diff options
Diffstat (limited to 'merge/rrnd.c')
| -rw-r--r-- | merge/rrnd.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/merge/rrnd.c b/merge/rrnd.c new file mode 100644 index 00000000000..15a50c0b89f --- /dev/null +++ b/merge/rrnd.c @@ -0,0 +1,110 @@ +/* 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 */ + +/* + Read a record with random-access. The position to the record must + get by mrg_info(). The next record can be read with pos= -1 */ + + +#include "mrgdef.h" + +static MRG_TABLE *find_table(MRG_TABLE *start,MRG_TABLE *end,mrg_off_t pos); + +/* + If filepos == -1, read next + Returns same as nisam_rrnd: + 0 = Ok. + 1 = Record deleted. + -1 = EOF (or something, errno should be HA_ERR_END_OF_FILE) +*/ + +int mrg_rrnd(MRG_INFO *info,byte *buf,mrg_off_t filepos) +{ + int error; + N_INFO *isam_info; + + if (filepos == ~(mrg_off_t) 0) /* Can't use HA_POS_ERROR */ + { + if (!info->current_table) + { + if (info->open_tables == info->end_table) + { /* No tables */ + my_errno=HA_ERR_END_OF_FILE; + return -1; + } + isam_info=(info->current_table=info->open_tables)->table; + if (info->cache_in_use) + nisam_extra(isam_info,HA_EXTRA_CACHE); + filepos=isam_info->s->pack.header_length; + isam_info->lastinx= (uint) -1; /* Can't forward or backward */ + } + else + { + isam_info=info->current_table->table; + filepos= isam_info->nextpos; + } + + for (;;) + { + isam_info->update&= HA_STATE_CHANGED; + if ((error=(*isam_info->s->read_rnd)(isam_info,(byte*) buf, + filepos,1)) >= 0 || + my_errno != HA_ERR_END_OF_FILE) + return (error); + if (info->cache_in_use) + nisam_extra(info->current_table->table,HA_EXTRA_NO_CACHE); + if (info->current_table+1 == info->end_table) + return(-1); + info->current_table++; + info->last_used_table=info->current_table; + if (info->cache_in_use) + nisam_extra(info->current_table->table,HA_EXTRA_CACHE); + info->current_table->file_offset= + info->current_table[-1].file_offset+ + info->current_table[-1].table->s->state.data_file_length; + + isam_info=info->current_table->table; + filepos=isam_info->s->pack.header_length; + isam_info->lastinx= (uint) -1; + } + } + info->current_table=find_table(info->open_tables, + info->last_used_table,filepos); + isam_info=info->current_table->table; + isam_info->update&= HA_STATE_CHANGED; + return ((*isam_info->s->read_rnd)(isam_info,(byte*) buf, + (ulong) (filepos - + info->current_table->file_offset), + 0)); +} + + + /* Find which table to use according to file-pos */ + +static MRG_TABLE *find_table(MRG_TABLE *start,MRG_TABLE *end,mrg_off_t pos) +{ + MRG_TABLE *mid; + + while (start != end) + { + mid=start+((uint) (end-start)+1)/2; + if (mid->file_offset > pos) + end=mid-1; + else + start=mid; + } + return start; +} |