libguile/gc-segment-table.c

   1 /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2006 Free Software Foundation, Inc.
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library 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 GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  16  */
  17
  18 #include <assert.h>
  19 #include <stdio.h>
  20 #include <string.h>
  21
  22 #include "libguile/_scm.h"
  23 #include "libguile/pairs.h"
  24 #include "libguile/gc.h"
  25 #include "libguile/private-gc.h"
  26
  27
  28 /*
  29   Heap segment table.
  30
  31   The table is sorted by the address of the data itself. This makes
  32   for easy lookups. This is not portable: according to ANSI C,
  33   pointers can only be compared within the same object (i.e. the same
  34   block of malloced memory.). For machines with weird architectures,
  35   this should be revised.
  36
  37   (Apparently, for this reason 1.6 and earlier had macros for pointer
  38   comparison. )
  39
  40   perhaps it is worthwhile to remove the 2nd level of indirection in
  41   the table, but this certainly makes for cleaner code.
  42 */
  43 scm_t_heap_segment **scm_i_heap_segment_table;
  44 size_t scm_i_heap_segment_table_size;
  45 static scm_t_cell *lowest_cell;
  46 static scm_t_cell *highest_cell;
  47
  48
  49 /*
  50   RETURN: index of inserted segment.
  51  */
  52 int
  53 scm_i_insert_segment (scm_t_heap_segment *seg)
  54 {
  55   size_t size = (scm_i_heap_segment_table_size + 1) * sizeof (scm_t_heap_segment *);
  56   SCM_SYSCALL(scm_i_heap_segment_table
  57               = ((scm_t_heap_segment **)
  58                  realloc ((char *)scm_i_heap_segment_table, size)));
  59
  60   /*
  61     We can't alloc 4 more bytes. This is hopeless.
  62    */
  63   if (!scm_i_heap_segment_table)
  64     {
  65       fprintf (stderr, "scm_i_get_new_heap_segment: Could not grow heap segment table.\n");
  66       abort ();
  67     }
  68
  69   if (!lowest_cell)
  70     {
  71       lowest_cell = seg->bounds[0];
  72       highest_cell = seg->bounds[1];
  73     }
  74   else
  75     {
  76       lowest_cell = SCM_MIN (lowest_cell, seg->bounds[0]);
  77       highest_cell = SCM_MAX (highest_cell, seg->bounds[1]);
  78     }
  79
  80
  81   {
  82     int i = 0;
  83     int j = 0;
  84
  85     while (i < scm_i_heap_segment_table_size
  86            && scm_i_heap_segment_table[i]->bounds[0] <= seg->bounds[0])
  87       i++;
  88
  89     /*
  90       We insert a new entry; if that happens to be before the
  91       "current" segment of a freelist, we must move the freelist index
  92       as well.
  93     */
  94     if (scm_i_master_freelist.heap_segment_idx >= i)
  95       scm_i_master_freelist.heap_segment_idx ++;
  96     if (scm_i_master_freelist2.heap_segment_idx >= i)
  97       scm_i_master_freelist2.heap_segment_idx ++;
  98
  99     for (j = scm_i_heap_segment_table_size; j > i; --j)
 100       scm_i_heap_segment_table[j] = scm_i_heap_segment_table[j - 1];
 101
 102     scm_i_heap_segment_table[i] = seg;
 103     scm_i_heap_segment_table_size ++;
 104
 105     return i;
 106   }
 107 }
 108
 109
 110 /*
 111   Determine whether the given value does actually represent a cell in
 112   some heap segment.  If this is the case, the number of the heap
 113   segment is returned.  Otherwise, -1 is returned.  Binary search is
 114   used to determine the heap segment that contains the cell.
 115
 116   I think this function is too long to be inlined. --hwn
 117 */
 118 int
 119 scm_i_find_heap_segment_containing_object (SCM obj)
 120 {
 121   if (!CELL_P (obj))
 122     return -1;
 123
 124   if ((scm_t_cell *) obj < lowest_cell || (scm_t_cell *) obj >= highest_cell)
 125     return -1;
 126
 127   {
 128     scm_t_cell *ptr = SCM2PTR (obj);
 129     unsigned int i = 0;
 130     unsigned int j = scm_i_heap_segment_table_size - 1;
 131
 132     if (ptr < scm_i_heap_segment_table[i]->bounds[0])
 133       return -1;
 134     else if (scm_i_heap_segment_table[j]->bounds[1] <= ptr)
 135       return -1;
 136     else
 137       {
 138         while (i < j)
 139           {
 140             if (ptr < scm_i_heap_segment_table[i]->bounds[1])
 141               {
 142                 break;
 143               }
 144             else if (scm_i_heap_segment_table[j]->bounds[0] <= ptr)
 145               {
 146                 i = j;
 147                 break;
 148               }
 149             else
 150               {
 151                 unsigned long int k = (i + j) / 2;
 152
 153                 if (k == i)
 154                   return -1;
 155                 else if (ptr <  scm_i_heap_segment_table[k]->bounds[1])
 156                   {
 157                     j = k;
 158                     ++i;
 159                     if (ptr <  scm_i_heap_segment_table[i]->bounds[0])
 160                       return -1;
 161                   }
 162                 else if (scm_i_heap_segment_table[k]->bounds[0] <= ptr)
 163                   {
 164                     i = k;
 165                     --j;
 166                     if (scm_i_heap_segment_table[j]->bounds[1] <= ptr)
 167                       return -1;
 168                   }
 169               }
 170           }
 171
 172         if (!SCM_DOUBLECELL_ALIGNED_P (obj) && scm_i_heap_segment_table[i]->span == 2)
 173           return -1;
 174         else if (SCM_GC_IN_CARD_HEADERP (ptr))
 175           return -1;
 176         else
 177           return i;
 178       }
 179   }
 180 }
 181
 182
 183 int
 184 scm_i_marked_count (void)
 185 {
 186   int i = 0;
 187   int c = 0;
 188   for (; i < scm_i_heap_segment_table_size; i++)
 189     {
 190       c += scm_i_heap_segment_marked_count (scm_i_heap_segment_table[i]);
 191     }
 192   return c;
 193 }
 194
 195
 196 SCM
 197 scm_i_sweep_some_segments (scm_t_cell_type_statistics *freelist,
 198                            scm_t_sweep_statistics *sweep_stats)
 199 {
 200   int i = freelist->heap_segment_idx;
 201   SCM collected = SCM_EOL;
 202
 203   if (i == -1)                  /* huh? --hwn */
 204     i++;
 205
 206   for (;
 207        i < scm_i_heap_segment_table_size; i++)
 208     {
 209       if (scm_i_heap_segment_table[i]->freelist != freelist)
 210         continue;
 211
 212       collected = scm_i_sweep_some_cards (scm_i_heap_segment_table[i],
 213                                           sweep_stats,
 214                                           DEFAULT_SWEEP_AMOUNT);
 215
 216       if (collected != SCM_EOL)       /* Don't increment i */
 217         break;
 218     }
 219
 220   freelist->heap_segment_idx = i;
 221
 222   return collected;
 223 }
 224
 225 void
 226 scm_i_reset_segments (void)
 227 {
 228   int i = 0;
 229   for (; i < scm_i_heap_segment_table_size; i++)
 230     {
 231       scm_t_heap_segment *seg = scm_i_heap_segment_table[i];
 232       seg->next_free_card = seg->bounds[0];
 233     }
 234 }
 235
 236
 237
 238
 239 /*
 240   Return a hashtab with counts of live objects, with tags as keys.
 241  */
 242 SCM
 243 scm_i_all_segments_statistics (SCM tab)
 244 {
 245   int i = 0;
 246   for (; i < scm_i_heap_segment_table_size; i++)
 247     {
 248       scm_t_heap_segment *seg = scm_i_heap_segment_table[i];
 249       scm_i_heap_segment_statistics (seg, tab);
 250     }
 251
 252   return tab;
 253 }
 254
 255
 256 unsigned long*
 257 scm_i_segment_table_info(int* size)
 258 {
 259   *size = scm_i_heap_segment_table_size;
 260   unsigned long *bounds = malloc (sizeof (unsigned long) * *size * 2);
 261   int i;
 262   if (!bounds)
 263     abort();
 264   for (i = *size; i-- > 0; )
 265     {
 266       bounds[2*i] = (unsigned long)scm_i_heap_segment_table[i]->bounds[0];
 267       bounds[2*i+1] = (unsigned long)scm_i_heap_segment_table[i]->bounds[1];
 268     }
 269   return bounds;
 270 }
 271
 272
 273 void
 274 scm_i_sweep_all_segments (char const *reason,
 275                           scm_t_sweep_statistics *sweep_stats)
 276 {
 277   unsigned i= 0;
 278   for (i = 0; i < scm_i_heap_segment_table_size; i++)
 279     {
 280       scm_i_sweep_segment (scm_i_heap_segment_table[i], sweep_stats);
 281     }
 282 }
 283
 284
 285 void
 286 scm_i_clear_mark_space (void)
 287 {
 288   int i = 0;
 289   for (; i < scm_i_heap_segment_table_size; i++)
 290     {
 291       scm_i_clear_segment_mark_space (scm_i_heap_segment_table[i]);
 292     }
 293 }