records.cpp
上传用户:romrleung
上传日期:2022-05-23
资源大小:18897k
文件大小:15k
- /* 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 */
- /* Functions for easy reading of records, possible through a cache */
- #include "mysql_priv.h"
- static int rr_quick(READ_RECORD *info);
- static int rr_sequential(READ_RECORD *info);
- static int rr_from_tempfile(READ_RECORD *info);
- static int rr_unpack_from_tempfile(READ_RECORD *info);
- static int rr_unpack_from_buffer(READ_RECORD *info);
- static int rr_from_pointers(READ_RECORD *info);
- static int rr_from_cache(READ_RECORD *info);
- static int init_rr_cache(READ_RECORD *info);
- static int rr_cmp(uchar *a,uchar *b);
- static int rr_index_first(READ_RECORD *info);
- static int rr_index(READ_RECORD *info);
- /*
- Initialize READ_RECORD structure to perform full index scan
- SYNOPSIS
- init_read_record_idx()
- info READ_RECORD structure to initialize.
- thd Thread handle
- table Table to be accessed
- print_error If true, call table->file->print_error() if an error
- occurs (except for end-of-records error)
- idx index to scan
-
- DESCRIPTION
- Initialize READ_RECORD structure to perform full index scan (in forward
- direction) using read_record.read_record() interface.
-
- This function has been added at late stage and is used only by
- UPDATE/DELETE. Other statements perform index scans using
- join_read_first/next functions.
- */
- void init_read_record_idx(READ_RECORD *info, THD *thd, TABLE *table,
- bool print_error, uint idx)
- {
- bzero((char*) info,sizeof(*info));
- info->table= table;
- info->file= table->file;
- info->record= table->record[0];
- info->print_error= print_error;
- table->status=0; /* And it's always found */
- if (!table->file->inited)
- {
- table->file->ha_index_init(idx);
- table->file->extra(HA_EXTRA_RETRIEVE_PRIMARY_KEY);
- }
- /* read_record will be changed to rr_index in rr_index_first */
- info->read_record= rr_index_first;
- }
- /* init struct for read with info->read_record */
- void init_read_record(READ_RECORD *info,THD *thd, TABLE *table,
- SQL_SELECT *select,
- int use_record_cache, bool print_error)
- {
- IO_CACHE *tempfile;
- DBUG_ENTER("init_read_record");
- bzero((char*) info,sizeof(*info));
- info->thd=thd;
- info->table=table;
- info->file= table->file;
- info->forms= &info->table; /* Only one table */
- if (table->sort.addon_field)
- {
- info->rec_buf= table->sort.addon_buf;
- info->ref_length= table->sort.addon_length;
- }
- else
- {
- info->record= table->record[0];
- info->ref_length= table->file->ref_length;
- }
- info->select=select;
- info->print_error=print_error;
- info->ignore_not_found_rows= 0;
- table->status=0; /* And it's always found */
- if (select && my_b_inited(&select->file))
- tempfile= &select->file;
- else
- tempfile= table->sort.io_cache;
- if (tempfile && my_b_inited(tempfile)) // Test if ref-records was used
- {
- DBUG_PRINT("info",("using rr_from_tempfile"));
- info->read_record= (table->sort.addon_field ?
- rr_unpack_from_tempfile : rr_from_tempfile);
- info->io_cache=tempfile;
- reinit_io_cache(info->io_cache,READ_CACHE,0L,0,0);
- info->ref_pos=table->file->ref;
- if (!table->file->inited)
- table->file->ha_rnd_init(0);
- /*
- table->sort.addon_field is checked because if we use addon fields,
- it doesn't make sense to use cache - we don't read from the table
- and table->sort.io_cache is read sequentially
- */
- if (!table->sort.addon_field &&
- ! (specialflag & SPECIAL_SAFE_MODE) &&
- thd->variables.read_rnd_buff_size &&
- !(table->file->table_flags() & HA_FAST_KEY_READ) &&
- (table->db_stat & HA_READ_ONLY ||
- table->reginfo.lock_type <= TL_READ_NO_INSERT) &&
- (ulonglong) table->reclength*(table->file->records+
- table->file->deleted) >
- (ulonglong) MIN_FILE_LENGTH_TO_USE_ROW_CACHE &&
- info->io_cache->end_of_file/info->ref_length*table->reclength >
- (my_off_t) MIN_ROWS_TO_USE_TABLE_CACHE &&
- !table->blob_fields)
- {
- if (! init_rr_cache(info))
- {
- DBUG_PRINT("info",("using rr_from_cache"));
- info->read_record=rr_from_cache;
- }
- }
- }
- else if (select && select->quick)
- {
- DBUG_PRINT("info",("using rr_quick"));
- if (!table->file->inited)
- table->file->ha_index_init(select->quick->index);
- info->read_record=rr_quick;
- }
- else if (table->sort.record_pointers)
- {
- DBUG_PRINT("info",("using record_pointers"));
- table->file->ha_rnd_init(0);
- info->cache_pos=table->sort.record_pointers;
- info->cache_end=info->cache_pos+
- table->sort.found_records*info->ref_length;
- info->read_record= (table->sort.addon_field ?
- rr_unpack_from_buffer : rr_from_pointers);
- }
- else
- {
- DBUG_PRINT("info",("using rr_sequential"));
- info->read_record=rr_sequential;
- table->file->ha_rnd_init(1);
- /* We can use record cache if we don't update dynamic length tables */
- if (!table->no_cache &&
- (use_record_cache > 0 ||
- (int) table->reginfo.lock_type <= (int) TL_READ_HIGH_PRIORITY ||
- !(table->db_options_in_use & HA_OPTION_PACK_RECORD) ||
- (use_record_cache < 0 &&
- !(table->file->table_flags() & HA_NOT_DELETE_WITH_CACHE))))
- VOID(table->file->extra_opt(HA_EXTRA_CACHE,
- thd->variables.read_buff_size));
- }
- DBUG_VOID_RETURN;
- } /* init_read_record */
- void end_read_record(READ_RECORD *info)
- { /* free cache if used */
- if (info->cache)
- {
- my_free_lock((char*) info->cache,MYF(0));
- info->cache=0;
- }
- if (info->table)
- {
- filesort_free_buffers(info->table);
- (void) info->file->extra(HA_EXTRA_NO_CACHE);
- if (info->read_record != rr_quick) // otherwise quick_range does it
- (void) info->file->ha_index_or_rnd_end();
- info->table=0;
- }
- }
- static int rr_handle_error(READ_RECORD *info, int error)
- {
- if (error == HA_ERR_END_OF_FILE)
- error= -1;
- else
- {
- if (info->print_error)
- info->table->file->print_error(error, MYF(0));
- if (error < 0) // Fix negative BDB errno
- error= 1;
- }
- return error;
- }
- /* Read a record from head-database */
- static int rr_quick(READ_RECORD *info)
- {
- int tmp;
- while ((tmp= info->select->quick->get_next()))
- {
- if (info->thd->killed)
- {
- my_error(ER_SERVER_SHUTDOWN, MYF(0));
- return 1;
- }
- if (tmp != HA_ERR_RECORD_DELETED)
- {
- tmp= rr_handle_error(info, tmp);
- break;
- }
- }
- return tmp;
- }
- /*
- Reads first row in an index scan
- SYNOPSIS
- rr_index_first()
- info Scan info
-
- RETURN
- 0 Ok
- -1 End of records
- 1 Error
- */
- static int rr_index_first(READ_RECORD *info)
- {
- int tmp= info->file->index_first(info->record);
- info->read_record= rr_index;
- if (tmp)
- tmp= rr_handle_error(info, tmp);
- return tmp;
- }
- /*
- Reads index sequentially after first row
- SYNOPSIS
- rr_index()
- info Scan info
-
- DESCRIPTION
- Read the next index record (in forward direction) and translate return
- value.
-
- RETURN
- 0 Ok
- -1 End of records
- 1 Error
- */
- static int rr_index(READ_RECORD *info)
- {
- int tmp= info->file->index_next(info->record);
- if (tmp)
- tmp= rr_handle_error(info, tmp);
- return tmp;
- }
- static int rr_sequential(READ_RECORD *info)
- {
- int tmp;
- while ((tmp=info->file->rnd_next(info->record)))
- {
- if (info->thd->killed)
- {
- my_error(ER_SERVER_SHUTDOWN,MYF(0));
- return 1;
- }
- /*
- rnd_next can return RECORD_DELETED for MyISAM when one thread is
- reading and another deleting without locks.
- */
- if (tmp != HA_ERR_RECORD_DELETED)
- {
- tmp= rr_handle_error(info, tmp);
- break;
- }
- }
- return tmp;
- }
- static int rr_from_tempfile(READ_RECORD *info)
- {
- int tmp;
- for (;;)
- {
- if (my_b_read(info->io_cache,info->ref_pos,info->ref_length))
- return -1; /* End of file */
- if (!(tmp=info->file->rnd_pos(info->record,info->ref_pos)))
- break;
- /* The following is extremely unlikely to happen */
- if (tmp == HA_ERR_RECORD_DELETED ||
- (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
- continue;
- tmp= rr_handle_error(info, tmp);
- break;
- }
- return tmp;
- } /* rr_from_tempfile */
- /*
- Read a result set record from a temporary file after sorting
- SYNOPSIS
- rr_unpack_from_tempfile()
- info Reference to the context including record descriptors
- DESCRIPTION
- The function first reads the next sorted record from the temporary file.
- into a buffer. If a success it calls a callback function that unpacks
- the fields values use in the result set from this buffer into their
- positions in the regular record buffer.
- RETURN
- 0 - Record successfully read.
- -1 - There is no record to be read anymore.
- */
- static int rr_unpack_from_tempfile(READ_RECORD *info)
- {
- if (my_b_read(info->io_cache, info->rec_buf, info->ref_length))
- return -1;
- TABLE *table= info->table;
- (*table->sort.unpack)(table->sort.addon_field, info->rec_buf);
- return 0;
- }
- static int rr_from_pointers(READ_RECORD *info)
- {
- int tmp;
- byte *cache_pos;
- for (;;)
- {
- if (info->cache_pos == info->cache_end)
- return -1; /* End of file */
- cache_pos= info->cache_pos;
- info->cache_pos+= info->ref_length;
- if (!(tmp=info->file->rnd_pos(info->record,cache_pos)))
- break;
- /* The following is extremely unlikely to happen */
- if (tmp == HA_ERR_RECORD_DELETED ||
- (tmp == HA_ERR_KEY_NOT_FOUND && info->ignore_not_found_rows))
- continue;
- tmp= rr_handle_error(info, tmp);
- break;
- }
- return tmp;
- }
- /*
- Read a result set record from a buffer after sorting
- SYNOPSIS
- rr_unpack_from_buffer()
- info Reference to the context including record descriptors
- DESCRIPTION
- The function first reads the next sorted record from the sort buffer.
- If a success it calls a callback function that unpacks
- the fields values use in the result set from this buffer into their
- positions in the regular record buffer.
- RETURN
- 0 - Record successfully read.
- -1 - There is no record to be read anymore.
- */
- static int rr_unpack_from_buffer(READ_RECORD *info)
- {
- if (info->cache_pos == info->cache_end)
- return -1; /* End of buffer */
- TABLE *table= info->table;
- (*table->sort.unpack)(table->sort.addon_field, info->cache_pos);
- info->cache_pos+= info->ref_length;
- return 0;
- }
- /* cacheing of records from a database */
- static int init_rr_cache(READ_RECORD *info)
- {
- uint rec_cache_size;
- THD *thd= current_thd;
- DBUG_ENTER("init_rr_cache");
- info->struct_length=3+MAX_REFLENGTH;
- info->reclength=ALIGN_SIZE(info->table->reclength+1);
- if (info->reclength < info->struct_length)
- info->reclength=ALIGN_SIZE(info->struct_length);
- info->error_offset=info->table->reclength;
- info->cache_records= thd->variables.read_rnd_buff_size /
- (info->reclength+info->struct_length);
- rec_cache_size=info->cache_records*info->reclength;
- info->rec_cache_size=info->cache_records*info->ref_length;
- // We have to allocate one more byte to use uint3korr (see comments for it)
- if (info->cache_records <= 2 ||
- !(info->cache=(byte*) my_malloc_lock(rec_cache_size+info->cache_records*
- info->struct_length+1,
- MYF(0))))
- DBUG_RETURN(1);
- #ifdef HAVE_purify
- bzero(info->cache,rec_cache_size); // Avoid warnings in qsort
- #endif
- DBUG_PRINT("info",("Allocated buffert for %d records",info->cache_records));
- info->read_positions=info->cache+rec_cache_size;
- info->cache_pos=info->cache_end=info->cache;
- DBUG_RETURN(0);
- } /* init_rr_cache */
- static int rr_from_cache(READ_RECORD *info)
- {
- reg1 uint i;
- ulong length;
- my_off_t rest_of_file;
- int16 error;
- byte *position,*ref_position,*record_pos;
- ulong record;
- for (;;)
- {
- if (info->cache_pos != info->cache_end)
- {
- if (info->cache_pos[info->error_offset])
- {
- shortget(error,info->cache_pos);
- if (info->print_error)
- info->table->file->print_error(error,MYF(0));
- }
- else
- {
- error=0;
- memcpy(info->record,info->cache_pos,(size_t) info->table->reclength);
- }
- info->cache_pos+=info->reclength;
- return ((int) error);
- }
- length=info->rec_cache_size;
- rest_of_file=info->io_cache->end_of_file - my_b_tell(info->io_cache);
- if ((my_off_t) length > rest_of_file)
- length= (ulong) rest_of_file;
- if (!length || my_b_read(info->io_cache,info->cache,length))
- {
- DBUG_PRINT("info",("Found end of file"));
- return -1; /* End of file */
- }
- length/=info->ref_length;
- position=info->cache;
- ref_position=info->read_positions;
- for (i=0 ; i < length ; i++,position+=info->ref_length)
- {
- memcpy(ref_position,position,(size_s) info->ref_length);
- ref_position+=MAX_REFLENGTH;
- int3store(ref_position,(long) i);
- ref_position+=3;
- }
- qsort(info->read_positions,length,info->struct_length,(qsort_cmp) rr_cmp);
- position=info->read_positions;
- for (i=0 ; i < length ; i++)
- {
- memcpy(info->ref_pos,position,(size_s) info->ref_length);
- position+=MAX_REFLENGTH;
- record=uint3korr(position);
- position+=3;
- record_pos=info->cache+record*info->reclength;
- if ((error=(int16) info->file->rnd_pos(record_pos,info->ref_pos)))
- {
- record_pos[info->error_offset]=1;
- shortstore(record_pos,error);
- DBUG_PRINT("error",("Got error: %d:%d when reading row",
- my_errno, error));
- }
- else
- record_pos[info->error_offset]=0;
- }
- info->cache_end=(info->cache_pos=info->cache)+length*info->reclength;
- }
- } /* rr_from_cache */
- static int rr_cmp(uchar *a,uchar *b)
- {
- if (a[0] != b[0])
- return (int) a[0] - (int) b[0];
- if (a[1] != b[1])
- return (int) a[1] - (int) b[1];
- if (a[2] != b[2])
- return (int) a[2] - (int) b[2];
- #if MAX_REFLENGTH == 4
- return (int) a[3] - (int) b[3];
- #else
- if (a[3] != b[3])
- return (int) a[3] - (int) b[3];
- if (a[4] != b[4])
- return (int) a[4] - (int) b[4];
- if (a[5] != b[5])
- return (int) a[1] - (int) b[5];
- if (a[6] != b[6])
- return (int) a[6] - (int) b[6];
- return (int) a[7] - (int) b[7];
- #endif
- }