dict/drdwr.c

   1 /* This file is part of the Zebra server.
   2    Copyright (C) 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 #if HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25 #include <sys/types.h>
  26 #include <fcntl.h>
  27 #if HAVE_UNISTD_H
  28 #include <unistd.h>
  29 #endif
  30 #include <string.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <assert.h>
  34
  35 #include "dict-p.h"
  36
  37 void dict_pr_lru(Dict_BFile bf)
  38 {
  39     struct Dict_file_block *p;
  40     for (p=bf->lru_back; p; p = p->lru_next)
  41     {
  42         printf(" %d", p->no);
  43     }
  44     printf("\n");
  45     fflush(stdout);
  46 }
  47
  48 static struct Dict_file_block *find_block(Dict_BFile bf, int no)
  49 {
  50     struct Dict_file_block *p;
  51
  52     for (p=bf->hash_array[no% bf->hash_size]; p; p=p->h_next)
  53         if (p->no == no)
  54             break;
  55     return p;
  56 }
  57
  58 static void release_block(Dict_BFile bf, struct Dict_file_block *p)
  59 {
  60     assert(p);
  61
  62     /* remove from lru queue */
  63     if (p->lru_prev)
  64         p->lru_prev->lru_next = p->lru_next;
  65     else
  66         bf->lru_back = p->lru_next;
  67     if (p->lru_next)
  68         p->lru_next->lru_prev = p->lru_prev;
  69     else
  70         bf->lru_front = p->lru_prev;
  71
  72     /* remove from hash chain */
  73     *p->h_prev = p->h_next;
  74     if (p->h_next)
  75         p->h_next->h_prev = p->h_prev;
  76
  77     /* move to list of free blocks */
  78     p->h_next = bf->free_list;
  79     bf->free_list = p;
  80 }
  81
  82 void dict_bf_flush_blocks(Dict_BFile bf, int no_to_flush)
  83 {
  84     struct Dict_file_block *p;
  85     int i;
  86     for (i=0; i != no_to_flush && bf->lru_back; i++)
  87     {
  88         p = bf->lru_back;
  89         if (p->dirty)
  90         {
  91             if (!bf->compact_flag)
  92                 bf_write(bf->bf, p->no, 0, 0, p->data);
  93             else
  94             {
  95                 int effective_block = p->no / bf->block_size;
  96                 int effective_offset = p->no -
  97                     effective_block * bf->block_size;
  98                 int remain = bf->block_size - effective_offset;
  99
 100                 if (remain >= p->nbytes)
 101                 {
 102                     bf_write(bf->bf, effective_block, effective_offset,
 103                              p->nbytes, p->data);
 104 #if 0
 105                     yaz_log(YLOG_LOG, "bf_write no=%d offset=%d size=%d",
 106                             effective_block, effective_offset,
 107                             p->nbytes);
 108 #endif
 109
 110                 }
 111                 else
 112                 {
 113 #if 0
 114                     yaz_log(YLOG_LOG, "bf_write1 no=%d offset=%d size=%d",
 115                             effective_block, effective_offset,
 116                             remain);
 117 #endif
 118                     bf_write(bf->bf, effective_block, effective_offset,
 119                              remain, p->data);
 120 #if 0
 121                     yaz_log(YLOG_LOG, "bf_write2 no=%d offset=%d size=%d",
 122                             effective_block+1, 0, p->nbytes - remain);
 123 #endif
 124                     bf_write(bf->bf, effective_block+1, 0,
 125                              p->nbytes - remain, (char*)p->data + remain);
 126                 }
 127             }
 128         }
 129         release_block(bf, p);
 130     }
 131 }
 132
 133 static struct Dict_file_block *alloc_block(Dict_BFile bf, int no)
 134 {
 135     struct Dict_file_block *p, **pp;
 136
 137     if (!bf->free_list)
 138         dict_bf_flush_blocks(bf, 1);
 139     assert(bf->free_list);
 140     p = bf->free_list;
 141     bf->free_list = p->h_next;
 142     p->dirty = 0;
 143     p->no = no;
 144
 145     /* insert at front in lru chain */
 146     p->lru_next = NULL;
 147     p->lru_prev = bf->lru_front;
 148     if (bf->lru_front)
 149         bf->lru_front->lru_next = p;
 150     else
 151         bf->lru_back = p;
 152     bf->lru_front = p;
 153
 154     /* insert in hash chain */
 155     pp = bf->hash_array + (no % bf->hash_size);
 156     p->h_next = *pp;
 157     p->h_prev = pp;
 158     if (*pp)
 159         (*pp)->h_prev = &p->h_next;
 160     *pp = p;
 161
 162     return p;
 163 }
 164
 165 static void move_to_front(Dict_BFile bf, struct Dict_file_block *p)
 166 {
 167     /* Already at front? */
 168     if (!p->lru_next)
 169         return ;
 170
 171     /* Remove */
 172     if (p->lru_prev)
 173         p->lru_prev->lru_next = p->lru_next;
 174     else
 175         bf->lru_back = p->lru_next;
 176     p->lru_next->lru_prev = p->lru_prev;
 177
 178     /* Insert at front */
 179     p->lru_next = NULL;
 180     p->lru_prev = bf->lru_front;
 181     if (bf->lru_front)
 182         bf->lru_front->lru_next = p;
 183     else
 184         bf->lru_back = p;
 185     bf->lru_front = p;
 186 }
 187
 188 int dict_bf_readp(Dict_BFile bf, int no, void **bufp)
 189 {
 190     struct Dict_file_block *p;
 191     int i;
 192     if ((p = find_block(bf, no)))
 193     {
 194         *bufp = p->data;
 195         move_to_front(bf, p);
 196         bf->hits++;
 197         return 1;
 198     }
 199     bf->misses++;
 200     p = alloc_block(bf, no);
 201
 202     if (!bf->compact_flag)
 203         i = bf_read(bf->bf, no, 0, 0, p->data);
 204     else
 205     {
 206         int effective_block = no / bf->block_size;
 207         int effective_offset = no - effective_block * bf->block_size;
 208
 209         i = bf_read(bf->bf, effective_block, effective_offset,
 210                     bf->block_size - effective_offset, p->data);
 211         if (i > 0 && effective_offset > 0)
 212             i = bf_read(bf->bf, effective_block+1, 0, effective_offset,
 213                         (char*) p->data + bf->block_size - effective_offset);
 214         i = 1;
 215     }
 216     if (i > 0)
 217     {
 218         *bufp = p->data;
 219         return i;
 220     }
 221     release_block(bf, p);
 222     *bufp = NULL;
 223     return i;
 224 }
 225
 226 int dict_bf_newp(Dict_BFile dbf, int no, void **bufp, int nbytes)
 227 {
 228     struct Dict_file_block *p;
 229     if (!(p = find_block(dbf, no)))
 230         p = alloc_block(dbf, no);
 231     else
 232         move_to_front(dbf, p);
 233     *bufp = p->data;
 234     memset(p->data, 0, dbf->block_size);
 235     p->dirty = 1;
 236     p->nbytes = nbytes;
 237 #if 0
 238     printf("bf_newp of %d:", no);
 239     dict_pr_lru(dbf);
 240 #endif
 241     return 1;
 242 }
 243
 244 int dict_bf_touch(Dict_BFile dbf, int no)
 245 {
 246     struct Dict_file_block *p;
 247     if ((p = find_block(dbf, no)))
 248     {
 249         p->dirty = 1;
 250         return 0;
 251     }
 252     return -1;
 253 }
 254
 255 /*
 256  * Local variables:
 257  * c-basic-offset: 4
 258  * c-file-style: "Stroustrup"
 259  * indent-tabs-mode: nil
 260  * End:
 261  * vim: shiftwidth=4 tabstop=8 expandtab
 262  */
 263