release/src/router/mysql/storage/myisam/mi_preload.c

   1 /*
   2    Copyright (c) 2003, 2011, Oracle and/or its affiliates. All rights reserved.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; version 2 of the License.
   7
   8    This program is distributed in the hope that it will be useful,
   9    but WITHOUT ANY WARRANTY; without even the implied warranty of
  10    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11    GNU General Public License for more details.
  12
  13    You should have received a copy of the GNU General Public License
  14    along with this program; if not, write to the Free Software
  15    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
  16 */
  17
  18 /*
  19   Preload indexes into key cache
  20 */
  21
  22 #include "myisamdef.h"
  23
  24
  25 /*
  26   Preload pages of the index file for a table into the key cache
  27
  28   SYNOPSIS
  29     mi_preload()
  30       info          open table
  31       map           map of indexes to preload into key cache
  32       ignore_leaves only non-leaves pages are to be preloaded
  33
  34   RETURN VALUE
  35     0 if a success. error code - otherwise.
  36
  37   NOTES.
  38     At present pages for all indexes are preloaded.
  39     In future only pages for indexes specified in the key_map parameter
  40     of the table will be preloaded.
  41 */
  42
  43 int mi_preload(MI_INFO *info, ulonglong key_map, my_bool ignore_leaves)
  44 {
  45   uint i;
  46   ulong length, block_length= 0;
  47   uchar *buff= NULL;
  48   MYISAM_SHARE* share= info->s;
  49   uint keys= share->state.header.keys;
  50   MI_KEYDEF *keyinfo= share->keyinfo;
  51   my_off_t key_file_length= share->state.state.key_file_length;
  52   my_off_t pos= share->base.keystart;
  53   DBUG_ENTER("mi_preload");
  54
  55   if (!keys || !mi_is_any_key_active(key_map) || key_file_length == pos)
  56     DBUG_RETURN(0);
  57
  58   /* Preload into a non initialized key cache should never happen. */
  59   DBUG_ASSERT(share->key_cache->key_cache_inited);
  60
  61   block_length= keyinfo[0].block_length;
  62
  63   if (ignore_leaves)
  64   {
  65     /* Check whether all indexes use the same block size */
  66     for (i= 1 ; i < keys ; i++)
  67     {
  68       if (keyinfo[i].block_length != block_length)
  69         DBUG_RETURN(my_errno= HA_ERR_NON_UNIQUE_BLOCK_SIZE);
  70     }
  71   }
  72   else
  73     block_length= share->key_cache->key_cache_block_size;
  74
  75   length= info->preload_buff_size/block_length * block_length;
  76   set_if_bigger(length, block_length);
  77
  78   if (!(buff= (uchar *) my_malloc(length, MYF(MY_WME))))
  79     DBUG_RETURN(my_errno= HA_ERR_OUT_OF_MEM);
  80
  81   if (flush_key_blocks(share->key_cache,share->kfile, FLUSH_RELEASE))
  82     goto err;
  83
  84   do
  85   {
  86     /* Read the next block of index file into the preload buffer */
  87     if ((my_off_t) length > (key_file_length-pos))
  88       length= (ulong) (key_file_length-pos);
  89     if (my_pread(share->kfile, (uchar*) buff, length, pos, MYF(MY_FAE|MY_FNABP)))
  90       goto err;
  91
  92     if (ignore_leaves)
  93     {
  94       uchar *end= buff+length;
  95       do
  96       {
  97         if (mi_test_if_nod(buff))
  98         {
  99           if (key_cache_insert(share->key_cache,
 100                                share->kfile, pos, DFLT_INIT_HITS,
 101                               (uchar*) buff, block_length))
 102             goto err;
 103         }
 104         pos+= block_length;
 105       }
 106       while ((buff+= block_length) != end);
 107       buff= end-length;
 108     }
 109     else
 110     {
 111       if (key_cache_insert(share->key_cache,
 112                            share->kfile, pos, DFLT_INIT_HITS,
 113                            (uchar*) buff, length))
 114         goto err;
 115       pos+= length;
 116     }
 117   }
 118   while (pos != key_file_length);
 119
 120   my_free((char*) buff, MYF(0));
 121   DBUG_RETURN(0);
 122
 123 err:
 124   my_free((char*) buff, MYF(MY_ALLOW_ZERO_PTR));
 125   DBUG_RETURN(my_errno= errno);
 126 }
 127