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 #define SCM_SET_GC_MARK(x) SCM_GC_CELL_SET_BIT (x)
 159 #define SCM_CLEAR_GC_MARK(x) SCM_GC_CELL_CLEAR_BIT (x)
 160
 161 /* Low level cell data accessing macros.  These macros should only be used
 162  * from within code related to garbage collection issues, since they will
 163  * never check the cells they are applied to - not even if guile is compiled
 164  * in debug mode.  In particular these macros will even work for free cells,
 165  * which should never be encountered by user code.  */
 166
 167 #define SCM_GC_CELL_OBJECT(x, n) (((SCM *)SCM2PTR (x)) [n])
 168 #define SCM_GC_CELL_WORD(x, n)   (SCM_UNPACK (SCM_GC_CELL_OBJECT ((x), (n))))
 169
 170 #define SCM_GC_SET_CELL_OBJECT(x, n, v) ((((SCM *)SCM2PTR (x)) [n]) = (v))
 171 #define SCM_GC_SET_CELL_WORD(x, n, v)  \
 172   (SCM_GC_SET_CELL_OBJECT ((x), (n), SCM_PACK (v)))
 173
 174 #define SCM_GC_CELL_TYPE(x) (SCM_GC_CELL_OBJECT ((x), 0))
 175
 176
 177 /* Except for the garbage collector, no part of guile should ever run over a
 178  * free cell.  Thus, if guile is compiled in debug mode the SCM_CELL_* and
 179  * SCM_SET_CELL_* macros below report an error if they are applied to a free
 180  * cell.  Some other plausibility checks are also performed.  However, if
 181  * guile is not compiled in debug mode, there won't be any time penalty at all
 182  * when using these macros.  */
 183
 184 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 185 #  define SCM_VALIDATE_CELL(cell, expr) (scm_assert_cell_valid (cell), (expr))
 186 #else
 187 #  define SCM_VALIDATE_CELL(cell, expr) (expr)
 188 #endif
 189
 190 #define SCM_CELL_WORD(x, n) \
 191   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_WORD ((x), (n)))
 192 #define SCM_CELL_WORD_0(x) SCM_CELL_WORD ((x), 0)
 193 #define SCM_CELL_WORD_1(x) SCM_CELL_WORD ((x), 1)
 194 #define SCM_CELL_WORD_2(x) SCM_CELL_WORD ((x), 2)
 195 #define SCM_CELL_WORD_3(x) SCM_CELL_WORD ((x), 3)
 196
 197 #define SCM_CELL_OBJECT(x, n) \
 198   SCM_VALIDATE_CELL ((x), SCM_GC_CELL_OBJECT ((x), (n)))
 199 #define SCM_CELL_OBJECT_0(x) SCM_CELL_OBJECT ((x), 0)
 200 #define SCM_CELL_OBJECT_1(x) SCM_CELL_OBJECT ((x), 1)
 201 #define SCM_CELL_OBJECT_2(x) SCM_CELL_OBJECT ((x), 2)
 202 #define SCM_CELL_OBJECT_3(x) SCM_CELL_OBJECT ((x), 3)
 203
 204 #define SCM_SET_CELL_WORD(x, n, v) \
 205   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_WORD ((x), (n), (v)))
 206 #define SCM_SET_CELL_WORD_0(x, v) SCM_SET_CELL_WORD ((x), 0, (v))
 207 #define SCM_SET_CELL_WORD_1(x, v) SCM_SET_CELL_WORD ((x), 1, (v))
 208 #define SCM_SET_CELL_WORD_2(x, v) SCM_SET_CELL_WORD ((x), 2, (v))
 209 #define SCM_SET_CELL_WORD_3(x, v) SCM_SET_CELL_WORD ((x), 3, (v))
 210
 211 #define SCM_SET_CELL_OBJECT(x, n, v) \
 212   SCM_VALIDATE_CELL ((x), SCM_GC_SET_CELL_OBJECT ((x), (n), (v)))
 213 #define SCM_SET_CELL_OBJECT_0(x, v) SCM_SET_CELL_OBJECT ((x), 0, (v))
 214 #define SCM_SET_CELL_OBJECT_1(x, v) SCM_SET_CELL_OBJECT ((x), 1, (v))
 215 #define SCM_SET_CELL_OBJECT_2(x, v) SCM_SET_CELL_OBJECT ((x), 2, (v))
 216 #define SCM_SET_CELL_OBJECT_3(x, v) SCM_SET_CELL_OBJECT ((x), 3, (v))
 217
 218 #define SCM_CELL_OBJECT_LOC(x, n) (SCM_VALIDATE_CELL((x), &SCM_GC_CELL_OBJECT ((x), (n))))
 219 #define SCM_CARLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 0))
 220 #define SCM_CDRLOC(x)             (SCM_CELL_OBJECT_LOC ((x), 1))
 221
 222 #define SCM_CELL_TYPE(x) SCM_CELL_WORD_0 (x)
 223 #define SCM_SET_CELL_TYPE(x, t) SCM_SET_CELL_WORD_0 ((x), (t))
 224
 225 /* Freelists consist of linked cells where the type entry holds the value
 226  * scm_tc_free_cell and the second entry holds a pointer to the next cell of
 227  * the freelist.  Due to this structure, freelist cells are not cons cells
 228  * and thus may not be accessed using SCM_CAR and SCM_CDR.  */
 229
 230 #define SCM_FREE_CELL_CDR(x) \
 231   (SCM_GC_CELL_OBJECT ((x), 1))
 232 #define SCM_SET_FREE_CELL_CDR(x, v) \
 233   (SCM_GC_SET_CELL_OBJECT ((x), 1, (v)))
 234
 235 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 236 /* Set this to != 0 if every cell that is accessed shall be checked:
 237  */
 238 SCM_API int scm_debug_cell_accesses_p;
 239 SCM_API int scm_expensive_debug_cell_accesses_p;
 240 SCM_API int scm_debug_cells_gc_interval ;
 241 void scm_i_expensive_validation_check (SCM cell);
 242 #endif
 243
 244 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_gc_admin_mutex;
 245
 246 #define scm_gc_running_p (SCM_I_CURRENT_THREAD->gc_running_p)
 247 SCM_INTERNAL scm_i_pthread_mutex_t scm_i_sweep_mutex;
 248
 249 #ifdef __ia64__
 250 void *scm_ia64_register_backing_store_base (void);
 251 void *scm_ia64_ar_bsp (const void *);
 252 #endif
 253
 254 \f
 255
 256 #if (SCM_ENABLE_DEPRECATED == 1)
 257 SCM_API size_t scm_default_init_heap_size_1;
 258 SCM_API int scm_default_min_yield_1;
 259 SCM_API size_t scm_default_init_heap_size_2;
 260 SCM_API int scm_default_min_yield_2;
 261 SCM_API size_t scm_default_max_segment_size;
 262 #else
 263 #define  scm_default_init_heap_size_1 deprecated
 264 #define  scm_default_min_yield_1 deprecated
 265 #define  scm_default_init_heap_size_2 deprecated
 266 #define  scm_default_min_yield_2 deprecated
 267 #define  scm_default_max_segment_size deprecated
 268 #endif
 269
 270
 271 SCM_API size_t scm_max_segment_size;
 272
 273 #define SCM_SET_FREELIST_LOC(key,ptr) scm_i_pthread_setspecific ((key), (ptr))
 274 #define SCM_FREELIST_LOC(key) ((SCM *) scm_i_pthread_getspecific (key))
 275 SCM_API scm_i_pthread_key_t scm_i_freelist;
 276 SCM_API scm_i_pthread_key_t scm_i_freelist2;
 277 SCM_API struct scm_t_cell_type_statistics scm_i_master_freelist;
 278 SCM_API struct scm_t_cell_type_statistics scm_i_master_freelist2;
 279
 280 SCM_API unsigned long scm_gc_malloc_collected;
 281 SCM_API unsigned long scm_cells_allocated;
 282 SCM_API int scm_gc_malloc_yield_percentage;
 283 SCM_API unsigned long scm_mallocated;
 284 SCM_API unsigned long scm_mtrigger;
 285
 286
 287
 288 SCM_API SCM scm_after_gc_hook;
 289
 290 SCM_API scm_t_c_hook scm_before_gc_c_hook;
 291 SCM_API scm_t_c_hook scm_before_mark_c_hook;
 292 SCM_API scm_t_c_hook scm_before_sweep_c_hook;
 293 SCM_API scm_t_c_hook scm_after_sweep_c_hook;
 294 SCM_API scm_t_c_hook scm_after_gc_c_hook;
 295
 296 #if defined (GUILE_DEBUG) || defined (GUILE_DEBUG_FREELIST)
 297 #if (SCM_ENABLE_DEPRECATED == 1)
 298 SCM scm_map_free_list (void);
 299 #else
 300 #define scm_map_free_list deprecated
 301 #define scm_free_list_length deprecated
 302 #endif
 303 #endif
 304
 305 #if (SCM_ENABLE_DEPRECATED == 1) && defined (GUILE_DEBUG_FREELIST)
 306 SCM_API SCM scm_gc_set_debug_check_freelist_x (SCM flag);
 307 #endif
 308 \f
 309
 310 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 311 SCM_API void scm_assert_cell_valid (SCM);
 312 #endif
 313
 314 SCM_API SCM scm_set_debug_cell_accesses_x (SCM flag);
 315
 316
 317 SCM_API SCM scm_object_address (SCM obj);
 318 SCM_API SCM scm_gc_stats (void);
 319 SCM_API SCM scm_gc_live_object_stats (void);
 320 SCM_API SCM scm_gc (void);
 321 SCM_API void scm_gc_for_alloc (struct scm_t_cell_type_statistics *freelist);
 322 SCM_API SCM scm_gc_for_newcell (struct scm_t_cell_type_statistics *master, SCM *freelist);
 323 SCM_INTERNAL void scm_i_gc (const char *what);
 324 SCM_API void scm_gc_mark (SCM p);
 325 SCM_API void scm_gc_mark_dependencies (SCM p);
 326 SCM_API void scm_mark_locations (SCM_STACKITEM x[], unsigned long n);
 327 SCM_API int scm_in_heap_p (SCM value);
 328 SCM_API void scm_gc_sweep (void);
 329
 330 SCM_API void *scm_malloc (size_t size);
 331 SCM_API void *scm_calloc (size_t size);
 332 SCM_API void *scm_realloc (void *mem, size_t size);
 333 SCM_API char *scm_strdup (const char *str);
 334 SCM_API char *scm_strndup (const char *str, size_t n);
 335 SCM_API void scm_gc_register_collectable_memory (void *mem, size_t size,
 336                                                  const char *what);
 337 SCM_API void scm_gc_unregister_collectable_memory (void *mem, size_t size,
 338                                                    const char *what);
 339 SCM_API void *scm_gc_calloc (size_t size, const char *what);
 340 SCM_API void *scm_gc_malloc (size_t size, const char *what);
 341 SCM_API void *scm_gc_realloc (void *mem, size_t old_size,
 342                               size_t new_size, const char *what);
 343 SCM_API void scm_gc_free (void *mem, size_t size, const char *what);
 344 SCM_API char *scm_gc_strdup (const char *str, const char *what);
 345 SCM_API char *scm_gc_strndup (const char *str, size_t n, const char *what);
 346
 347 SCM_API void scm_remember_upto_here_1 (SCM obj);
 348 SCM_API void scm_remember_upto_here_2 (SCM obj1, SCM obj2);
 349 SCM_API void scm_remember_upto_here (SCM obj1, ...);
 350
 351 /* In GCC we can force a reference to an SCM by making it an input to an
 352    empty asm.  This avoids the code size and slowdown of an actual function
 353    call.  Unfortunately there doesn't seem to be any way to do the varargs
 354    scm_remember_upto_here like this.
 355
 356    __volatile__ ensures nothing will be moved across the asm, and it won't
 357    be optimized away (or only if proved unreachable).  Constraint "g" can be
 358    used on all processors and allows any memory or general register (or
 359    immediate) operand.  The actual asm syntax doesn't matter, we don't want
 360    to use it, just ensure the operand is still alive.  See "Extended Asm" in
 361    the GCC manual for more.  */
 362
 363 #ifdef __GNUC__
 364 #define scm_remember_upto_here_1(x)             \
 365   do {                                          \
 366     __asm__ __volatile__ ("" : : "g" (x));      \
 367   } while (0)
 368 #define scm_remember_upto_here_2(x, y)          \
 369   do {                                          \
 370     scm_remember_upto_here_1 (x);               \
 371     scm_remember_upto_here_1 (y);               \
 372   } while (0)
 373 #endif
 374
 375 SCM_API SCM scm_return_first (SCM elt, ...);
 376 SCM_API int scm_return_first_int (int x, ...);
 377 SCM_API SCM scm_permanent_object (SCM obj);
 378 SCM_API SCM scm_gc_protect_object (SCM obj);
 379 SCM_API SCM scm_gc_unprotect_object (SCM obj);
 380 SCM_API void scm_gc_register_root (SCM *p);
 381 SCM_API void scm_gc_unregister_root (SCM *p);
 382 SCM_API void scm_gc_register_roots (SCM *b, unsigned long n);
 383 SCM_API void scm_gc_unregister_roots (SCM *b, unsigned long n);
 384 SCM_API void scm_storage_prehistory (void);
 385 SCM_API int scm_init_storage (void);
 386 SCM_API void *scm_get_stack_base (void);
 387 SCM_INTERNAL void scm_init_gc (void);
 388
 389 #if SCM_ENABLE_DEPRECATED == 1
 390
 391 SCM_API SCM scm_deprecated_newcell (void);
 392 SCM_API SCM scm_deprecated_newcell2 (void);
 393
 394 #define SCM_NEWCELL(_into) \
 395   do { _into = scm_deprecated_newcell (); } while (0)
 396 #define SCM_NEWCELL2(_into) \
 397   do { _into = scm_deprecated_newcell2 (); } while (0)
 398
 399 SCM_API void * scm_must_malloc (size_t len, const char *what);
 400 SCM_API void * scm_must_realloc (void *where,
 401                                  size_t olen, size_t len,
 402                                  const char *what);
 403 SCM_API char *scm_must_strdup (const char *str);
 404 SCM_API char *scm_must_strndup (const char *str, size_t n);
 405 SCM_API void scm_done_malloc (long size);
 406 SCM_API void scm_done_free (long size);
 407 SCM_API void scm_must_free (void *obj);
 408
 409 #endif
 410
 411 #endif  /* SCM_GC_H */
 412
 413 /*
 414   Local Variables:
 415   c-file-style: "gnu"
 416   End:
 417 */