libguile/gc.h

   1 /* classes: h_files */
   2
   3 #ifndef SCM_GC_H
   4 #define SCM_GC_H
   5
   6 /* Copyright (C) 1995,1996,1998,1999,2000,2001, 2002, 2003, 2004, 2006, 2008 Free Software Foundation, Inc.
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 \f
  24
  25 #include "libguile/__scm.h"
  26
  27 #include "libguile/hooks.h"
  28 #include "libguile/threads.h"
  29
  30 \f
  31
  32 /* Cell allocation and garbage collection work rouhgly in the
  33    following manner:
  34
  35    Each thread has a 'freelist', which is a list of available cells.
  36    (It actually has two freelists, one for single cells and one for
  37    double cells.  Everything works analogous for double cells.)
  38
  39    When a thread wants to allocate a cell and the freelist is empty,
  40    it refers to a global list of unswept 'cards'.  A card is a small
  41    block of cells that are contigous in memory, together with the
  42    corresponding mark bits.  A unswept card is one where the mark bits
  43    are set for cells that have been in use during the last global mark
  44    phase, but the unmarked cells of the card have not been scanned and
  45    freed yet.
  46
  47    The thread takes one of the unswept cards and sweeps it, thereby
  48    building a new freelist that it then uses.  Sweeping a card will
  49    call the smob free functions of unmarked cells, for example, and
  50    thus, these free functions can run at any time, in any thread.
  51
  52    When there are no more unswept cards available, the thread performs
  53    a global garbage collection.  For this, all other threads are
  54    stopped.  A global mark is performed and all cards are put into the
  55    global list of unswept cards.  Whennecessary, new cards are
  56    allocated and initialized at this time.  The other threads are then
  57    started again.
  58 */
  59
  60 typedef struct scm_t_cell
  61 {
  62   SCM word_0;
  63   SCM word_1;
  64 } scm_t_cell;
  65
  66 /*
  67   CARDS
  68
  69   A card is a small `page' of memory; it will be the unit for lazy
  70   sweeping, generations, etc. The first cell of a card contains a
  71   pointer to the mark bitvector, so that we can find the bitvector
  72   efficiently: we knock off some lowerorder bits.
  73
  74   The size on a 32 bit machine is 256 cells = 2kb. The card [XXX]
  75 */
  76
  77
  78
  79 /* Cray machines have pointers that are incremented once for each
  80  * word, rather than each byte, the 3 most significant bits encode the
  81  * byte within the word.  The following macros deal with this by
  82  * storing the native Cray pointers like the ones that looks like scm
  83  * expects.  This is done for any pointers that point to a cell,
  84  * pointers to scm_vector elts, functions, &c are not munged.
  85  */
  86 #ifdef _UNICOS
  87 #  define SCM2PTR(x) ((scm_t_cell *) (SCM_UNPACK (x) >> 3))
  88 #  define PTR2SCM(x) (SCM_PACK (((scm_t_bits) (x)) << 3))
  89 #else
  90 #  define SCM2PTR(x) ((scm_t_cell *) (SCM_UNPACK (x)))
  91 #  define PTR2SCM(x) (SCM_PACK ((scm_t_bits) (x)))
  92 #endif /* def _UNICOS */
  93
  94
  95 #define SCM_GC_CARD_N_HEADER_CELLS 1
  96 #define SCM_GC_CARD_N_CELLS        256
  97 #define SCM_GC_SIZEOF_CARD         SCM_GC_CARD_N_CELLS * sizeof (scm_t_cell)
  98
  99 #define SCM_GC_CARD_BVEC(card)  ((scm_t_c_bvec_long *) ((card)->word_0))
 100 #define SCM_GC_SET_CARD_BVEC(card, bvec) \
 101     ((card)->word_0 = (SCM) (bvec))
 102 #define SCM_GC_GET_CARD_FLAGS(card) ((long) ((card)->word_1))
 103 #define SCM_GC_SET_CARD_FLAGS(card, flags) \
 104     ((card)->word_1 = (SCM) (flags))
 105
 106 #define SCM_GC_GET_CARD_FLAG(card, shift) \
 107  (SCM_GC_GET_CARD_FLAGS (card) & (1L << (shift)))
 108 #define SCM_GC_SET_CARD_FLAG(card, shift) \
 109  (SCM_GC_SET_CARD_FLAGS (card, SCM_GC_GET_CARD_FLAGS(card) | (1L << (shift))))
 110 #define SCM_GC_CLEAR_CARD_FLAG(card, shift) \
 111  (SCM_GC_SET_CARD_FLAGS (card, SCM_GC_GET_CARD_FLAGS(card) & ~(1L << (shift))))
 112
 113 /*
 114   Remove card flags. They hamper lazy initialization, and aren't used
 115   anyways.
 116  */
 117
 118 /* card addressing. for efficiency, cards are *always* aligned to
 119    SCM_GC_CARD_SIZE. */
 120
 121 #define SCM_GC_CARD_SIZE_MASK  (SCM_GC_SIZEOF_CARD-1)
 122 #define SCM_GC_CARD_ADDR_MASK  (~SCM_GC_CARD_SIZE_MASK)
 123
 124 #define SCM_GC_CELL_CARD(x)    ((scm_t_cell *) ((long) (x) & SCM_GC_CARD_ADDR_MASK))
 125 #define SCM_GC_CELL_OFFSET(x)  (((long) (x) & SCM_GC_CARD_SIZE_MASK) >> SCM_CELL_SIZE_SHIFT)
 126 #define SCM_GC_CELL_BVEC(x)    SCM_GC_CARD_BVEC (SCM_GC_CELL_CARD (x))
 127 #define SCM_GC_SET_CELL_BVEC(x, bvec)    SCM_GC_SET_CARD_BVEC (SCM_GC_CELL_CARD (x), bvec)
 128 #define SCM_GC_CELL_GET_BIT(x) SCM_C_BVEC_GET (SCM_GC_CELL_BVEC (x), SCM_GC_CELL_OFFSET (x))
 129 #define SCM_GC_CELL_SET_BIT(x) SCM_C_BVEC_SET (SCM_GC_CELL_BVEC (x), SCM_GC_CELL_OFFSET (x))
 130 #define SCM_GC_CELL_CLEAR_BIT(x) SCM_C_BVEC_CLEAR (SCM_GC_CELL_BVEC (x), SCM_GC_CELL_OFFSET (x))
 131
 132 #define SCM_GC_CARD_UP(x)      SCM_GC_CELL_CARD ((char *) (x) + SCM_GC_SIZEOF_CARD - 1)
 133 #define SCM_GC_CARD_DOWN       SCM_GC_CELL_CARD
 134
 135 /* low level bit banging aids */
 136 typedef unsigned long scm_t_c_bvec_long;
 137
 138 #if (SCM_SIZEOF_UNSIGNED_LONG == 8)
 139 #       define SCM_C_BVEC_LONG_BITS    64
 140 #       define SCM_C_BVEC_OFFSET_SHIFT 6
 141 #       define SCM_C_BVEC_POS_MASK     63
 142 #       define SCM_CELL_SIZE_SHIFT     4
 143 #else
 144 #       define SCM_C_BVEC_LONG_BITS    32
 145 #       define SCM_C_BVEC_OFFSET_SHIFT 5
 146 #       define SCM_C_BVEC_POS_MASK     31
 147 #       define SCM_CELL_SIZE_SHIFT     3
 148 #endif
 149
 150 #define SCM_C_BVEC_OFFSET(pos) (pos >> SCM_C_BVEC_OFFSET_SHIFT)
 151
 152 #define SCM_C_BVEC_GET(bvec, pos) (bvec[SCM_C_BVEC_OFFSET (pos)] & (1L << (pos & SCM_C_BVEC_POS_MASK)))
 153 #define SCM_C_BVEC_SET(bvec, pos) (bvec[SCM_C_BVEC_OFFSET (pos)] |= (1L << (pos & SCM_C_BVEC_POS_MASK)))
 154 #define SCM_C_BVEC_CLEAR(bvec, pos) (bvec[SCM_C_BVEC_OFFSET (pos)] &= ~(1L << (pos & SCM_C_BVEC_POS_MASK)))
 155
 156 /* testing and changing GC marks */
 157 #define SCM_GC_MARK_P(x)   SCM_GC_CELL_GET_BIT (x)
 158
 159 void ensure_marking(void);
 160 #define SCM_SET_GC_MARK(x) SCM_GC_CELL_SET_BIT (x)
 161 #define SCM_CLEAR_GC_MARK(x) SCM_GC_CELL_CLEAR_BIT (x)
 162
 163 /* Low level cell data accessing macros.  These macros should only be used
 164  * from within code related to garbage collection issues, since they will
 165  * never check the cells they are applied to - not even if guile is compiled
 166  * in debug mode.  In particular these macros will even work for free cells,
 167  * which should never be encountered by user code.  */
 168
 169 #define SCM_GC_CELL_OBJECT(x, n) (((SCM *)SCM2PTR (x)) [n])
 170 #define SCM_GC_CELL_WORD(x, n)   (SCM_UNPACK (SCM_GC_CELL_OBJECT ((x), (n))))
 171
 172 #define SCM_GC_SET_CELL_OBJECT(x, n, v) ((((SCM *)SCM2PTR (x)) [n]) = (v))
 173 #define SCM_GC_SET_CELL_WORD(x, n, v)  \
 174   (SCM_GC_SET_CELL_OBJECT ((x), (n), SCM_PACK (v)))
 175
 176 #define SCM_GC_CELL_TYPE(x) (SCM_GC_CELL_OBJECT ((x), 0))
 177
 178
 179 /* Except for the garbage collector, no part of guile should ever run over a
 180  * free cell.  Thus, if guile is compiled in debug mode the SCM_CELL_* and
 181  * SCM_SET_CELL_* macros below report an error if they are applied to a free
 182  * cell.  Some other plausibility checks are also performed.  However, if
 183  * guile is not compiled in debug mode, there won't be any time penalty at all
 184  * when using these macros.  */
 185
 186 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 187 #  define SCM_VALIDATE_CELL(cell, expr) (scm_assert_cell_valid (cell), (expr))
 188 #else
 189 #  define SCM_VALIDATE_CELL(cell, expr) (expr)
 190 #endif
 191
 192 #define SCM_CELL_WORD(x, n) \
 193   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_WORD ((x), (n)))
 194 #define SCM_CELL_WORD_0(x) SCM_CELL_WORD ((x), 0)
 195 #define SCM_CELL_WORD_1(x) SCM_CELL_WORD ((x), 1)
 196 #define SCM_CELL_WORD_2(x) SCM_CELL_WORD ((x), 2)
 197 #define SCM_CELL_WORD_3(x) SCM_CELL_WORD ((x), 3)
 198
 199 #define SCM_CELL_OBJECT(x, n) \
 200   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_OBJECT ((x), (n)))
 201 #define SCM_CELL_OBJECT_0(x) SCM_CELL_OBJECT ((x), 0)
 202 #define SCM_CELL_OBJECT_1(x) SCM_CELL_OBJECT ((x), 1)
 203 #define SCM_CELL_OBJECT_2(x) SCM_CELL_OBJECT ((x), 2)
 204 #define SCM_CELL_OBJECT_3(x) SCM_CELL_OBJECT ((x), 3)
 205
 206 #define SCM_SET_CELL_WORD(x, n, v) \
 207   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_WORD ((x), (n), (v)))
 208 #define SCM_SET_CELL_WORD_0(x, v) SCM_SET_CELL_WORD ((x), 0, (v))
 209 #define SCM_SET_CELL_WORD_1(x, v) SCM_SET_CELL_WORD ((x), 1, (v))
 210 #define SCM_SET_CELL_WORD_2(x, v) SCM_SET_CELL_WORD ((x), 2, (v))
 211 #define SCM_SET_CELL_WORD_3(x, v) SCM_SET_CELL_WORD ((x), 3, (v))
 212
 213 #define SCM_SET_CELL_OBJECT(x, n, v) \
 214   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_OBJECT ((x), (n), (v)))
 215 #define SCM_SET_CELL_OBJECT_0(x, v) SCM_SET_CELL_OBJECT ((x), 0, (v))
 216 #define SCM_SET_CELL_OBJECT_1(x, v) SCM_SET_CELL_OBJECT ((x), 1, (v))
 217 #define SCM_SET_CELL_OBJECT_2(x, v) SCM_SET_CELL_OBJECT ((x), 2, (v))
 218 #define SCM_SET_CELL_OBJECT_3(x, v) SCM_SET_CELL_OBJECT ((x), 3, (v))
 219
 220 #define SCM_CELL_OBJECT_LOC(x, n) (SCM_VALIDATE_CELL((x), &SCM_GC_CELL_OBJECT ((x), (n))))
 221 #define SCM_CARLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 0))
 222 #define SCM_CDRLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 1))
 223
 224 #define SCM_CELL_TYPE(x) SCM_CELL_WORD_0 (x)
 225 #define SCM_SET_CELL_TYPE(x, t) SCM_SET_CELL_WORD_0 ((x), (t))
 226
 227 /* Freelists consist of linked cells where the type entry holds the value
 228  * scm_tc_free_cell and the second entry holds a pointer to the next cell of
 229  * the freelist.  Due to this structure, freelist cells are not cons cells
 230  * and thus may not be accessed using SCM_CAR and SCM_CDR.  */
 231
 232 #define SCM_FREE_CELL_CDR(x) \
 233   (SCM_GC_CELL_OBJECT ((x), 1))
 234 #define SCM_SET_FREE_CELL_CDR(x, v) \
 235   (SCM_GC_SET_CELL_OBJECT ((x), 1, (v)))
 236
 237 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 238 /* Set this to != 0 if every cell that is accessed shall be checked:
 239  */
 240 SCM_API int scm_debug_cell_accesses_p;
 241 SCM_API int scm_expensive_debug_cell_accesses_p;
 242 SCM_API int scm_debug_cells_gc_interval ;
 243 void scm_i_expensive_validation_check (SCM cell);
 244 #endif
 245
 246 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_gc_admin_mutex;
 247
 248 #define scm_gc_running_p (SCM_I_CURRENT_THREAD->gc_running_p)
 249 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_sweep_mutex;
 250
 251 #ifdef __ia64__
 252 void *scm_ia64_register_backing_store_base (void);
 253 void *scm_ia64_ar_bsp (const void *);
 254 #endif
 255
 256 \f
 257
 258 #if (SCM_ENABLE_DEPRECATED == 1)
 259 SCM_API size_t scm_default_init_heap_size_1;
 260 SCM_API int scm_default_min_yield_1;
 261 SCM_API size_t scm_default_init_heap_size_2;
 262 SCM_API int scm_default_min_yield_2;
 263 SCM_API size_t scm_default_max_segment_size;
 264 #else
 265 #define  scm_default_init_heap_size_1 deprecated
 266 #define  scm_default_min_yield_1 deprecated
 267 #define  scm_default_init_heap_size_2 deprecated
 268 #define  scm_default_min_yield_2 deprecated
 269 #define  scm_default_max_segment_size deprecated
 270 #endif
 271
 272
 273 SCM_API size_t scm_max_segment_size;
 274
 275 #define SCM_SET_FREELIST_LOC(key,ptr) scm_i_pthread_setspecific ((key), (ptr))
 276 #define SCM_FREELIST_LOC(key) ((SCM *) scm_i_pthread_getspecific (key))
 277 SCM_API scm_i_pthread_key_t scm_i_freelist;
 278 SCM_API scm_i_pthread_key_t scm_i_freelist2;
 279 SCM_API struct scm_t_cell_type_statistics scm_i_master_freelist;
 280 SCM_API struct scm_t_cell_type_statistics scm_i_master_freelist2;
 281
 282 SCM_API unsigned long scm_gc_malloc_collected;
 283 SCM_API unsigned long scm_cells_allocated;
 284 SCM_API int scm_gc_malloc_yield_percentage;
 285 SCM_API unsigned long scm_mallocated;
 286 SCM_API unsigned long scm_mtrigger;
 287
 288
 289
 290 SCM_API SCM scm_after_gc_hook;
 291
 292 SCM_API scm_t_c_hook scm_before_gc_c_hook;
 293 SCM_API scm_t_c_hook scm_before_mark_c_hook;
 294 SCM_API scm_t_c_hook scm_before_sweep_c_hook;
 295 SCM_API scm_t_c_hook scm_after_sweep_c_hook;
 296 SCM_API scm_t_c_hook scm_after_gc_c_hook;
 297
 298 #if defined (GUILE_DEBUG) || defined (GUILE_DEBUG_FREELIST)
 299 #if (SCM_ENABLE_DEPRECATED == 1)
 300 SCM scm_map_free_list (void);
 301 #else
 302 #define scm_map_free_list deprecated
 303 #define scm_free_list_length deprecated
 304 #endif
 305 #endif
 306
 307 #if (SCM_ENABLE_DEPRECATED == 1) && defined (GUILE_DEBUG_FREELIST)
 308 SCM_API SCM scm_gc_set_debug_check_freelist_x (SCM flag);
 309 #endif
 310 \f
 311
 312 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 313 SCM_API void scm_assert_cell_valid (SCM);
 314 #endif
 315
 316 SCM_API SCM scm_set_debug_cell_accesses_x (SCM flag);
 317
 318
 319 SCM_API SCM scm_object_address (SCM obj);
 320 SCM_API SCM scm_gc_stats (void);
 321 SCM_API SCM scm_gc_live_object_stats (void);
 322 SCM_API SCM scm_gc (void);
 323 SCM_API void scm_gc_for_alloc (struct scm_t_cell_type_statistics *freelist);
 324 SCM_API SCM scm_gc_for_newcell (struct scm_t_cell_type_statistics *master, SCM *freelist);
 325 SCM_INTERNAL void scm_i_gc (const char *what);
 326 SCM_API void scm_gc_mark (SCM p);
 327 SCM_API void scm_gc_mark_dependencies (SCM p);
 328 SCM_API void scm_mark_locations (SCM_STACKITEM x[], unsigned long n);
 329 SCM_API int scm_in_heap_p (SCM value);
 330 SCM_API void scm_gc_sweep (void);
 331
 332 SCM_API void *scm_malloc (size_t size);
 333 SCM_API void *scm_calloc (size_t size);
 334 SCM_API void *scm_realloc (void *mem, size_t size);
 335 SCM_API char *scm_strdup (const char *str);
 336 SCM_API char *scm_strndup (const char *str, size_t n);
 337 SCM_API void scm_gc_register_collectable_memory (void *mem, size_t size,
 338                                                  const char *what);
 339 SCM_API void scm_gc_unregister_collectable_memory (void *mem, size_t size,
 340                                                    const char *what);
 341 SCM_API void *scm_gc_calloc (size_t size, const char *what);
 342 SCM_API void *scm_gc_malloc (size_t size, const char *what);
 343 SCM_API void *scm_gc_realloc (void *mem, size_t old_size,
 344                               size_t new_size, const char *what);
 345 SCM_API void scm_gc_free (void *mem, size_t size, const char *what);
 346 SCM_API char *scm_gc_strdup (const char *str, const char *what);
 347 SCM_API char *scm_gc_strndup (const char *str, size_t n, const char *what);
 348
 349 SCM_API void scm_remember_upto_here_1 (SCM obj);
 350 SCM_API void scm_remember_upto_here_2 (SCM obj1, SCM obj2);
 351 SCM_API void scm_remember_upto_here (SCM obj1, ...);
 352
 353 /* In GCC we can force a reference to an SCM by making it an input to an
 354    empty asm.  This avoids the code size and slowdown of an actual function
 355    call.  Unfortunately there doesn't seem to be any way to do the varargs
 356    scm_remember_upto_here like this.
 357
 358    __volatile__ ensures nothing will be moved across the asm, and it won't
 359    be optimized away (or only if proved unreachable).  Constraint "g" can be
 360    used on all processors and allows any memory or general register (or
 361    immediate) operand.  The actual asm syntax doesn't matter, we don't want
 362    to use it, just ensure the operand is still alive.  See "Extended Asm" in
 363    the GCC manual for more.  */
 364
 365 #ifdef __GNUC__
 366 #define scm_remember_upto_here_1(x)             \
 367   do {                                          \
 368     __asm__ __volatile__ ("" : : "g" (x));      \
 369   } while (0)
 370 #define scm_remember_upto_here_2(x, y)          \
 371   do {                                          \
 372     scm_remember_upto_here_1 (x);               \
 373     scm_remember_upto_here_1 (y);               \
 374   } while (0)
 375 #endif
 376
 377 SCM_API SCM scm_return_first (SCM elt, ...);
 378 SCM_API int scm_return_first_int (int x, ...);
 379 SCM_API SCM scm_permanent_object (SCM obj);
 380 SCM_API SCM scm_gc_protect_object (SCM obj);
 381 SCM_API SCM scm_gc_unprotect_object (SCM obj);
 382 SCM_API void scm_gc_register_root (SCM *p);
 383 SCM_API void scm_gc_unregister_root (SCM *p);
 384 SCM_API void scm_gc_register_roots (SCM *b, unsigned long n);
 385 SCM_API void scm_gc_unregister_roots (SCM *b, unsigned long n);
 386 SCM_API void scm_storage_prehistory (void);
 387 SCM_API int scm_init_storage (void);
 388 SCM_API void *scm_get_stack_base (void);
 389 SCM_INTERNAL void scm_init_gc (void);
 390
 391 #if SCM_ENABLE_DEPRECATED == 1
 392
 393 SCM_API SCM scm_deprecated_newcell (void);
 394 SCM_API SCM scm_deprecated_newcell2 (void);
 395
 396 #define SCM_NEWCELL(_into) \
 397   do { _into = scm_deprecated_newcell (); } while (0)
 398 #define SCM_NEWCELL2(_into) \
 399   do { _into = scm_deprecated_newcell2 (); } while (0)
 400
 401 SCM_API void * scm_must_malloc (size_t len, const char *what);
 402 SCM_API void * scm_must_realloc (void *where,
 403                                  size_t olen, size_t len,
 404                                  const char *what);
 405 SCM_API char *scm_must_strdup (const char *str);
 406 SCM_API char *scm_must_strndup (const char *str, size_t n);
 407 SCM_API void scm_done_malloc (long size);
 408 SCM_API void scm_done_free (long size);
 409 SCM_API void scm_must_free (void *obj);
 410
 411 #endif
 412
 413 #endif  /* SCM_GC_H */
 414
 415 /*
 416   Local Variables:
 417   c-file-style: "gnu"
 418   End:
 419 */