mirror of
https://github.com/MariaDB/server.git
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117 lines
3.5 KiB
C
117 lines
3.5 KiB
C
/* Copyright (c) 2000-2002, 2005-2007 MySQL AB
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Use is subject to license terms
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
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/*
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Read a record with random-access. The position to the record must
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get by myrg_info(). The next record can be read with pos= -1 */
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#include "myrg_def.h"
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static MYRG_TABLE *find_table(MYRG_TABLE *start,MYRG_TABLE *end,ulonglong pos);
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/*
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If filepos == HA_OFFSET_ERROR, read next
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Returns same as mi_rrnd:
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0 = Ok.
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HA_ERR_RECORD_DELETED = Record is deleted.
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HA_ERR_END_OF_FILE = EOF.
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*/
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int myrg_rrnd(MYRG_INFO *info,uchar *buf,ulonglong filepos)
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{
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int error;
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MI_INFO *isam_info;
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DBUG_ENTER("myrg_rrnd");
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DBUG_PRINT("info",("offset: %lu", (ulong) filepos));
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if (filepos == HA_OFFSET_ERROR)
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{
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if (!info->current_table)
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{
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if (info->open_tables == info->end_table)
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{ /* No tables */
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DBUG_RETURN(my_errno=HA_ERR_END_OF_FILE);
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}
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isam_info=(info->current_table=info->open_tables)->table;
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if (info->cache_in_use)
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mi_extra(isam_info,HA_EXTRA_CACHE,(uchar*) &info->cache_size);
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filepos=isam_info->s->pack.header_length;
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isam_info->lastinx= (uint) -1; /* Can't forward or backward */
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}
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else
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{
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isam_info=info->current_table->table;
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filepos= isam_info->nextpos;
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}
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for (;;)
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{
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isam_info->update&= HA_STATE_CHANGED;
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if ((error=(*isam_info->s->read_rnd)(isam_info,(uchar*) buf,
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(my_off_t) filepos,1)) !=
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HA_ERR_END_OF_FILE)
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DBUG_RETURN(error);
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if (info->cache_in_use)
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mi_extra(info->current_table->table, HA_EXTRA_NO_CACHE,
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(uchar*) &info->cache_size);
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if (info->current_table+1 == info->end_table)
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DBUG_RETURN(HA_ERR_END_OF_FILE);
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info->current_table++;
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info->last_used_table=info->current_table;
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if (info->cache_in_use)
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mi_extra(info->current_table->table, HA_EXTRA_CACHE,
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(uchar*) &info->cache_size);
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info->current_table->file_offset=
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info->current_table[-1].file_offset+
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info->current_table[-1].table->state->data_file_length;
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isam_info=info->current_table->table;
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filepos=isam_info->s->pack.header_length;
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isam_info->lastinx= (uint) -1;
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}
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}
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info->current_table=find_table(info->open_tables,
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info->end_table-1,filepos);
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isam_info=info->current_table->table;
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isam_info->update&= HA_STATE_CHANGED;
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DBUG_RETURN((*isam_info->s->read_rnd)
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(isam_info, (uchar*) buf,
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(my_off_t) (filepos - info->current_table->file_offset),
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0));
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}
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/* Find which table to use according to file-pos */
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static MYRG_TABLE *find_table(MYRG_TABLE *start, MYRG_TABLE *end,
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ulonglong pos)
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{
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MYRG_TABLE *mid;
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DBUG_ENTER("find_table");
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while (start != end)
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{
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mid=start+((uint) (end-start)+1)/2;
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if (mid->file_offset > pos)
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end=mid-1;
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else
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start=mid;
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}
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DBUG_PRINT("info",("offset: %lu, table: %s",
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(ulong) pos, start->table->filename));
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DBUG_RETURN(start);
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}
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