initializable.hpp

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/*
 * Copyright (c) 2014-2015, Hewlett-Packard Development Company, LP.
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * HP designates this particular file as subject to the "Classpath" exception
 * as provided by HP in the LICENSE.txt file that accompanied this code.
 */
#ifndef FOEDUS_INITIALIZABLE_HPP_
#define FOEDUS_INITIALIZABLE_HPP_

#include "foedus/cxx11.hpp"
#include "foedus/error_stack.hpp"
namespace foedus {
class Initializable {
 public:
  virtual ~Initializable() {}

  virtual ErrorStack  initialize() = 0;

  virtual bool        is_initialized() const = 0;

  virtual ErrorStack  uninitialize() = 0;
};

class DefaultInitializable : public virtual Initializable {
 public:
  DefaultInitializable() : initialized_(false) {}
  virtual ~DefaultInitializable() {}

  DefaultInitializable(const DefaultInitializable&) CXX11_FUNC_DELETE;
  DefaultInitializable& operator=(const DefaultInitializable&) CXX11_FUNC_DELETE;

  ErrorStack  initialize() CXX11_OVERRIDE CXX11_FINAL {
    if (is_initialized()) {
      return ERROR_STACK(kErrorCodeAlreadyInitialized);
    }
    ErrorStack init_error = initialize_once();
    if (init_error.is_error()) {
      // if error happes in the middle of initialization, we release resources we acquired.
      CHECK_ERROR(uninitialize_once());
      return init_error;
    }
    initialized_ = true;
    return kRetOk;
  }

  ErrorStack  uninitialize() CXX11_OVERRIDE CXX11_FINAL {
    if (!is_initialized()) {
      return kRetOk;
    }
    CHECK_ERROR(uninitialize_once());
    initialized_ = false;
    return kRetOk;
  }

  bool        is_initialized() const CXX11_OVERRIDE CXX11_FINAL {
    return initialized_;
  }

  virtual ErrorStack  initialize_once() = 0;
  virtual ErrorStack  uninitialize_once() = 0;

 private:
  bool    initialized_;
};

class UninitializeGuard {
 public:
  enum Policy {
    kAbortIfNotExplicitlyUninitialized = 0,
    kAbortIfUninitializeError,
    kWarnIfUninitializeError,
    kSilent,
  };
  UninitializeGuard(Initializable *target, Policy policy = kAbortIfUninitializeError)
    : target_(target), policy_(policy) {}
  ~UninitializeGuard();

 private:
  Initializable*  target_;
  Policy          policy_;
};

}  // namespace foedus
#endif  // FOEDUS_INITIALIZABLE_HPP_