Allow providers to override ambient transaction access

src/EFCore.Cosmos/Storage/Internal/CosmosTransactionManager.cs

@@ -73,6 +73,15 @@ public virtual void RollbackTransaction()
         public virtual Task RollbackTransactionAsync(CancellationToken cancellationToken = default)
             => throw new NotSupportedException(CosmosStrings.TransactionsNotSupported);
 
+        /// <summary>
+        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
+        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
+        ///     any release. You should only use it directly in your code with extreme caution and knowing that
+        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
+        /// </summary>
+        public virtual Transaction CurrentAmbientTransaction
+            => null;
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in

src/EFCore.Relational/Storage/RelationalConnection.cs

@@ -182,6 +182,11 @@ public virtual DbConnection DbConnection
             }
         }
 
+        /// <summary>
+        ///     The current ambient transaction. Defaults to <see cref="Transaction.Current" />.
+        /// </summary>
+        public virtual Transaction? CurrentAmbientTransaction => Transaction.Current;
+
         /// <summary>
         ///     Gets the current transaction.
         /// </summary>
@@ -397,7 +402,7 @@ private void EnsureNoTransactions()
                 throw new InvalidOperationException(RelationalStrings.TransactionAlreadyStarted);
             }
 
-            if (Transaction.Current != null)
+            if (CurrentAmbientTransaction != null)
             {
                 throw new InvalidOperationException(RelationalStrings.ConflictingAmbientTransaction);
             }
@@ -748,7 +753,7 @@ protected virtual Task OpenDbConnectionAsync(bool errorsExpected, CancellationTo
 
         private void HandleAmbientTransactions()
         {
-            var current = Transaction.Current;
+            var current = CurrentAmbientTransaction;
 
             if (current == null)
             {

src/EFCore.Relational/Update/Internal/BatchExecutor.cs

@@ -76,10 +76,11 @@ public virtual int Execute(
             var createdSavepoint = false;
             try
             {
+                var transactionEnlistManager = connection as ITransactionEnlistmentManager;
                 if (transaction == null
-                    && (connection as ITransactionEnlistmentManager)?.EnlistedTransaction == null
-                    && Transaction.Current == null
-                    && CurrentContext.Context.Database.AutoTransactionsEnabled)
+                        && transactionEnlistManager?.EnlistedTransaction is null
+                        && transactionEnlistManager?.CurrentAmbientTransaction is null
+                        && CurrentContext.Context.Database.AutoTransactionsEnabled)
                 {
                     transaction = connection.BeginTransaction();
                     beganTransaction = true;
@@ -170,9 +171,10 @@ public virtual async Task<int> ExecuteAsync(
             var createdSavepoint = false;
             try
             {
+                var transactionEnlistManager = connection as ITransactionEnlistmentManager;
                 if (transaction == null
-                    && (connection as ITransactionEnlistmentManager)?.EnlistedTransaction == null
-                    && Transaction.Current == null
+                    && transactionEnlistManager?.EnlistedTransaction is null
+                    && transactionEnlistManager?.CurrentAmbientTransaction is null
                     && CurrentContext.Context.Database.AutoTransactionsEnabled)
                 {
                     transaction = await connection.BeginTransactionAsync(cancellationToken).ConfigureAwait(false);

src/EFCore/Storage/ExecutionStrategy.cs

@@ -328,9 +328,10 @@ private async Task<ExecutionResult<TResult>> ExecuteImplementationAsync<TState,
         /// </summary>
         protected virtual void OnFirstExecution()
         {
-            if (Dependencies.CurrentContext.Context.Database.CurrentTransaction != null
-                || Dependencies.CurrentContext.Context.Database.GetEnlistedTransaction() != null
-                || Transaction.Current != null)
+            if (Dependencies.CurrentContext.Context.Database.CurrentTransaction is not null
+                || Dependencies.CurrentContext.Context.Database.GetEnlistedTransaction() is not null
+                || (((IDatabaseFacadeDependenciesAccessor)Dependencies.CurrentContext.Context.Database).Dependencies.TransactionManager as
+                    ITransactionEnlistmentManager)?.CurrentAmbientTransaction is not null)
             {
                 throw new InvalidOperationException(
                     CoreStrings.ExecutionStrategyExistingTransaction(

src/EFCore/Storage/ITransactionEnlistmentManager.cs

@@ -19,6 +19,11 @@ namespace Microsoft.EntityFrameworkCore.Storage
     /// </summary>
     public interface ITransactionEnlistmentManager
     {
+        /// <summary>
+        ///     The current ambient transaction. Defaults to <see cref="Transaction.Current" />.
+        /// </summary>
+        Transaction? CurrentAmbientTransaction => Transaction.Current;
+
         /// <summary>
         ///     The currently enlisted transaction.
         /// </summary>