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Diffstat (limited to '')
| -rw-r--r-- | storage/myisammrg/myrg_rrnd.c | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/storage/myisammrg/myrg_rrnd.c b/storage/myisammrg/myrg_rrnd.c new file mode 100644 index 00000000..a97f6d30 --- /dev/null +++ b/storage/myisammrg/myrg_rrnd.c @@ -0,0 +1,117 @@ +/* Copyright (c) 2000-2002, 2005-2007 MySQL AB + Use is subject to license terms + + 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */ + +/* + Read a record with random-access. The position to the record must + get by myrg_info(). The next record can be read with pos= -1 */ + + +#include "myrg_def.h" + +static MYRG_TABLE *find_table(MYRG_TABLE *start,MYRG_TABLE *end,ulonglong pos); + +/* + If filepos == HA_OFFSET_ERROR, read next + Returns same as mi_rrnd: + 0 = Ok. + HA_ERR_RECORD_DELETED = Record is deleted. + HA_ERR_END_OF_FILE = EOF. +*/ + +int myrg_rrnd(MYRG_INFO *info,uchar *buf,ulonglong filepos) +{ + int error; + MI_INFO *isam_info; + DBUG_ENTER("myrg_rrnd"); + DBUG_PRINT("info",("offset: %lu", (ulong) filepos)); + + if (filepos == HA_OFFSET_ERROR) + { + if (!info->current_table) + { + if (info->open_tables == info->end_table) + { /* No tables */ + DBUG_RETURN(my_errno=HA_ERR_END_OF_FILE); + } + isam_info=(info->current_table=info->open_tables)->table; + if (info->cache_in_use) + mi_extra(isam_info,HA_EXTRA_CACHE,(uchar*) &info->cache_size); + 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,(uchar*) buf, + (my_off_t) filepos,1)) != + HA_ERR_END_OF_FILE) + DBUG_RETURN(error); + if (info->cache_in_use) + mi_extra(info->current_table->table, HA_EXTRA_NO_CACHE, + (uchar*) &info->cache_size); + if (info->current_table+1 == info->end_table) + DBUG_RETURN(HA_ERR_END_OF_FILE); + info->current_table++; + info->last_used_table=info->current_table; + if (info->cache_in_use) + mi_extra(info->current_table->table, HA_EXTRA_CACHE, + (uchar*) &info->cache_size); + info->current_table->file_offset= + info->current_table[-1].file_offset+ + info->current_table[-1].table->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->end_table-1,filepos); + isam_info=info->current_table->table; + isam_info->update&= HA_STATE_CHANGED; + DBUG_RETURN((*isam_info->s->read_rnd) + (isam_info, (uchar*) buf, + (my_off_t) (filepos - info->current_table->file_offset), + 0)); +} + + + /* Find which table to use according to file-pos */ + +static MYRG_TABLE *find_table(MYRG_TABLE *start, MYRG_TABLE *end, + ulonglong pos) +{ + MYRG_TABLE *mid; + DBUG_ENTER("find_table"); + + while (start != end) + { + mid=start+((uint) (end-start)+1)/2; + if (mid->file_offset > pos) + end=mid-1; + else + start=mid; + } + DBUG_PRINT("info",("offset: %lu, table: %s", + (ulong) pos, start->table->filename)); + DBUG_RETURN(start); +} |