Clear events when DbContext is disposed or returned to the pool

Fixes #23108

All.sln.DotSettings

@@ -192,6 +192,7 @@ Licensed under the Apache License, Version 2.0. See License.txt in the project r
 	<s:Boolean x:Key="/Default/Environment/InjectedLayers/InjectedLayerCustomization/=FileEF4F00E20178B341995BD2EFE53739B5/@KeyIndexDefined">True</s:Boolean>
 	<s:Double x:Key="/Default/Environment/InjectedLayers/InjectedLayerCustomization/=FileEF4F00E20178B341995BD2EFE53739B5/RelativePriority/@EntryValue">2</s:Double>
 	<s:String x:Key="/Default/Environment/PerformanceGuide/SwitchBehaviour/=VsBulb/@EntryIndexedValue">DO_NOTHING</s:String>
+	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EFeature_002EServices_002EDaemon_002ESettings_002EMigration_002ESwaWarningsModeSettingsMigrate/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpAttributeForSingleLineMethodUpgrade/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpKeepExistingMigration/@EntryIndexedValue">True</s:Boolean>
 	<s:Boolean x:Key="/Default/Environment/SettingsMigration/IsMigratorApplied/=JetBrains_002EReSharper_002EPsi_002ECSharp_002ECodeStyle_002ECSharpPlaceAttributeOnSameLineMigration/@EntryIndexedValue">True</s:Boolean>

src/EFCore/DbContext.cs

@@ -756,9 +756,7 @@ void IResettableService.ResetState()
                 service.ResetState();
             }
 
-            SavingChanges = null;
-            SavedChanges = null;
-            SaveChangesFailed = null;
+            ClearEvents();
 
             _disposed = true;
         }
@@ -769,7 +767,6 @@ void IResettableService.ResetState()
         ///     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>
-        /// <param name="cancellationToken"> A <see cref="CancellationToken" /> to observe while waiting for the task to complete. </param>
         [EntityFrameworkInternal]
         async Task IResettableService.ResetStateAsync(CancellationToken cancellationToken)
         {
@@ -778,6 +775,8 @@ async Task IResettableService.ResetStateAsync(CancellationToken cancellationToke
                 await service.ResetStateAsync(cancellationToken).ConfigureAwait(false);
             }
 
+            ClearEvents();
+
             _disposed = true;
         }
 
@@ -825,6 +824,9 @@ private bool DisposeSync()
                 if (_lease.ContextDisposed())
                 {
                     _disposed = true;
+
+                    ClearEvents();
+
                     _lease = DbContextLease.InactiveLease;
                 }
             }
@@ -842,6 +844,8 @@ private bool DisposeSync()
                 _changeTracker = null;
                 _database = null;
 
+                ClearEvents();
+
                 return true;
             }
 
@@ -854,6 +858,14 @@ private bool DisposeSync()
         public virtual ValueTask DisposeAsync()
             => DisposeSync() ? _serviceScope.DisposeAsyncIfAvailable() : default;
 
+
+        private void ClearEvents()
+        {
+            SavingChanges = null;
+            SavedChanges = null;
+            SaveChangesFailed = null;
+        }
+
         /// <summary>
         ///     Gets an <see cref="EntityEntry{TEntity}" /> for the given entity. The entry provides
         ///     access to change tracking information and operations for the entity.

test/EFCore.SqlServer.FunctionalTests/DbContextPoolingTest.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Diagnostics;
 using System.Linq;
+using System.Reflection;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.EntityFrameworkCore.ChangeTracking;
@@ -496,9 +497,20 @@ public async Task Context_configuration_is_reset(bool useInterface, bool async)
             context1.ChangeTracker.CascadeDeleteTiming = CascadeTiming.Immediate;
             context1.ChangeTracker.DeleteOrphansTiming = CascadeTiming.Immediate;
             context1.Database.AutoTransactionsEnabled = true;
+            context1.SavingChanges += (sender, args) => { };
+            context1.SavedChanges += (sender, args) => { };
+            context1.SaveChangesFailed += (sender, args) => { };
+
+            Assert.NotNull(GetContextEventField(context1, nameof(DbContext.SavingChanges)));
+            Assert.NotNull(GetContextEventField(context1, nameof(DbContext.SavedChanges)));
+            Assert.NotNull(GetContextEventField(context1, nameof(DbContext.SaveChangesFailed)));
 
             await Dispose(serviceScope, async);
 
+            Assert.Null(GetContextEventField(context1, nameof(DbContext.SavingChanges)));
+            Assert.Null(GetContextEventField(context1, nameof(DbContext.SavedChanges)));
+            Assert.Null(GetContextEventField(context1, nameof(DbContext.SaveChangesFailed)));
+
             serviceScope = serviceProvider.CreateScope();
             scopedProvider = serviceScope.ServiceProvider;
 
@@ -531,9 +543,20 @@ public async Task Context_configuration_is_reset_with_factory(bool async)
             context1.ChangeTracker.CascadeDeleteTiming = CascadeTiming.Immediate;
             context1.ChangeTracker.DeleteOrphansTiming = CascadeTiming.Immediate;
             context1.Database.AutoTransactionsEnabled = true;
+            context1.SavingChanges += (sender, args) => { };
+            context1.SavedChanges += (sender, args) => { };
+            context1.SaveChangesFailed += (sender, args) => { };
+
+            Assert.NotNull(GetContextEventField(context1, nameof(DbContext.SavingChanges)));
+            Assert.NotNull(GetContextEventField(context1, nameof(DbContext.SavedChanges)));
+            Assert.NotNull(GetContextEventField(context1, nameof(DbContext.SaveChangesFailed)));
 
             await Dispose(context1, async);
 
+            Assert.Null(GetContextEventField(context1, nameof(DbContext.SavingChanges)));
+            Assert.Null(GetContextEventField(context1, nameof(DbContext.SavedChanges)));
+            Assert.Null(GetContextEventField(context1, nameof(DbContext.SaveChangesFailed)));
+
             var context2 = factory.CreateDbContext();
 
             Assert.Same(context1, context2);
@@ -553,6 +576,10 @@ public void Change_tracker_can_be_cleared_without_resetting_context_config()
                 new DbContextOptionsBuilder().UseSqlServer(
                     SqlServerNorthwindTestStoreFactory.NorthwindConnectionString).Options);
 
+            Assert.Null(GetContextEventField(context, nameof(DbContext.SavingChanges)));
+            Assert.Null(GetContextEventField(context, nameof(DbContext.SavedChanges)));
+            Assert.Null(GetContextEventField(context, nameof(DbContext.SaveChangesFailed)));
+
             context.ChangeTracker.AutoDetectChangesEnabled = true;
             context.ChangeTracker.LazyLoadingEnabled = true;
             context.ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
@@ -561,6 +588,9 @@ public void Change_tracker_can_be_cleared_without_resetting_context_config()
             context.Database.AutoTransactionsEnabled = true;
             context.ChangeTracker.Tracked += ChangeTracker_OnTracked;
             context.ChangeTracker.StateChanged += ChangeTracker_OnStateChanged;
+            context.SavingChanges += (sender, args) => { };
+            context.SavedChanges += (sender, args) => { };
+            context.SaveChangesFailed += (sender, args) => { };
 
             context.ChangeTracker.Clear();
 
@@ -579,8 +609,16 @@ public void Change_tracker_can_be_cleared_without_resetting_context_config()
 
             Assert.True(_changeTracker_OnTracked);
             Assert.True(_changeTracker_OnStateChanged);
+
+            Assert.NotNull(GetContextEventField(context, nameof(DbContext.SavingChanges)));
+            Assert.NotNull(GetContextEventField(context, nameof(DbContext.SavedChanges)));
+            Assert.NotNull(GetContextEventField(context, nameof(DbContext.SaveChangesFailed)));
         }
 
+        private object GetContextEventField(DbContext context, string eventName)
+            => typeof(DbContext)
+                .GetField(eventName, BindingFlags.GetField | BindingFlags.NonPublic | BindingFlags.Instance)
+                .GetValue(context);
         private bool _changeTracker_OnTracked;
 
         private void ChangeTracker_OnTracked(object sender, EntityTrackedEventArgs e)