MemoryMap.cpp
/*
* Copyright (C) 2010 Regents of the University of Michigan
*
* 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, either version 3 of the License, or
* (at your option) any later version.
*
* 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, see <http://www.gnu.org/licenses/>.
*/
#include <sys/stat.h>
#include <sys/types.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <iostream>
#include <stdio.h>
#include <stdexcept>
#include <stdlib.h>
#include <string>
#include "MemoryMap.h"
#ifndef _WIN32
#include <sys/mman.h>
#include <unistd.h>
#endif
#ifndef MAP_POPULATE
#define MAP_POPULATE 0x0000
#endif
#ifndef MAP_NONBLOCK
#define MAP_NONBLOCK 0x0000
#endif
MemoryMap::MemoryMap()
{
constructor_clear();
#if defined(_WIN32)
SYSTEM_INFO sysinfo = {0};
::GetSystemInfo(&sysinfo);
DWORD cbView = sysinfo.dwAllocationGranularity;
#else
page_size = sysconf(_SC_PAGE_SIZE);
#endif
}
MemoryMap::~MemoryMap()
{
destructor_clear();
};
void MemoryMap::debug_print()
{
#if defined(_WIN32)
std::cout << "fd = " << file_handle << std::endl;
#else
std::cout << "fd = " << fd << std::endl;
#endif
std::cout << "data = 0x" << std::hex << data << std::endl;
std::cout << "offset = 0x" << std::hex << offset << std::endl;
std::cout << "mapped_length = 0x" << std::hex << mapped_length << std::endl;
std::cout << "total_length = 0x" << std::hex << total_length << std::endl;
std::cout << "page_size = 0x" << std::hex << page_size << std::endl;
};
void MemoryMap::constructor_clear()
{
#if defined(_WIN32)
file_handle = NULL;
map_handle = NULL;
#else
fd = -1;
#endif
data = (void *) NULL;
offset = 0;
mapped_length = 0;
total_length = 0;
useMemoryMapFlag = true;
};
void MemoryMap::destructor_clear()
{
#if defined(_WIN32)
if (data!=NULL)
{
// free windows mapped object
::UnmapViewOfFile((LPVOID) data);
}
if (map_handle != NULL)
::CloseHandle(map_handle);
if (file_handle != NULL)
::CloseHandle(file_handle);
#else
if (data!=NULL)
{
// free unix mapped object
munmap(data, mapped_length);
}
// free unix resources
if (fd!=-1)
{
::close(fd);
}
#endif
constructor_clear();
}
bool MemoryMap::allocate()
{
data = (void *) malloc(mapped_length);
if (data == NULL)
{
#ifdef __WIN32__
::CloseHandle(file_handle);
#else
::close(fd);
#endif
perror("MemoryMap::open");
constructor_clear();
return true;
}
#ifdef __WIN32__
DWORD resultSize = 0;
ReadFile(file_handle, data, mapped_length, &resultSize, NULL);
#else
size_t resultSize = read(fd, data, mapped_length);
#endif
if ( resultSize != mapped_length)
{
#ifdef __WIN32__
::CloseHandle(file_handle);
#else
::close(fd);
#endif
perror("MemoryMap::open");
constructor_clear();
return true;
}
return false;
}
bool MemoryMap::open(const char * file, int flags)
{
const char * message = "MemoryMap::open - problem opening file %s";
#if defined(_WIN32)
file_handle = CreateFile(file,
(flags==O_RDONLY) ? GENERIC_READ : (GENERIC_READ | GENERIC_WRITE),
FILE_SHARE_READ | FILE_SHARE_WRITE, // subsequent opens may either read or write
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
if(file_handle == INVALID_HANDLE_VALUE)
{
fprintf(stderr, message, file);
constructor_clear();
return true;
}
LARGE_INTEGER file_size = {0};
::GetFileSizeEx(file_handle, &file_size);
mapped_length = total_length = file_size.QuadPart;
#else
struct stat buf;
fd = ::open(file, flags);
if ((fd==-1) || (fstat(fd, &buf) != 0))
{
fprintf(stderr, message, file);
constructor_clear();
return true;
}
mapped_length = total_length = buf.st_size;
#endif
if(!useMemoryMapFlag)
{
return allocate();
}
#if defined(_WIN32)
assert(offset == 0);
map_handle = CreateFileMapping(file_handle, NULL,
(flags==O_RDONLY) ? PAGE_READONLY : PAGE_READWRITE,
file_size.HighPart, // upper 32 bits of map size
file_size.LowPart, // lower 32 bits of map size
NULL);
if(map_handle == NULL)
{
::CloseHandle(file_handle);
fprintf(stderr, message, file);
constructor_clear();
return true;
}
data = MapViewOfFile(map_handle,
(flags == O_RDONLY) ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
0, 0, mapped_length);
if (data == NULL)
{
CloseHandle(map_handle);
CloseHandle(file_handle);
fprintf(stderr, message, file);
constructor_clear();
return true;
}
#else
data = ::mmap(NULL, mapped_length,
(flags == O_RDONLY) ? PROT_READ : PROT_READ | PROT_WRITE,
MAP_SHARED, fd, offset);
if (data == MAP_FAILED)
{
::close(fd);
fprintf(stderr, message, file);
constructor_clear();
return true;
}
#endif
return false;
}
bool MemoryMap::create(const char *file, size_t size)
{
if (file==NULL)
{
data = calloc(size, 1);
return(data==NULL);
}
const char * message = "MemoryMap::create - problem creating file %s";
#ifdef __WIN32__
file_handle = CreateFile(file,
GENERIC_READ | GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
CREATE_ALWAYS,
FILE_ATTRIBUTE_NORMAL,
NULL);
if (file_handle == INVALID_HANDLE_VALUE)
{
fprintf(stderr, message, file);
constructor_clear();
return true;
}
SetFilePointer(file_handle, size - 1, NULL, FILE_BEGIN);
char dummy = 0;
DWORD check = 0;
WriteFile(file_handle, &dummy, 1, &check, NULL);
if (check != 0)
{
CloseHandle(file_handle);
DeleteFile(file);
fprintf(stderr, message, file);
constructor_clear();
return true;
}
CloseHandle(file_handle);
open(file, O_RDWR);
#else
fd = ::open(file, O_RDWR|O_CREAT|O_TRUNC, 0666);
if(fd == -1)
{
fprintf(stderr, message, file);
constructor_clear();
return true;
}
lseek(fd, (off_t) size - 1, SEEK_SET);
char dummy = 0;
if(write(fd, &dummy, 1)!=1)
{
fprintf(stderr, message, file);
constructor_clear();
return true;
}
data = ::mmap(NULL, size, PROT_READ|PROT_WRITE,
MAP_SHARED, fd, offset);
if (data == MAP_FAILED)
{
::close(fd);
unlink(file);
fprintf(stderr, message, file);
constructor_clear();
return true;
}
mapped_length = total_length = size;
#endif
return false;
}
bool MemoryMap::create(size_t size)
{
return create(NULL, size);
}
bool MemoryMap::close()
{
destructor_clear();
return false;
}
void MemoryMap::test()
{
int result;
result = this->open("test/test_memmap_data.txt");
assert(result == 0);
assert(data!=NULL);
assert(mapped_length == 183); // length of the above file
close();
// now try non memory mapped (direct slow file I/O)
useMemoryMap(false);
result = this->open("test/test_memmap_data.txt");
assert(result == 0);
assert(data!=NULL);
assert(mapped_length == 183); // length of the above file
close();
}
int MemoryMap::prefetch()
{
int sum = 0;
size_t i;
for (i=0; i<mapped_length; i += page_size) sum += *(i + (char *) data);
return sum;
}
#if defined(TEST)
//
// compile test using:
// g++ -DTEST -o testMemoryMap MemoryMap.cpp Error.o -lz
//
int main(int argc, const char *argv)
{
MemoryMap map;
map.test();
// map.debug_print();
exit(0);
}
#endif
MemoryMap
There are a pair of related data structures in the operating system, and also a few simple algorithms...
Definition: MemoryMap.h:156
MemoryMap::open
virtual bool open(const char *file, int flags=O_RDONLY)
open a previously created mapped vector
Definition: MemoryMap.cpp:156
MemoryMap::create
virtual bool create(const char *file, size_t size)
create the memory mapped file on disk
Definition: MemoryMap.cpp:243