Events which can cause data loss are executed in context of disabled change registration

Author: alex-kulakov

Orm/Xtensive.Orm/Orm/Session.Persist.cs

@@ -135,16 +135,14 @@ private async ValueTask Persist(PersistReason reason, bool isAsync, Cancellation
       var ts = await InnerOpenTransaction(
         TransactionOpenMode.Default, IsolationLevel.Unspecified, false, isAsync, token);
 
-      IDisposable changesGuard = null;
       try {
         IsPersisting = true;
         persistingIsFailed = false;
         SystemEvents.NotifyPersisting();
         Events.NotifyPersisting();
 
-        changesGuard = PreventRegistryChanges();
         using (OpenSystemLogicOnlyRegion()) {
-          DemandTransaction();
+          _ = DemandTransaction();
           if (IsDebugEventLoggingEnabled) {
             OrmLog.Debug(nameof(Strings.LogSessionXPersistingReasonY), this, reason);
           }
@@ -176,16 +174,11 @@ private async ValueTask Persist(PersistReason reason, bool isAsync, Cancellation
           }
           catch (Exception) {
             persistingIsFailed = true;
-            changesGuard.Dispose();
-            changesGuard = null;
-
             RollbackChangesOfEntitySets();
             RestoreEntityChangesAfterPersistFailed();
             throw;
           }
           finally {
-            changesGuard.DisposeSafely();
-            changesGuard = null;
             if (persistIsSuccessful || !Configuration.Supports(SessionOptions.NonTransactionalEntityStates)) {
               DropDifferenceBackup();
               foreach (var item in itemsToPersist.GetItems(PersistenceState.New)) {
@@ -217,13 +210,13 @@ private async ValueTask Persist(PersistReason reason, bool isAsync, Cancellation
             }
           }
         }
-
-        SystemEvents.NotifyPersisted();
-        Events.NotifyPersisted();
+        using (PreventRegistryChanges()) {
+          SystemEvents.NotifyPersisted();
+          Events.NotifyPersisted();
+        }
       }
       finally {
         IsPersisting = false;
-        changesGuard.DisposeSafely();
         if (isAsync) {
           await ts.DisposeAsync().ConfigureAwait(false);
         }

Orm/Xtensive.Orm/Orm/Session.Transactions.cs

@@ -259,8 +259,10 @@ internal async ValueTask CommitTransaction(Transaction transaction, bool isAsync
 
       ValidationContext.Validate(ValidationReason.Commit);
 
-      SystemEvents.NotifyTransactionCommitting(transaction);
-      Events.NotifyTransactionCommitting(transaction);
+      using (PreventRegistryChanges()) {
+        SystemEvents.NotifyTransactionCommitting(transaction);
+        Events.NotifyTransactionCommitting(transaction);
+      }
 
       Handler.CompletingTransaction(transaction);
       if (transaction.IsNested) {
@@ -366,24 +368,28 @@ internal void CompleteTransaction(Transaction transaction)
       Transaction = transaction.Outer;
 
       switch (transaction.State) {
-      case TransactionState.Committed:
-        if (IsDebugEventLoggingEnabled) {
-          OrmLog.Debug(nameof(Strings.LogSessionXCommittedTransaction), this);
-        }
+        case TransactionState.Committed:
+          if (IsDebugEventLoggingEnabled) {
+            OrmLog.Debug(nameof(Strings.LogSessionXCommittedTransaction), this);
+          }
 
-        SystemEvents.NotifyTransactionCommitted(transaction);
-        Events.NotifyTransactionCommitted(transaction);
-        break;
-      case TransactionState.RolledBack:
-        if (IsDebugEventLoggingEnabled) {
-          OrmLog.Debug(nameof(Strings.LogSessionXRolledBackTransaction), this);
-        }
+          using (PreventRegistryChanges()) {
+            SystemEvents.NotifyTransactionCommitted(transaction);
+            Events.NotifyTransactionCommitted(transaction);
+          }
+          break;
+        case TransactionState.RolledBack:
+          if (IsDebugEventLoggingEnabled) {
+            OrmLog.Debug(nameof(Strings.LogSessionXRolledBackTransaction), this);
+          }
 
-        SystemEvents.NotifyTransactionRollbacked(transaction);
-        Events.NotifyTransactionRollbacked(transaction);
-        break;
-      default:
-        throw new ArgumentOutOfRangeException("transaction.State");
+          using (PreventRegistryChanges()) {
+            SystemEvents.NotifyTransactionRollbacked(transaction);
+            Events.NotifyTransactionRollbacked(transaction);
+          }
+          break;
+        default:
+          throw new ArgumentOutOfRangeException("transaction.State");
       }
     }