the begginning

utils/idbdatafile/IDBFactory.h

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+/* Copyright (C) 2014 InfiniDB, Inc.
+
+   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; version 2 of
+   the License.
+
+   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, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA. */
+
+#ifndef IDBFACTORY_H_
+#define IDBFACTORY_H_
+
+#include <string>
+#include <map>
+#include <stdexcept>
+
+#include "IDBDataFile.h"
+
+namespace idbdatafile
+{
+
+class FileFactoryBase;
+class IDBFileSystem;
+
+struct FileFactoryEnt
+{
+	FileFactoryEnt() :
+		type(IDBDataFile::UNKNOWN),
+		name("unknown"),
+		factory(0),
+		filesystem(0) {;}
+
+	FileFactoryEnt(
+			IDBDataFile::Types t,
+			const std::string& n,
+			FileFactoryBase* f,
+			IDBFileSystem* fs) :
+		type(t),
+		name(n),
+		factory(f),
+		filesystem(fs) {;}
+
+	IDBDataFile::Types     type;
+	std::string	           name;
+	FileFactoryBase*       factory;
+	IDBFileSystem*         filesystem;
+};
+
+typedef FileFactoryEnt (*FileFactoryEntryFunc)();
+
+/**
+ * IDBFactory manages the factory plugins that know how to create
+ * files of different types.  The plugin architecture allows IDB
+ * to defer dependencies until plugin load.  This class is a static
+ * class and is threadsafe.
+ *
+ */
+class IDBFactory
+{
+public:
+	/**
+	 * This method installs the default plugs for Buffered and Unbuffered files.
+	 * It is called automatically from the IDBPolicy::init() body so that clients
+	 * don't have to worry about it.
+	 */
+	static bool installDefaultPlugins();
+
+	/**
+	 * This method installs a dynamic plugin.  The plugin argument must refer
+	 * to a ".so" file that exposes an extern "C" functions:
+	 *     FileFactoryEnt   plugin_instance()
+	 */
+	static bool installPlugin(const std::string& plugin);
+
+	/**
+	 * This method calls the Factory for the specified type
+	 */
+	static IDBDataFile* open(IDBDataFile::Types type, const char* fname, const char* mode, unsigned opts, unsigned colWidth);
+
+	/**
+	 * This retrieves the IDBFileSystem for the specified type
+	 */
+	static IDBFileSystem& getFs(IDBDataFile::Types type);
+
+	/**
+	 * This retrieves the IDBFileSystem for the specified type
+	 */
+	static const std::string& name(IDBDataFile::Types type);
+
+private:
+	typedef std::map<IDBDataFile::Types,FileFactoryEnt> FactoryMap;
+	typedef FactoryMap::const_iterator FactoryMapCIter;
+
+	static FactoryMap s_plugins;
+
+	IDBFactory();
+	virtual ~IDBFactory();
+};
+
+inline
+const std::string& IDBFactory::name(IDBDataFile::Types type)
+{
+	if( s_plugins.find(type) == s_plugins.end() )
+	{
+    	throw std::runtime_error("unknown plugin type in IDBFactory::name");
+	}
+
+	return s_plugins[type].name;
+}
+
+}
+
+#endif /* IDBFACTORY_H_ */