| 1 | /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 16 | */ |
| 17 | |
| 18 | |
| 19 | /* #define DEBUGINFO */ |
| 20 | |
| 21 | #if HAVE_CONFIG_H |
| 22 | # include <config.h> |
| 23 | #endif |
| 24 | |
| 25 | #include <stdio.h> |
| 26 | #include <errno.h> |
| 27 | #include <string.h> |
| 28 | #include <assert.h> |
| 29 | |
| 30 | #ifdef __ia64__ |
| 31 | #include <ucontext.h> |
| 32 | extern unsigned long * __libc_ia64_register_backing_store_base; |
| 33 | #endif |
| 34 | |
| 35 | #include "libguile/_scm.h" |
| 36 | #include "libguile/eval.h" |
| 37 | #include "libguile/stime.h" |
| 38 | #include "libguile/stackchk.h" |
| 39 | #include "libguile/struct.h" |
| 40 | #include "libguile/smob.h" |
| 41 | #include "libguile/unif.h" |
| 42 | #include "libguile/async.h" |
| 43 | #include "libguile/ports.h" |
| 44 | #include "libguile/root.h" |
| 45 | #include "libguile/strings.h" |
| 46 | #include "libguile/vectors.h" |
| 47 | #include "libguile/weaks.h" |
| 48 | #include "libguile/hashtab.h" |
| 49 | #include "libguile/tags.h" |
| 50 | |
| 51 | #include "libguile/private-gc.h" |
| 52 | #include "libguile/validate.h" |
| 53 | #include "libguile/deprecation.h" |
| 54 | #include "libguile/gc.h" |
| 55 | |
| 56 | #ifdef GUILE_DEBUG_MALLOC |
| 57 | #include "libguile/debug-malloc.h" |
| 58 | #endif |
| 59 | |
| 60 | #ifdef HAVE_MALLOC_H |
| 61 | #include <malloc.h> |
| 62 | #endif |
| 63 | |
| 64 | #ifdef HAVE_UNISTD_H |
| 65 | #include <unistd.h> |
| 66 | #endif |
| 67 | |
| 68 | |
| 69 | |
| 70 | unsigned int scm_gc_running_p = 0; |
| 71 | |
| 72 | /* Lock this mutex before doing lazy sweeping. |
| 73 | */ |
| 74 | scm_t_rec_mutex scm_i_sweep_mutex; |
| 75 | |
| 76 | /* Set this to != 0 if every cell that is accessed shall be checked: |
| 77 | */ |
| 78 | int scm_debug_cell_accesses_p = 0; |
| 79 | int scm_expensive_debug_cell_accesses_p = 0; |
| 80 | |
| 81 | /* Set this to 0 if no additional gc's shall be performed, otherwise set it to |
| 82 | * the number of cell accesses after which a gc shall be called. |
| 83 | */ |
| 84 | int scm_debug_cells_gc_interval = 0; |
| 85 | |
| 86 | /* |
| 87 | Global variable, so you can switch it off at runtime by setting |
| 88 | scm_i_cell_validation_already_running. |
| 89 | */ |
| 90 | int scm_i_cell_validation_already_running ; |
| 91 | |
| 92 | #if (SCM_DEBUG_CELL_ACCESSES == 1) |
| 93 | |
| 94 | |
| 95 | /* |
| 96 | |
| 97 | Assert that the given object is a valid reference to a valid cell. This |
| 98 | test involves to determine whether the object is a cell pointer, whether |
| 99 | this pointer actually points into a heap segment and whether the cell |
| 100 | pointed to is not a free cell. Further, additional garbage collections may |
| 101 | get executed after a user defined number of cell accesses. This helps to |
| 102 | find places in the C code where references are dropped for extremely short |
| 103 | periods. |
| 104 | |
| 105 | */ |
| 106 | void |
| 107 | scm_i_expensive_validation_check (SCM cell) |
| 108 | { |
| 109 | if (!scm_in_heap_p (cell)) |
| 110 | { |
| 111 | fprintf (stderr, "scm_assert_cell_valid: this object does not live in the heap: %lux\n", |
| 112 | (unsigned long) SCM_UNPACK (cell)); |
| 113 | abort (); |
| 114 | } |
| 115 | |
| 116 | /* If desired, perform additional garbage collections after a user |
| 117 | * defined number of cell accesses. |
| 118 | */ |
| 119 | if (scm_debug_cells_gc_interval) |
| 120 | { |
| 121 | static unsigned int counter = 0; |
| 122 | |
| 123 | if (counter != 0) |
| 124 | { |
| 125 | --counter; |
| 126 | } |
| 127 | else |
| 128 | { |
| 129 | counter = scm_debug_cells_gc_interval; |
| 130 | scm_igc ("scm_assert_cell_valid"); |
| 131 | } |
| 132 | } |
| 133 | } |
| 134 | |
| 135 | void |
| 136 | scm_assert_cell_valid (SCM cell) |
| 137 | { |
| 138 | if (!scm_i_cell_validation_already_running && scm_debug_cell_accesses_p) |
| 139 | { |
| 140 | scm_i_cell_validation_already_running = 1; /* set to avoid recursion */ |
| 141 | |
| 142 | /* |
| 143 | During GC, no user-code should be run, and the guile core |
| 144 | should use non-protected accessors. |
| 145 | */ |
| 146 | if (scm_gc_running_p) |
| 147 | return; |
| 148 | |
| 149 | /* |
| 150 | Only scm_in_heap_p and rescanning the heap is wildly |
| 151 | expensive. |
| 152 | */ |
| 153 | if (scm_expensive_debug_cell_accesses_p) |
| 154 | scm_i_expensive_validation_check (cell); |
| 155 | |
| 156 | if (!SCM_GC_MARK_P (cell)) |
| 157 | { |
| 158 | fprintf (stderr, |
| 159 | "scm_assert_cell_valid: this object is unmarked. \n" |
| 160 | "It has been garbage-collected in the last GC run: " |
| 161 | "%lux\n", |
| 162 | (unsigned long) SCM_UNPACK (cell)); |
| 163 | abort (); |
| 164 | } |
| 165 | |
| 166 | scm_i_cell_validation_already_running = 0; /* re-enable */ |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | |
| 171 | |
| 172 | SCM_DEFINE (scm_set_debug_cell_accesses_x, "set-debug-cell-accesses!", 1, 0, 0, |
| 173 | (SCM flag), |
| 174 | "If @var{flag} is @code{#f}, cell access checking is disabled.\n" |
| 175 | "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n" |
| 176 | "but no additional calls to garbage collection are issued.\n" |
| 177 | "If @var{flag} is a number, strict cell access checking is enabled,\n" |
| 178 | "with an additional garbage collection after the given\n" |
| 179 | "number of cell accesses.\n" |
| 180 | "This procedure only exists when the compile-time flag\n" |
| 181 | "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.") |
| 182 | #define FUNC_NAME s_scm_set_debug_cell_accesses_x |
| 183 | { |
| 184 | if (SCM_FALSEP (flag)) |
| 185 | { |
| 186 | scm_debug_cell_accesses_p = 0; |
| 187 | } |
| 188 | else if (SCM_EQ_P (flag, SCM_BOOL_T)) |
| 189 | { |
| 190 | scm_debug_cells_gc_interval = 0; |
| 191 | scm_debug_cell_accesses_p = 1; |
| 192 | scm_expensive_debug_cell_accesses_p = 0; |
| 193 | } |
| 194 | else if (SCM_INUMP (flag)) |
| 195 | { |
| 196 | long int f = SCM_INUM (flag); |
| 197 | if (f <= 0) |
| 198 | SCM_OUT_OF_RANGE (1, flag); |
| 199 | scm_debug_cells_gc_interval = f; |
| 200 | scm_debug_cell_accesses_p = 1; |
| 201 | scm_expensive_debug_cell_accesses_p = 1; |
| 202 | } |
| 203 | else |
| 204 | { |
| 205 | SCM_WRONG_TYPE_ARG (1, flag); |
| 206 | } |
| 207 | return SCM_UNSPECIFIED; |
| 208 | } |
| 209 | #undef FUNC_NAME |
| 210 | #else |
| 211 | |
| 212 | /* |
| 213 | Provide a stub, so people can use their Scheme code on non-debug |
| 214 | versions of GUILE as well. |
| 215 | */ |
| 216 | SCM_DEFINE (scm_set_debug_cell_accesses_x, "set-debug-cell-accesses!", 1, 0, 0, |
| 217 | (SCM flag), |
| 218 | "This function is used to turn on checking for a debug version of GUILE. This version does not support this functionality\n") |
| 219 | #define FUNC_NAME s_scm_set_debug_cell_accesses_x |
| 220 | { |
| 221 | |
| 222 | /* |
| 223 | do nothing |
| 224 | */ |
| 225 | fprintf (stderr, "\nWARNING: GUILE was not compiled with SCM_DEBUG_CELL_ACCESSES"); |
| 226 | scm_remember_upto_here (flag); |
| 227 | return SCM_UNSPECIFIED; |
| 228 | } |
| 229 | #undef FUNC_NAME |
| 230 | |
| 231 | #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */ |
| 232 | |
| 233 | \f |
| 234 | |
| 235 | scm_t_key scm_i_freelist; |
| 236 | scm_t_key scm_i_freelist2; |
| 237 | |
| 238 | |
| 239 | /* scm_mtrigger |
| 240 | * is the number of bytes of malloc allocation needed to trigger gc. |
| 241 | */ |
| 242 | unsigned long scm_mtrigger; |
| 243 | |
| 244 | /* scm_gc_heap_lock |
| 245 | * If set, don't expand the heap. Set only during gc, during which no allocation |
| 246 | * is supposed to take place anyway. |
| 247 | */ |
| 248 | int scm_gc_heap_lock = 0; |
| 249 | |
| 250 | /* GC Blocking |
| 251 | * Don't pause for collection if this is set -- just |
| 252 | * expand the heap. |
| 253 | */ |
| 254 | int scm_block_gc = 1; |
| 255 | |
| 256 | /* During collection, this accumulates objects holding |
| 257 | * weak references. |
| 258 | */ |
| 259 | SCM scm_weak_vectors; |
| 260 | |
| 261 | /* GC Statistics Keeping |
| 262 | */ |
| 263 | unsigned long scm_cells_allocated = 0; |
| 264 | unsigned long scm_mallocated = 0; |
| 265 | unsigned long scm_gc_cells_collected; |
| 266 | unsigned long scm_gc_cells_collected_1 = 0; /* previous GC yield */ |
| 267 | unsigned long scm_gc_malloc_collected; |
| 268 | unsigned long scm_gc_ports_collected; |
| 269 | unsigned long scm_gc_time_taken = 0; |
| 270 | static unsigned long t_before_gc; |
| 271 | unsigned long scm_gc_mark_time_taken = 0; |
| 272 | unsigned long scm_gc_times = 0; |
| 273 | unsigned long scm_gc_cells_swept = 0; |
| 274 | double scm_gc_cells_marked_acc = 0.; |
| 275 | double scm_gc_cells_swept_acc = 0.; |
| 276 | int scm_gc_cell_yield_percentage =0; |
| 277 | int scm_gc_malloc_yield_percentage = 0; |
| 278 | |
| 279 | |
| 280 | SCM_SYMBOL (sym_cells_allocated, "cells-allocated"); |
| 281 | SCM_SYMBOL (sym_heap_size, "cell-heap-size"); |
| 282 | SCM_SYMBOL (sym_mallocated, "bytes-malloced"); |
| 283 | SCM_SYMBOL (sym_mtrigger, "gc-malloc-threshold"); |
| 284 | SCM_SYMBOL (sym_heap_segments, "cell-heap-segments"); |
| 285 | SCM_SYMBOL (sym_gc_time_taken, "gc-time-taken"); |
| 286 | SCM_SYMBOL (sym_gc_mark_time_taken, "gc-mark-time-taken"); |
| 287 | SCM_SYMBOL (sym_times, "gc-times"); |
| 288 | SCM_SYMBOL (sym_cells_marked, "cells-marked"); |
| 289 | SCM_SYMBOL (sym_cells_swept, "cells-swept"); |
| 290 | SCM_SYMBOL (sym_malloc_yield, "malloc-yield"); |
| 291 | SCM_SYMBOL (sym_cell_yield, "cell-yield"); |
| 292 | |
| 293 | |
| 294 | |
| 295 | |
| 296 | /* Number of calls to SCM_NEWCELL since startup. */ |
| 297 | unsigned scm_newcell_count; |
| 298 | unsigned scm_newcell2_count; |
| 299 | |
| 300 | |
| 301 | /* {Scheme Interface to GC} |
| 302 | */ |
| 303 | extern int scm_gc_malloc_yield_percentage; |
| 304 | SCM_DEFINE (scm_gc_stats, "gc-stats", 0, 0, 0, |
| 305 | (), |
| 306 | "Return an association list of statistics about Guile's current\n" |
| 307 | "use of storage.\n") |
| 308 | #define FUNC_NAME s_scm_gc_stats |
| 309 | { |
| 310 | long i = 0; |
| 311 | SCM heap_segs = SCM_EOL ; |
| 312 | unsigned long int local_scm_mtrigger; |
| 313 | unsigned long int local_scm_mallocated; |
| 314 | unsigned long int local_scm_heap_size; |
| 315 | int local_scm_gc_cell_yield_percentage; |
| 316 | int local_scm_gc_malloc_yield_percentage; |
| 317 | unsigned long int local_scm_cells_allocated; |
| 318 | unsigned long int local_scm_gc_time_taken; |
| 319 | unsigned long int local_scm_gc_times; |
| 320 | unsigned long int local_scm_gc_mark_time_taken; |
| 321 | double local_scm_gc_cells_swept; |
| 322 | double local_scm_gc_cells_marked; |
| 323 | SCM answer; |
| 324 | unsigned long *bounds = 0; |
| 325 | int table_size = scm_i_heap_segment_table_size; |
| 326 | SCM_DEFER_INTS; |
| 327 | |
| 328 | /* |
| 329 | temporarily store the numbers, so as not to cause GC. |
| 330 | */ |
| 331 | |
| 332 | bounds = malloc (sizeof (int) * table_size * 2); |
| 333 | if (!bounds) |
| 334 | abort(); |
| 335 | for (i = table_size; i--; ) |
| 336 | { |
| 337 | bounds[2*i] = (unsigned long)scm_i_heap_segment_table[i]->bounds[0]; |
| 338 | bounds[2*i+1] = (unsigned long)scm_i_heap_segment_table[i]->bounds[1]; |
| 339 | } |
| 340 | |
| 341 | |
| 342 | /* Below, we cons to produce the resulting list. We want a snapshot of |
| 343 | * the heap situation before consing. |
| 344 | */ |
| 345 | local_scm_mtrigger = scm_mtrigger; |
| 346 | local_scm_mallocated = scm_mallocated; |
| 347 | local_scm_heap_size = SCM_HEAP_SIZE; |
| 348 | |
| 349 | local_scm_cells_allocated = scm_cells_allocated; |
| 350 | |
| 351 | local_scm_gc_time_taken = scm_gc_time_taken; |
| 352 | local_scm_gc_mark_time_taken = scm_gc_mark_time_taken; |
| 353 | local_scm_gc_times = scm_gc_times; |
| 354 | local_scm_gc_malloc_yield_percentage = scm_gc_malloc_yield_percentage; |
| 355 | local_scm_gc_cell_yield_percentage= scm_gc_cell_yield_percentage; |
| 356 | |
| 357 | local_scm_gc_cells_swept = |
| 358 | (double) scm_gc_cells_swept_acc |
| 359 | + (double) scm_gc_cells_swept; |
| 360 | local_scm_gc_cells_marked = scm_gc_cells_marked_acc |
| 361 | +(double) scm_gc_cells_swept |
| 362 | -(double) scm_gc_cells_collected; |
| 363 | |
| 364 | for (i = table_size; i--;) |
| 365 | { |
| 366 | heap_segs = scm_cons (scm_cons (scm_ulong2num (bounds[2*i]), |
| 367 | scm_ulong2num (bounds[2*i+1])), |
| 368 | heap_segs); |
| 369 | } |
| 370 | |
| 371 | answer = scm_list_n (scm_cons (sym_gc_time_taken, scm_ulong2num (local_scm_gc_time_taken)), |
| 372 | scm_cons (sym_cells_allocated, scm_ulong2num (local_scm_cells_allocated)), |
| 373 | scm_cons (sym_heap_size, scm_ulong2num (local_scm_heap_size)), |
| 374 | scm_cons (sym_mallocated, scm_ulong2num (local_scm_mallocated)), |
| 375 | scm_cons (sym_mtrigger, scm_ulong2num (local_scm_mtrigger)), |
| 376 | scm_cons (sym_times, scm_ulong2num (local_scm_gc_times)), |
| 377 | scm_cons (sym_gc_mark_time_taken, scm_ulong2num (local_scm_gc_mark_time_taken)), |
| 378 | scm_cons (sym_cells_marked, scm_i_dbl2big (local_scm_gc_cells_marked)), |
| 379 | scm_cons (sym_cells_swept, scm_i_dbl2big (local_scm_gc_cells_swept)), |
| 380 | scm_cons (sym_malloc_yield, scm_long2num (local_scm_gc_malloc_yield_percentage)), |
| 381 | scm_cons (sym_cell_yield, scm_long2num (local_scm_gc_cell_yield_percentage)), |
| 382 | scm_cons (sym_heap_segments, heap_segs), |
| 383 | SCM_UNDEFINED); |
| 384 | SCM_ALLOW_INTS; |
| 385 | |
| 386 | free (bounds); |
| 387 | return answer; |
| 388 | } |
| 389 | #undef FUNC_NAME |
| 390 | |
| 391 | static void |
| 392 | gc_start_stats (const char *what SCM_UNUSED) |
| 393 | { |
| 394 | t_before_gc = scm_c_get_internal_run_time (); |
| 395 | |
| 396 | scm_gc_cells_marked_acc += (double) scm_gc_cells_swept |
| 397 | - (double) scm_gc_cells_collected; |
| 398 | scm_gc_cells_swept_acc += (double) scm_gc_cells_swept; |
| 399 | |
| 400 | scm_gc_cell_yield_percentage = ( scm_gc_cells_collected * 100 ) / SCM_HEAP_SIZE; |
| 401 | |
| 402 | scm_gc_cells_swept = 0; |
| 403 | scm_gc_cells_collected_1 = scm_gc_cells_collected; |
| 404 | |
| 405 | /* |
| 406 | CELLS SWEPT is another word for the number of cells that were |
| 407 | examined during GC. YIELD is the number that we cleaned |
| 408 | out. MARKED is the number that weren't cleaned. |
| 409 | */ |
| 410 | scm_gc_cells_collected = 0; |
| 411 | scm_gc_malloc_collected = 0; |
| 412 | scm_gc_ports_collected = 0; |
| 413 | } |
| 414 | |
| 415 | static void |
| 416 | gc_end_stats () |
| 417 | { |
| 418 | unsigned long t = scm_c_get_internal_run_time (); |
| 419 | scm_gc_time_taken += (t - t_before_gc); |
| 420 | |
| 421 | ++scm_gc_times; |
| 422 | } |
| 423 | |
| 424 | |
| 425 | SCM_DEFINE (scm_object_address, "object-address", 1, 0, 0, |
| 426 | (SCM obj), |
| 427 | "Return an integer that for the lifetime of @var{obj} is uniquely\n" |
| 428 | "returned by this function for @var{obj}") |
| 429 | #define FUNC_NAME s_scm_object_address |
| 430 | { |
| 431 | return scm_ulong2num ((unsigned long) SCM_UNPACK (obj)); |
| 432 | } |
| 433 | #undef FUNC_NAME |
| 434 | |
| 435 | |
| 436 | SCM_DEFINE (scm_gc, "gc", 0, 0, 0, |
| 437 | (), |
| 438 | "Scans all of SCM objects and reclaims for further use those that are\n" |
| 439 | "no longer accessible.") |
| 440 | #define FUNC_NAME s_scm_gc |
| 441 | { |
| 442 | scm_igc ("call"); |
| 443 | return SCM_UNSPECIFIED; |
| 444 | } |
| 445 | #undef FUNC_NAME |
| 446 | |
| 447 | |
| 448 | \f |
| 449 | |
| 450 | /* When we get POSIX threads support, the master will be global and |
| 451 | * common while the freelist will be individual for each thread. |
| 452 | */ |
| 453 | |
| 454 | SCM |
| 455 | scm_gc_for_newcell (scm_t_cell_type_statistics *freelist, SCM *free_cells) |
| 456 | { |
| 457 | SCM cell; |
| 458 | |
| 459 | scm_rec_mutex_lock (&scm_i_sweep_mutex); |
| 460 | |
| 461 | *free_cells = scm_i_sweep_some_segments (freelist); |
| 462 | if (*free_cells == SCM_EOL && scm_i_gc_grow_heap_p (freelist)) |
| 463 | { |
| 464 | freelist->heap_segment_idx = scm_i_get_new_heap_segment (freelist, abort_on_error); |
| 465 | *free_cells = scm_i_sweep_some_segments (freelist); |
| 466 | } |
| 467 | |
| 468 | if (*free_cells == SCM_EOL && !scm_block_gc) |
| 469 | { |
| 470 | /* |
| 471 | with the advent of lazy sweep, GC yield is only know just |
| 472 | before doing the GC. |
| 473 | */ |
| 474 | scm_i_adjust_min_yield (freelist); |
| 475 | |
| 476 | /* |
| 477 | out of fresh cells. Try to get some new ones. |
| 478 | */ |
| 479 | |
| 480 | scm_igc ("cells"); |
| 481 | |
| 482 | *free_cells = scm_i_sweep_some_segments (freelist); |
| 483 | } |
| 484 | |
| 485 | if (*free_cells == SCM_EOL) |
| 486 | { |
| 487 | /* |
| 488 | failed getting new cells. Get new juice or die. |
| 489 | */ |
| 490 | freelist->heap_segment_idx = scm_i_get_new_heap_segment (freelist, abort_on_error); |
| 491 | *free_cells = scm_i_sweep_some_segments (freelist); |
| 492 | } |
| 493 | |
| 494 | if (*free_cells == SCM_EOL) |
| 495 | abort (); |
| 496 | |
| 497 | cell = *free_cells; |
| 498 | |
| 499 | *free_cells = SCM_FREE_CELL_CDR (cell); |
| 500 | |
| 501 | scm_rec_mutex_unlock (&scm_i_sweep_mutex); |
| 502 | |
| 503 | return cell; |
| 504 | } |
| 505 | |
| 506 | |
| 507 | scm_t_c_hook scm_before_gc_c_hook; |
| 508 | scm_t_c_hook scm_before_mark_c_hook; |
| 509 | scm_t_c_hook scm_before_sweep_c_hook; |
| 510 | scm_t_c_hook scm_after_sweep_c_hook; |
| 511 | scm_t_c_hook scm_after_gc_c_hook; |
| 512 | |
| 513 | void |
| 514 | scm_igc (const char *what) |
| 515 | { |
| 516 | scm_rec_mutex_lock (&scm_i_sweep_mutex); |
| 517 | ++scm_gc_running_p; |
| 518 | scm_c_hook_run (&scm_before_gc_c_hook, 0); |
| 519 | |
| 520 | #ifdef DEBUGINFO |
| 521 | fprintf (stderr,"gc reason %s\n", what); |
| 522 | |
| 523 | fprintf (stderr, |
| 524 | SCM_NULLP (*SCM_FREELIST_LOC (scm_i_freelist)) |
| 525 | ? "*" |
| 526 | : (SCM_NULLP (*SCM_FREELIST_LOC (scm_i_freelist2)) ? "o" : "m")); |
| 527 | #endif |
| 528 | |
| 529 | /* During the critical section, only the current thread may run. */ |
| 530 | scm_i_thread_put_to_sleep (); |
| 531 | |
| 532 | if (!scm_root || !scm_stack_base || scm_block_gc) |
| 533 | { |
| 534 | --scm_gc_running_p; |
| 535 | return; |
| 536 | } |
| 537 | |
| 538 | gc_start_stats (what); |
| 539 | |
| 540 | if (scm_gc_heap_lock) |
| 541 | /* We've invoked the collector while a GC is already in progress. |
| 542 | That should never happen. */ |
| 543 | abort (); |
| 544 | |
| 545 | ++scm_gc_heap_lock; |
| 546 | |
| 547 | /* |
| 548 | Let's finish the sweep. The conservative GC might point into the |
| 549 | garbage, and marking that would create a mess. |
| 550 | */ |
| 551 | scm_i_sweep_all_segments("GC"); |
| 552 | if (scm_mallocated < scm_i_deprecated_memory_return) |
| 553 | { |
| 554 | /* The byte count of allocated objects has underflowed. This is |
| 555 | probably because you forgot to report the sizes of objects you |
| 556 | have allocated, by calling scm_done_malloc or some such. When |
| 557 | the GC freed them, it subtracted their size from |
| 558 | scm_mallocated, which underflowed. */ |
| 559 | fprintf (stderr, |
| 560 | "scm_gc_sweep: Byte count of allocated objects has underflowed.\n" |
| 561 | "This is probably because the GC hasn't been correctly informed\n" |
| 562 | "about object sizes\n"); |
| 563 | abort (); |
| 564 | } |
| 565 | scm_mallocated -= scm_i_deprecated_memory_return; |
| 566 | |
| 567 | |
| 568 | |
| 569 | scm_c_hook_run (&scm_before_mark_c_hook, 0); |
| 570 | |
| 571 | scm_mark_all (); |
| 572 | |
| 573 | scm_gc_mark_time_taken += (scm_c_get_internal_run_time () - t_before_gc); |
| 574 | |
| 575 | scm_c_hook_run (&scm_before_sweep_c_hook, 0); |
| 576 | |
| 577 | /* |
| 578 | Moved this lock upwards so that we can alloc new heap at the end of a sweep. |
| 579 | |
| 580 | DOCME: why should the heap be locked anyway? |
| 581 | */ |
| 582 | --scm_gc_heap_lock; |
| 583 | |
| 584 | scm_gc_sweep (); |
| 585 | |
| 586 | |
| 587 | /* |
| 588 | TODO: this hook should probably be moved to just before the mark, |
| 589 | since that's where the sweep is finished in lazy sweeping. |
| 590 | |
| 591 | MDJ 030219 <djurfeldt@nada.kth.se>: No, probably not. The |
| 592 | original meaning implied at least two things: that it would be |
| 593 | called when |
| 594 | |
| 595 | 1. the freelist is re-initialized (no evaluation possible, though) |
| 596 | |
| 597 | and |
| 598 | |
| 599 | 2. the heap is "fresh" |
| 600 | (it is well-defined what data is used and what is not) |
| 601 | |
| 602 | Neither of these conditions would hold just before the mark phase. |
| 603 | |
| 604 | Of course, the lazy sweeping has muddled the distinction between |
| 605 | scm_before_sweep_c_hook and scm_after_sweep_c_hook, but even if |
| 606 | there were no difference, it would still be useful to have two |
| 607 | distinct classes of hook functions since this can prevent some |
| 608 | bad interference when several modules adds gc hooks. |
| 609 | */ |
| 610 | scm_c_hook_run (&scm_after_sweep_c_hook, 0); |
| 611 | gc_end_stats (); |
| 612 | |
| 613 | scm_i_thread_wake_up (); |
| 614 | |
| 615 | /* |
| 616 | See above. |
| 617 | */ |
| 618 | scm_c_hook_run (&scm_after_gc_c_hook, 0); |
| 619 | --scm_gc_running_p; |
| 620 | scm_rec_mutex_unlock (&scm_i_sweep_mutex); |
| 621 | |
| 622 | /* |
| 623 | For debugging purposes, you could do |
| 624 | scm_i_sweep_all_segments("debug"), but then the remains of the |
| 625 | cell aren't left to analyse. |
| 626 | */ |
| 627 | } |
| 628 | |
| 629 | \f |
| 630 | /* {GC Protection Helper Functions} |
| 631 | */ |
| 632 | |
| 633 | |
| 634 | /* |
| 635 | * If within a function you need to protect one or more scheme objects from |
| 636 | * garbage collection, pass them as parameters to one of the |
| 637 | * scm_remember_upto_here* functions below. These functions don't do |
| 638 | * anything, but since the compiler does not know that they are actually |
| 639 | * no-ops, it will generate code that calls these functions with the given |
| 640 | * parameters. Therefore, you can be sure that the compiler will keep those |
| 641 | * scheme values alive (on the stack or in a register) up to the point where |
| 642 | * scm_remember_upto_here* is called. In other words, place the call to |
| 643 | * scm_remember_upto_here* _behind_ the last code in your function, that |
| 644 | * depends on the scheme object to exist. |
| 645 | * |
| 646 | * Example: We want to make sure that the string object str does not get |
| 647 | * garbage collected during the execution of 'some_function' in the code |
| 648 | * below, because otherwise the characters belonging to str would be freed and |
| 649 | * 'some_function' might access freed memory. To make sure that the compiler |
| 650 | * keeps str alive on the stack or in a register such that it is visible to |
| 651 | * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the |
| 652 | * call to 'some_function'. Note that this would not be necessary if str was |
| 653 | * used anyway after the call to 'some_function'. |
| 654 | * char *chars = SCM_STRING_CHARS (str); |
| 655 | * some_function (chars); |
| 656 | * scm_remember_upto_here_1 (str); // str will be alive up to this point. |
| 657 | */ |
| 658 | |
| 659 | void |
| 660 | scm_remember_upto_here_1 (SCM obj SCM_UNUSED) |
| 661 | { |
| 662 | /* Empty. Protects a single object from garbage collection. */ |
| 663 | } |
| 664 | |
| 665 | void |
| 666 | scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED, SCM obj2 SCM_UNUSED) |
| 667 | { |
| 668 | /* Empty. Protects two objects from garbage collection. */ |
| 669 | } |
| 670 | |
| 671 | void |
| 672 | scm_remember_upto_here (SCM obj SCM_UNUSED, ...) |
| 673 | { |
| 674 | /* Empty. Protects any number of objects from garbage collection. */ |
| 675 | } |
| 676 | |
| 677 | /* |
| 678 | These crazy functions prevent garbage collection |
| 679 | of arguments after the first argument by |
| 680 | ensuring they remain live throughout the |
| 681 | function because they are used in the last |
| 682 | line of the code block. |
| 683 | It'd be better to have a nice compiler hint to |
| 684 | aid the conservative stack-scanning GC. --03/09/00 gjb */ |
| 685 | SCM |
| 686 | scm_return_first (SCM elt, ...) |
| 687 | { |
| 688 | return elt; |
| 689 | } |
| 690 | |
| 691 | int |
| 692 | scm_return_first_int (int i, ...) |
| 693 | { |
| 694 | return i; |
| 695 | } |
| 696 | |
| 697 | |
| 698 | SCM |
| 699 | scm_permanent_object (SCM obj) |
| 700 | { |
| 701 | SCM_REDEFER_INTS; |
| 702 | scm_permobjs = scm_cons (obj, scm_permobjs); |
| 703 | SCM_REALLOW_INTS; |
| 704 | return obj; |
| 705 | } |
| 706 | |
| 707 | |
| 708 | /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all |
| 709 | other references are dropped, until the object is unprotected by calling |
| 710 | scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest, |
| 711 | i. e. it is possible to protect the same object several times, but it is |
| 712 | necessary to unprotect the object the same number of times to actually get |
| 713 | the object unprotected. It is an error to unprotect an object more often |
| 714 | than it has been protected before. The function scm_protect_object returns |
| 715 | OBJ. |
| 716 | */ |
| 717 | |
| 718 | /* Implementation note: For every object X, there is a counter which |
| 719 | scm_gc_protect_object(X) increments and scm_gc_unprotect_object(X) decrements. |
| 720 | */ |
| 721 | |
| 722 | SCM |
| 723 | scm_gc_protect_object (SCM obj) |
| 724 | { |
| 725 | SCM handle; |
| 726 | |
| 727 | /* This critical section barrier will be replaced by a mutex. */ |
| 728 | SCM_REDEFER_INTS; |
| 729 | |
| 730 | handle = scm_hashq_create_handle_x (scm_protects, obj, SCM_MAKINUM (0)); |
| 731 | SCM_SETCDR (handle, scm_sum (SCM_CDR (handle), SCM_MAKINUM (1))); |
| 732 | |
| 733 | SCM_REALLOW_INTS; |
| 734 | |
| 735 | return obj; |
| 736 | } |
| 737 | |
| 738 | |
| 739 | /* Remove any protection for OBJ established by a prior call to |
| 740 | scm_protect_object. This function returns OBJ. |
| 741 | |
| 742 | See scm_protect_object for more information. */ |
| 743 | SCM |
| 744 | scm_gc_unprotect_object (SCM obj) |
| 745 | { |
| 746 | SCM handle; |
| 747 | |
| 748 | /* This critical section barrier will be replaced by a mutex. */ |
| 749 | SCM_REDEFER_INTS; |
| 750 | |
| 751 | handle = scm_hashq_get_handle (scm_protects, obj); |
| 752 | |
| 753 | if (SCM_FALSEP (handle)) |
| 754 | { |
| 755 | fprintf (stderr, "scm_unprotect_object called on unprotected object\n"); |
| 756 | abort (); |
| 757 | } |
| 758 | else |
| 759 | { |
| 760 | SCM count = scm_difference (SCM_CDR (handle), SCM_MAKINUM (1)); |
| 761 | if (SCM_EQ_P (count, SCM_MAKINUM (0))) |
| 762 | scm_hashq_remove_x (scm_protects, obj); |
| 763 | else |
| 764 | SCM_SETCDR (handle, count); |
| 765 | } |
| 766 | |
| 767 | SCM_REALLOW_INTS; |
| 768 | |
| 769 | return obj; |
| 770 | } |
| 771 | |
| 772 | void |
| 773 | scm_gc_register_root (SCM *p) |
| 774 | { |
| 775 | SCM handle; |
| 776 | SCM key = scm_long2num ((long) p); |
| 777 | |
| 778 | /* This critical section barrier will be replaced by a mutex. */ |
| 779 | SCM_REDEFER_INTS; |
| 780 | |
| 781 | handle = scm_hashv_create_handle_x (scm_gc_registered_roots, key, SCM_MAKINUM (0)); |
| 782 | SCM_SETCDR (handle, scm_sum (SCM_CDR (handle), SCM_MAKINUM (1))); |
| 783 | |
| 784 | SCM_REALLOW_INTS; |
| 785 | } |
| 786 | |
| 787 | void |
| 788 | scm_gc_unregister_root (SCM *p) |
| 789 | { |
| 790 | SCM handle; |
| 791 | SCM key = scm_long2num ((long) p); |
| 792 | |
| 793 | /* This critical section barrier will be replaced by a mutex. */ |
| 794 | SCM_REDEFER_INTS; |
| 795 | |
| 796 | handle = scm_hashv_get_handle (scm_gc_registered_roots, key); |
| 797 | |
| 798 | if (SCM_FALSEP (handle)) |
| 799 | { |
| 800 | fprintf (stderr, "scm_gc_unregister_root called on unregistered root\n"); |
| 801 | abort (); |
| 802 | } |
| 803 | else |
| 804 | { |
| 805 | SCM count = scm_difference (SCM_CDR (handle), SCM_MAKINUM (1)); |
| 806 | if (SCM_EQ_P (count, SCM_MAKINUM (0))) |
| 807 | scm_hashv_remove_x (scm_gc_registered_roots, key); |
| 808 | else |
| 809 | SCM_SETCDR (handle, count); |
| 810 | } |
| 811 | |
| 812 | SCM_REALLOW_INTS; |
| 813 | } |
| 814 | |
| 815 | void |
| 816 | scm_gc_register_roots (SCM *b, unsigned long n) |
| 817 | { |
| 818 | SCM *p = b; |
| 819 | for (; p < b + n; ++p) |
| 820 | scm_gc_register_root (p); |
| 821 | } |
| 822 | |
| 823 | void |
| 824 | scm_gc_unregister_roots (SCM *b, unsigned long n) |
| 825 | { |
| 826 | SCM *p = b; |
| 827 | for (; p < b + n; ++p) |
| 828 | scm_gc_unregister_root (p); |
| 829 | } |
| 830 | |
| 831 | int scm_i_terminating; |
| 832 | |
| 833 | /* called on process termination. */ |
| 834 | #ifdef HAVE_ATEXIT |
| 835 | static void |
| 836 | cleanup (void) |
| 837 | #else |
| 838 | #ifdef HAVE_ON_EXIT |
| 839 | extern int on_exit (void (*procp) (), int arg); |
| 840 | |
| 841 | static void |
| 842 | cleanup (int status, void *arg) |
| 843 | #else |
| 844 | #error Dont know how to setup a cleanup handler on your system. |
| 845 | #endif |
| 846 | #endif |
| 847 | { |
| 848 | scm_i_terminating = 1; |
| 849 | scm_flush_all_ports (); |
| 850 | } |
| 851 | |
| 852 | \f |
| 853 | |
| 854 | |
| 855 | /* |
| 856 | MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC. |
| 857 | */ |
| 858 | |
| 859 | /* Get an integer from an environment variable. */ |
| 860 | int |
| 861 | scm_getenv_int (const char *var, int def) |
| 862 | { |
| 863 | char *end = 0; |
| 864 | char *val = getenv (var); |
| 865 | long res = def; |
| 866 | if (!val) |
| 867 | return def; |
| 868 | res = strtol (val, &end, 10); |
| 869 | if (end == val) |
| 870 | return def; |
| 871 | return res; |
| 872 | } |
| 873 | |
| 874 | void |
| 875 | scm_storage_prehistory () |
| 876 | { |
| 877 | scm_c_hook_init (&scm_before_gc_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 878 | scm_c_hook_init (&scm_before_mark_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 879 | scm_c_hook_init (&scm_before_sweep_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 880 | scm_c_hook_init (&scm_after_sweep_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 881 | scm_c_hook_init (&scm_after_gc_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 882 | } |
| 883 | |
| 884 | int |
| 885 | scm_init_storage () |
| 886 | { |
| 887 | size_t j; |
| 888 | |
| 889 | /* Fixme: Should use mutexattr from the low-level API. */ |
| 890 | scm_rec_mutex_init (&scm_i_sweep_mutex, &scm_i_plugin_rec_mutex); |
| 891 | |
| 892 | j = SCM_NUM_PROTECTS; |
| 893 | while (j) |
| 894 | scm_sys_protects[--j] = SCM_BOOL_F; |
| 895 | scm_block_gc = 1; |
| 896 | |
| 897 | scm_gc_init_freelist(); |
| 898 | scm_gc_init_malloc (); |
| 899 | |
| 900 | j = SCM_HEAP_SEG_SIZE; |
| 901 | |
| 902 | |
| 903 | /* Initialise the list of ports. */ |
| 904 | scm_i_port_table = (scm_t_port **) |
| 905 | malloc (sizeof (scm_t_port *) * scm_i_port_table_room); |
| 906 | if (!scm_i_port_table) |
| 907 | return 1; |
| 908 | |
| 909 | #ifdef HAVE_ATEXIT |
| 910 | atexit (cleanup); |
| 911 | #else |
| 912 | #ifdef HAVE_ON_EXIT |
| 913 | on_exit (cleanup, 0); |
| 914 | #endif |
| 915 | #endif |
| 916 | |
| 917 | scm_stand_in_procs = SCM_EOL; |
| 918 | scm_permobjs = SCM_EOL; |
| 919 | scm_protects = scm_c_make_hash_table (31); |
| 920 | scm_gc_registered_roots = scm_c_make_hash_table (31); |
| 921 | |
| 922 | return 0; |
| 923 | } |
| 924 | |
| 925 | \f |
| 926 | |
| 927 | SCM scm_after_gc_hook; |
| 928 | |
| 929 | static SCM gc_async; |
| 930 | |
| 931 | /* The function gc_async_thunk causes the execution of the after-gc-hook. It |
| 932 | * is run after the gc, as soon as the asynchronous events are handled by the |
| 933 | * evaluator. |
| 934 | */ |
| 935 | static SCM |
| 936 | gc_async_thunk (void) |
| 937 | { |
| 938 | scm_c_run_hook (scm_after_gc_hook, SCM_EOL); |
| 939 | return SCM_UNSPECIFIED; |
| 940 | } |
| 941 | |
| 942 | |
| 943 | /* The function mark_gc_async is run by the scm_after_gc_c_hook at the end of |
| 944 | * the garbage collection. The only purpose of this function is to mark the |
| 945 | * gc_async (which will eventually lead to the execution of the |
| 946 | * gc_async_thunk). |
| 947 | */ |
| 948 | static void * |
| 949 | mark_gc_async (void * hook_data SCM_UNUSED, |
| 950 | void *func_data SCM_UNUSED, |
| 951 | void *data SCM_UNUSED) |
| 952 | { |
| 953 | /* If cell access debugging is enabled, the user may choose to perform |
| 954 | * additional garbage collections after an arbitrary number of cell |
| 955 | * accesses. We don't want the scheme level after-gc-hook to be performed |
| 956 | * for each of these garbage collections for the following reason: The |
| 957 | * execution of the after-gc-hook causes cell accesses itself. Thus, if the |
| 958 | * after-gc-hook was performed with every gc, and if the gc was performed |
| 959 | * after a very small number of cell accesses, then the number of cell |
| 960 | * accesses during the execution of the after-gc-hook will suffice to cause |
| 961 | * the execution of the next gc. Then, guile would keep executing the |
| 962 | * after-gc-hook over and over again, and would never come to do other |
| 963 | * things. |
| 964 | * |
| 965 | * To overcome this problem, if cell access debugging with additional |
| 966 | * garbage collections is enabled, the after-gc-hook is never run by the |
| 967 | * garbage collecter. When running guile with cell access debugging and the |
| 968 | * execution of the after-gc-hook is desired, then it is necessary to run |
| 969 | * the hook explicitly from the user code. This has the effect, that from |
| 970 | * the scheme level point of view it seems that garbage collection is |
| 971 | * performed with a much lower frequency than it actually is. Obviously, |
| 972 | * this will not work for code that depends on a fixed one to one |
| 973 | * relationship between the execution counts of the C level garbage |
| 974 | * collection hooks and the execution count of the scheme level |
| 975 | * after-gc-hook. |
| 976 | */ |
| 977 | #if (SCM_DEBUG_CELL_ACCESSES == 1) |
| 978 | if (scm_debug_cells_gc_interval == 0) |
| 979 | scm_system_async_mark (gc_async); |
| 980 | #else |
| 981 | scm_system_async_mark (gc_async); |
| 982 | #endif |
| 983 | |
| 984 | return NULL; |
| 985 | } |
| 986 | |
| 987 | void |
| 988 | scm_init_gc () |
| 989 | { |
| 990 | scm_gc_init_mark (); |
| 991 | |
| 992 | scm_after_gc_hook = scm_permanent_object (scm_make_hook (SCM_INUM0)); |
| 993 | scm_c_define ("after-gc-hook", scm_after_gc_hook); |
| 994 | |
| 995 | gc_async = scm_c_make_subr ("%gc-thunk", scm_tc7_subr_0, |
| 996 | gc_async_thunk); |
| 997 | |
| 998 | scm_c_hook_add (&scm_after_gc_c_hook, mark_gc_async, NULL, 0); |
| 999 | |
| 1000 | #include "libguile/gc.x" |
| 1001 | } |
| 1002 | |
| 1003 | |
| 1004 | void |
| 1005 | scm_gc_sweep (void) |
| 1006 | #define FUNC_NAME "scm_gc_sweep" |
| 1007 | { |
| 1008 | scm_i_deprecated_memory_return = 0; |
| 1009 | |
| 1010 | scm_i_gc_sweep_freelist_reset (&scm_i_master_freelist); |
| 1011 | scm_i_gc_sweep_freelist_reset (&scm_i_master_freelist2); |
| 1012 | |
| 1013 | /* |
| 1014 | NOTHING HERE: LAZY SWEEPING ! |
| 1015 | */ |
| 1016 | scm_i_reset_segments (); |
| 1017 | |
| 1018 | /* When we move to POSIX threads private freelists should probably |
| 1019 | be GC-protected instead. */ |
| 1020 | *SCM_FREELIST_LOC (scm_i_freelist) = SCM_EOL; |
| 1021 | *SCM_FREELIST_LOC (scm_i_freelist2) = SCM_EOL; |
| 1022 | |
| 1023 | /* Invalidate the freelists of other threads. */ |
| 1024 | scm_i_thread_invalidate_freelists (); |
| 1025 | } |
| 1026 | |
| 1027 | #undef FUNC_NAME |
| 1028 | |
| 1029 | |
| 1030 | |
| 1031 | /* |
| 1032 | Local Variables: |
| 1033 | c-file-style: "gnu" |
| 1034 | End: |
| 1035 | */ |