// $Id$
// vim:tabstop=2
/***********************************************************************
 Moses - factored phrase-based language decoder
 Copyright (C) 2006 University of Edinburgh

 This library is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser General Public
 License as published by the Free Software Foundation; either
 version 2.1 of the License, or (at your option) any later version.

 This library 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
 Lesser General Public License for more details.

 You should have received a copy of the GNU Lesser General Public
 License along with this library; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 ***********************************************************************/

#ifndef moses_MmapAllocator_h
#define moses_MmapAllocator_h

#include <limits>
#include <iostream>
#include <cstdio>

#if defined(_WIN32) || defined(_WIN64)
#define _WINSOCKAPI_
#include <windows.h>
#include <io.h>
#else
#include <sys/mman.h>
#include <unistd.h>
#endif

#include "util/mmap.hh"

namespace Moses2
{
template<class T>
class MmapAllocator
{
protected:
  std::FILE* m_file_ptr;
  size_t m_file_desc;

  size_t m_page_size;
  size_t m_map_size;

  char* m_data_ptr;
  size_t m_data_offset;
  bool m_fixed;
  size_t* m_count;

public:
  typedef T value_type;
  typedef T* pointer;
  typedef const T* const_pointer;
  typedef T& reference;
  typedef const T& const_reference;
  typedef std::size_t size_type;
  typedef std::ptrdiff_t difference_type;

  MmapAllocator() throw () :
    m_file_ptr(std::tmpfile()), m_file_desc(fileno(m_file_ptr)), m_page_size(
      util::SizePage()), m_map_size(0), m_data_ptr(0), m_data_offset(0), m_fixed(
        false), m_count(new size_t(0)) {
  }

  MmapAllocator(std::FILE* f_ptr) throw () :
    m_file_ptr(f_ptr), m_file_desc(fileno(m_file_ptr)), m_page_size(
      util::SizePage()), m_map_size(0), m_data_ptr(0), m_data_offset(0), m_fixed(
        false), m_count(new size_t(0)) {
  }

  MmapAllocator(std::FILE* f_ptr, size_t data_offset) throw () :
    m_file_ptr(f_ptr), m_file_desc(fileno(m_file_ptr)), m_page_size(
      util::SizePage()), m_map_size(0), m_data_ptr(0), m_data_offset(
        data_offset), m_fixed(true), m_count(new size_t(0)) {
  }

  MmapAllocator(std::string fileName) throw () :
    m_file_ptr(std::fopen(fileName.c_str(), "wb+")), m_file_desc(
      fileno(m_file_ptr)), m_page_size(util::SizePage()), m_map_size(0), m_data_ptr(
        0), m_data_offset(0), m_fixed(false), m_count(new size_t(0)) {
  }

  MmapAllocator(const MmapAllocator& c) throw () :
    m_file_ptr(c.m_file_ptr), m_file_desc(c.m_file_desc), m_page_size(
      c.m_page_size), m_map_size(c.m_map_size), m_data_ptr(c.m_data_ptr), m_data_offset(
        c.m_data_offset), m_fixed(c.m_fixed), m_count(c.m_count) {
    (*m_count)++;
  }

  ~MmapAllocator() throw () {
    if (m_data_ptr && *m_count == 0) {
      util::UnmapOrThrow(m_data_ptr, m_map_size);
      if (!m_fixed && std::ftell(m_file_ptr) != -1) std::fclose(m_file_ptr);
    }
    (*m_count)--;
  }

  template<class U>
  struct rebind {
    typedef MmapAllocator<U> other;
  };

  pointer address(reference value) const {
    return &value;
  }

  const_pointer address(const_reference value) const {
    return &value;
  }

  size_type max_size() const throw () {
    return std::numeric_limits<size_t>::max() / sizeof(value_type);
  }

  pointer allocate(size_type num, const void* = 0) {
    m_map_size = num * sizeof(T);

#if defined(_WIN32) || defined(_WIN64)
    // On Windows, MAP_SHARED is not defined and MapOrThrow ignores the flags.
    const int map_shared = 0;
#else
    const int map_shared = MAP_SHARED;
#endif
    if (!m_fixed) {
      size_t read = 0;
#ifdef _WIN32
      read += _chsize_s(m_file_desc, m_map_size);
#else
      read += ftruncate(m_file_desc, m_map_size);
#endif
      m_data_ptr = (char *) util::MapOrThrow(m_map_size, true, map_shared,
                                             false, m_file_desc, 0);
      return (pointer) m_data_ptr;
    } else {
      const size_t map_offset = (m_data_offset / m_page_size) * m_page_size;
      const size_t relative_offset = m_data_offset - map_offset;
      const size_t adjusted_map_size = m_map_size + relative_offset;

      m_data_ptr = (char *) util::MapOrThrow(adjusted_map_size, false,
                                             map_shared, false, m_file_desc, map_offset);

      return (pointer) (m_data_ptr + relative_offset);
    }
  }

  void deallocate(pointer p, size_type num) {
    if (!m_fixed) {
      util::UnmapOrThrow(p, num * sizeof(T));
    } else {
      const size_t map_offset = (m_data_offset / m_page_size) * m_page_size;
      const size_t relative_offset = m_data_offset - map_offset;
      const size_t adjusted_map_size = m_map_size + relative_offset;

      util::UnmapOrThrow((pointer) ((char*) p - relative_offset),
                         adjusted_map_size);
    }
  }

  void construct(pointer p, const T& value) {
    if (!m_fixed) new (p) value_type(value);
  }
  void destroy(pointer p) {
    if (!m_fixed) p->~T();
  }

  template<class T1, class T2>
  friend bool operator==(const MmapAllocator<T1>&,
                         const MmapAllocator<T2>&) throw ();

  template<class T1, class T2>
  friend bool operator!=(const MmapAllocator<T1>&,
                         const MmapAllocator<T2>&) throw ();
};

template<class T1, class T2>
bool operator==(const MmapAllocator<T1>& a1,
                const MmapAllocator<T2>& a2) throw ()
{
  bool equal = true;
  equal &= a1.m_file_ptr == a2.m_file_ptr;
  equal &= a1.m_file_desc == a2.m_file_desc;
  equal &= a1.m_page_size == a2.m_page_size;
  equal &= a1.m_map_size == a2.m_map_size;
  equal &= a1.m_data_ptr == a2.m_data_ptr;
  equal &= a1.m_data_offset == a2.m_data_offset;
  equal &= a1.m_fixed == a2.m_fixed;
  return equal;
}

template<class T1, class T2>
bool operator!=(const MmapAllocator<T1>& a1,
                const MmapAllocator<T2>& a2) throw ()
{
  return !(a1 == a2);
}

}

#endif