Core/DBLayer: Added new async query callback api

(cherry picked from commit fcabeed7544285f3244465ccfc5337c59e63c6b0)

src/server/database/Database/QueryCallbackProcessor.cpp

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2008-2017 TrinityCore <http://www.trinitycore.org/>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "QueryCallbackProcessor.h"
+#include "QueryCallback.h"
+#include <algorithm>
+
+QueryCallbackProcessor::QueryCallbackProcessor()
+{
+}
+
+QueryCallbackProcessor::~QueryCallbackProcessor()
+{
+}
+
+void QueryCallbackProcessor::AddQuery(QueryCallbackNew&& query)
+{
+    _callbacks.emplace_back(std::move(query));
+}
+
+void QueryCallbackProcessor::ProcessReadyQueries()
+{
+    _callbacks.erase(std::remove_if(_callbacks.begin(), _callbacks.end(), [](QueryCallbackNew& callback)
+    {
+        return callback.InvokeIfReady() == QueryCallbackNew::Completed;
+    }), _callbacks.end());
+}