// //////////////////////////////////////////////////////////
// MemoryMapped.cpp
// Copyright (c) 2013 Stephan Brumme. All rights reserved.
// see http://create.stephan-brumme.com/disclaimer.html
//

#include "Pregel/MemoryMapped.h"

#include "ApplicationFeatures/PageSizeFeature.h"
#include "Basics/FileUtils.h"
#include "Basics/StaticStrings.h"
#include "Basics/StringUtils.h"
#include "Basics/files.h"
#include "Basics/memory-map.h"
#include "Basics/tri-strings.h"
#include "Logger/Logger.h"

#include <iomanip>
#include <sstream>

#include <cstdio>
#include <stdexcept>

using namespace arangodb;
using namespace arangodb::basics;

/// open file, mappedBytes = 0 maps the whole file
MemoryMapped::MemoryMapped(const std::string& filename, size_t mappedBytes,
                           CacheHint hint)
    : _filename(filename),
      _filesize(0),
      _hint(hint),
      _mappedBytes(mappedBytes),
      _file(0),
#ifdef _MSC_VER
      _mappedFile(NULL),
#endif
      _mappedView(NULL) {
  open(filename, mappedBytes, hint);
}

/// close file (see close() )
MemoryMapped::~MemoryMapped() { close(); }

/// open file
bool MemoryMapped::open(const std::string& filename, size_t mappedBytes,
                        CacheHint hint) {
  // already open ?
  if (isValid()) return false;

  _file = 0;
  _filesize = 0;
  _hint = hint;
#ifdef _MSC_VER
  _mappedFile = NULL;
#endif
  _mappedView = NULL;

#ifdef _MSC_VER
  // Windows

  DWORD winHint = 0;
  switch (_hint) {
    case Normal:
      winHint = FILE_ATTRIBUTE_NORMAL;
      break;
    case SequentialScan:
      winHint = FILE_FLAG_SEQUENTIAL_SCAN;
      break;
    case RandomAccess:
      winHint = FILE_FLAG_RANDOM_ACCESS;
      break;
    default:
      break;
  }

  // open file
  _file = ::CreateFileA(filename.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL,
                        OPEN_EXISTING, winHint, NULL);
  if (!_file) return false;

  // file size
  LARGE_INTEGER result;
  if (!GetFileSizeEx(_file, &result)) return false;
  _filesize = static_cast<uint64_t>(result.QuadPart);

  // convert to mapped mode
  _mappedFile = ::CreateFileMapping(_file, NULL, PAGE_READONLY, 0, 0, NULL);
  if (!_mappedFile) return false;

#else

  // Linux

  // open file
  _file = ::open(filename.c_str(), O_RDONLY | O_LARGEFILE);
  if (_file == -1) {
    _file = 0;
    return false;
  }

  // file size
  struct stat64 statInfo;
  if (fstat64(_file, &statInfo) < 0) return false;

  _filesize = statInfo.st_size;
#endif

  // initial mapping
  remap(0, mappedBytes);

  if (!_mappedView) return false;

  // everything's fine
  return true;
}

/// close file
void MemoryMapped::close() {
  // kill pointer
  if (_mappedView) {
#ifdef _MSC_VER
    ::UnmapViewOfFile(_mappedView);
#else
    ::munmap(_mappedView, _filesize);
#endif
    _mappedView = NULL;
  }

#ifdef _MSC_VER
  if (_mappedFile) {
    ::CloseHandle(_mappedFile);
    _mappedFile = NULL;
  }
#endif

  // close underlying file
  if (_file) {
#ifdef _MSC_VER
    ::CloseHandle(_file);
#else
    ::close(_file);
#endif
    _file = 0;
  }

  _filesize = 0;
}

/// access position, no range checking (faster)
unsigned char MemoryMapped::operator[](size_t offset) const {
  return ((unsigned char*)_mappedView)[offset];
}

/// access position, including range checking
unsigned char MemoryMapped::at(size_t offset) const {
  // checks
  if (!_mappedView) throw std::invalid_argument("No view mapped");
  if (offset >= _filesize) throw std::out_of_range("View is not large enough");

  return operator[](offset);
}

/// raw access
const unsigned char* MemoryMapped::getData() const {
  return (const unsigned char*)_mappedView;
}

/// true, if file successfully opened
bool MemoryMapped::isValid() const { return _mappedView != NULL; }

/// get file size
uint64_t MemoryMapped::size() const { return _filesize; }

/// get number of actually mapped bytes
size_t MemoryMapped::mappedSize() const { return _mappedBytes; }

/// replace mapping by a new one of the same file, offset MUST be a multiple of
/// the page size
bool MemoryMapped::remap(uint64_t offset, size_t mappedBytes) {
  if (!_file) return false;

  if (mappedBytes == WholeFile) mappedBytes = _filesize;

  // close old mapping
  if (_mappedView) {
#ifdef _MSC_VER
    ::UnmapViewOfFile(_mappedView);
#else
    ::munmap(_mappedView, _mappedBytes);
#endif
    _mappedView = NULL;
  }

  // don't go further than end of file
  if (offset > _filesize) return false;
  if (offset + mappedBytes > _filesize)
    mappedBytes = size_t(_filesize - offset);

#ifdef _MSC_VER
  // Windows

  DWORD offsetLow = DWORD(offset & 0xFFFFFFFF);
  DWORD offsetHigh = DWORD(offset >> 32);
  _mappedBytes = mappedBytes;

  // get memory address
  _mappedView = ::MapViewOfFile(_mappedFile, FILE_MAP_READ, offsetHigh,
                                offsetLow, mappedBytes);

  if (_mappedView == NULL) {
    _mappedBytes = 0;
    _mappedView = NULL;
    return false;
  }

  return true;

#else

  // Linux
  // new mapping
  _mappedView =
      ::mmap64(NULL, mappedBytes, PROT_READ, MAP_SHARED, _file, offset);
  if (_mappedView == MAP_FAILED) {
    _mappedBytes = 0;
    _mappedView = NULL;
    return false;
  }

  _mappedBytes = mappedBytes;

  // tweak performance
  int linuxHint = 0;
  switch (_hint) {
    case Normal:
      linuxHint = MADV_NORMAL;
      break;
    case SequentialScan:
      linuxHint = MADV_SEQUENTIAL;
      break;
    case RandomAccess:
      linuxHint = MADV_RANDOM;
      break;
    default:
      break;
  }
  // assume that file will be accessed soon
  // linuxHint |= MADV_WILLNEED;
  // assume that file will be large
  // linuxHint |= MADV_HUGEPAGE;

  ::madvise(_mappedView, _mappedBytes, linuxHint);

  return true;
#endif
}

/// get OS page size (for remap)
int MemoryMapped::getpagesize() {
#ifdef _MSC_VER
  SYSTEM_INFO sysInfo;
  GetSystemInfo(&sysInfo);
  return sysInfo.dwAllocationGranularity;
#else
  return sysconf(_SC_PAGESIZE);  //::getpagesize();
#endif
}