mariadb-columnstore-engine/utils/idbdatafile/IDBFactory.h

/* 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. */

#pragma once

#include <string>
#include <map>
#include <vector>
#include <stdexcept>

#include "IDBDataFile.h"

namespace idbdatafile
{
class FileFactoryBase;
class IDBFileSystem;

struct FileFactoryEnt
{
  FileFactoryEnt(IDBDataFile::Types t, const std::string& n, FileFactoryBase* f, IDBFileSystem* fs)
   : type(t), name(n), factory(f), filesystem(fs)
  {
    ;
  }

  FileFactoryEnt(const FileFactoryEnt&) = delete;
  FileFactoryEnt& operator=(const FileFactoryEnt&) = delete;
  FileFactoryEnt& operator=(FileFactoryEnt&&) = delete;
  FileFactoryEnt(FileFactoryEnt&& temporary)
    : factory(temporary.factory)
    , filesystem(temporary.filesystem)
  {
    temporary.factory = nullptr;
    temporary.filesystem = nullptr;
  }



  ~FileFactoryEnt();

  IDBDataFile::Types type = IDBDataFile::UNKNOWN;
  std::string name = "unknown";
  FileFactoryBase* factory = nullptr;
  IDBFileSystem* filesystem = nullptr;
};

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 lists the loaded plugins by type.
   */
  static std::vector<IDBDataFile::Types> listPlugins();

  /**
   * 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() = delete;
  ~IDBFactory() = delete;
};

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.at(type).name;
}

}  // namespace idbdatafile