RecordsetEnumerating / RecordsetEnumerated Session events

Orm/Xtensive.Orm/Orm/Providers/CommandProcessing/DataReader.cs

@@ -17,31 +17,37 @@ namespace Xtensive.Orm.Providers
   /// over either regular <see cref="IEnumerable{T}"/> of <see cref="Tuple"/>s
   /// or over the running <see cref="Command"/> instance.
   /// </summary>
-  public interface DataReader : IEnumerator<Tuple>, IAsyncEnumerator<Tuple>
+  public abstract class DataReader : IEnumerator<Tuple>, IAsyncEnumerator<Tuple>
   {
-    bool IsInMemory { get; }
-    Tuple Current { get; }
+    public abstract bool MoveNext();
+    public abstract ValueTask<bool> MoveNextAsync();
+    public abstract void Reset();
+    public abstract void Dispose();
+    public abstract ValueTask DisposeAsync();
+
+    public abstract Tuple Current { get; }
+    object IEnumerator.Current => Current;
+
+    public abstract bool IsInMemory { get; }
   }
 
   internal sealed class InMemoryDataReader(IEnumerable<Tuple> tuples) : DataReader
   {
     private readonly IEnumerator<Tuple> source = tuples.GetEnumerator();
 
-    public bool IsInMemory => true;
-
-    public Tuple Current => source.Current;
+    public override bool IsInMemory => true;
 
-    object IEnumerator.Current => Current;
+    public override Tuple Current => source.Current;
 
-    public bool MoveNext() => source.MoveNext();
+    public override bool MoveNext() => source.MoveNext();
 
-    public void Reset() => source.Reset();
+    public override void Reset() => source.Reset();
 
-    public void Dispose() => source.Dispose();
+    public override void Dispose() => source.Dispose();
 
-    public async ValueTask DisposeAsync() => await ((IAsyncEnumerator<Tuple>) source).DisposeAsync().ConfigureAwaitFalse();
+    public override async ValueTask DisposeAsync() => await ((IAsyncEnumerator<Tuple>) source).DisposeAsync().ConfigureAwaitFalse();
 
-    public ValueTask<bool> MoveNextAsync() => ValueTask.FromResult(MoveNext());
+    public override ValueTask<bool> MoveNextAsync() => ValueTask.FromResult(MoveNext());
   }
 
   internal sealed class CommandDataReader(Command command, DbDataReaderAccessor accessor, CancellationToken token) : DataReader
@@ -50,16 +56,13 @@ internal sealed class CommandDataReader(Command command, DbDataReaderAccessor ac
     /// Indicates current <see cref="DataReader"/> is built
     /// over <see cref="IEnumerable{T}"/> of <see cref="Tuple"/>s data source.
     /// </summary>
-    public bool IsInMemory => false;
+    public override bool IsInMemory => false;
 
     /// <inheritdoc cref="IEnumerator{T}.Current"/>
-    public Tuple Current => command.ReadTupleWith(accessor);
-
-    /// <inheritdoc/>
-    object IEnumerator.Current => Current;
+    public override Tuple Current => command.ReadTupleWith(accessor);
 
     /// <inheritdoc/>
-    public bool MoveNext()
+    public override bool MoveNext()
     {
       if (command.NextRow()) {
         return true;
@@ -71,7 +74,7 @@ public bool MoveNext()
     }
 
     /// <inheritdoc/>
-    public async ValueTask<bool> MoveNextAsync()
+    public override async ValueTask<bool> MoveNextAsync()
     {
       if (await command.NextRowAsync(token).ConfigureAwaitFalse()) {
         return true;
@@ -83,12 +86,12 @@ public async ValueTask<bool> MoveNextAsync()
     }
 
     /// <inheritdoc/>
-    public void Reset() => throw new NotSupportedException("Multiple enumeration is not supported.");
+    public override void Reset() => throw new NotSupportedException("Multiple enumeration is not supported.");
 
     /// <inheritdoc/>
-    public void Dispose() => command.Dispose();
+    public override void Dispose() => command.Dispose();
 
     /// <inheritdoc/>
-    public async ValueTask DisposeAsync() => await command.DisposeAsync().ConfigureAwaitFalse();
+    public override async ValueTask DisposeAsync() => await command.DisposeAsync().ConfigureAwaitFalse();
   }
-}
+}

Orm/Xtensive.Orm/Orm/Providers/EnumerationContext.cs

@@ -19,11 +19,9 @@ namespace Xtensive.Orm.Providers
   /// </summary>
   public sealed class EnumerationContext : Rse.Providers.EnumerationContext
   {
-    private class EnumerationFinalizer : ICompletableScope
+    private class EnumerationFinalizer(EnumerationContext context, Queue<Action> finalizationQueue, TransactionScope transactionScope, SessionEventAccessor events)
+      : ICompletableScope
     {
-      private readonly Queue<Action> finalizationQueue;
-      private readonly TransactionScope transactionScope;
-
       public void Complete()
       {
         if (IsCompleted)
@@ -36,16 +34,11 @@ public void Complete()
 
       public void Dispose()
       {
-        while (finalizationQueue.TryDequeue(out var materializeSelf)) {
+        while (finalizationQueue?.TryDequeue(out var materializeSelf) == true) {
           materializeSelf.Invoke();
         }
-        transactionScope.DisposeSafely();
-      }
-
-      public EnumerationFinalizer(Queue<Action> finalizationQueue, TransactionScope transactionScope)
-      {
-        this.finalizationQueue = finalizationQueue;
-        this.transactionScope = transactionScope;
+        transactionScope?.Dispose();
+        events.NotifyRecordsetEnumerated(context);
       }
     }
 
@@ -56,7 +49,7 @@ public EnumerationFinalizer(Queue<Action> finalizationQueue, TransactionScope tr
     /// Gets the session handler.
     /// </summary>
     /// <value>The session handler.</value>
-    public Session Session { get; private set; }
+    public Session Session { get; }
 
     /// <inheritdoc/>
     protected override EnumerationContextOptions Options { get { return options; } }
@@ -71,9 +64,10 @@ public override ICompletableScope BeginEnumeration()
       var tx = Session.OpenAutoTransaction();
       if (!Session.Configuration.Supports(SessionOptions.NonTransactionalReads))
         Session.DemandTransaction();
-      if (MaterializationContext!=null && MaterializationContext.MaterializationQueue!=null)
-        return new EnumerationFinalizer(MaterializationContext.MaterializationQueue, tx);
-      return tx;
+      var events = Session.Events;
+      return events.NotifyRecordsetEnumerating(this) || MaterializationContext?.MaterializationQueue != null
+        ? new EnumerationFinalizer(this, MaterializationContext?.MaterializationQueue, tx, events)
+        : tx;
     }
 
     // Constructors

Orm/Xtensive.Orm/Orm/SessionEventAccessor.cs

@@ -12,6 +12,7 @@
 using System.Linq.Expressions;
 using Xtensive.Core;
 using Xtensive.Orm.Model;
+using Xtensive.Orm.Providers;
 
 namespace Xtensive.Orm
 {
@@ -244,6 +245,16 @@ public sealed class SessionEventAccessor
     /// </summary>
     public event EventHandler<TransactionEventArgs> TransactionRollbacked;
 
+    /// <summary>
+    /// Occurs when Recordset enumeration begins
+    /// </summary>
+    public event EventHandler<EnumerationContext> RecordsetEnumerating;
+
+    /// <summary>
+    /// Occurs when Recordset enumeration ends
+    /// </summary>
+    public event EventHandler<EnumerationContext> RecordsetEnumerated;
+
     #endregion
 
     #region NotifyXxx methods
@@ -497,6 +508,21 @@ internal void NotifyTransactionRollbacked(Transaction transaction)
         TransactionRollbacked(this, new TransactionEventArgs(transaction));
     }
 
+    internal bool NotifyRecordsetEnumerating(EnumerationContext context)
+    {
+      if (RecordsetEnumerating != null && AreNotificationsEnabled()) {
+        RecordsetEnumerating(this, context);
+        return true;
+      }
+      return false;
+    }
+
+    internal void NotifyRecordsetEnumerated(EnumerationContext context)
+    {
+      if (RecordsetEnumerated != null && AreNotificationsEnabled())
+        RecordsetEnumerated(this, context);
+    }
+
     #endregion
 
     private bool AreNotificationsEnabled()
@@ -513,4 +539,4 @@ internal SessionEventAccessor(Session session, bool systemEvents)
       SystemEvents = systemEvents;
     }
   }
-}
+}