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src/server/database/Database/DatabaseLoader.h

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+/*
+ * This file is part of the AzerothCore Project. See AUTHORS file for Copyright information
+ *
+ * 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/>.
+ */
+
+#ifndef DatabaseLoader_h__
+#define DatabaseLoader_h__
+
+#include "Define.h"
+#include <functional>
+#include <queue>
+#include <stack>
+#include <string>
+
+template <class T>
+class DatabaseWorkerPool;
+
+// A helper class to initiate all database worker pools,
+// handles updating, delays preparing of statements and cleans up on failure.
+class AC_DATABASE_API DatabaseLoader
+{
+public:
+    DatabaseLoader(std::string const& logger, uint32 const defaultUpdateMask = 7, std::string_view modulesList = {});
+
+    // Register a database to the loader (lazy implemented)
+    template <class T>
+    DatabaseLoader& AddDatabase(DatabaseWorkerPool<T>& pool, std::string const& name);
+
+    // Load all databases
+    bool Load();
+
+    enum DatabaseTypeFlags
+    {
+        DATABASE_NONE       = 0,
+
+        DATABASE_LOGIN      = 1,
+        DATABASE_CHARACTER  = 2,
+        DATABASE_WORLD      = 4,
+
+        DATABASE_MASK_ALL   = DATABASE_LOGIN | DATABASE_CHARACTER | DATABASE_WORLD
+    };
+
+    [[nodiscard]] uint32 GetUpdateFlags() const
+    {
+        return _updateFlags;
+    }
+
+private:
+    bool OpenDatabases();
+    bool PopulateDatabases();
+    bool UpdateDatabases();
+    bool PrepareStatements();
+
+    using Predicate = std::function<bool()>;
+    using Closer = std::function<void()>;
+
+    // Invokes all functions in the given queue and closes the databases on errors.
+    // Returns false when there was an error.
+    bool Process(std::queue<Predicate>& queue);
+
+    std::string const _logger;
+    std::string_view _modulesList;
+    bool const _autoSetup;
+    uint32 const _updateFlags;
+
+    std::queue<Predicate> _open, _populate, _update, _prepare;
+    std::stack<Closer> _close;
+};
+
+#endif // DatabaseLoader_h__