Perf | Optimize async method allocations (#328)

Author: Wraith2

src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SqlCommand.cs

@@ -70,6 +70,8 @@ public sealed partial class SqlCommand : DbCommand, ICloneable
         private static readonly DiagnosticListener _diagnosticListener = new DiagnosticListener(SqlClientDiagnosticListenerExtensions.DiagnosticListenerName);
         private bool _parentOperationStarted = false;
 
+        internal static readonly Action<object> s_cancelIgnoreFailure = CancelIgnoreFailureCallback;
+
         // Prepare
         // Against 7.0 Serve a prepare/unprepare requires an extra roundtrip to the server.
         //
@@ -2137,7 +2139,7 @@ public override Task<int> ExecuteNonQueryAsync(CancellationToken cancellationTok
                     source.SetCanceled();
                     return source.Task;
                 }
-                registration = cancellationToken.Register(s => ((SqlCommand)s).CancelIgnoreFailure(), this);
+                registration = cancellationToken.Register(s_cancelIgnoreFailure, this);
             }
 
             Task<int> returnedTask = source.Task;
@@ -2225,7 +2227,7 @@ protected override Task<DbDataReader> ExecuteDbDataReaderAsync(CommandBehavior b
                     source.SetCanceled();
                     return source.Task;
                 }
-                registration = cancellationToken.Register(s => ((SqlCommand)s).CancelIgnoreFailure(), this);
+                registration = cancellationToken.Register(s_cancelIgnoreFailure, this);
             }
 
             Task<SqlDataReader> returnedTask = source.Task;
@@ -2373,7 +2375,7 @@ public Task<XmlReader> ExecuteXmlReaderAsync(CancellationToken cancellationToken
                     source.SetCanceled();
                     return source.Task;
                 }
-                registration = cancellationToken.Register(s => ((SqlCommand)s).CancelIgnoreFailure(), this);
+                registration = cancellationToken.Register(s_cancelIgnoreFailure, this);
             }
 
             Task<XmlReader> returnedTask = source.Task;
@@ -5947,6 +5949,11 @@ internal void CompletePendingReadWithFailure(int errorCode, bool resetForcePendi
             }
         }
 #endif
+        internal static void CancelIgnoreFailureCallback(object state)
+        {
+            SqlCommand command = (SqlCommand)state;
+            command.CancelIgnoreFailure();
+        }
 
         internal void CancelIgnoreFailure()
         {