37#define MAP_POPULATE 0x0000
40#define MAP_NONBLOCK 0x0000
47 SYSTEM_INFO sysinfo = {0};
48 ::GetSystemInfo(&sysinfo);
49 DWORD cbView = sysinfo.dwAllocationGranularity;
51 page_size = sysconf(_SC_PAGE_SIZE);
55MemoryMap::~MemoryMap()
60void MemoryMap::debug_print()
63 std::cout <<
"fd = " << file_handle << std::endl;
65 std::cout <<
"fd = " << fd << std::endl;
67 std::cout <<
"data = 0x" << std::hex << data << std::endl;
68 std::cout <<
"offset = 0x" << std::hex << offset << std::endl;
69 std::cout <<
"mapped_length = 0x" << std::hex << mapped_length << std::endl;
70 std::cout <<
"total_length = 0x" << std::hex << total_length << std::endl;
71 std::cout <<
"page_size = 0x" << std::hex << page_size << std::endl;
74void MemoryMap::constructor_clear()
86 useMemoryMapFlag =
true;
89void MemoryMap::destructor_clear()
95 ::UnmapViewOfFile((LPVOID) data);
97 if (map_handle != NULL)
98 ::CloseHandle(map_handle);
99 if (file_handle != NULL)
100 ::CloseHandle(file_handle);
105 munmap(data, mapped_length);
118bool MemoryMap::allocate()
120 data = (
void *) malloc(mapped_length);
125 ::CloseHandle(file_handle);
129 perror(
"MemoryMap::open");
135 DWORD resultSize = 0;
136 ReadFile(file_handle, data, mapped_length, &resultSize, NULL);
138 size_t resultSize = read(fd, data, mapped_length);
141 if ( resultSize != mapped_length)
144 ::CloseHandle(file_handle);
148 perror(
"MemoryMap::open");
158 const char * message =
"MemoryMap::open - problem opening file %s";
160 file_handle = CreateFile(file,
161 (flags==O_RDONLY) ? GENERIC_READ : (GENERIC_READ | GENERIC_WRITE),
162 FILE_SHARE_READ | FILE_SHARE_WRITE,
165 FILE_ATTRIBUTE_NORMAL,
168 if(file_handle == INVALID_HANDLE_VALUE)
170 fprintf(stderr, message, file);
175 LARGE_INTEGER file_size = {0};
176 ::GetFileSizeEx(file_handle, &file_size);
177 mapped_length = total_length = file_size.QuadPart;
182 if ((fd==-1) || (fstat(fd, &buf) != 0))
184 fprintf(stderr, message, file);
188 mapped_length = total_length = buf.st_size;
191 if(!useMemoryMapFlag)
199 map_handle = CreateFileMapping(file_handle, NULL,
200 (flags==O_RDONLY) ? PAGE_READONLY : PAGE_READWRITE,
205 if(map_handle == NULL)
207 ::CloseHandle(file_handle);
208 fprintf(stderr, message, file);
213 data = MapViewOfFile(map_handle,
214 (flags == O_RDONLY) ? FILE_MAP_READ : FILE_MAP_ALL_ACCESS,
215 0, 0, mapped_length);
219 CloseHandle(map_handle);
220 CloseHandle(file_handle);
222 fprintf(stderr, message, file);
227 data = ::mmap(NULL, mapped_length,
228 (flags == O_RDONLY) ? PROT_READ : PROT_READ | PROT_WRITE,
229 MAP_SHARED, fd, offset);
231 if (data == MAP_FAILED)
234 fprintf(stderr, message, file);
247 data = calloc(size, 1);
251 const char * message =
"MemoryMap::create - problem creating file %s";
254 file_handle = CreateFile(file,
255 GENERIC_READ | GENERIC_WRITE,
256 FILE_SHARE_READ | FILE_SHARE_WRITE,
259 FILE_ATTRIBUTE_NORMAL,
262 if (file_handle == INVALID_HANDLE_VALUE)
264 fprintf(stderr, message, file);
269 SetFilePointer(file_handle, size - 1, NULL, FILE_BEGIN);
272 WriteFile(file_handle, &dummy, 1, &check, NULL);
276 CloseHandle(file_handle);
278 fprintf(stderr, message, file);
282 CloseHandle(file_handle);
285 fd =
::open(file, O_RDWR|O_CREAT|O_TRUNC, 0666);
288 fprintf(stderr, message, file);
293 lseek(fd, (off_t) size - 1, SEEK_SET);
295 if(write(fd, &dummy, 1)!=1)
297 fprintf(stderr, message, file);
302 data = ::mmap(NULL, size, PROT_READ|PROT_WRITE,
303 MAP_SHARED, fd, offset);
305 if (data == MAP_FAILED)
309 fprintf(stderr, message, file);
313 mapped_length = total_length = size;
321 return create(NULL, size);
324bool MemoryMap::close()
330void MemoryMap::test()
334 result = this->
open(
"test/test_memmap_data.txt");
337 assert(mapped_length == 183);
342 result = this->
open(
"test/test_memmap_data.txt");
345 assert(mapped_length == 183);
349int MemoryMap::prefetch()
354 for (i=0; i<mapped_length; i += page_size) sum += *(i + (
char *) data);
365int main(
int argc,
const char *argv)
There are a pair of related data structures in the operating system, and also a few simple algorithms...
virtual bool open(const char *file, int flags=O_RDONLY)
open a previously created mapped vector
virtual bool create(const char *file, size_t size)
create the memory mapped file on disk