my_lockmem.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:3k
- /* Copyright (C) 2000 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; either version 2 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, write to the Free Software
- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
- /* Alloc a block of locked memory */
- #include "mysys_priv.h"
- #include "mysys_err.h"
- #include <my_list.h>
- #ifdef HAVE_MLOCK
- #include <sys/mman.h>
- struct st_mem_list
- {
- LIST list;
- byte *page;
- uint size;
- };
- LIST *mem_list;
- byte *my_malloc_lock(uint size,myf MyFlags)
- {
- int success;
- uint pagesize=sysconf(_SC_PAGESIZE);
- byte *ptr;
- struct st_mem_list *element;
- DBUG_ENTER("my_malloc_lock");
- size=((size-1) & ~(pagesize-1))+pagesize;
- if (!(ptr=memalign(pagesize,size)))
- {
- if (MyFlags & (MY_FAE+MY_WME))
- my_error(EE_OUTOFMEMORY, MYF(ME_BELL+ME_WAITTANG),size);
- DBUG_RETURN(0);
- }
- success = mlock((byte*) ptr,size);
- if (success != 0 && geteuid() == 0)
- {
- DBUG_PRINT("warning",("Failed to lock memory. errno %dn",
- errno));
- fprintf(stderr, "Warning: Failed to lock memory. errno %dn",
- errno);
- }
- else
- {
- /* Add block in a list for munlock */
- if (!(element=(struct st_mem_list*) my_malloc(sizeof(*element),MyFlags)))
- {
- VOID(munlock((byte*) ptr,size));
- free(ptr);
- DBUG_RETURN(0);
- }
- element->list.data=(byte*) element;
- element->page=ptr;
- element->size=size;
- pthread_mutex_lock(&THR_LOCK_malloc);
- mem_list=list_add(mem_list,&element->list);
- pthread_mutex_unlock(&THR_LOCK_malloc);
- }
- DBUG_RETURN(ptr);
- }
- void my_free_lock(byte *ptr,myf Myflags __attribute__((unused)))
- {
- LIST *list;
- struct st_mem_list *element=0;
- pthread_mutex_lock(&THR_LOCK_malloc);
- for (list=mem_list ; list ; list=list->next)
- {
- element=(struct st_mem_list*) list->data;
- if (ptr == element->page)
- { /* Found locked mem */
- VOID(munlock((byte*) ptr,element->size));
- mem_list=list_delete(mem_list,list);
- break;
- }
- }
- pthread_mutex_unlock(&THR_LOCK_malloc);
- if (element)
- my_free((gptr) element,MYF(0));
- free(ptr); /* Free even if not locked */
- }
- #endif /* HAVE_MLOCK */