MetaLogWriter.h

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/* -*- c++ -*-
 * Copyright (C) 2007-2015 Hypertable, Inc.
 *
 * This file is part of Hypertable.
 *
 * Hypertable 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 3 of the
 * License, or any later version.
 *
 * Hypertable 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 Hypertable_Lib_MetaLogWriter_h
#define Hypertable_Lib_MetaLogWriter_h

#include "MetaLogDefinition.h"
#include "MetaLogEntity.h"

#include <Common/Filesystem.h>

#include <AsyncComm/Comm.h>
#include <AsyncComm/DispatchHandler.h>

#include <condition_variable>
#include <deque>
#include <memory>
#include <mutex>
#include <utility>
#include <vector>

namespace Hypertable {

  namespace MetaLog {


    class Writer {
    public:

      Writer(FilesystemPtr &fs, DefinitionPtr &definition, const std::string &path,
             std::vector<EntityPtr> &initial_entities);

      ~Writer();

      void close();

      void record_state(EntityPtr entity);

      void record_state(std::vector<EntityPtr> &entities);

      void record_removal(EntityPtr entity);

      void record_removal(std::vector<EntityPtr> &entities);

      void signal_write_ready();

      static bool skip_recover_entry;

    private:

      class WriteScheduler : public DispatchHandler {
      public:

        WriteScheduler(Writer *writer);

        virtual ~WriteScheduler();

        void schedule();

        void handle(EventPtr &event) override;

      private:
        std::mutex m_mutex;
        std::condition_variable m_cond;
        Writer *m_writer {};
        Comm *m_comm {};
        int32_t m_interval {};
        bool m_scheduled {};
      };

      typedef std::shared_ptr<WriteScheduler> WriteSchedulerPtr;

      void write_header();

      void purge_old_log_files();

      void roll();

      void service_write_queue();

      std::mutex m_mutex;

      condition_variable m_cond;
      
      FilesystemPtr m_fs;

      DefinitionPtr m_definition;

      std::string  m_path;

      std::string  m_filename;

      int m_fd {-1};

      std::string  m_backup_path;

      std::string  m_backup_filename;

      int m_backup_fd;

      int32_t m_offset {};

      std::deque<int32_t> m_file_ids;

      int64_t m_max_file_size {};

      size_t m_history_size {};

      int32_t m_replication {};

      Filesystem::Flags m_flush_method {};

      // Serialized entity (length and smart pointer to buffer)
      typedef std::pair<size_t, std::shared_ptr<uint8_t>> SerializedEntityT;

      std::map<int64_t, SerializedEntityT> m_entity_map;

      bool m_write_ready {};

      std::vector<StaticBufferPtr> m_write_queue;

      WriteSchedulerPtr m_write_scheduler;

    };

    typedef std::shared_ptr<Writer> WriterPtr;
    
  }

}

#endif // Hypertable_Lib_MetaLogWriter_h