From 70a31f4727a941479ec273d81c5db3a1c3175fe4 Mon Sep 17 00:00:00 2001
From: "Dailey, Alaric" <alaricd@pengdows.com>
Date: Thu, 29 Oct 2026 02:12:59 -0500
Subject: [PATCH] fix(spanner): clear transaction connection after completion

---
 .../SpannerTransactionTests.cs                | 49 +++++++++++++++++++
 .../SpannerTransaction.cs                     |  5 +-
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data.Tests/SpannerTransactionTests.cs b/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data.Tests/SpannerTransactionTests.cs
index c9638e557cf2..1911a91ae320 100644
--- a/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data.Tests/SpannerTransactionTests.cs
+++ b/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data.Tests/SpannerTransactionTests.cs
@@ -16,6 +16,7 @@
 using Google.Cloud.Spanner.V1.Internal.Logging;
 using Google.Cloud.Spanner.V1.Tests;
 using System;
+using System.Threading.Tasks;
 using Xunit;
 
 namespace Google.Cloud.Spanner.Data.Tests;
@@ -47,6 +48,54 @@ public void MaxCommitDelay_DefaultsToNull()
         Assert.Null(transaction.TransactionOptions.MaxCommitDelay);
     }
 
+    [Fact]
+    public void Connection_IsNullAfterDispose()
+    {
+        SpannerClient spannerClientMock = SpannerClientHelpers.CreateMockClient(Logger.DefaultLogger);
+        spannerClientMock.SetupCreateSessionAsync();
+        SpannerConnection connection = SpannerCommandTests.BuildSpannerConnection(spannerClientMock);
+        SpannerTransaction transaction = connection.BeginTransaction();
+
+        Assert.Same(connection, transaction.Connection);
+
+        transaction.Dispose();
+
+        Assert.Null(transaction.Connection);
+    }
+
+    [Fact]
+    public async Task Connection_IsNullAfterCommit()
+    {
+        SpannerClient spannerClientMock = SpannerClientHelpers.CreateMockClient(Logger.DefaultLogger);
+        spannerClientMock.SetupCreateSessionAsync().SetupExecuteStreamingSql().SetupCommitAsync();
+        SpannerConnection connection = SpannerCommandTests.BuildSpannerConnection(spannerClientMock);
+        SpannerTransaction transaction = connection.BeginTransaction();
+
+        using (var command = connection.CreateSelectCommand("SELECT 1"))
+        {
+            command.Transaction = transaction;
+            using var reader = await command.ExecuteReaderAsync();
+            Assert.True(reader.HasRows);
+        }
+
+        await transaction.CommitAsync();
+
+        Assert.Null(transaction.Connection);
+    }
+
+    [Fact]
+    public async Task Connection_IsNullAfterRollback()
+    {
+        SpannerClient spannerClientMock = SpannerClientHelpers.CreateMockClient(Logger.DefaultLogger);
+        spannerClientMock.SetupCreateSessionAsync().SetupRollbackAsync();
+        SpannerConnection connection = SpannerCommandTests.BuildSpannerConnection(spannerClientMock);
+        SpannerTransaction transaction = connection.BeginTransaction();
+
+        await transaction.RollbackAsync();
+
+        Assert.Null(transaction.Connection);
+    }
+
     [Theory, MemberData(nameof(ValidMaxCommitDelayValues))]
     public void MaxCommitDelay_Valid(TimeSpan? maxCommitDelay)
     {
diff --git a/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data/SpannerTransaction.cs b/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data/SpannerTransaction.cs
index e47a12fdc9c4..76c3320a87e7 100644
--- a/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data/SpannerTransaction.cs
+++ b/apis/Google.Cloud.Spanner.Data/Google.Cloud.Spanner.Data/SpannerTransaction.cs
@@ -64,6 +64,7 @@ public sealed class SpannerTransaction : SpannerTransactionBase, ISpannerTransac
         private readonly bool _isRetriable = false;
         private int _disposed = 0;
         private int _commited = 0;
+        private int _completed = 0;
 
         // Flag indicating whether the transaction has executed at least one statement.
         // The TransactionTag may no longer be set once the transaction has executed one
@@ -153,7 +154,7 @@ public int CommitTimeout
         public TimestampBound TimestampBound => _creationOptions.TimestampBound ?? _creationOptions.TransactionId?.TimestampBound;
 
         /// <inheritdoc />
-        protected override DbConnection DbConnection => SpannerConnection;
+        protected override DbConnection DbConnection => _disposed == 0 && _completed == 0 ? SpannerConnection : null;
 
         /// <summary>
         /// <see cref="SpannerConnection"/> associated with this transaction.
@@ -448,6 +449,7 @@ Task<IEnumerable<long>> ISpannerTransaction.ExecuteBatchDmlAsync(ExecuteBatchDml
                     settings => settings.CommitSettings, TransactionOptions.EffectiveCommitTimeout(SpannerConnection), cancellationToken);
                 var response = await _session.CommitAsync(request, callSettings).ConfigureAwait(false);
                 Interlocked.Exchange(ref _commited, 1);
+                Interlocked.Exchange(ref _completed, 1);
                 // We dispose of the SpannerTransaction to inmediately release the session to the pool when possible.
                 Dispose();
                 if (response.CommitTimestamp == null)
@@ -503,6 +505,7 @@ public override async Task RollbackAsync(CancellationToken cancellationToken = d
             await  ExecuteHelper.WithErrorTranslationAndProfiling(
                 () => _session.RollbackAsync(new RollbackRequest(), callSettings),
                 "SpannerTransaction.Rollback", SpannerConnection.Logger).ConfigureAwait(false);
+            Interlocked.Exchange(ref _completed, 1);
             Dispose();
         }