mariadb/mysys/my_mmap.c
Vladislav Vaintroub 4171483b53 Backport Fix for Bug#24509 - 2048 file descriptor limit on windows needs increasing.
The patch replaces the use of the POSIX I/O interfaces in mysys on Windows with 
the Win32 API calls (CreateFile, WriteFile, etc). The Windows HANDLE for the open
 file is stored in the my_file_info struct, along with a flag for append mode 
(because the Windows API does not support opening files in append mode in all cases)
The default max open files has been increased to 16384 and can be increased further
by setting --max-open-files=<value> during the server start.

Noteworthy benefit of this patch is that it removes limits from the table_cache size - 
allowing for more simultaneus users
2011-06-12 15:52:07 +02:00

80 lines
2.2 KiB
C

/* Copyright (C) 2000-2003 MySQL AB
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; version 2 of the License.
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, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#include "mysys_priv.h"
#ifdef HAVE_SYS_MMAN_H
/*
system msync() only syncs mmap'ed area to fs cache.
fsync() is required to really sync to disc
*/
int my_msync(int fd, void *addr, size_t len, int flags)
{
msync(addr, len, flags);
return my_sync(fd, MYF(0));
}
#elif defined(_WIN32)
static SECURITY_ATTRIBUTES mmap_security_attributes=
{sizeof(SECURITY_ATTRIBUTES), 0, TRUE};
void *my_mmap(void *addr, size_t len, int prot,
int flags, File fd, my_off_t offset)
{
HANDLE hFileMap;
LPVOID ptr;
HANDLE hFile= (HANDLE)my_get_osfhandle(fd);
if (hFile == INVALID_HANDLE_VALUE)
return MAP_FAILED;
hFileMap=CreateFileMapping(hFile, &mmap_security_attributes,
PAGE_READWRITE, 0, (DWORD) len, NULL);
if (hFileMap == 0)
return MAP_FAILED;
ptr=MapViewOfFile(hFileMap,
prot & PROT_WRITE ? FILE_MAP_WRITE : FILE_MAP_READ,
(DWORD)(offset >> 32), (DWORD)offset, len);
/*
MSDN explicitly states that it's possible to close File Mapping Object
even when a view is not unmapped - then the object will be held open
implicitly until unmap, as every view stores internally a handler of
a corresponding File Mapping Object
*/
CloseHandle(hFileMap);
if (ptr)
return ptr;
return MAP_FAILED;
}
int my_munmap(void *addr, size_t len)
{
return UnmapViewOfFile(addr) ? 0 : -1;
}
int my_msync(int fd, void *addr, size_t len, int flags)
{
return FlushViewOfFile(addr, len) ? 0 : -1;
}
#else
#warning "no mmap!"
#endif