/* 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. */

/*
 * InfiniDB FOSS License Exception
 * We want free and open source software applications under certain
 * licenses to be able to use the GPL-licensed InfiniDB idbhdfs
 * libraries despite the fact that not all such FOSS licenses are
 * compatible with version 2 of the GNU General Public License.
 * Therefore there are special exceptions to the terms and conditions
 * of the GPLv2 as applied to idbhdfs libraries, which are
 * identified and described in more detail in the FOSS License
 * Exception in the file utils/idbhdfs/FOSS-EXCEPTION.txt
 */

#ifndef HDFSFILE_H_
#define HDFSFILE_H_

#include <stdexcept>
#include <boost/utility.hpp>
#include <boost/thread.hpp>

#include "hdfs.h"

#include "IDBDataFile.h"

namespace idbdatafile
{

/**
 * the HdfsFile implements IDBDataFile for a file in the Hadoop file system
 * (HDFS).  HDFS implements only a subset of POSIX file capability but the
 * IDBDataFile interface was limited to what HDFS can support.  See
 * IDBDataFile documentation for further description of member functions
 */
class HdfsFile: public IDBDataFile, boost::noncopyable
{
public:
    HdfsFile(const char* fname, const char* mode, unsigned opts);
    /* virtual */ ~HdfsFile();

    /* virtual */ ssize_t pread(void* ptr, off64_t offset, size_t count);
    /* virtual */ ssize_t read(void* ptr, size_t count);
    /* virtual */ ssize_t write(const void* ptr, size_t count);
    /* virtual */ int seek(off64_t offset, int whence);
    /* virtual */ int truncate(off64_t length);
    /* virtual */ off64_t size();
    /* virtual */ off64_t tell();
    /* virtual */ int flush();
    /* virtual */ time_t mtime();

protected:
    /* virtual */
    int close();

private:
    int reopen();  // 0 is success, < 0 is failure, errno is set.
    ssize_t real_pread(void* ptr, off64_t offset, size_t count);

    volatile hdfsFile m_file;
    hdfsFS   m_fs;
    int      m_flags;
    boost::mutex m_mutex;
};

}

#endif /* HDFSFILE_H_ */