolationLevel isol
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#if !NETSTANDARD1_3
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public override void EnlistTransaction(System.Transactions.Transaction transaction)
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{
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throw new NotSupportedException("System.Transactions.Transaction is not supported. Use BeginTransaction instead.");
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if (m_xaTransaction != null)
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throw new MySqlException("Already enlisted in a Transaction.");
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if (CurrentTransaction != null)
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throw new InvalidOperationException("Can't enlist in a Transaction when there is an active MySqlTransaction.");
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if (transaction != null)
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{
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m_xaTransaction = new MySqlXaTransaction(this);
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m_xaTransaction.Start(transaction);
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}
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}
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internal void UnenlistTransaction(MySqlXaTransaction xaTransaction)
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{
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if (!object.ReferenceEquals(xaTransaction, m_xaTransaction))
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throw new InvalidOperationException("Active transaction is not the one being unenlisted from.");
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m_xaTransaction = null;
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if (m_shouldCloseWhenUnenlisted)
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{
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m_shouldCloseWhenUnenlisted = false;
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Close();
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}
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}
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MySqlXaTransaction m_xaTransaction;
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#endif
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public override void Close() => DoClose();
@@ -111,10 +139,6 @@ private async Task OpenAsync(IOBehavior ioBehavior, CancellationToken cancellati
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VerifyNotDisposed();
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if (State != ConnectionState.Closed)
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throw new InvalidOperationException("Cannot Open when State is {0}.".FormatInvariant(State));
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#if !NETSTANDARD1_3
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if (System.Transactions.Transaction.Current != null)
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throw new NotSupportedException("Ambient transactions are not supported. Use BeginTransaction instead.");
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#endif
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SetState(ConnectionState.Connecting);
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@@ -135,6 +159,11 @@ private async Task OpenAsync(IOBehavior ioBehavior, CancellationToken cancellati
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SetState(ConnectionState.Closed);
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throw new MySqlException("Unable to connect to any of the specified MySQL hosts.", ex);
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}
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#if !NETSTANDARD1_3
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if (System.Transactions.Transaction.Current != null)
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EnlistTransaction(System.Transactions.Transaction.Current);
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#endif
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}
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public override string ConnectionString
@@ -195,7 +224,7 @@ protected override void Dispose(bool disposing)
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}
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finally
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{
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m_isDisposed = true;
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m_isDisposed = !m_shouldCloseWhenUnenlisted;
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base.Dispose(disposing);
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}
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}
@@ -316,6 +345,19 @@ private void VerifyNotDisposed()
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private void DoClose()
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{
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#if !NETSTANDARD1_3
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// If participating in a distributed transaction, keep the connection open so we can commit or rollback.
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// This handles the common pattern of disposing a connection before disposing a TransactionScope (e.g., nested using blocks)
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if (m_xaTransaction != null)
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{
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m_shouldCloseWhenUnenlisted = true;
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return;
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}
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#else
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// fix "field is never assigned" compiler error
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m_shouldCloseWhenUnenlisted = false;
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#endif
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if (m_connectionState != ConnectionState.Closed)
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{
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try
@@ -355,6 +397,7 @@ private void CloseDatabase()
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ConnectionState m_connectionState;
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bool m_hasBeenOpened;
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bool m_isDisposed;
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bool m_shouldCloseWhenUnenlisted;
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Dictionary<string, CachedProcedure> m_cachedProcedures;
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}
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}

‎src/MySqlConnector/MySqlClient/MySqlXaTransaction.cs

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@@ -0,0 +1,65 @@
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#if !NETSTANDARD1_3
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using System;
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using System.Globalization;
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using System.Threading;
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using System.Transactions;
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namespace MySql.Data.MySqlClient
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{
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internal sealed class MySqlXaTransaction : IEnlistmentNotification
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{
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public MySqlXaTransaction(MySqlConnection connection) => m_connection = connection;
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public void Start(Transaction transaction)
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{
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// generate an "xid" with "gtrid" (Global TRansaction ID) from the .NET Transaction and "bqual" (Branch QUALifier)
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// unique to this object
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var id = Interlocked.Increment(ref s_currentId);
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m_xid = "'" + transaction.TransactionInformation.LocalIdentifier + "', '" + id.ToString(CultureInfo.InvariantCulture) + "'";
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ExecuteXaCommand("START");
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// TODO: Support EnlistDurable and enable recovery via "XA RECOVER"
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transaction.EnlistVolatile(this, EnlistmentOptions.None);
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}
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public void Prepare(PreparingEnlistment enlistment)
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{
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ExecuteXaCommand("END");
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ExecuteXaCommand("PREPARE");
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enlistment.Prepared();
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}
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public void Commit(Enlistment enlistment)
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{
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ExecuteXaCommand("COMMIT");
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enlistment.Done();
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m_connection.UnenlistTransaction(this);
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}
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public void Rollback(Enlistment enlistment)
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{
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ExecuteXaCommand("END");
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ExecuteXaCommand("ROLLBACK");
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enlistment.Done();
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m_connection.UnenlistTransaction(this);
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}
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public void InDoubt(Enlistment enlistment) => throw new NotSupportedException();
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private void ExecuteXaCommand(string statement)
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{
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using (var cmd = m_connection.CreateCommand())
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{
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cmd.CommandText = "XA " + statement + " " + m_xid;
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cmd.ExecuteNonQuery();
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}
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}
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static int s_currentId;
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readonly MySqlConnection m_connection;
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string m_xid;
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}
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}
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#endif

‎tests/SideBySide/SideBySide.csproj

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@@ -47,6 +47,7 @@
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<ItemGroup Condition=" '$(TargetFramework)' == 'net462' ">
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<Reference Include="System" />
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<Reference Include="System.Transactions" />
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<Reference Include="Microsoft.CSharp" />
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</ItemGroup>
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