src/datafile/oMemoryMapped.cc

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#include "oMemoryMapped.hh"

#include <stdexcept>
#include <cstdio>
#include <iostream>

// OS-specific
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
// Windows
#include <windows.h>
#else
// Linux
// enable large file support on 32 bit systems
#ifndef _LARGEFILE64_SOURCE
#define _LARGEFILE64_SOURCE
#endif
#ifdef  _FILE_OFFSET_BITS
#undef  _FILE_OFFSET_BITS
#endif
#define _FILE_OFFSET_BITS 64
// and include needed headers
#include <sys/stat.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#endif

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oMemoryMapped::oMemoryMapped()
: _filename   (),
  _filesize   (0),
  _hint       (Normal),
  _mappedBytes(0),
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
  _mappedFile (NULL),
#endif
  _file       (0),
  _mappedView (NULL)
{
}

// =====================================================================
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oMemoryMapped::oMemoryMapped(const std::string& filename, size_t mappedBytes, CacheHint hint)
: _filename   (filename),
  _filesize   (0),
  _hint       (hint),
  _mappedBytes(mappedBytes),
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
  _mappedFile (NULL),
#endif
  _file       (0),
  _mappedView (NULL)
{
  Open(filename, mappedBytes, hint);
}

// =====================================================================
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oMemoryMapped::~oMemoryMapped()
{
  Close();
}

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int oMemoryMapped::Open(const std::string& filename, size_t mappedBytes, CacheHint hint)
{
  // already open ?
  if (IsValid())
  {
    Cerr("***** oMemoryMapped::Open() -> File is already open !" << endl);
    return 1;
  }

  _file       = 0;
  _filesize   = 0;
  _hint       = hint;
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
  _mappedFile = NULL;
#endif
  _mappedView = NULL;

#if defined(_WIN32) || defined(CASTOR_USE_MINGW)

  // ===================================================================
  // 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)
  {
    Cerr("***** oMemoryMapped::Open() -> Failed to create windows file from function CreateFileA() !" << endl);
    return 1;
  }

  // file size
  LARGE_INTEGER result;
  if (!GetFileSizeEx(_file, &result))
  {
    Cerr("***** oMemoryMapped::Open() -> Failed to get file size from windows function GetFileSizeEx() !" << endl);
    return 1;
  }
  _filesize = static_cast<uint64_t>(result.QuadPart);

  // convert to mapped mode
  _mappedFile = ::CreateFileMapping(_file, NULL, PAGE_READONLY, 0, 0, NULL);
  if (!_mappedFile)
  {
    Cerr("***** oMemoryMapped::Open() -> Failed to convert file to mapped mode from windows function CreateFileMapping() !" << endl);
    return 1;
  }

#else

  // ===================================================================
  // Linux
  // ===================================================================

  // open file
  //_file = ::open(filename.c_str(), O_RDONLY | O_LARGEFILE);
  _file = ::open(filename.c_str(), O_RDONLY);
  
  if (_file == -1)
  {
    _file = 0;
    Cerr("***** oMemoryMapped::Open() -> Failed to open file from unix function open() !" << endl);
    return 1;
  }

  // file size
  struct stat statInfo;
  if (fstat(_file, &statInfo) < 0)
  {
    Cerr("***** oMemoryMapped::Open() -> Failed to get correct file size from unix function fstat() !" << endl);
    return 1;
  }

  _filesize = statInfo.st_size;
#endif

  // initial mapping
  if (Remap(0, mappedBytes))
  {
    Cerr("***** oMemoryMapped::Open() -> A problem occurred while calling the oMemoryMapped::Remap() function !" << endl);
    return 1;
  }

  // check
  if (!_mappedView)
  {
    Cerr("***** oMemoryMapped::Open() -> Failed to get a correct mapped view after calling the oMemoryMapped::Remap() function !" << endl);
    return 1;
  }

  // everything's fine
  return 0;
}

// =====================================================================
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void oMemoryMapped::Close()
{
  // kill pointer
  if (_mappedView)
  {
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
    ::UnmapViewOfFile(_mappedView);
#else
    ::munmap(_mappedView, _filesize);
#endif
    _mappedView = NULL;
  }

#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
  if (_mappedFile)
  {
    ::CloseHandle(_mappedFile);
    _mappedFile = NULL;
  }
#endif

  // close underlying file
  if (_file)
  {
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
    ::CloseHandle(_file);
#else
    ::close(_file);
#endif
    _file = 0;
  }

  _filesize = 0;
}

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unsigned char oMemoryMapped::operator[](size_t offset) const
{
  return ((unsigned char*)_mappedView)[offset];
}

// =====================================================================
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unsigned char oMemoryMapped::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);
}

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const unsigned char* oMemoryMapped::GetData() const
{
  return (const unsigned char*)_mappedView;
}

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bool oMemoryMapped::IsValid() const
{
  return _mappedView != NULL;
}

// =====================================================================
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uint64_t oMemoryMapped::size() const
{
  return _filesize;
}

// =====================================================================
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size_t oMemoryMapped::mappedSize() const
{
  return _mappedBytes;
}

// =====================================================================
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int oMemoryMapped::Remap(uint64_t offset, size_t mappedBytes)
{
  if (!_file)
  {
    Cerr("***** oMemoryMapped::Remap() -> Cannot remap a file that has not been created !" << endl);
    return 1;
  }

  if (mappedBytes == WholeFile)
    mappedBytes = _filesize;

  // close old mapping
  if (_mappedView)
  {
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
    ::UnmapViewOfFile(_mappedView);
#else
    ::munmap(_mappedView, _mappedBytes);
#endif
    _mappedView = NULL;
  }

  // don't go further than end of file
  if (offset > _filesize)
  {
    Cerr("***** oMemoryMapped::Remap() -> Provided offset is after the end of file !" << endl);
    return 1;
  }
  if (offset + mappedBytes > _filesize)
    mappedBytes = size_t(_filesize - offset);

#if defined(_WIN32) || defined(CASTOR_USE_MINGW)

  // ===================================================================
  // 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;
    Cerr("***** oMemoryMapped::Remap() -> Mapped view is null after calling windows function MapViewOfFile() !" << endl);
    return 1;
  }

#else

  // ===================================================================
  // Linux
  // ===================================================================

  // new mapping
  //_mappedView = ::mmap64(NULL, mappedBytes, PROT_READ, MAP_SHARED, _file, offset);
  _mappedView = ::mmap(NULL, mappedBytes, PROT_READ, MAP_SHARED, _file, offset);
  
  if (_mappedView == MAP_FAILED)
  {
    _mappedBytes = 0;
    _mappedView  = NULL;
    Cerr("***** oMemoryMapped::Remap() -> Mapping failed after calling the unix function mmap64() !" << endl);
    return 1;
  }

  _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;
//  linuxHint [= MADV_NOHUGEPAGE;

  ::madvise(_mappedView, _mappedBytes, linuxHint);

#endif

  // end
  return 0;
}

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int oMemoryMapped::GetPageSize()
{
#if defined(_WIN32) || defined(CASTOR_USE_MINGW)
  SYSTEM_INFO sysInfo;
  GetSystemInfo(&sysInfo);
  return sysInfo.dwAllocationGranularity;
#else
  return sysconf(_SC_PAGESIZE); //::getpagesize();
#endif
}

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