dict/drdwr.c

   1 /* This file is part of the Zebra server.
   2    Copyright (C) 1994-2010 Index Data
   3
   4    Zebra is free software; you can redistribute it and/or modify it under
   5    the terms of the GNU General Public License as published by the Free
   6    Software Foundation; either version 2, or (at your option) any later
   7    version.
   8
   9    Zebra is distributed in the hope that it will be useful, but WITHOUT ANY
  10    WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12    for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software
  16    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17
  18 */
  19
  20
  21
  22 #include <sys/types.h>
  23 #include <fcntl.h>
  24 #if HAVE_UNISTD_H
  25 #include <unistd.h>
  26 #endif
  27 #include <string.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <assert.h>
  31
  32 #include "dict-p.h"
  33
  34 void dict_pr_lru(Dict_BFile bf)
  35 {
  36     struct Dict_file_block *p;
  37     for (p=bf->lru_back; p; p = p->lru_next)
  38     {
  39         printf(" %d", p->no);
  40     }
  41     printf("\n");
  42     fflush(stdout);
  43 }
  44
  45 static struct Dict_file_block *find_block(Dict_BFile bf, int no)
  46 {
  47     struct Dict_file_block *p;
  48
  49     for (p=bf->hash_array[no% bf->hash_size]; p; p=p->h_next)
  50         if (p->no == no)
  51             break;
  52     return p;
  53 }
  54
  55 static void release_block(Dict_BFile bf, struct Dict_file_block *p)
  56 {
  57     assert(p);
  58
  59     /* remove from lru queue */
  60     if (p->lru_prev)
  61         p->lru_prev->lru_next = p->lru_next;
  62     else
  63         bf->lru_back = p->lru_next;
  64     if (p->lru_next)
  65         p->lru_next->lru_prev = p->lru_prev;
  66     else
  67         bf->lru_front = p->lru_prev;
  68
  69     /* remove from hash chain */
  70     *p->h_prev = p->h_next;
  71     if (p->h_next)
  72         p->h_next->h_prev = p->h_prev;
  73
  74     /* move to list of free blocks */
  75     p->h_next = bf->free_list;
  76     bf->free_list = p;
  77 }
  78
  79 void dict_bf_flush_blocks(Dict_BFile bf, int no_to_flush)
  80 {
  81     struct Dict_file_block *p;
  82     int i;
  83     for (i=0; i != no_to_flush && bf->lru_back; i++)
  84     {
  85         p = bf->lru_back;
  86         if (p->dirty)
  87         {
  88             if (!bf->compact_flag)
  89                 bf_write(bf->bf, p->no, 0, 0, p->data);
  90             else
  91             {
  92                 int effective_block = p->no / bf->block_size;
  93                 int effective_offset = p->no -
  94                     effective_block * bf->block_size;
  95                 int remain = bf->block_size - effective_offset;
  96
  97                 if (remain >= p->nbytes)
  98                 {
  99                     bf_write(bf->bf, effective_block, effective_offset,
 100                              p->nbytes, p->data);
 101 #if 0
 102                     yaz_log(YLOG_LOG, "bf_write no=%d offset=%d size=%d",
 103                             effective_block, effective_offset,
 104                             p->nbytes);
 105 #endif
 106
 107                 }
 108                 else
 109                 {
 110 #if 0
 111                     yaz_log(YLOG_LOG, "bf_write1 no=%d offset=%d size=%d",
 112                             effective_block, effective_offset,
 113                             remain);
 114 #endif
 115                     bf_write(bf->bf, effective_block, effective_offset,
 116                              remain, p->data);
 117 #if 0
 118                     yaz_log(YLOG_LOG, "bf_write2 no=%d offset=%d size=%d",
 119                             effective_block+1, 0, p->nbytes - remain);
 120 #endif
 121                     bf_write(bf->bf, effective_block+1, 0,
 122                              p->nbytes - remain, (char*)p->data + remain);
 123                 }
 124             }
 125         }
 126         release_block(bf, p);
 127     }
 128 }
 129
 130 static struct Dict_file_block *alloc_block(Dict_BFile bf, int no)
 131 {
 132     struct Dict_file_block *p, **pp;
 133
 134     if (!bf->free_list)
 135         dict_bf_flush_blocks(bf, 1);
 136     assert(bf->free_list);
 137     p = bf->free_list;
 138     bf->free_list = p->h_next;
 139     p->dirty = 0;
 140     p->no = no;
 141
 142     /* insert at front in lru chain */
 143     p->lru_next = NULL;
 144     p->lru_prev = bf->lru_front;
 145     if (bf->lru_front)
 146         bf->lru_front->lru_next = p;
 147     else
 148         bf->lru_back = p;
 149     bf->lru_front = p;
 150
 151     /* insert in hash chain */
 152     pp = bf->hash_array + (no % bf->hash_size);
 153     p->h_next = *pp;
 154     p->h_prev = pp;
 155     if (*pp)
 156         (*pp)->h_prev = &p->h_next;
 157     *pp = p;
 158
 159     return p;
 160 }
 161
 162 static void move_to_front(Dict_BFile bf, struct Dict_file_block *p)
 163 {
 164     /* Already at front? */
 165     if (!p->lru_next)
 166         return ;
 167
 168     /* Remove */
 169     if (p->lru_prev)
 170         p->lru_prev->lru_next = p->lru_next;
 171     else
 172         bf->lru_back = p->lru_next;
 173     p->lru_next->lru_prev = p->lru_prev;
 174
 175     /* Insert at front */
 176     p->lru_next = NULL;
 177     p->lru_prev = bf->lru_front;
 178     if (bf->lru_front)
 179         bf->lru_front->lru_next = p;
 180     else
 181         bf->lru_back = p;
 182     bf->lru_front = p;
 183 }
 184
 185 int dict_bf_readp(Dict_BFile bf, int no, void **bufp)
 186 {
 187     struct Dict_file_block *p;
 188     int i;
 189     if ((p = find_block(bf, no)))
 190     {
 191         *bufp = p->data;
 192         move_to_front(bf, p);
 193         bf->hits++;
 194         return 1;
 195     }
 196     bf->misses++;
 197     p = alloc_block(bf, no);
 198
 199     if (!bf->compact_flag)
 200         i = bf_read(bf->bf, no, 0, 0, p->data);
 201     else
 202     {
 203         int effective_block = no / bf->block_size;
 204         int effective_offset = no - effective_block * bf->block_size;
 205
 206         i = bf_read(bf->bf, effective_block, effective_offset,
 207                     bf->block_size - effective_offset, p->data);
 208         if (i > 0 && effective_offset > 0)
 209             i = bf_read(bf->bf, effective_block+1, 0, effective_offset,
 210                         (char*) p->data + bf->block_size - effective_offset);
 211         i = 1;
 212     }
 213     if (i > 0)
 214     {
 215         *bufp = p->data;
 216         return i;
 217     }
 218     release_block(bf, p);
 219     *bufp = NULL;
 220     return i;
 221 }
 222
 223 int dict_bf_newp(Dict_BFile dbf, int no, void **bufp, int nbytes)
 224 {
 225     struct Dict_file_block *p;
 226     if (!(p = find_block(dbf, no)))
 227         p = alloc_block(dbf, no);
 228     else
 229         move_to_front(dbf, p);
 230     *bufp = p->data;
 231     memset(p->data, 0, dbf->block_size);
 232     p->dirty = 1;
 233     p->nbytes = nbytes;
 234 #if 0
 235     printf("bf_newp of %d:", no);
 236     dict_pr_lru(dbf);
 237 #endif
 238     return 1;
 239 }
 240
 241 int dict_bf_touch(Dict_BFile dbf, int no)
 242 {
 243     struct Dict_file_block *p;
 244     if ((p = find_block(dbf, no)))
 245     {
 246         p->dirty = 1;
 247         return 0;
 248     }
 249     return -1;
 250 }
 251
 252 /*
 253  * Local variables:
 254  * c-basic-offset: 4
 255  * c-file-style: "Stroustrup"
 256  * indent-tabs-mode: nil
 257  * End:
 258  * vim: shiftwidth=4 tabstop=8 expandtab
 259  */
 260