| 1 | /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001, 2002, 2003, 2006, |
| 2 | * 2008, 2009, 2010, 2011, 2012, 2013, 2014 Free Software Foundation, Inc. |
| 3 | * |
| 4 | * This library is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU Lesser General Public License |
| 6 | * as published by the Free Software Foundation; either version 3 of |
| 7 | * the License, or (at your option) any later version. |
| 8 | * |
| 9 | * This library is distributed in the hope that it will be useful, but |
| 10 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | * Lesser General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU Lesser General Public |
| 15 | * License along with this library; if not, write to the Free Software |
| 16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 17 | * 02110-1301 USA |
| 18 | */ |
| 19 | |
| 20 | /* #define DEBUGINFO */ |
| 21 | |
| 22 | #ifdef HAVE_CONFIG_H |
| 23 | # include <config.h> |
| 24 | #endif |
| 25 | |
| 26 | #define SCM_BUILDING_DEPRECATED_CODE |
| 27 | |
| 28 | #include "libguile/gen-scmconfig.h" |
| 29 | |
| 30 | #include <stdio.h> |
| 31 | #include <errno.h> |
| 32 | #include <string.h> |
| 33 | #include <stdlib.h> |
| 34 | #include <math.h> |
| 35 | |
| 36 | #ifdef __ia64__ |
| 37 | #include <ucontext.h> |
| 38 | extern unsigned long * __libc_ia64_register_backing_store_base; |
| 39 | #endif |
| 40 | |
| 41 | #include "libguile/_scm.h" |
| 42 | #include "libguile/eval.h" |
| 43 | #include "libguile/stime.h" |
| 44 | #include "libguile/stackchk.h" |
| 45 | #include "libguile/struct.h" |
| 46 | #include "libguile/smob.h" |
| 47 | #include "libguile/arrays.h" |
| 48 | #include "libguile/async.h" |
| 49 | #include "libguile/ports.h" |
| 50 | #include "libguile/root.h" |
| 51 | #include "libguile/strings.h" |
| 52 | #include "libguile/vectors.h" |
| 53 | #include "libguile/weaks.h" |
| 54 | #include "libguile/hashtab.h" |
| 55 | #include "libguile/tags.h" |
| 56 | |
| 57 | #include "libguile/private-gc.h" |
| 58 | #include "libguile/validate.h" |
| 59 | #include "libguile/deprecation.h" |
| 60 | #include "libguile/gc.h" |
| 61 | #include "libguile/dynwind.h" |
| 62 | |
| 63 | #include "libguile/bdw-gc.h" |
| 64 | |
| 65 | /* For GC_set_start_callback. */ |
| 66 | #include <gc/gc_mark.h> |
| 67 | |
| 68 | #ifdef GUILE_DEBUG_MALLOC |
| 69 | #include "libguile/debug-malloc.h" |
| 70 | #endif |
| 71 | |
| 72 | #include <unistd.h> |
| 73 | |
| 74 | /* Set this to != 0 if every cell that is accessed shall be checked: |
| 75 | */ |
| 76 | int scm_debug_cell_accesses_p = 0; |
| 77 | int scm_expensive_debug_cell_accesses_p = 0; |
| 78 | |
| 79 | /* Set this to 0 if no additional gc's shall be performed, otherwise set it to |
| 80 | * the number of cell accesses after which a gc shall be called. |
| 81 | */ |
| 82 | int scm_debug_cells_gc_interval = 0; |
| 83 | |
| 84 | #if SCM_ENABLE_DEPRECATED == 1 |
| 85 | /* Hash table that keeps a reference to objects the user wants to protect from |
| 86 | garbage collection. It could arguably be private but applications have come |
| 87 | to rely on it (e.g., Lilypond 2.13.9). */ |
| 88 | SCM scm_protects; |
| 89 | #else |
| 90 | static SCM scm_protects; |
| 91 | #endif |
| 92 | |
| 93 | #if (SCM_DEBUG_CELL_ACCESSES == 1) |
| 94 | |
| 95 | |
| 96 | /* |
| 97 | |
| 98 | Assert that the given object is a valid reference to a valid cell. This |
| 99 | test involves to determine whether the object is a cell pointer, whether |
| 100 | this pointer actually points into a heap segment and whether the cell |
| 101 | pointed to is not a free cell. Further, additional garbage collections may |
| 102 | get executed after a user defined number of cell accesses. This helps to |
| 103 | find places in the C code where references are dropped for extremely short |
| 104 | periods. |
| 105 | |
| 106 | */ |
| 107 | void |
| 108 | scm_i_expensive_validation_check (SCM cell) |
| 109 | { |
| 110 | /* If desired, perform additional garbage collections after a user |
| 111 | * defined number of cell accesses. |
| 112 | */ |
| 113 | if (scm_debug_cells_gc_interval) |
| 114 | { |
| 115 | static unsigned int counter = 0; |
| 116 | |
| 117 | if (counter != 0) |
| 118 | { |
| 119 | --counter; |
| 120 | } |
| 121 | else |
| 122 | { |
| 123 | counter = scm_debug_cells_gc_interval; |
| 124 | scm_gc (); |
| 125 | } |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | /* Whether cell validation is already running. */ |
| 130 | static int scm_i_cell_validation_already_running = 0; |
| 131 | |
| 132 | void |
| 133 | scm_assert_cell_valid (SCM cell) |
| 134 | { |
| 135 | if (!scm_i_cell_validation_already_running && scm_debug_cell_accesses_p) |
| 136 | { |
| 137 | scm_i_cell_validation_already_running = 1; /* set to avoid recursion */ |
| 138 | |
| 139 | /* |
| 140 | During GC, no user-code should be run, and the guile core |
| 141 | should use non-protected accessors. |
| 142 | */ |
| 143 | if (scm_gc_running_p) |
| 144 | return; |
| 145 | |
| 146 | /* |
| 147 | Only scm_in_heap_p and rescanning the heap is wildly |
| 148 | expensive. |
| 149 | */ |
| 150 | if (scm_expensive_debug_cell_accesses_p) |
| 151 | scm_i_expensive_validation_check (cell); |
| 152 | |
| 153 | scm_i_cell_validation_already_running = 0; /* re-enable */ |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | |
| 158 | |
| 159 | SCM_DEFINE (scm_set_debug_cell_accesses_x, "set-debug-cell-accesses!", 1, 0, 0, |
| 160 | (SCM flag), |
| 161 | "If @var{flag} is @code{#f}, cell access checking is disabled.\n" |
| 162 | "If @var{flag} is @code{#t}, cheap cell access checking is enabled,\n" |
| 163 | "but no additional calls to garbage collection are issued.\n" |
| 164 | "If @var{flag} is a number, strict cell access checking is enabled,\n" |
| 165 | "with an additional garbage collection after the given\n" |
| 166 | "number of cell accesses.\n" |
| 167 | "This procedure only exists when the compile-time flag\n" |
| 168 | "@code{SCM_DEBUG_CELL_ACCESSES} was set to 1.") |
| 169 | #define FUNC_NAME s_scm_set_debug_cell_accesses_x |
| 170 | { |
| 171 | if (scm_is_false (flag)) |
| 172 | { |
| 173 | scm_debug_cell_accesses_p = 0; |
| 174 | } |
| 175 | else if (scm_is_eq (flag, SCM_BOOL_T)) |
| 176 | { |
| 177 | scm_debug_cells_gc_interval = 0; |
| 178 | scm_debug_cell_accesses_p = 1; |
| 179 | scm_expensive_debug_cell_accesses_p = 0; |
| 180 | } |
| 181 | else |
| 182 | { |
| 183 | scm_debug_cells_gc_interval = scm_to_signed_integer (flag, 0, INT_MAX); |
| 184 | scm_debug_cell_accesses_p = 1; |
| 185 | scm_expensive_debug_cell_accesses_p = 1; |
| 186 | } |
| 187 | return SCM_UNSPECIFIED; |
| 188 | } |
| 189 | #undef FUNC_NAME |
| 190 | |
| 191 | |
| 192 | #endif /* SCM_DEBUG_CELL_ACCESSES == 1 */ |
| 193 | |
| 194 | \f |
| 195 | |
| 196 | /* Compatibility. */ |
| 197 | |
| 198 | #ifndef HAVE_GC_GET_HEAP_USAGE_SAFE |
| 199 | static void |
| 200 | GC_get_heap_usage_safe (GC_word *pheap_size, GC_word *pfree_bytes, |
| 201 | GC_word *punmapped_bytes, GC_word *pbytes_since_gc, |
| 202 | GC_word *ptotal_bytes) |
| 203 | { |
| 204 | *pheap_size = GC_get_heap_size (); |
| 205 | *pfree_bytes = GC_get_free_bytes (); |
| 206 | #ifdef HAVE_GC_GET_UNMAPPED_BYTES |
| 207 | *punmapped_bytes = GC_get_unmapped_bytes (); |
| 208 | #else |
| 209 | *punmapped_bytes = 0; |
| 210 | #endif |
| 211 | *pbytes_since_gc = GC_get_bytes_since_gc (); |
| 212 | *ptotal_bytes = GC_get_total_bytes (); |
| 213 | } |
| 214 | #endif |
| 215 | |
| 216 | #ifndef HAVE_GC_GET_FREE_SPACE_DIVISOR |
| 217 | static GC_word |
| 218 | GC_get_free_space_divisor (void) |
| 219 | { |
| 220 | return GC_free_space_divisor; |
| 221 | } |
| 222 | #endif |
| 223 | |
| 224 | \f |
| 225 | /* Hooks. */ |
| 226 | scm_t_c_hook scm_before_gc_c_hook; |
| 227 | scm_t_c_hook scm_before_mark_c_hook; |
| 228 | scm_t_c_hook scm_before_sweep_c_hook; |
| 229 | scm_t_c_hook scm_after_sweep_c_hook; |
| 230 | scm_t_c_hook scm_after_gc_c_hook; |
| 231 | |
| 232 | |
| 233 | static void |
| 234 | run_before_gc_c_hook (void) |
| 235 | { |
| 236 | if (!SCM_I_CURRENT_THREAD) |
| 237 | /* GC while a thread is spinning up; punt. */ |
| 238 | return; |
| 239 | |
| 240 | scm_c_hook_run (&scm_before_gc_c_hook, NULL); |
| 241 | } |
| 242 | |
| 243 | |
| 244 | /* GC Statistics Keeping |
| 245 | */ |
| 246 | unsigned long scm_gc_ports_collected = 0; |
| 247 | static long gc_time_taken = 0; |
| 248 | static long gc_start_time = 0; |
| 249 | |
| 250 | static unsigned long free_space_divisor; |
| 251 | static unsigned long minimum_free_space_divisor; |
| 252 | static double target_free_space_divisor; |
| 253 | |
| 254 | static unsigned long protected_obj_count = 0; |
| 255 | |
| 256 | |
| 257 | SCM_SYMBOL (sym_gc_time_taken, "gc-time-taken"); |
| 258 | SCM_SYMBOL (sym_heap_size, "heap-size"); |
| 259 | SCM_SYMBOL (sym_heap_free_size, "heap-free-size"); |
| 260 | SCM_SYMBOL (sym_heap_total_allocated, "heap-total-allocated"); |
| 261 | SCM_SYMBOL (sym_heap_allocated_since_gc, "heap-allocated-since-gc"); |
| 262 | SCM_SYMBOL (sym_protected_objects, "protected-objects"); |
| 263 | SCM_SYMBOL (sym_times, "gc-times"); |
| 264 | |
| 265 | |
| 266 | /* {Scheme Interface to GC} |
| 267 | */ |
| 268 | extern int scm_gc_malloc_yield_percentage; |
| 269 | SCM_DEFINE (scm_gc_stats, "gc-stats", 0, 0, 0, |
| 270 | (), |
| 271 | "Return an association list of statistics about Guile's current\n" |
| 272 | "use of storage.\n") |
| 273 | #define FUNC_NAME s_scm_gc_stats |
| 274 | { |
| 275 | SCM answer; |
| 276 | GC_word heap_size, free_bytes, unmapped_bytes, bytes_since_gc, total_bytes; |
| 277 | size_t gc_times; |
| 278 | |
| 279 | GC_get_heap_usage_safe (&heap_size, &free_bytes, &unmapped_bytes, |
| 280 | &bytes_since_gc, &total_bytes); |
| 281 | #ifdef HAVE_GC_GET_GC_NO |
| 282 | /* This function was added in 7.2alpha2 (June 2009). */ |
| 283 | gc_times = GC_get_gc_no (); |
| 284 | #else |
| 285 | /* This symbol is deprecated as of 7.3. */ |
| 286 | gc_times = GC_gc_no; |
| 287 | #endif |
| 288 | |
| 289 | answer = |
| 290 | scm_list_n (scm_cons (sym_gc_time_taken, scm_from_long (gc_time_taken)), |
| 291 | scm_cons (sym_heap_size, scm_from_size_t (heap_size)), |
| 292 | scm_cons (sym_heap_free_size, scm_from_size_t (free_bytes)), |
| 293 | scm_cons (sym_heap_total_allocated, |
| 294 | scm_from_size_t (total_bytes)), |
| 295 | scm_cons (sym_heap_allocated_since_gc, |
| 296 | scm_from_size_t (bytes_since_gc)), |
| 297 | scm_cons (sym_protected_objects, |
| 298 | scm_from_ulong (protected_obj_count)), |
| 299 | scm_cons (sym_times, scm_from_size_t (gc_times)), |
| 300 | SCM_UNDEFINED); |
| 301 | |
| 302 | return answer; |
| 303 | } |
| 304 | #undef FUNC_NAME |
| 305 | |
| 306 | |
| 307 | SCM_DEFINE (scm_gc_dump, "gc-dump", 0, 0, 0, |
| 308 | (void), |
| 309 | "Dump information about the garbage collector's internal data " |
| 310 | "structures and memory usage to the standard output.") |
| 311 | #define FUNC_NAME s_scm_gc_dump |
| 312 | { |
| 313 | GC_dump (); |
| 314 | |
| 315 | return SCM_UNSPECIFIED; |
| 316 | } |
| 317 | #undef FUNC_NAME |
| 318 | |
| 319 | |
| 320 | SCM_DEFINE (scm_object_address, "object-address", 1, 0, 0, |
| 321 | (SCM obj), |
| 322 | "Return an integer that for the lifetime of @var{obj} is uniquely\n" |
| 323 | "returned by this function for @var{obj}") |
| 324 | #define FUNC_NAME s_scm_object_address |
| 325 | { |
| 326 | return scm_from_ulong (SCM_UNPACK (obj)); |
| 327 | } |
| 328 | #undef FUNC_NAME |
| 329 | |
| 330 | |
| 331 | SCM_DEFINE (scm_gc_disable, "gc-disable", 0, 0, 0, |
| 332 | (), |
| 333 | "Disables the garbage collector. Nested calls are permitted. " |
| 334 | "GC is re-enabled once @code{gc-enable} has been called the " |
| 335 | "same number of times @code{gc-disable} was called.") |
| 336 | #define FUNC_NAME s_scm_gc_disable |
| 337 | { |
| 338 | GC_disable (); |
| 339 | return SCM_UNSPECIFIED; |
| 340 | } |
| 341 | #undef FUNC_NAME |
| 342 | |
| 343 | SCM_DEFINE (scm_gc_enable, "gc-enable", 0, 0, 0, |
| 344 | (), |
| 345 | "Enables the garbage collector.") |
| 346 | #define FUNC_NAME s_scm_gc_enable |
| 347 | { |
| 348 | GC_enable (); |
| 349 | return SCM_UNSPECIFIED; |
| 350 | } |
| 351 | #undef FUNC_NAME |
| 352 | |
| 353 | |
| 354 | SCM_DEFINE (scm_gc, "gc", 0, 0, 0, |
| 355 | (), |
| 356 | "Scans all of SCM objects and reclaims for further use those that are\n" |
| 357 | "no longer accessible.") |
| 358 | #define FUNC_NAME s_scm_gc |
| 359 | { |
| 360 | scm_i_gc ("call"); |
| 361 | /* If you're calling scm_gc(), you probably want synchronous |
| 362 | finalization. */ |
| 363 | GC_invoke_finalizers (); |
| 364 | return SCM_UNSPECIFIED; |
| 365 | } |
| 366 | #undef FUNC_NAME |
| 367 | |
| 368 | void |
| 369 | scm_i_gc (const char *what) |
| 370 | { |
| 371 | #ifndef HAVE_GC_SET_START_CALLBACK |
| 372 | run_before_gc_c_hook (); |
| 373 | #endif |
| 374 | GC_gcollect (); |
| 375 | } |
| 376 | |
| 377 | |
| 378 | \f |
| 379 | /* {GC Protection Helper Functions} |
| 380 | */ |
| 381 | |
| 382 | |
| 383 | /* |
| 384 | * If within a function you need to protect one or more scheme objects from |
| 385 | * garbage collection, pass them as parameters to one of the |
| 386 | * scm_remember_upto_here* functions below. These functions don't do |
| 387 | * anything, but since the compiler does not know that they are actually |
| 388 | * no-ops, it will generate code that calls these functions with the given |
| 389 | * parameters. Therefore, you can be sure that the compiler will keep those |
| 390 | * scheme values alive (on the stack or in a register) up to the point where |
| 391 | * scm_remember_upto_here* is called. In other words, place the call to |
| 392 | * scm_remember_upto_here* _behind_ the last code in your function, that |
| 393 | * depends on the scheme object to exist. |
| 394 | * |
| 395 | * Example: We want to make sure that the string object str does not get |
| 396 | * garbage collected during the execution of 'some_function' in the code |
| 397 | * below, because otherwise the characters belonging to str would be freed and |
| 398 | * 'some_function' might access freed memory. To make sure that the compiler |
| 399 | * keeps str alive on the stack or in a register such that it is visible to |
| 400 | * the conservative gc we add the call to scm_remember_upto_here_1 _after_ the |
| 401 | * call to 'some_function'. Note that this would not be necessary if str was |
| 402 | * used anyway after the call to 'some_function'. |
| 403 | * char *chars = scm_i_string_chars (str); |
| 404 | * some_function (chars); |
| 405 | * scm_remember_upto_here_1 (str); // str will be alive up to this point. |
| 406 | */ |
| 407 | |
| 408 | /* Remove any macro versions of these while defining the functions. |
| 409 | Functions are always included in the library, for upward binary |
| 410 | compatibility and in case combinations of GCC and non-GCC are used. */ |
| 411 | #undef scm_remember_upto_here_1 |
| 412 | #undef scm_remember_upto_here_2 |
| 413 | |
| 414 | void |
| 415 | scm_remember_upto_here_1 (SCM obj SCM_UNUSED) |
| 416 | { |
| 417 | /* Empty. Protects a single object from garbage collection. */ |
| 418 | } |
| 419 | |
| 420 | void |
| 421 | scm_remember_upto_here_2 (SCM obj1 SCM_UNUSED, SCM obj2 SCM_UNUSED) |
| 422 | { |
| 423 | /* Empty. Protects two objects from garbage collection. */ |
| 424 | } |
| 425 | |
| 426 | void |
| 427 | scm_remember_upto_here (SCM obj SCM_UNUSED, ...) |
| 428 | { |
| 429 | /* Empty. Protects any number of objects from garbage collection. */ |
| 430 | } |
| 431 | |
| 432 | /* |
| 433 | These crazy functions prevent garbage collection |
| 434 | of arguments after the first argument by |
| 435 | ensuring they remain live throughout the |
| 436 | function because they are used in the last |
| 437 | line of the code block. |
| 438 | It'd be better to have a nice compiler hint to |
| 439 | aid the conservative stack-scanning GC. --03/09/00 gjb */ |
| 440 | SCM |
| 441 | scm_return_first (SCM elt, ...) |
| 442 | { |
| 443 | return elt; |
| 444 | } |
| 445 | |
| 446 | int |
| 447 | scm_return_first_int (int i, ...) |
| 448 | { |
| 449 | return i; |
| 450 | } |
| 451 | |
| 452 | |
| 453 | SCM |
| 454 | scm_permanent_object (SCM obj) |
| 455 | { |
| 456 | return (scm_gc_protect_object (obj)); |
| 457 | } |
| 458 | |
| 459 | |
| 460 | /* Protect OBJ from the garbage collector. OBJ will not be freed, even if all |
| 461 | other references are dropped, until the object is unprotected by calling |
| 462 | scm_gc_unprotect_object (OBJ). Calls to scm_gc_protect/unprotect_object nest, |
| 463 | i. e. it is possible to protect the same object several times, but it is |
| 464 | necessary to unprotect the object the same number of times to actually get |
| 465 | the object unprotected. It is an error to unprotect an object more often |
| 466 | than it has been protected before. The function scm_protect_object returns |
| 467 | OBJ. |
| 468 | */ |
| 469 | |
| 470 | /* Implementation note: For every object X, there is a counter which |
| 471 | scm_gc_protect_object (X) increments and scm_gc_unprotect_object (X) decrements. |
| 472 | */ |
| 473 | |
| 474 | |
| 475 | |
| 476 | SCM |
| 477 | scm_gc_protect_object (SCM obj) |
| 478 | { |
| 479 | SCM handle; |
| 480 | |
| 481 | /* This critical section barrier will be replaced by a mutex. */ |
| 482 | /* njrev: Indeed; if my comment above is correct, there is the same |
| 483 | critsec/mutex inconsistency here. */ |
| 484 | SCM_CRITICAL_SECTION_START; |
| 485 | |
| 486 | handle = scm_hashq_create_handle_x (scm_protects, obj, scm_from_int (0)); |
| 487 | SCM_SETCDR (handle, scm_sum (SCM_CDR (handle), scm_from_int (1))); |
| 488 | |
| 489 | protected_obj_count ++; |
| 490 | |
| 491 | SCM_CRITICAL_SECTION_END; |
| 492 | |
| 493 | return obj; |
| 494 | } |
| 495 | |
| 496 | |
| 497 | /* Remove any protection for OBJ established by a prior call to |
| 498 | scm_protect_object. This function returns OBJ. |
| 499 | |
| 500 | See scm_protect_object for more information. */ |
| 501 | SCM |
| 502 | scm_gc_unprotect_object (SCM obj) |
| 503 | { |
| 504 | SCM handle; |
| 505 | |
| 506 | /* This critical section barrier will be replaced by a mutex. */ |
| 507 | /* njrev: and again. */ |
| 508 | SCM_CRITICAL_SECTION_START; |
| 509 | |
| 510 | if (scm_gc_running_p) |
| 511 | { |
| 512 | fprintf (stderr, "scm_unprotect_object called during GC.\n"); |
| 513 | abort (); |
| 514 | } |
| 515 | |
| 516 | handle = scm_hashq_get_handle (scm_protects, obj); |
| 517 | |
| 518 | if (scm_is_false (handle)) |
| 519 | { |
| 520 | fprintf (stderr, "scm_unprotect_object called on unprotected object\n"); |
| 521 | abort (); |
| 522 | } |
| 523 | else |
| 524 | { |
| 525 | SCM count = scm_difference (SCM_CDR (handle), scm_from_int (1)); |
| 526 | if (scm_is_eq (count, scm_from_int (0))) |
| 527 | scm_hashq_remove_x (scm_protects, obj); |
| 528 | else |
| 529 | SCM_SETCDR (handle, count); |
| 530 | } |
| 531 | protected_obj_count --; |
| 532 | |
| 533 | SCM_CRITICAL_SECTION_END; |
| 534 | |
| 535 | return obj; |
| 536 | } |
| 537 | |
| 538 | void |
| 539 | scm_gc_register_root (SCM *p) |
| 540 | { |
| 541 | /* Nothing. */ |
| 542 | } |
| 543 | |
| 544 | void |
| 545 | scm_gc_unregister_root (SCM *p) |
| 546 | { |
| 547 | /* Nothing. */ |
| 548 | } |
| 549 | |
| 550 | void |
| 551 | scm_gc_register_roots (SCM *b, unsigned long n) |
| 552 | { |
| 553 | SCM *p = b; |
| 554 | for (; p < b + n; ++p) |
| 555 | scm_gc_register_root (p); |
| 556 | } |
| 557 | |
| 558 | void |
| 559 | scm_gc_unregister_roots (SCM *b, unsigned long n) |
| 560 | { |
| 561 | SCM *p = b; |
| 562 | for (; p < b + n; ++p) |
| 563 | scm_gc_unregister_root (p); |
| 564 | } |
| 565 | |
| 566 | \f |
| 567 | |
| 568 | |
| 569 | /* |
| 570 | MOVE THIS FUNCTION. IT DOES NOT HAVE ANYTHING TODO WITH GC. |
| 571 | */ |
| 572 | |
| 573 | /* Get an integer from an environment variable. */ |
| 574 | int |
| 575 | scm_getenv_int (const char *var, int def) |
| 576 | { |
| 577 | char *end = 0; |
| 578 | char *val = getenv (var); |
| 579 | long res = def; |
| 580 | if (!val) |
| 581 | return def; |
| 582 | res = strtol (val, &end, 10); |
| 583 | if (end == val) |
| 584 | return def; |
| 585 | return res; |
| 586 | } |
| 587 | |
| 588 | #ifndef HAVE_GC_SET_FINALIZE_ON_DEMAND |
| 589 | static void |
| 590 | GC_set_finalize_on_demand (int foo) |
| 591 | { |
| 592 | GC_finalize_on_demand = foo; |
| 593 | } |
| 594 | #endif |
| 595 | |
| 596 | void |
| 597 | scm_storage_prehistory () |
| 598 | { |
| 599 | #ifdef HAVE_GC_SET_ALL_INTERIOR_POINTERS |
| 600 | /* This function was added in 7.2alpha2 (June 2009). */ |
| 601 | GC_set_all_interior_pointers (0); |
| 602 | #else |
| 603 | /* This symbol is deprecated in 7.3. */ |
| 604 | GC_all_interior_pointers = 0; |
| 605 | #endif |
| 606 | |
| 607 | free_space_divisor = scm_getenv_int ("GC_FREE_SPACE_DIVISOR", 3); |
| 608 | minimum_free_space_divisor = free_space_divisor; |
| 609 | target_free_space_divisor = free_space_divisor; |
| 610 | GC_set_free_space_divisor (free_space_divisor); |
| 611 | GC_set_finalize_on_demand (1); |
| 612 | |
| 613 | GC_INIT (); |
| 614 | |
| 615 | #if (! ((defined GC_VERSION_MAJOR) && (GC_VERSION_MAJOR >= 7))) \ |
| 616 | && (defined SCM_I_GSC_USE_PTHREAD_THREADS) |
| 617 | /* When using GC 6.8, this call is required to initialize thread-local |
| 618 | freelists (shouldn't be necessary with GC 7.0). */ |
| 619 | GC_init (); |
| 620 | #endif |
| 621 | |
| 622 | GC_expand_hp (SCM_DEFAULT_INIT_HEAP_SIZE_2); |
| 623 | |
| 624 | /* We only need to register a displacement for those types for which the |
| 625 | higher bits of the type tag are used to store a pointer (that is, a |
| 626 | pointer to an 8-octet aligned region). For `scm_tc3_struct', this is |
| 627 | handled in `scm_alloc_struct ()'. */ |
| 628 | GC_REGISTER_DISPLACEMENT (scm_tc3_cons); |
| 629 | /* GC_REGISTER_DISPLACEMENT (scm_tc3_unused); */ |
| 630 | |
| 631 | /* Sanity check. */ |
| 632 | if (!GC_is_visible (&scm_protects)) |
| 633 | abort (); |
| 634 | |
| 635 | scm_c_hook_init (&scm_before_gc_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 636 | scm_c_hook_init (&scm_before_mark_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 637 | scm_c_hook_init (&scm_before_sweep_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 638 | scm_c_hook_init (&scm_after_sweep_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 639 | scm_c_hook_init (&scm_after_gc_c_hook, 0, SCM_C_HOOK_NORMAL); |
| 640 | } |
| 641 | |
| 642 | scm_i_pthread_mutex_t scm_i_gc_admin_mutex = SCM_I_PTHREAD_MUTEX_INITIALIZER; |
| 643 | |
| 644 | void |
| 645 | scm_init_gc_protect_object () |
| 646 | { |
| 647 | scm_protects = scm_c_make_hash_table (31); |
| 648 | |
| 649 | #if 0 |
| 650 | /* We can't have a cleanup handler since we have no thread to run it |
| 651 | in. */ |
| 652 | |
| 653 | #ifdef HAVE_ATEXIT |
| 654 | atexit (cleanup); |
| 655 | #else |
| 656 | #ifdef HAVE_ON_EXIT |
| 657 | on_exit (cleanup, 0); |
| 658 | #endif |
| 659 | #endif |
| 660 | |
| 661 | #endif |
| 662 | } |
| 663 | |
| 664 | \f |
| 665 | |
| 666 | SCM scm_after_gc_hook; |
| 667 | |
| 668 | static SCM after_gc_async_cell; |
| 669 | |
| 670 | /* The function after_gc_async_thunk causes the execution of the |
| 671 | * after-gc-hook. It is run after the gc, as soon as the asynchronous |
| 672 | * events are handled by the evaluator. |
| 673 | */ |
| 674 | static SCM |
| 675 | after_gc_async_thunk (void) |
| 676 | { |
| 677 | /* Fun, no? Hook-run *and* run-hook? */ |
| 678 | scm_c_hook_run (&scm_after_gc_c_hook, NULL); |
| 679 | scm_c_run_hook (scm_after_gc_hook, SCM_EOL); |
| 680 | return SCM_UNSPECIFIED; |
| 681 | } |
| 682 | |
| 683 | |
| 684 | /* The function queue_after_gc_hook is run by the scm_before_gc_c_hook |
| 685 | * at the end of the garbage collection. The only purpose of this |
| 686 | * function is to mark the after_gc_async (which will eventually lead to |
| 687 | * the execution of the after_gc_async_thunk). |
| 688 | */ |
| 689 | static void * |
| 690 | queue_after_gc_hook (void * hook_data SCM_UNUSED, |
| 691 | void *fn_data SCM_UNUSED, |
| 692 | void *data SCM_UNUSED) |
| 693 | { |
| 694 | /* If cell access debugging is enabled, the user may choose to perform |
| 695 | * additional garbage collections after an arbitrary number of cell |
| 696 | * accesses. We don't want the scheme level after-gc-hook to be performed |
| 697 | * for each of these garbage collections for the following reason: The |
| 698 | * execution of the after-gc-hook causes cell accesses itself. Thus, if the |
| 699 | * after-gc-hook was performed with every gc, and if the gc was performed |
| 700 | * after a very small number of cell accesses, then the number of cell |
| 701 | * accesses during the execution of the after-gc-hook will suffice to cause |
| 702 | * the execution of the next gc. Then, guile would keep executing the |
| 703 | * after-gc-hook over and over again, and would never come to do other |
| 704 | * things. |
| 705 | * |
| 706 | * To overcome this problem, if cell access debugging with additional |
| 707 | * garbage collections is enabled, the after-gc-hook is never run by the |
| 708 | * garbage collecter. When running guile with cell access debugging and the |
| 709 | * execution of the after-gc-hook is desired, then it is necessary to run |
| 710 | * the hook explicitly from the user code. This has the effect, that from |
| 711 | * the scheme level point of view it seems that garbage collection is |
| 712 | * performed with a much lower frequency than it actually is. Obviously, |
| 713 | * this will not work for code that depends on a fixed one to one |
| 714 | * relationship between the execution counts of the C level garbage |
| 715 | * collection hooks and the execution count of the scheme level |
| 716 | * after-gc-hook. |
| 717 | */ |
| 718 | |
| 719 | #if (SCM_DEBUG_CELL_ACCESSES == 1) |
| 720 | if (scm_debug_cells_gc_interval == 0) |
| 721 | #endif |
| 722 | { |
| 723 | scm_i_thread *t = SCM_I_CURRENT_THREAD; |
| 724 | |
| 725 | if (scm_is_false (SCM_CDR (after_gc_async_cell))) |
| 726 | { |
| 727 | SCM_SETCDR (after_gc_async_cell, t->active_asyncs); |
| 728 | t->active_asyncs = after_gc_async_cell; |
| 729 | t->pending_asyncs = 1; |
| 730 | } |
| 731 | } |
| 732 | |
| 733 | return NULL; |
| 734 | } |
| 735 | |
| 736 | \f |
| 737 | |
| 738 | static void * |
| 739 | start_gc_timer (void * hook_data SCM_UNUSED, |
| 740 | void *fn_data SCM_UNUSED, |
| 741 | void *data SCM_UNUSED) |
| 742 | { |
| 743 | if (!gc_start_time) |
| 744 | gc_start_time = scm_c_get_internal_run_time (); |
| 745 | |
| 746 | return NULL; |
| 747 | } |
| 748 | |
| 749 | static void * |
| 750 | accumulate_gc_timer (void * hook_data SCM_UNUSED, |
| 751 | void *fn_data SCM_UNUSED, |
| 752 | void *data SCM_UNUSED) |
| 753 | { |
| 754 | if (gc_start_time) |
| 755 | { |
| 756 | long now = scm_c_get_internal_run_time (); |
| 757 | gc_time_taken += now - gc_start_time; |
| 758 | gc_start_time = 0; |
| 759 | } |
| 760 | |
| 761 | return NULL; |
| 762 | } |
| 763 | |
| 764 | /* Return some idea of the memory footprint of a process, in bytes. |
| 765 | Currently only works on Linux systems. */ |
| 766 | static size_t |
| 767 | get_image_size (void) |
| 768 | { |
| 769 | unsigned long size, resident, share; |
| 770 | size_t ret = 0; |
| 771 | |
| 772 | FILE *fp = fopen ("/proc/self/statm", "r"); |
| 773 | |
| 774 | if (fp && fscanf (fp, "%lu %lu %lu", &size, &resident, &share) == 3) |
| 775 | ret = resident * 4096; |
| 776 | |
| 777 | if (fp) |
| 778 | fclose (fp); |
| 779 | |
| 780 | return ret; |
| 781 | } |
| 782 | |
| 783 | /* These are discussed later. */ |
| 784 | static size_t bytes_until_gc; |
| 785 | static scm_i_pthread_mutex_t bytes_until_gc_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER; |
| 786 | |
| 787 | /* Make GC run more frequently when the process image size is growing, |
| 788 | measured against the number of bytes allocated through the GC. |
| 789 | |
| 790 | If Guile is allocating at a GC-managed heap size H, libgc will tend |
| 791 | to limit the process image size to H*N. But if at the same time the |
| 792 | user program is mallocating at a rate M bytes per GC-allocated byte, |
| 793 | then the process stabilizes at H*N*M -- assuming that collecting data |
| 794 | will result in malloc'd data being freed. It doesn't take a very |
| 795 | large M for this to be a bad situation. To limit the image size, |
| 796 | Guile should GC more often -- the bigger the M, the more often. |
| 797 | |
| 798 | Numeric functions that produce bigger and bigger integers are |
| 799 | pessimal, because M is an increasing function of time. Here is an |
| 800 | example of such a function: |
| 801 | |
| 802 | (define (factorial n) |
| 803 | (define (fac n acc) |
| 804 | (if (<= n 1) |
| 805 | acc |
| 806 | (fac (1- n) (* n acc)))) |
| 807 | (fac n 1)) |
| 808 | |
| 809 | It is possible for a process to grow for reasons that will not be |
| 810 | solved by faster GC. In that case M will be estimated as |
| 811 | artificially high for a while, and so GC will happen more often on |
| 812 | the Guile side. But when it stabilizes, Guile can ease back the GC |
| 813 | frequency. |
| 814 | |
| 815 | The key is to measure process image growth, not mallocation rate. |
| 816 | For maximum effectiveness, Guile reacts quickly to process growth, |
| 817 | and exponentially backs down when the process stops growing. |
| 818 | |
| 819 | See http://thread.gmane.org/gmane.lisp.guile.devel/12552/focus=12936 |
| 820 | for further discussion. |
| 821 | */ |
| 822 | static void * |
| 823 | adjust_gc_frequency (void * hook_data SCM_UNUSED, |
| 824 | void *fn_data SCM_UNUSED, |
| 825 | void *data SCM_UNUSED) |
| 826 | { |
| 827 | static size_t prev_image_size = 0; |
| 828 | static size_t prev_bytes_alloced = 0; |
| 829 | size_t image_size; |
| 830 | size_t bytes_alloced; |
| 831 | |
| 832 | scm_i_pthread_mutex_lock (&bytes_until_gc_lock); |
| 833 | bytes_until_gc = GC_get_heap_size (); |
| 834 | scm_i_pthread_mutex_unlock (&bytes_until_gc_lock); |
| 835 | |
| 836 | image_size = get_image_size (); |
| 837 | bytes_alloced = GC_get_total_bytes (); |
| 838 | |
| 839 | #define HEURISTICS_DEBUG 0 |
| 840 | |
| 841 | #if HEURISTICS_DEBUG |
| 842 | fprintf (stderr, "prev image / alloced: %lu / %lu\n", prev_image_size, prev_bytes_alloced); |
| 843 | fprintf (stderr, " image / alloced: %lu / %lu\n", image_size, bytes_alloced); |
| 844 | fprintf (stderr, "divisor %lu / %f\n", free_space_divisor, target_free_space_divisor); |
| 845 | #endif |
| 846 | |
| 847 | if (prev_image_size && bytes_alloced != prev_bytes_alloced) |
| 848 | { |
| 849 | double growth_rate, new_target_free_space_divisor; |
| 850 | double decay_factor = 0.5; |
| 851 | double hysteresis = 0.1; |
| 852 | |
| 853 | growth_rate = ((double) image_size - prev_image_size) |
| 854 | / ((double)bytes_alloced - prev_bytes_alloced); |
| 855 | |
| 856 | #if HEURISTICS_DEBUG |
| 857 | fprintf (stderr, "growth rate %f\n", growth_rate); |
| 858 | #endif |
| 859 | |
| 860 | new_target_free_space_divisor = minimum_free_space_divisor; |
| 861 | |
| 862 | if (growth_rate > 0) |
| 863 | new_target_free_space_divisor *= 1.0 + growth_rate; |
| 864 | |
| 865 | #if HEURISTICS_DEBUG |
| 866 | fprintf (stderr, "new divisor %f\n", new_target_free_space_divisor); |
| 867 | #endif |
| 868 | |
| 869 | if (new_target_free_space_divisor < target_free_space_divisor) |
| 870 | /* Decay down. */ |
| 871 | target_free_space_divisor = |
| 872 | (decay_factor * target_free_space_divisor |
| 873 | + (1.0 - decay_factor) * new_target_free_space_divisor); |
| 874 | else |
| 875 | /* Jump up. */ |
| 876 | target_free_space_divisor = new_target_free_space_divisor; |
| 877 | |
| 878 | #if HEURISTICS_DEBUG |
| 879 | fprintf (stderr, "new target divisor %f\n", target_free_space_divisor); |
| 880 | #endif |
| 881 | |
| 882 | if (free_space_divisor + 0.5 + hysteresis < target_free_space_divisor |
| 883 | || free_space_divisor - 0.5 - hysteresis > target_free_space_divisor) |
| 884 | { |
| 885 | free_space_divisor = lround (target_free_space_divisor); |
| 886 | #if HEURISTICS_DEBUG |
| 887 | fprintf (stderr, "new divisor %lu\n", free_space_divisor); |
| 888 | #endif |
| 889 | GC_set_free_space_divisor (free_space_divisor); |
| 890 | } |
| 891 | } |
| 892 | |
| 893 | prev_image_size = image_size; |
| 894 | prev_bytes_alloced = bytes_alloced; |
| 895 | |
| 896 | return NULL; |
| 897 | } |
| 898 | |
| 899 | /* The adjust_gc_frequency routine handles transients in the process |
| 900 | image size. It can't handle instense non-GC-managed steady-state |
| 901 | allocation though, as it decays the FSD at steady-state down to its |
| 902 | minimum value. |
| 903 | |
| 904 | The only real way to handle continuous, high non-GC allocation is to |
| 905 | let the GC know about it. This routine can handle non-GC allocation |
| 906 | rates that are similar in size to the GC-managed heap size. |
| 907 | */ |
| 908 | |
| 909 | void |
| 910 | scm_gc_register_allocation (size_t size) |
| 911 | { |
| 912 | scm_i_pthread_mutex_lock (&bytes_until_gc_lock); |
| 913 | if (bytes_until_gc - size > bytes_until_gc) |
| 914 | { |
| 915 | bytes_until_gc = GC_get_heap_size (); |
| 916 | scm_i_pthread_mutex_unlock (&bytes_until_gc_lock); |
| 917 | GC_gcollect (); |
| 918 | } |
| 919 | else |
| 920 | { |
| 921 | bytes_until_gc -= size; |
| 922 | scm_i_pthread_mutex_unlock (&bytes_until_gc_lock); |
| 923 | } |
| 924 | } |
| 925 | |
| 926 | |
| 927 | \f |
| 928 | |
| 929 | char const * |
| 930 | scm_i_tag_name (scm_t_bits tag) |
| 931 | { |
| 932 | switch (tag & 0x7f) /* 7 bits */ |
| 933 | { |
| 934 | case scm_tcs_struct: |
| 935 | return "struct"; |
| 936 | case scm_tcs_cons_imcar: |
| 937 | return "cons (immediate car)"; |
| 938 | case scm_tcs_cons_nimcar: |
| 939 | return "cons (non-immediate car)"; |
| 940 | case scm_tc7_pointer: |
| 941 | return "foreign"; |
| 942 | case scm_tc7_hashtable: |
| 943 | return "hashtable"; |
| 944 | case scm_tc7_fluid: |
| 945 | return "fluid"; |
| 946 | case scm_tc7_dynamic_state: |
| 947 | return "dynamic state"; |
| 948 | case scm_tc7_frame: |
| 949 | return "frame"; |
| 950 | case scm_tc7_objcode: |
| 951 | return "objcode"; |
| 952 | case scm_tc7_vm: |
| 953 | return "vm"; |
| 954 | case scm_tc7_vm_cont: |
| 955 | return "vm continuation"; |
| 956 | case scm_tc7_wvect: |
| 957 | return "weak vector"; |
| 958 | case scm_tc7_vector: |
| 959 | return "vector"; |
| 960 | case scm_tc7_number: |
| 961 | switch (tag) |
| 962 | { |
| 963 | case scm_tc16_real: |
| 964 | return "real"; |
| 965 | break; |
| 966 | case scm_tc16_big: |
| 967 | return "bignum"; |
| 968 | break; |
| 969 | case scm_tc16_complex: |
| 970 | return "complex number"; |
| 971 | break; |
| 972 | case scm_tc16_fraction: |
| 973 | return "fraction"; |
| 974 | break; |
| 975 | } |
| 976 | break; |
| 977 | case scm_tc7_string: |
| 978 | return "string"; |
| 979 | break; |
| 980 | case scm_tc7_stringbuf: |
| 981 | return "string buffer"; |
| 982 | break; |
| 983 | case scm_tc7_symbol: |
| 984 | return "symbol"; |
| 985 | break; |
| 986 | case scm_tc7_variable: |
| 987 | return "variable"; |
| 988 | break; |
| 989 | case scm_tc7_port: |
| 990 | return "port"; |
| 991 | break; |
| 992 | case scm_tc7_smob: |
| 993 | { |
| 994 | int k = 0xff & (tag >> 8); |
| 995 | return (scm_smobs[k].name); |
| 996 | } |
| 997 | break; |
| 998 | } |
| 999 | |
| 1000 | return NULL; |
| 1001 | } |
| 1002 | |
| 1003 | |
| 1004 | |
| 1005 | \f |
| 1006 | void |
| 1007 | scm_init_gc () |
| 1008 | { |
| 1009 | /* `GC_INIT ()' was invoked in `scm_storage_prehistory ()'. */ |
| 1010 | |
| 1011 | scm_after_gc_hook = scm_make_hook (SCM_INUM0); |
| 1012 | scm_c_define ("after-gc-hook", scm_after_gc_hook); |
| 1013 | |
| 1014 | /* When the async is to run, the cdr of the gc_async pair gets set to |
| 1015 | the asyncs queue of the current thread. */ |
| 1016 | after_gc_async_cell = scm_cons (scm_c_make_gsubr ("%after-gc-thunk", 0, 0, 0, |
| 1017 | after_gc_async_thunk), |
| 1018 | SCM_BOOL_F); |
| 1019 | |
| 1020 | scm_c_hook_add (&scm_before_gc_c_hook, queue_after_gc_hook, NULL, 0); |
| 1021 | scm_c_hook_add (&scm_before_gc_c_hook, start_gc_timer, NULL, 0); |
| 1022 | scm_c_hook_add (&scm_after_gc_c_hook, accumulate_gc_timer, NULL, 0); |
| 1023 | |
| 1024 | #if HAVE_GC_GET_HEAP_USAGE_SAFE |
| 1025 | /* GC_get_heap_usage does not take a lock, and so can run in the GC |
| 1026 | start hook. */ |
| 1027 | scm_c_hook_add (&scm_before_gc_c_hook, adjust_gc_frequency, NULL, 0); |
| 1028 | #else |
| 1029 | /* GC_get_heap_usage might take a lock (and did from 7.2alpha1 to |
| 1030 | 7.2alpha7), so call it in the after_gc_hook. */ |
| 1031 | scm_c_hook_add (&scm_after_gc_c_hook, adjust_gc_frequency, NULL, 0); |
| 1032 | #endif |
| 1033 | |
| 1034 | #ifdef HAVE_GC_SET_START_CALLBACK |
| 1035 | GC_set_start_callback (run_before_gc_c_hook); |
| 1036 | #endif |
| 1037 | |
| 1038 | #include "libguile/gc.x" |
| 1039 | } |
| 1040 | |
| 1041 | |
| 1042 | void |
| 1043 | scm_gc_sweep (void) |
| 1044 | #define FUNC_NAME "scm_gc_sweep" |
| 1045 | { |
| 1046 | /* FIXME */ |
| 1047 | fprintf (stderr, "%s: doing nothing\n", FUNC_NAME); |
| 1048 | } |
| 1049 | #undef FUNC_NAME |
| 1050 | |
| 1051 | /* |
| 1052 | Local Variables: |
| 1053 | c-file-style: "gnu" |
| 1054 | End: |
| 1055 | */ |