2 * Copyright 1988, 1989 Hans-J. Boehm, Alan J. Demers
3 * Copyright (c) 1991-1995 by Xerox Corporation. All rights reserved.
4 * Copyright 1996-1999 by Silicon Graphics. All rights reserved.
5 * Copyright 1999 by Hewlett-Packard Company. All rights reserved.
7 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
8 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
10 * Permission is hereby granted to use or copy this program
11 * for any purpose, provided the above notices are retained on all copies.
12 * Permission to modify the code and to distribute modified code is granted,
13 * provided the above notices are retained, and a notice that the code was
14 * modified is included with the above copyright notice.
18 * Note that this defines a large number of tuning hooks, which can
19 * safely be ignored in nearly all cases. For normal use it suffices
20 * to call only GC_MALLOC and perhaps GC_REALLOC.
21 * For better performance, also look at GC_MALLOC_ATOMIC, and
22 * GC_enable_incremental. If you need an action to be performed
23 * immediately before an object is collected, look at GC_register_finalizer.
24 * If you are using Solaris threads, look at the end of this file.
25 * Everything else is best ignored unless you encounter performance
34 * Some tests for old macros. These violate our namespace rules and will
35 * disappear shortly. Use the GC_ names.
37 #if defined(SOLARIS_THREADS) || defined(_SOLARIS_THREADS)
38 # define GC_SOLARIS_THREADS
40 #if defined(_SOLARIS_PTHREADS)
41 # define GC_SOLARIS_PTHREADS
43 #if defined(IRIX_THREADS)
44 # define GC_IRIX_THREADS
46 #if defined(HPUX_THREADS)
47 # define GC_HPUX_THREADS
49 #if defined(OSF1_THREADS)
50 # define GC_OSF1_THREADS
52 #if defined(LINUX_THREADS)
53 # define GC_LINUX_THREADS
55 #if defined(WIN32_THREADS)
56 # define GC_WIN32_THREADS
58 #if defined(USE_LD_WRAP)
59 # define GC_USE_LD_WRAP
62 #if !defined(_REENTRANT) && (defined(GC_SOLARIS_THREADS) \
63 || defined(GC_SOLARIS_PTHREADS) \
64 || defined(GC_HPUX_THREADS) \
65 || defined(GC_LINUX_THREADS))
67 /* Better late than never. This fails if system headers that */
68 /* depend on this were previously included. */
71 #if defined(GC_SOLARIS_PTHREADS) && !defined(GC_SOLARIS_THREADS)
72 # define GC_SOLARIS_THREADS
75 # if defined(GC_SOLARIS_PTHREADS) || defined(GC_FREEBSD_THREADS) || \
76 defined(GC_IRIX_THREADS) || defined(GC_LINUX_THREADS) || \
77 defined(GC_HPUX_THREADS) || defined(GC_OSF1_THREADS)
84 /* Yet more kluges for WinCE */
85 # include <stdlib.h> /* size_t is defined here */
86 typedef long ptrdiff_t; /* ptrdiff_t is not defined */
89 #if defined(__MINGW32__) && defined(GC_WIN32_THREADS)
91 # define GC_API __declspec(dllexport)
93 # define GC_API __declspec(dllimport)
97 #if (defined(__DMC__) || defined(_MSC_VER)) \
98 && (defined(_DLL) && !defined(GC_NOT_DLL) \
101 # define GC_API extern __declspec(dllexport)
103 # define GC_API __declspec(dllimport)
107 #if defined(__WATCOMC__) && defined(GC_DLL)
109 # define GC_API extern __declspec(dllexport)
111 # define GC_API extern __declspec(dllimport)
116 #define GC_API extern
119 # if defined(__STDC__) || defined(__cplusplus)
120 # define GC_PROTO(args) args
121 typedef void * GC_PTR;
122 # define GC_CONST const
124 # define GC_PROTO(args) ()
125 typedef char * GC_PTR;
134 /* Define word and signed_word to be unsigned and signed types of the */
135 /* size as char * or void *. There seems to be no way to do this */
136 /* even semi-portably. The following is probably no better/worse */
137 /* than almost anything else. */
138 /* The ANSI standard suggests that size_t and ptr_diff_t might be */
139 /* better choices. But those appear to have incorrect definitions */
140 /* on may systems. Notably "typedef int size_t" seems to be both */
141 /* frequent and WRONG. */
142 typedef unsigned long GC_word;
143 typedef long GC_signed_word;
145 /* Public read-only variables */
147 GC_API GC_word GC_gc_no;/* Counter incremented per collection. */
148 /* Includes empty GCs at startup. */
150 GC_API int GC_parallel; /* GC is parallelized for performance on */
151 /* multiprocessors. Currently set only */
152 /* implicitly if collector is built with */
153 /* -DPARALLEL_MARK and if either: */
154 /* Env variable GC_NPROC is set to > 1, or */
155 /* GC_NPROC is not set and this is an MP. */
156 /* If GC_parallel is set, incremental */
157 /* collection is aonly partially functional, */
158 /* and may not be desirable. */
161 /* Public R/W variables */
163 GC_API GC_PTR (*GC_oom_fn) GC_PROTO((size_t bytes_requested));
164 /* When there is insufficient memory to satisfy */
165 /* an allocation request, we return */
166 /* (*GC_oom_fn)(). By default this just */
168 /* If it returns, it must return 0 or a valid */
169 /* pointer to a previously allocated heap */
172 GC_API int GC_find_leak;
173 /* Do not actually garbage collect, but simply */
174 /* report inaccessible memory that was not */
175 /* deallocated with GC_free. Initial value */
176 /* is determined by FIND_LEAK macro. */
178 GC_API int GC_all_interior_pointers;
179 /* Arrange for pointers to object interiors to */
180 /* be recognized as valid. May not be changed */
181 /* after GC initialization. */
182 /* Initial value is determined by */
183 /* -DALL_INTERIOR_POINTERS. */
184 /* Unless DONT_ADD_BYTE_AT_END is defined, this */
185 /* also affects whether sizes are increased by */
186 /* at least a byte to allow "off the end" */
187 /* pointer recognition. */
188 /* MUST BE 0 or 1. */
190 GC_API int GC_quiet; /* Disable statistics output. Only matters if */
191 /* collector has been compiled with statistics */
192 /* enabled. This involves a performance cost, */
193 /* and is thus not the default. */
195 GC_API int GC_finalize_on_demand;
196 /* If nonzero, finalizers will only be run in */
197 /* response to an explicit GC_invoke_finalizers */
198 /* call. The default is determined by whether */
199 /* the FINALIZE_ON_DEMAND macro is defined */
200 /* when the collector is built. */
202 GC_API int GC_java_finalization;
203 /* Mark objects reachable from finalizable */
204 /* objects in a separate postpass. This makes */
205 /* it a bit safer to use non-topologically- */
206 /* ordered finalization. Default value is */
207 /* determined by JAVA_FINALIZATION macro. */
209 GC_API void (* GC_finalizer_notifier)();
210 /* Invoked by the collector when there are */
211 /* objects to be finalized. Invoked at most */
212 /* once per GC cycle. Never invoked unless */
213 /* GC_finalize_on_demand is set. */
214 /* Typically this will notify a finalization */
215 /* thread, which will call GC_invoke_finalizers */
218 GC_API int GC_dont_gc; /* Dont collect unless explicitly requested, e.g. */
219 /* because it's not safe. */
221 GC_API int GC_dont_expand;
222 /* Dont expand heap unless explicitly requested */
225 GC_API int GC_use_entire_heap;
226 /* Causes the nonincremental collector to use the */
227 /* entire heap before collecting. This was the only */
228 /* option for GC versions < 5.0. This sometimes */
229 /* results in more large block fragmentation, since */
230 /* very larg blocks will tend to get broken up */
231 /* during each GC cycle. It is likely to result in a */
232 /* larger working set, but lower collection */
233 /* frequencies, and hence fewer instructions executed */
234 /* in the collector. */
236 GC_API int GC_full_freq; /* Number of partial collections between */
237 /* full collections. Matters only if */
238 /* GC_incremental is set. */
239 /* Full collections are also triggered if */
240 /* the collector detects a substantial */
241 /* increase in the number of in-use heap */
242 /* blocks. Values in the tens are now */
243 /* perfectly reasonable, unlike for */
244 /* earlier GC versions. */
246 GC_API GC_word GC_non_gc_bytes;
247 /* Bytes not considered candidates for collection. */
248 /* Used only to control scheduling of collections. */
249 /* Updated by GC_malloc_uncollectable and GC_free. */
252 GC_API int GC_no_dls;
253 /* Don't register dynamic library data segments. */
254 /* Wizards only. Should be used only if the */
255 /* application explicitly registers all roots. */
256 /* In Microsoft Windows environments, this will */
257 /* usually also prevent registration of the */
258 /* main data segment as part of the root set. */
260 GC_API GC_word GC_free_space_divisor;
261 /* We try to make sure that we allocate at */
262 /* least N/GC_free_space_divisor bytes between */
263 /* collections, where N is the heap size plus */
264 /* a rough estimate of the root set size. */
265 /* Initially, GC_free_space_divisor = 4. */
266 /* Increasing its value will use less space */
267 /* but more collection time. Decreasing it */
268 /* will appreciably decrease collection time */
269 /* at the expense of space. */
270 /* GC_free_space_divisor = 1 will effectively */
271 /* disable collections. */
273 GC_API GC_word GC_max_retries;
274 /* The maximum number of GCs attempted before */
275 /* reporting out of memory after heap */
276 /* expansion fails. Initially 0. */
279 GC_API char *GC_stackbottom; /* Cool end of user stack. */
280 /* May be set in the client prior to */
281 /* calling any GC_ routines. This */
282 /* avoids some overhead, and */
283 /* potentially some signals that can */
284 /* confuse debuggers. Otherwise the */
285 /* collector attempts to set it */
287 /* For multithreaded code, this is the */
288 /* cold end of the stack for the */
289 /* primordial thread. */
291 GC_API int GC_dont_precollect; /* Don't collect as part of */
292 /* initialization. Should be set only */
293 /* if the client wants a chance to */
294 /* manually initialize the root set */
295 /* before the first collection. */
296 /* Interferes with blacklisting. */
299 /* Public procedures */
301 * general purpose allocation routines, with roughly malloc calling conv.
302 * The atomic versions promise that no relevant pointers are contained
303 * in the object. The nonatomic versions guarantee that the new object
304 * is cleared. GC_malloc_stubborn promises that no changes to the object
305 * will occur after GC_end_stubborn_change has been called on the
306 * result of GC_malloc_stubborn. GC_malloc_uncollectable allocates an object
307 * that is scanned for pointers to collectable objects, but is not itself
308 * collectable. The object is scanned even if it does not appear to
309 * be reachable. GC_malloc_uncollectable and GC_free called on the resulting
310 * object implicitly update GC_non_gc_bytes appropriately.
312 * Note that the GC_malloc_stubborn support is stubbed out by default
313 * starting in 6.0. GC_malloc_stubborn is an alias for GC_malloc unless
314 * the collector is built with STUBBORN_ALLOC defined.
316 GC_API GC_PTR GC_malloc GC_PROTO((size_t size_in_bytes));
317 GC_API GC_PTR GC_malloc_atomic GC_PROTO((size_t size_in_bytes));
318 GC_API GC_PTR GC_malloc_uncollectable GC_PROTO((size_t size_in_bytes));
319 GC_API GC_PTR GC_malloc_stubborn GC_PROTO((size_t size_in_bytes));
321 /* The following is only defined if the library has been suitably */
323 GC_API GC_PTR GC_malloc_atomic_uncollectable GC_PROTO((size_t size_in_bytes));
325 /* Explicitly deallocate an object. Dangerous if used incorrectly. */
326 /* Requires a pointer to the base of an object. */
327 /* If the argument is stubborn, it should not be changeable when freed. */
328 /* An object should not be enable for finalization when it is */
329 /* explicitly deallocated. */
330 /* GC_free(0) is a no-op, as required by ANSI C for free. */
331 GC_API void GC_free GC_PROTO((GC_PTR object_addr));
334 * Stubborn objects may be changed only if the collector is explicitly informed.
335 * The collector is implicitly informed of coming change when such
336 * an object is first allocated. The following routines inform the
337 * collector that an object will no longer be changed, or that it will
338 * once again be changed. Only nonNIL pointer stores into the object
339 * are considered to be changes. The argument to GC_end_stubborn_change
340 * must be exacly the value returned by GC_malloc_stubborn or passed to
341 * GC_change_stubborn. (In the second case it may be an interior pointer
342 * within 512 bytes of the beginning of the objects.)
343 * There is a performance penalty for allowing more than
344 * one stubborn object to be changed at once, but it is acceptable to
345 * do so. The same applies to dropping stubborn objects that are still
348 GC_API void GC_change_stubborn GC_PROTO((GC_PTR));
349 GC_API void GC_end_stubborn_change GC_PROTO((GC_PTR));
351 /* Return a pointer to the base (lowest address) of an object given */
352 /* a pointer to a location within the object. */
353 /* I.e. map an interior pointer to the corresponding bas pointer. */
354 /* Note that with debugging allocation, this returns a pointer to the */
355 /* actual base of the object, i.e. the debug information, not to */
356 /* the base of the user object. */
357 /* Return 0 if displaced_pointer doesn't point to within a valid */
359 GC_API GC_PTR GC_base GC_PROTO((GC_PTR displaced_pointer));
361 /* Given a pointer to the base of an object, return its size in bytes. */
362 /* The returned size may be slightly larger than what was originally */
364 GC_API size_t GC_size GC_PROTO((GC_PTR object_addr));
366 /* For compatibility with C library. This is occasionally faster than */
367 /* a malloc followed by a bcopy. But if you rely on that, either here */
368 /* or with the standard C library, your code is broken. In my */
369 /* opinion, it shouldn't have been invented, but now we're stuck. -HB */
370 /* The resulting object has the same kind as the original. */
371 /* If the argument is stubborn, the result will have changes enabled. */
372 /* It is an error to have changes enabled for the original object. */
373 /* Follows ANSI comventions for NULL old_object. */
374 GC_API GC_PTR GC_realloc
375 GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes));
377 /* Explicitly increase the heap size. */
378 /* Returns 0 on failure, 1 on success. */
379 GC_API int GC_expand_hp GC_PROTO((size_t number_of_bytes));
381 /* Limit the heap size to n bytes. Useful when you're debugging, */
382 /* especially on systems that don't handle running out of memory well. */
383 /* n == 0 ==> unbounded. This is the default. */
384 GC_API void GC_set_max_heap_size GC_PROTO((GC_word n));
386 /* Inform the collector that a certain section of statically allocated */
387 /* memory contains no pointers to garbage collected memory. Thus it */
388 /* need not be scanned. This is sometimes important if the application */
389 /* maps large read/write files into the address space, which could be */
390 /* mistaken for dynamic library data segments on some systems. */
391 GC_API void GC_exclude_static_roots GC_PROTO((GC_PTR start, GC_PTR finish));
393 /* Clear the set of root segments. Wizards only. */
394 GC_API void GC_clear_roots GC_PROTO((void));
396 /* Add a root segment. Wizards only. */
397 GC_API void GC_add_roots GC_PROTO((char * low_address,
398 char * high_address_plus_1));
400 /* Add a displacement to the set of those considered valid by the */
401 /* collector. GC_register_displacement(n) means that if p was returned */
402 /* by GC_malloc, then (char *)p + n will be considered to be a valid */
403 /* pointer to n. N must be small and less than the size of p. */
404 /* (All pointers to the interior of objects from the stack are */
405 /* considered valid in any case. This applies to heap objects and */
407 /* Preferably, this should be called before any other GC procedures. */
408 /* Calling it later adds to the probability of excess memory */
410 /* This is a no-op if the collector was compiled with recognition of */
411 /* arbitrary interior pointers enabled, which is now the default. */
412 GC_API void GC_register_displacement GC_PROTO((GC_word n));
414 /* The following version should be used if any debugging allocation is */
416 GC_API void GC_debug_register_displacement GC_PROTO((GC_word n));
418 /* Explicitly trigger a full, world-stop collection. */
419 GC_API void GC_gcollect GC_PROTO((void));
421 /* Trigger a full world-stopped collection. Abort the collection if */
422 /* and when stop_func returns a nonzero value. Stop_func will be */
423 /* called frequently, and should be reasonably fast. This works even */
424 /* if virtual dirty bits, and hence incremental collection is not */
425 /* available for this architecture. Collections can be aborted faster */
426 /* than normal pause times for incremental collection. However, */
427 /* aborted collections do no useful work; the next collection needs */
428 /* to start from the beginning. */
429 /* Return 0 if the collection was aborted, 1 if it succeeded. */
430 typedef int (* GC_stop_func) GC_PROTO((void));
431 GC_API int GC_try_to_collect GC_PROTO((GC_stop_func stop_func));
433 /* Return the number of bytes in the heap. Excludes collector private */
434 /* data structures. Includes empty blocks and fragmentation loss. */
435 /* Includes some pages that were allocated but never written. */
436 GC_API size_t GC_get_heap_size GC_PROTO((void));
438 /* Return a lower bound on the number of free bytes in the heap. */
439 GC_API size_t GC_get_free_bytes GC_PROTO((void));
441 /* Return the number of bytes allocated since the last collection. */
442 GC_API size_t GC_get_bytes_since_gc GC_PROTO((void));
444 /* Return the total number of bytes allocated in this process. */
445 /* Never decreases. */
446 GC_API size_t GC_get_total_bytes GC_PROTO((void));
448 /* Enable incremental/generational collection. */
449 /* Not advisable unless dirty bits are */
450 /* available or most heap objects are */
451 /* pointerfree(atomic) or immutable. */
452 /* Don't use in leak finding mode. */
453 /* Ignored if GC_dont_gc is true. */
454 /* Only the generational piece of this is */
455 /* functional if GC_parallel is TRUE. */
456 GC_API void GC_enable_incremental GC_PROTO((void));
458 /* Perform some garbage collection work, if appropriate. */
459 /* Return 0 if there is no more work to be done. */
460 /* Typically performs an amount of work corresponding roughly */
461 /* to marking from one page. May do more work if further */
462 /* progress requires it, e.g. if incremental collection is */
463 /* disabled. It is reasonable to call this in a wait loop */
464 /* until it returns 0. */
465 GC_API int GC_collect_a_little GC_PROTO((void));
467 /* Allocate an object of size lb bytes. The client guarantees that */
468 /* as long as the object is live, it will be referenced by a pointer */
469 /* that points to somewhere within the first 256 bytes of the object. */
470 /* (This should normally be declared volatile to prevent the compiler */
471 /* from invalidating this assertion.) This routine is only useful */
472 /* if a large array is being allocated. It reduces the chance of */
473 /* accidentally retaining such an array as a result of scanning an */
474 /* integer that happens to be an address inside the array. (Actually, */
475 /* it reduces the chance of the allocator not finding space for such */
476 /* an array, since it will try hard to avoid introducing such a false */
477 /* reference.) On a SunOS 4.X or MS Windows system this is recommended */
478 /* for arrays likely to be larger than 100K or so. For other systems, */
479 /* or if the collector is not configured to recognize all interior */
480 /* pointers, the threshold is normally much higher. */
481 GC_API GC_PTR GC_malloc_ignore_off_page GC_PROTO((size_t lb));
482 GC_API GC_PTR GC_malloc_atomic_ignore_off_page GC_PROTO((size_t lb));
484 #if defined(__sgi) && !defined(__GNUC__) && _COMPILER_VERSION >= 720
485 # define GC_ADD_CALLER
486 # define GC_RETURN_ADDR (GC_word)__return_address
490 # define GC_EXTRAS GC_RETURN_ADDR, __FILE__, __LINE__
491 # define GC_EXTRA_PARAMS GC_word ra, GC_CONST char * s, int i
493 # define GC_EXTRAS __FILE__, __LINE__
494 # define GC_EXTRA_PARAMS GC_CONST char * s, int i
497 /* Debugging (annotated) allocation. GC_gcollect will check */
498 /* objects allocated in this way for overwrites, etc. */
499 GC_API GC_PTR GC_debug_malloc
500 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
501 GC_API GC_PTR GC_debug_malloc_atomic
502 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
503 GC_API GC_PTR GC_debug_malloc_uncollectable
504 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
505 GC_API GC_PTR GC_debug_malloc_stubborn
506 GC_PROTO((size_t size_in_bytes, GC_EXTRA_PARAMS));
507 GC_API void GC_debug_free GC_PROTO((GC_PTR object_addr));
508 GC_API GC_PTR GC_debug_realloc
509 GC_PROTO((GC_PTR old_object, size_t new_size_in_bytes,
512 GC_API void GC_debug_change_stubborn GC_PROTO((GC_PTR));
513 GC_API void GC_debug_end_stubborn_change GC_PROTO((GC_PTR));
515 # define GC_MALLOC(sz) GC_debug_malloc(sz, GC_EXTRAS)
516 # define GC_MALLOC_ATOMIC(sz) GC_debug_malloc_atomic(sz, GC_EXTRAS)
517 # define GC_MALLOC_UNCOLLECTABLE(sz) GC_debug_malloc_uncollectable(sz, \
519 # define GC_REALLOC(old, sz) GC_debug_realloc(old, sz, GC_EXTRAS)
520 # define GC_FREE(p) GC_debug_free(p)
521 # define GC_REGISTER_FINALIZER(p, f, d, of, od) \
522 GC_debug_register_finalizer(p, f, d, of, od)
523 # define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
524 GC_debug_register_finalizer_ignore_self(p, f, d, of, od)
525 # define GC_REGISTER_FINALIZER_NO_ORDER(p, f, d, of, od) \
526 GC_debug_register_finalizer_no_order(p, f, d, of, od)
527 # define GC_MALLOC_STUBBORN(sz) GC_debug_malloc_stubborn(sz, GC_EXTRAS);
528 # define GC_CHANGE_STUBBORN(p) GC_debug_change_stubborn(p)
529 # define GC_END_STUBBORN_CHANGE(p) GC_debug_end_stubborn_change(p)
530 # define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
531 GC_general_register_disappearing_link(link, GC_base(obj))
532 # define GC_REGISTER_DISPLACEMENT(n) GC_debug_register_displacement(n)
534 # define GC_MALLOC(sz) GC_malloc(sz)
535 # define GC_MALLOC_ATOMIC(sz) GC_malloc_atomic(sz)
536 # define GC_MALLOC_UNCOLLECTABLE(sz) GC_malloc_uncollectable(sz)
537 # define GC_REALLOC(old, sz) GC_realloc(old, sz)
538 # define GC_FREE(p) GC_free(p)
539 # define GC_REGISTER_FINALIZER(p, f, d, of, od) \
540 GC_register_finalizer(p, f, d, of, od)
541 # define GC_REGISTER_FINALIZER_IGNORE_SELF(p, f, d, of, od) \
542 GC_register_finalizer_ignore_self(p, f, d, of, od)
543 # define GC_REGISTER_FINALIZER_NO_ORDER(p, f, d, of, od) \
544 GC_register_finalizer_no_order(p, f, d, of, od)
545 # define GC_MALLOC_STUBBORN(sz) GC_malloc_stubborn(sz)
546 # define GC_CHANGE_STUBBORN(p) GC_change_stubborn(p)
547 # define GC_END_STUBBORN_CHANGE(p) GC_end_stubborn_change(p)
548 # define GC_GENERAL_REGISTER_DISAPPEARING_LINK(link, obj) \
549 GC_general_register_disappearing_link(link, obj)
550 # define GC_REGISTER_DISPLACEMENT(n) GC_register_displacement(n)
552 /* The following are included because they are often convenient, and */
553 /* reduce the chance for a misspecifed size argument. But calls may */
554 /* expand to something syntactically incorrect if t is a complicated */
555 /* type expression. */
556 # define GC_NEW(t) (t *)GC_MALLOC(sizeof (t))
557 # define GC_NEW_ATOMIC(t) (t *)GC_MALLOC_ATOMIC(sizeof (t))
558 # define GC_NEW_STUBBORN(t) (t *)GC_MALLOC_STUBBORN(sizeof (t))
559 # define GC_NEW_UNCOLLECTABLE(t) (t *)GC_MALLOC_UNCOLLECTABLE(sizeof (t))
561 /* Finalization. Some of these primitives are grossly unsafe. */
562 /* The idea is to make them both cheap, and sufficient to build */
563 /* a safer layer, closer to PCedar finalization. */
564 /* The interface represents my conclusions from a long discussion */
565 /* with Alan Demers, Dan Greene, Carl Hauser, Barry Hayes, */
566 /* Christian Jacobi, and Russ Atkinson. It's not perfect, and */
567 /* probably nobody else agrees with it. Hans-J. Boehm 3/13/92 */
568 typedef void (*GC_finalization_proc)
569 GC_PROTO((GC_PTR obj, GC_PTR client_data));
571 GC_API void GC_register_finalizer
572 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
573 GC_finalization_proc *ofn, GC_PTR *ocd));
574 GC_API void GC_debug_register_finalizer
575 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
576 GC_finalization_proc *ofn, GC_PTR *ocd));
577 /* When obj is no longer accessible, invoke */
578 /* (*fn)(obj, cd). If a and b are inaccessible, and */
579 /* a points to b (after disappearing links have been */
580 /* made to disappear), then only a will be */
581 /* finalized. (If this does not create any new */
582 /* pointers to b, then b will be finalized after the */
583 /* next collection.) Any finalizable object that */
584 /* is reachable from itself by following one or more */
585 /* pointers will not be finalized (or collected). */
586 /* Thus cycles involving finalizable objects should */
587 /* be avoided, or broken by disappearing links. */
588 /* All but the last finalizer registered for an object */
590 /* Finalization may be removed by passing 0 as fn. */
591 /* Finalizers are implicitly unregistered just before */
592 /* they are invoked. */
593 /* The old finalizer and client data are stored in */
595 /* Fn is never invoked on an accessible object, */
596 /* provided hidden pointers are converted to real */
597 /* pointers only if the allocation lock is held, and */
598 /* such conversions are not performed by finalization */
600 /* If GC_register_finalizer is aborted as a result of */
601 /* a signal, the object may be left with no */
602 /* finalization, even if neither the old nor new */
603 /* finalizer were NULL. */
604 /* Obj should be the nonNULL starting address of an */
605 /* object allocated by GC_malloc or friends. */
606 /* Note that any garbage collectable object referenced */
607 /* by cd will be considered accessible until the */
608 /* finalizer is invoked. */
610 /* Another versions of the above follow. It ignores */
611 /* self-cycles, i.e. pointers from a finalizable object to */
612 /* itself. There is a stylistic argument that this is wrong, */
613 /* but it's unavoidable for C++, since the compiler may */
614 /* silently introduce these. It's also benign in that specific */
616 /* Note that cd will still be viewed as accessible, even if it */
617 /* refers to the object itself. */
618 GC_API void GC_register_finalizer_ignore_self
619 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
620 GC_finalization_proc *ofn, GC_PTR *ocd));
621 GC_API void GC_debug_register_finalizer_ignore_self
622 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
623 GC_finalization_proc *ofn, GC_PTR *ocd));
625 /* Another version of the above. It ignores all cycles. */
626 /* It should probably only be used by Java implementations. */
627 /* Note that cd will still be viewed as accessible, even if it */
628 /* refers to the object itself. */
629 GC_API void GC_register_finalizer_no_order
630 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
631 GC_finalization_proc *ofn, GC_PTR *ocd));
632 GC_API void GC_debug_register_finalizer_no_order
633 GC_PROTO((GC_PTR obj, GC_finalization_proc fn, GC_PTR cd,
634 GC_finalization_proc *ofn, GC_PTR *ocd));
637 /* The following routine may be used to break cycles between */
638 /* finalizable objects, thus causing cyclic finalizable */
639 /* objects to be finalized in the correct order. Standard */
640 /* use involves calling GC_register_disappearing_link(&p), */
641 /* where p is a pointer that is not followed by finalization */
642 /* code, and should not be considered in determining */
643 /* finalization order. */
644 GC_API int GC_register_disappearing_link GC_PROTO((GC_PTR * /* link */));
645 /* Link should point to a field of a heap allocated */
646 /* object obj. *link will be cleared when obj is */
647 /* found to be inaccessible. This happens BEFORE any */
648 /* finalization code is invoked, and BEFORE any */
649 /* decisions about finalization order are made. */
650 /* This is useful in telling the finalizer that */
651 /* some pointers are not essential for proper */
652 /* finalization. This may avoid finalization cycles. */
653 /* Note that obj may be resurrected by another */
654 /* finalizer, and thus the clearing of *link may */
655 /* be visible to non-finalization code. */
656 /* There's an argument that an arbitrary action should */
657 /* be allowed here, instead of just clearing a pointer. */
658 /* But this causes problems if that action alters, or */
659 /* examines connectivity. */
660 /* Returns 1 if link was already registered, 0 */
662 /* Only exists for backward compatibility. See below: */
664 GC_API int GC_general_register_disappearing_link
665 GC_PROTO((GC_PTR * /* link */, GC_PTR obj));
666 /* A slight generalization of the above. *link is */
667 /* cleared when obj first becomes inaccessible. This */
668 /* can be used to implement weak pointers easily and */
669 /* safely. Typically link will point to a location */
670 /* holding a disguised pointer to obj. (A pointer */
671 /* inside an "atomic" object is effectively */
672 /* disguised.) In this way soft */
673 /* pointers are broken before any object */
674 /* reachable from them are finalized. Each link */
675 /* May be registered only once, i.e. with one obj */
676 /* value. This was added after a long email discussion */
677 /* with John Ellis. */
678 /* Obj must be a pointer to the first word of an object */
679 /* we allocated. It is unsafe to explicitly deallocate */
680 /* the object containing link. Explicitly deallocating */
681 /* obj may or may not cause link to eventually be */
683 GC_API int GC_unregister_disappearing_link GC_PROTO((GC_PTR * /* link */));
684 /* Returns 0 if link was not actually registered. */
685 /* Undoes a registration by either of the above two */
688 /* Auxiliary fns to make finalization work correctly with displaced */
689 /* pointers introduced by the debugging allocators. */
690 GC_API GC_PTR GC_make_closure GC_PROTO((GC_finalization_proc fn, GC_PTR data));
691 GC_API void GC_debug_invoke_finalizer GC_PROTO((GC_PTR obj, GC_PTR data));
693 /* Returns !=0 if GC_invoke_finalizers has something to do. */
694 GC_API int GC_should_invoke_finalizers GC_PROTO((void));
696 GC_API int GC_invoke_finalizers GC_PROTO((void));
697 /* Run finalizers for all objects that are ready to */
698 /* be finalized. Return the number of finalizers */
699 /* that were run. Normally this is also called */
700 /* implicitly during some allocations. If */
701 /* GC-finalize_on_demand is nonzero, it must be called */
704 /* GC_set_warn_proc can be used to redirect or filter warning messages. */
705 /* p may not be a NULL pointer. */
706 typedef void (*GC_warn_proc) GC_PROTO((char *msg, GC_word arg));
707 GC_API GC_warn_proc GC_set_warn_proc GC_PROTO((GC_warn_proc p));
708 /* Returns old warning procedure. */
710 /* The following is intended to be used by a higher level */
711 /* (e.g. Java-like) finalization facility. It is expected */
712 /* that finalization code will arrange for hidden pointers to */
713 /* disappear. Otherwise objects can be accessed after they */
714 /* have been collected. */
715 /* Note that putting pointers in atomic objects or in */
716 /* nonpointer slots of "typed" objects is equivalent to */
717 /* disguising them in this way, and may have other advantages. */
718 # if defined(I_HIDE_POINTERS) || defined(GC_I_HIDE_POINTERS)
719 typedef GC_word GC_hidden_pointer;
720 # define HIDE_POINTER(p) (~(GC_hidden_pointer)(p))
721 # define REVEAL_POINTER(p) ((GC_PTR)(HIDE_POINTER(p)))
722 /* Converting a hidden pointer to a real pointer requires verifying */
723 /* that the object still exists. This involves acquiring the */
724 /* allocator lock to avoid a race with the collector. */
725 # endif /* I_HIDE_POINTERS */
727 typedef GC_PTR (*GC_fn_type) GC_PROTO((GC_PTR client_data));
728 GC_API GC_PTR GC_call_with_alloc_lock
729 GC_PROTO((GC_fn_type fn, GC_PTR client_data));
731 /* The following routines are primarily intended for use with a */
732 /* preprocessor which inserts calls to check C pointer arithmetic. */
734 /* Check that p and q point to the same object. */
735 /* Fail conspicuously if they don't. */
736 /* Returns the first argument. */
737 /* Succeeds if neither p nor q points to the heap. */
738 /* May succeed if both p and q point to between heap objects. */
739 GC_API GC_PTR GC_same_obj GC_PROTO((GC_PTR p, GC_PTR q));
741 /* Checked pointer pre- and post- increment operations. Note that */
742 /* the second argument is in units of bytes, not multiples of the */
743 /* object size. This should either be invoked from a macro, or the */
744 /* call should be automatically generated. */
745 GC_API GC_PTR GC_pre_incr GC_PROTO((GC_PTR *p, size_t how_much));
746 GC_API GC_PTR GC_post_incr GC_PROTO((GC_PTR *p, size_t how_much));
748 /* Check that p is visible */
749 /* to the collector as a possibly pointer containing location. */
750 /* If it isn't fail conspicuously. */
751 /* Returns the argument in all cases. May erroneously succeed */
752 /* in hard cases. (This is intended for debugging use with */
753 /* untyped allocations. The idea is that it should be possible, though */
754 /* slow, to add such a call to all indirect pointer stores.) */
755 /* Currently useless for multithreaded worlds. */
756 GC_API GC_PTR GC_is_visible GC_PROTO((GC_PTR p));
758 /* Check that if p is a pointer to a heap page, then it points to */
759 /* a valid displacement within a heap object. */
760 /* Fail conspicuously if this property does not hold. */
761 /* Uninteresting with GC_all_interior_pointers. */
762 /* Always returns its argument. */
763 GC_API GC_PTR GC_is_valid_displacement GC_PROTO((GC_PTR p));
765 /* Safer, but slow, pointer addition. Probably useful mainly with */
766 /* a preprocessor. Useful only for heap pointers. */
768 # define GC_PTR_ADD3(x, n, type_of_result) \
769 ((type_of_result)GC_same_obj((x)+(n), (x)))
770 # define GC_PRE_INCR3(x, n, type_of_result) \
771 ((type_of_result)GC_pre_incr(&(x), (n)*sizeof(*x))
772 # define GC_POST_INCR2(x, type_of_result) \
773 ((type_of_result)GC_post_incr(&(x), sizeof(*x))
775 # define GC_PTR_ADD(x, n) \
776 GC_PTR_ADD3(x, n, typeof(x))
777 # define GC_PRE_INCR(x, n) \
778 GC_PRE_INCR3(x, n, typeof(x))
779 # define GC_POST_INCR(x, n) \
780 GC_POST_INCR3(x, typeof(x))
782 /* We can't do this right without typeof, which ANSI */
783 /* decided was not sufficiently useful. Repeatedly */
784 /* mentioning the arguments seems too dangerous to be */
785 /* useful. So does not casting the result. */
786 # define GC_PTR_ADD(x, n) ((x)+(n))
788 #else /* !GC_DEBUG */
789 # define GC_PTR_ADD3(x, n, type_of_result) ((x)+(n))
790 # define GC_PTR_ADD(x, n) ((x)+(n))
791 # define GC_PRE_INCR3(x, n, type_of_result) ((x) += (n))
792 # define GC_PRE_INCR(x, n) ((x) += (n))
793 # define GC_POST_INCR2(x, n, type_of_result) ((x)++)
794 # define GC_POST_INCR(x, n) ((x)++)
797 /* Safer assignment of a pointer to a nonstack location. */
800 # define GC_PTR_STORE(p, q) \
801 (*(void **)GC_is_visible(p) = GC_is_valid_displacement(q))
803 # define GC_PTR_STORE(p, q) \
804 (*(char **)GC_is_visible(p) = GC_is_valid_displacement(q))
806 #else /* !GC_DEBUG */
807 # define GC_PTR_STORE(p, q) *((p) = (q))
810 /* Fynctions called to report pointer checking errors */
811 GC_API void (*GC_same_obj_print_proc) GC_PROTO((GC_PTR p, GC_PTR q));
813 GC_API void (*GC_is_valid_displacement_print_proc)
814 GC_PROTO((GC_PTR p));
816 GC_API void (*GC_is_visible_print_proc)
817 GC_PROTO((GC_PTR p));
820 /* For pthread support, we generally need to intercept a number of */
821 /* thread library calls. We do that here by macro defining them. */
823 #if !defined(GC_USE_LD_WRAP) && \
824 (defined(GC_PTHREADS) || defined(GC_SOLARIS_THREADS))
825 # include "gc_pthread_redirects.h"
828 # if defined(PCR) || defined(GC_SOLARIS_THREADS) || \
829 defined(GC_PTHREADS) || defined(GC_WIN32_THREADS)
830 /* Any flavor of threads except SRC_M3. */
831 /* This returns a list of objects, linked through their first */
832 /* word. Its use can greatly reduce lock contention problems, since */
833 /* the allocation lock can be acquired and released many fewer times. */
834 /* lb must be large enough to hold the pointer field. */
835 /* It is used internally by gc_local_alloc.h, which provides a simpler */
836 /* programming interface on Linux. */
837 GC_PTR GC_malloc_many(size_t lb);
838 #define GC_NEXT(p) (*(GC_PTR *)(p)) /* Retrieve the next element */
839 /* in returned list. */
840 extern void GC_thr_init(); /* Needed for Solaris/X86 */
842 #endif /* THREADS && !SRC_M3 */
844 #if defined(GC_WIN32_THREADS) && defined(_WIN32_WCE)
845 # include <windows.h>
848 * win32_threads.c implements the real WinMain, which will start a new thread
849 * to call GC_WinMain after initializing the garbage collector.
851 int WINAPI GC_WinMain(
853 HINSTANCE hPrevInstance,
858 * All threads must be created using GC_CreateThread, so that they will be
859 * recorded in the thread table.
861 HANDLE WINAPI GC_CreateThread(
862 LPSECURITY_ATTRIBUTES lpThreadAttributes,
863 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
864 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId );
867 # define WinMain GC_WinMain
868 # define CreateThread GC_CreateThread
874 * If you are planning on putting
875 * the collector in a SunOS 5 dynamic library, you need to call GC_INIT()
876 * from the statically loaded program section.
877 * This circumvents a Solaris 2.X (X<=4) linker bug.
879 #if defined(sparc) || defined(__sparc)
880 # define GC_INIT() { extern end, etext; \
881 GC_noop(&end, &etext); }
883 # if defined(__CYGWIN32__) && defined(GC_USE_DLL)
885 * Similarly gnu-win32 DLLs need explicit initialization
887 # define GC_INIT() { GC_add_roots(DATASTART, DATAEND); }
893 #if !defined(_WIN32_WCE) \
894 && ((defined(_MSDOS) || defined(_MSC_VER)) && (_M_IX86 >= 300) \
895 || defined(_WIN32) && !defined(__CYGWIN32__) && !defined(__CYGWIN__))
896 /* win32S may not free all resources on process exit. */
897 /* This explicitly deallocates the heap. */
898 GC_API void GC_win32_free_heap ();
901 #if ( defined(_AMIGA) && !defined(GC_AMIGA_MAKINGLIB) )
902 /* Allocation really goes through GC_amiga_allocwrapper_do */
903 # include "gc_amiga_redirects.h"
906 #if defined(GC_REDIRECT_TO_LOCAL) && !defined(GC_LOCAL_ALLOC_H)
907 # include "gc_local_alloc.h"
911 } /* end of extern "C" */
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