_page.c
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:4k
- /* Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult 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 */
- /* L{ser och skriver nyckelblock */
- #include "isamdef.h"
- #ifdef __WIN__
- #include <errno.h>
- #endif
- /* Fetch a key-page in memory */
- uchar *_nisam_fetch_keypage(register N_INFO *info, N_KEYDEF *keyinfo,
- my_off_t page, uchar *buff, int return_buffer)
- {
- uchar *tmp;
- tmp=(uchar*) key_cache_read(dflt_key_cache,
- info->s->kfile,page,DFLT_INIT_HITS,(byte*) buff,
- (uint) keyinfo->base.block_length,
- (uint) keyinfo->base.block_length,
- return_buffer);
- if (tmp == info->buff)
- {
- info->update|=HA_STATE_BUFF_SAVED;
- info->int_pos=(ulong) page;
- info->buff_used=1;
- }
- else
- {
- info->update&= ~HA_STATE_BUFF_SAVED;
- if (tmp)
- info->int_pos=(ulong) page;
- else
- {
- info->int_pos=NI_POS_ERROR;
- DBUG_PRINT("error",("Got errno: %d from key_cache_read",my_errno));
- my_errno=HA_ERR_CRASHED;
- }
- }
- return tmp;
- } /* _nisam_fetch_keypage */
- /* Write a key-page on disk */
- int _nisam_write_keypage(register N_INFO *info, register N_KEYDEF *keyinfo,
- my_off_t page, uchar *buff)
- {
- reg3 uint length;
- #ifndef QQ /* Safety check */
- if (page < info->s->base.keystart ||
- page+keyinfo->base.block_length > info->s->state.key_file_length ||
- page & (nisam_block_size-1))
- {
- DBUG_PRINT("error",("Trying to write outside key region: %lu",
- (long) page));
- my_errno=EINVAL;
- return(-1);
- }
- DBUG_PRINT("page",("write page at: %lu",(long) page,buff));
- DBUG_DUMP("buff",(byte*) buff,getint(buff));
- #endif
- if ((length=keyinfo->base.block_length) > IO_SIZE*2 &&
- info->s->state.key_file_length != page+length)
- length= ((getint(buff)+IO_SIZE-1) & (uint) ~(IO_SIZE-1));
- #ifdef HAVE_purify
- {
- length=getint(buff);
- bzero((byte*) buff+length,keyinfo->base.block_length-length);
- length=keyinfo->base.block_length;
- }
- #endif
- return (key_cache_write(dflt_key_cache,
- info->s->kfile,page,DFLT_INIT_HITS,
- (byte*) buff,length,
- (uint) keyinfo->base.block_length,
- (int) (info->lock_type != F_UNLCK)));
- } /* nisam_write_keypage */
- /* Remove page from disk */
- int _nisam_dispose(register N_INFO *info, N_KEYDEF *keyinfo, my_off_t pos)
- {
- uint keynr= (uint) (keyinfo - info->s->keyinfo);
- ulong old_link; /* ulong is ok here */
- DBUG_ENTER("_nisam_dispose");
- old_link=info->s->state.key_del[keynr];
- info->s->state.key_del[keynr]=(ulong) pos;
- DBUG_RETURN(key_cache_write(dflt_key_cache,
- info->s->kfile,pos,DFLT_INIT_HITS,
- (byte*) &old_link,
- sizeof(long),
- (uint) keyinfo->base.block_length,
- (int) (info->lock_type != F_UNLCK)));
- } /* _nisam_dispose */
- /* Make new page on disk */
- ulong _nisam_new(register N_INFO *info, N_KEYDEF *keyinfo)
- {
- uint keynr= (uint) (keyinfo - info->s->keyinfo);
- ulong pos;
- DBUG_ENTER("_nisam_new");
- if ((pos=info->s->state.key_del[keynr]) == NI_POS_ERROR)
- {
- if (info->s->state.key_file_length >= info->s->base.max_key_file_length)
- {
- my_errno=HA_ERR_INDEX_FILE_FULL;
- DBUG_RETURN(NI_POS_ERROR);
- }
- pos=info->s->state.key_file_length;
- info->s->state.key_file_length+= keyinfo->base.block_length;
- }
- else
- {
- if (!key_cache_read(dflt_key_cache,
- info->s->kfile,pos,DFLT_INIT_HITS,
- (byte*) &info->s->state.key_del[keynr],
- (uint) sizeof(long),
- (uint) keyinfo->base.block_length,0))
- pos= NI_POS_ERROR;
- }
- DBUG_PRINT("exit",("Pos: %d",pos));
- DBUG_RETURN(pos);
- } /* _nisam_new */