Makes QueryCommand implement IAsyncDisposable

Extensions/Xtensive.Orm.BulkOperations/Internals/BulkDeleteOperation.cs

@@ -34,19 +34,21 @@ protected override int ExecuteInternal()
       return command.ExecuteNonQuery();
     }
 
-    protected override Task<int> ExecuteInternalAsync(CancellationToken token = default)
+    protected async override Task<int> ExecuteInternalAsync(CancellationToken token = default)
     {
       if (PrimaryIndexes.Length > 1) {
         throw new NotImplementedException("Inheritance is not implemented");
       }
 
-      base.ExecuteInternal();
+      _ = base.ExecuteInternal();
 
       var request = GetRequest(query);
       Bindings = request.ParameterBindings.ToList();
 
       var command = CreateCommand(request);
-      return command.ExecuteNonQueryAsync(token);
+      await using (command.ConfigureAwait(false)) {
+        return await command.ExecuteNonQueryAsync(token).ConfigureAwait(false);
+      }
     }
 
     private QueryCommand CreateCommand(QueryTranslationResult request)

Extensions/Xtensive.Orm.BulkOperations/Internals/BulkUpdateOperation.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2019-2020 Xtensive LLC.
+// Copyright (C) 2019-2020 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 
@@ -38,18 +38,20 @@ protected override int ExecuteInternal()
       return command.ExecuteNonQuery();
     }
 
-    protected override Task<int> ExecuteInternalAsync(CancellationToken token = default)
+    protected async override Task<int> ExecuteInternalAsync(CancellationToken token = default)
     {
       if (PrimaryIndexes.Length > 1) {
         throw new NotImplementedException("Inheritance is not implemented");
       }
 
-      base.ExecuteInternal();
+      _ = base.ExecuteInternal();
       var request = GetRequest(query);
       Bindings = request.ParameterBindings.ToList();
 
       var command = CreateCommand(request);
-      return command.ExecuteNonQueryAsync(token);
+      await using (command.ConfigureAwait(false)) {
+        return await command.ExecuteNonQueryAsync(token).ConfigureAwait(false);
+      }
     }
 
     private QueryCommand CreateCommand(QueryTranslationResult request)

Extensions/Xtensive.Orm.BulkOperations/Internals/InsertOperation.cs

@@ -1,4 +1,4 @@
-// Copyright (C) 2019-2020 Xtensive LLC.
+// Copyright (C) 2019-2020 Xtensive LLC.
 // This code is distributed under MIT license terms.
 // See the License.txt file in the project root for more information.
 
@@ -32,15 +32,17 @@ protected override int ExecuteInternal()
       return command.ExecuteNonQuery();
     }
 
-    protected override Task<int> ExecuteInternalAsync(CancellationToken token = default)
+    protected async override Task<int> ExecuteInternalAsync(CancellationToken token = default)
     {
       if (PrimaryIndexes.Length > 1) {
         throw new NotImplementedException("Inheritance is not implemented");
       }
       Bindings = new List<QueryParameterBinding>();
 
       var command = CreateCommand();
-      return command.ExecuteNonQueryAsync(token);
+      await using (command.ConfigureAwait(false)) {
+        return await command.ExecuteNonQueryAsync(token).ConfigureAwait(false);
+      }
     }
 
     private QueryCommand CreateCommand()

Orm/Xtensive.Orm/Orm/Services/QueryBuilding/QueryCommand.cs

@@ -18,7 +18,7 @@ namespace Xtensive.Orm.Services
   /// Unlike <see cref="DbCommand"/> this type is aware of <see cref="Session.Events"/>
   /// and does all necessary logging of executed SQL.
   /// </summary>
-  public sealed class QueryCommand : IDisposable
+  public sealed class QueryCommand : IDisposable, IAsyncDisposable
   {
     private readonly StorageDriver driver;
     private readonly Session session;
@@ -117,6 +117,18 @@ public void Dispose()
       realCommand?.Dispose();
     }
 
+    public ValueTask DisposeAsync()
+    {
+      if (disposed) {
+        return default;
+      }
+      disposed = true;
+      if (realCommand != null) {
+        return realCommand.DisposeAsync();
+      }
+      return default;
+    }
+
     // Constructors
 
     internal QueryCommand(StorageDriver driver, Session session, DbCommand realCommand)