1 #if defined(GC_WIN32_THREADS)
3 #include "private/gc_priv.h"
9 /* Cygwin-specific forward decls */
10 # undef pthread_create
11 # undef pthread_sigmask
15 # define DEBUG_CYGWIN_THREADS 0
17 void * GC_start_routine(void * arg);
18 void GC_thread_exit_proc(void *arg);
22 /* The type of the first argument to InterlockedExchange. */
23 /* Documented to be LONG volatile *, but at least gcc likes */
28 # define MAX_THREADS 256
30 /* Things may get quite slow for large numbers of threads, */
31 /* since we look them up with sequential search. */
34 GC_bool GC_thr_initialized = FALSE;
36 DWORD GC_main_thread = 0;
38 struct GC_thread_Rep {
39 LONG in_use; /* Updated without lock. */
40 /* We assert that unused */
41 /* entries have invalid ids of */
42 /* zero and zero stack fields. */
45 ptr_t stack_base; /* The cold end of the stack. */
46 /* 0 ==> entry not valid. */
47 /* !in_use ==> stack_base == 0 */
51 void *status; /* hold exit value until join in case it's a pointer */
53 short flags; /* Protected by GC lock. */
54 # define FINISHED 1 /* Thread has exited. */
55 # define DETACHED 2 /* Thread is intended to be detached. */
59 typedef volatile struct GC_thread_Rep * GC_thread;
62 * We generally assume that volatile ==> memory ordering, at least among
66 volatile GC_bool GC_please_stop = FALSE;
68 volatile struct GC_thread_Rep thread_table[MAX_THREADS];
70 volatile LONG GC_max_thread_index = 0; /* Largest index in thread_table */
71 /* that was ever used. */
73 extern LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
75 int GC_thread_is_registered (void)
81 * This may be called from DllMain, and hence operates under unusual
84 static GC_thread GC_new_thread(void) {
86 /* It appears to be unsafe to acquire a lock here, since this */
87 /* code is apparently not preeemptible on some systems. */
88 /* (This is based on complaints, not on Microsoft's official */
89 /* documentation, which says this should perform "only simple */
90 /* initialization tasks".) */
91 /* Hence we make do with nonblocking synchronization. */
93 /* The following should be a noop according to the win32 */
94 /* documentation. There is empirical evidence that it */
96 # if defined(MPROTECT_VDB)
97 if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
99 /* cast away volatile qualifier */
100 for (i = 0; InterlockedExchange((IE_t)&thread_table[i].in_use,1) != 0; i++) {
101 /* Compare-and-swap would make this cleaner, but that's not */
102 /* supported before Windows 98 and NT 4.0. In Windows 2000, */
103 /* InterlockedExchange is supposed to be replaced by */
104 /* InterlockedExchangePointer, but that's not really what I */
106 if (i == MAX_THREADS - 1)
107 ABORT("too many threads");
109 /* Update GC_max_thread_index if necessary. The following is safe, */
110 /* and unlike CompareExchange-based solutions seems to work on all */
111 /* Windows95 and later platforms. */
112 /* Unfortunately, GC_max_thread_index may be temporarily out of */
113 /* bounds, so readers have to compensate. */
114 while (i > GC_max_thread_index) {
115 InterlockedIncrement((IE_t)&GC_max_thread_index);
117 if (GC_max_thread_index >= MAX_THREADS) {
118 /* We overshot due to simultaneous increments. */
119 /* Setting it to MAX_THREADS-1 is always safe. */
120 GC_max_thread_index = MAX_THREADS - 1;
124 thread_table[i].pthread_id = pthread_self();
126 if (!DuplicateHandle(GetCurrentProcess(),
129 (HANDLE*)&thread_table[i].handle,
132 DUPLICATE_SAME_ACCESS)) {
133 DWORD last_error = GetLastError();
134 GC_printf1("Last error code: %lx\n", last_error);
135 ABORT("DuplicateHandle failed");
137 thread_table[i].stack_base = GC_get_stack_base();
138 /* Up until this point, GC_push_all_stacks considers this thread */
140 if (thread_table[i].stack_base == NULL)
141 ABORT("Failed to find stack base in GC_new_thread");
142 /* Up until this point, this entry is viewed as reserved but invalid */
143 /* by GC_delete_thread. */
144 thread_table[i].id = GetCurrentThreadId();
145 /* If this thread is being created while we are trying to stop */
146 /* the world, wait here. Hopefully this can't happen on any */
147 /* systems that don't allow us to block here. */
148 while (GC_please_stop) Sleep(20);
149 return thread_table + i;
153 * GC_max_thread_index may temporarily be larger than MAX_THREADS.
154 * To avoid subscript errors, we check on access.
159 LONG GC_get_max_thread_index()
161 LONG my_max = GC_max_thread_index;
163 if (my_max >= MAX_THREADS) return MAX_THREADS-1;
167 /* This is intended to be lock-free, though that */
168 /* assumes that the CloseHandle becomes visible before the */
169 /* in_use assignment. */
170 static void GC_delete_gc_thread(GC_thread thr)
172 CloseHandle(thr->handle);
173 /* cast away volatile qualifier */
178 # endif /* CYGWIN32 */
182 static void GC_delete_thread(DWORD thread_id) {
184 LONG my_max = GC_get_max_thread_index();
188 (!thread_table[i].in_use || thread_table[i].id != thread_id);
189 /* Must still be in_use, since nobody else can store our thread_id. */
192 WARN("Removing nonexisiting thread %ld\n", (GC_word)thread_id);
194 GC_delete_gc_thread(thread_table+i);
201 /* Return a GC_thread corresponding to a given pthread_t. */
202 /* Returns 0 if it's not there. */
203 /* We assume that this is only called for pthread ids that */
204 /* have not yet terminated or are still joinable. */
205 static GC_thread GC_lookup_thread(pthread_t id)
208 LONG my_max = GC_get_max_thread_index();
212 (!thread_table[i].in_use || thread_table[i].pthread_id != id
213 || !thread_table[i].in_use);
214 /* Must still be in_use, since nobody else can store our thread_id. */
216 if (i > my_max) return 0;
217 return thread_table + i;
220 #endif /* CYGWIN32 */
222 void GC_push_thread_structures GC_PROTO((void))
224 /* Unlike the other threads implementations, the thread table here */
225 /* contains no pointers to the collectable heap. Thus we have */
226 /* no private structures we need to preserve. */
228 { int i; /* pthreads may keep a pointer in the thread exit value */
229 LONG my_max = GC_get_max_thread_index();
231 for (i = 0; i <= my_max; i++)
232 if (thread_table[i].in_use)
233 GC_push_all((ptr_t)&(thread_table[i].status),
234 (ptr_t)(&(thread_table[i].status)+1));
241 DWORD thread_id = GetCurrentThreadId();
244 if (!GC_thr_initialized) ABORT("GC_stop_world() called before GC_thr_init()");
246 GC_please_stop = TRUE;
247 for (i = 0; i <= GC_get_max_thread_index(); i++)
248 if (thread_table[i].stack_base != 0
249 && thread_table[i].id != thread_id) {
251 /* SuspendThread will fail if thread is running kernel code */
252 while (SuspendThread(thread_table[i].handle) == (DWORD)-1)
255 /* Apparently the Windows 95 GetOpenFileName call creates */
256 /* a thread that does not properly get cleaned up, and */
257 /* SuspendThread on its descriptor may provoke a crash. */
258 /* This reduces the probability of that event, though it still */
259 /* appears there's a race here. */
261 if (GetExitCodeThread(thread_table[i].handle,&exitCode) &&
262 exitCode != STILL_ACTIVE) {
263 thread_table[i].stack_base = 0; /* prevent stack from being pushed */
265 /* this breaks pthread_join on Cygwin, which is guaranteed to */
266 /* only see user pthreads */
267 thread_table[i].in_use = FALSE;
268 CloseHandle(thread_table[i].handle);
272 if (SuspendThread(thread_table[i].handle) == (DWORD)-1)
273 ABORT("SuspendThread failed");
275 thread_table[i].suspended = TRUE;
279 void GC_start_world()
281 DWORD thread_id = GetCurrentThreadId();
283 LONG my_max = GC_get_max_thread_index();
285 for (i = 0; i <= my_max; i++)
286 if (thread_table[i].stack_base != 0 && thread_table[i].suspended
287 && thread_table[i].id != thread_id) {
288 if (ResumeThread(thread_table[i].handle) == (DWORD)-1)
289 ABORT("ResumeThread failed");
290 thread_table[i].suspended = FALSE;
292 GC_please_stop = FALSE;
296 # pragma warning(disable:4715)
298 ptr_t GC_current_stackbottom()
300 DWORD thread_id = GetCurrentThreadId();
302 LONG my_max = GC_get_max_thread_index();
304 for (i = 0; i <= my_max; i++)
305 if (thread_table[i].stack_base && thread_table[i].id == thread_id)
306 return thread_table[i].stack_base;
307 ABORT("no thread table entry for current thread");
310 # pragma warning(default:4715)
314 /* The VirtualQuery calls below won't work properly on WinCE, but */
315 /* since each stack is restricted to an aligned 64K region of */
316 /* virtual memory we can just take the next lowest multiple of 64K. */
317 # define GC_get_stack_min(s) \
318 ((ptr_t)(((DWORD)(s) - 1) & 0xFFFF0000))
320 static ptr_t GC_get_stack_min(ptr_t s)
323 MEMORY_BASIC_INFORMATION info;
324 VirtualQuery(s, &info, sizeof(info));
326 bottom = info.BaseAddress;
327 VirtualQuery(bottom - 1, &info, sizeof(info));
328 } while ((info.Protect & PAGE_READWRITE)
329 && !(info.Protect & PAGE_GUARD));
334 void GC_push_all_stacks()
336 DWORD thread_id = GetCurrentThreadId();
337 GC_bool found_me = FALSE;
342 LONG my_max = GC_get_max_thread_index();
344 for (i = 0; i <= my_max; i++) {
345 thread = thread_table + i;
346 if (thread -> in_use && thread -> stack_base) {
347 if (thread -> id == thread_id) {
352 context.ContextFlags = CONTEXT_INTEGER|CONTEXT_CONTROL;
353 if (!GetThreadContext(thread_table[i].handle, &context))
354 ABORT("GetThreadContext failed");
356 /* Push all registers that might point into the heap. Frame */
357 /* pointer registers are included in case client code was */
358 /* compiled with the 'omit frame pointer' optimisation. */
359 # define PUSH1(reg) GC_push_one((word)context.reg)
360 # define PUSH2(r1,r2) PUSH1(r1), PUSH1(r2)
361 # define PUSH4(r1,r2,r3,r4) PUSH2(r1,r2), PUSH2(r3,r4)
363 PUSH4(Edi,Esi,Ebx,Edx), PUSH2(Ecx,Eax), PUSH1(Ebp);
364 sp = (ptr_t)context.Esp;
365 # elif defined(ARM32)
366 PUSH4(R0,R1,R2,R3),PUSH4(R4,R5,R6,R7),PUSH4(R8,R9,R10,R11),PUSH1(R12);
367 sp = (ptr_t)context.Sp;
369 PUSH4(R0,R1,R2,R3), PUSH4(R4,R5,R6,R7), PUSH4(R8,R9,R10,R11);
370 PUSH2(R12,R13), PUSH1(R14);
371 sp = (ptr_t)context.R15;
373 PUSH4(IntAt,IntV0,IntV1,IntA0), PUSH4(IntA1,IntA2,IntA3,IntT0);
374 PUSH4(IntT1,IntT2,IntT3,IntT4), PUSH4(IntT5,IntT6,IntT7,IntS0);
375 PUSH4(IntS1,IntS2,IntS3,IntS4), PUSH4(IntS5,IntS6,IntS7,IntT8);
376 PUSH4(IntT9,IntK0,IntK1,IntS8);
377 sp = (ptr_t)context.IntSp;
379 PUSH4(Gpr0, Gpr3, Gpr4, Gpr5), PUSH4(Gpr6, Gpr7, Gpr8, Gpr9);
380 PUSH4(Gpr10,Gpr11,Gpr12,Gpr14), PUSH4(Gpr15,Gpr16,Gpr17,Gpr18);
381 PUSH4(Gpr19,Gpr20,Gpr21,Gpr22), PUSH4(Gpr23,Gpr24,Gpr25,Gpr26);
382 PUSH4(Gpr27,Gpr28,Gpr29,Gpr30), PUSH1(Gpr31);
383 sp = (ptr_t)context.Gpr1;
384 # elif defined(ALPHA)
385 PUSH4(IntV0,IntT0,IntT1,IntT2), PUSH4(IntT3,IntT4,IntT5,IntT6);
386 PUSH4(IntT7,IntS0,IntS1,IntS2), PUSH4(IntS3,IntS4,IntS5,IntFp);
387 PUSH4(IntA0,IntA1,IntA2,IntA3), PUSH4(IntA4,IntA5,IntT8,IntT9);
388 PUSH4(IntT10,IntT11,IntT12,IntAt);
389 sp = (ptr_t)context.IntSp;
391 # error "architecture is not supported"
395 stack_min = GC_get_stack_min(thread->stack_base);
397 if (sp >= stack_min && sp < thread->stack_base)
398 GC_push_all_stack(sp, thread->stack_base);
400 WARN("Thread stack pointer 0x%lx out of range, pushing everything\n",
402 GC_push_all_stack(stack_min, thread->stack_base);
406 if (!found_me) ABORT("Collecting from unknown thread.");
409 void GC_get_next_stack(char *start, char **lo, char **hi)
412 # define ADDR_LIMIT (char *)(-1L)
413 char * current_min = ADDR_LIMIT;
414 LONG my_max = GC_get_max_thread_index();
416 for (i = 0; i <= my_max; i++) {
417 char * s = (char *)thread_table[i].stack_base;
419 if (0 != s && s > start && s < current_min) {
424 if (current_min == ADDR_LIMIT) {
428 *lo = GC_get_stack_min(current_min);
429 if (*lo < start) *lo = start;
432 #if !defined(CYGWIN32)
434 #if !defined(MSWINCE) && defined(GC_DLL)
436 /* We register threads from DllMain */
438 GC_API HANDLE WINAPI GC_CreateThread(
439 LPSECURITY_ATTRIBUTES lpThreadAttributes,
440 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
441 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
443 return CreateThread(lpThreadAttributes, dwStackSize, lpStartAddress,
444 lpParameter, dwCreationFlags, lpThreadId);
447 #else /* defined(MSWINCE) || !defined(GC_DLL)) */
449 /* We have no DllMain to take care of new threads. Thus we */
450 /* must properly intercept thread creation. */
453 LPTHREAD_START_ROUTINE start;
457 static DWORD WINAPI thread_start(LPVOID arg);
459 GC_API HANDLE WINAPI GC_CreateThread(
460 LPSECURITY_ATTRIBUTES lpThreadAttributes,
461 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
462 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
464 HANDLE thread_h = NULL;
468 if (!GC_is_initialized) GC_init();
469 /* make sure GC is initialized (i.e. main thread is attached) */
471 args = GC_malloc_uncollectable(sizeof(thread_args));
472 /* Handed off to and deallocated by child thread. */
474 SetLastError(ERROR_NOT_ENOUGH_MEMORY);
478 /* set up thread arguments */
479 args -> start = lpStartAddress;
480 args -> param = lpParameter;
482 thread_h = CreateThread(lpThreadAttributes,
483 dwStackSize, thread_start,
484 args, dwCreationFlags,
490 static DWORD WINAPI thread_start(LPVOID arg)
493 thread_args *args = (thread_args *)arg;
497 /* Clear the thread entry even if we exit with an exception. */
498 /* This is probably pointless, since an uncaught exception is */
499 /* supposed to result in the process being killed. */
502 #endif /* __GNUC__ */
503 ret = args->start (args->param);
506 #endif /* __GNUC__ */
508 GC_delete_thread(GetCurrentThreadId());
511 #endif /* __GNUC__ */
515 #endif /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL)) */
517 #endif /* !CYGWIN32 */
523 HINSTANCE hPrevInstance;
528 DWORD WINAPI main_thread_start(LPVOID arg);
530 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
531 LPWSTR lpCmdLine, int nShowCmd)
535 main_thread_args args = {
536 hInstance, hPrevInstance, lpCmdLine, nShowCmd
541 /* initialize everything */
544 /* start the main thread */
545 thread_h = GC_CreateThread(
546 NULL, 0, main_thread_start, &args, 0, &thread_id);
548 if (thread_h != NULL)
550 WaitForSingleObject (thread_h, INFINITE);
551 GetExitCodeThread (thread_h, &exit_code);
552 CloseHandle (thread_h);
556 DeleteCriticalSection(&GC_allocate_ml);
558 return (int) exit_code;
561 DWORD WINAPI main_thread_start(LPVOID arg)
563 main_thread_args * args = (main_thread_args *) arg;
565 return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance,
566 args->lpCmdLine, args->nShowCmd);
569 # else /* !MSWINCE */
571 /* Called by GC_init() - we hold the allocation lock. */
573 if (GC_thr_initialized) return;
574 GC_main_thread = GetCurrentThreadId();
575 GC_thr_initialized = TRUE;
577 /* Add the initial thread, so we can stop it. */
584 void *(*start_routine)(void *);
589 int GC_pthread_join(pthread_t pthread_id, void **retval) {
594 # if DEBUG_CYGWIN_THREADS
595 GC_printf3("thread 0x%x(0x%x) is joining thread 0x%x.\n",
596 (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
599 /* Thread being joined might not have registered itself yet. */
600 /* After the join,thread id may have been recycled. */
601 /* FIXME: It would be better if this worked more like */
602 /* pthread_support.c. */
604 while ((me = GC_lookup_thread(pthread_id)) == 0) Sleep(10);
606 result = pthread_join(pthread_id, retval);
608 GC_delete_gc_thread(me);
610 # if DEBUG_CYGWIN_THREADS
611 GC_printf3("thread 0x%x(0x%x) completed join with thread 0x%x.\n",
612 (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
618 /* Cygwin-pthreads calls CreateThread internally, but it's not
619 * easily interceptible by us..
620 * so intercept pthread_create instead
623 GC_pthread_create(pthread_t *new_thread,
624 const pthread_attr_t *attr,
625 void *(*start_routine)(void *), void *arg) {
627 struct start_info * si;
629 if (!GC_is_initialized) GC_init();
630 /* make sure GC is initialized (i.e. main thread is attached) */
632 /* This is otherwise saved only in an area mmapped by the thread */
633 /* library, which isn't visible to the collector. */
634 si = GC_malloc_uncollectable(sizeof(struct start_info));
635 if (0 == si) return(EAGAIN);
637 si -> start_routine = start_routine;
640 pthread_attr_getdetachstate(attr, &si->detached)
641 == PTHREAD_CREATE_DETACHED) {
645 # if DEBUG_CYGWIN_THREADS
646 GC_printf2("About to create a thread from 0x%x(0x%x)\n",
647 (int)pthread_self(), GetCurrentThreadId);
649 result = pthread_create(new_thread, attr, GC_start_routine, si);
651 if (result) { /* failure */
658 void * GC_start_routine(void * arg)
660 struct start_info * si = arg;
662 void *(*start)(void *);
664 pthread_t pthread_id;
669 # if DEBUG_CYGWIN_THREADS
670 GC_printf2("thread 0x%x(0x%x) starting...\n",(int)pthread_self(),
671 GetCurrentThreadId());
674 /* If a GC occurs before the thread is registered, that GC will */
675 /* ignore this thread. That's fine, since it will block trying to */
676 /* acquire the allocation lock, and won't yet hold interesting */
679 /* We register the thread here instead of in the parent, so that */
680 /* we don't need to hold the allocation lock during pthread_create. */
681 me = GC_new_thread();
684 start = si -> start_routine;
685 start_arg = si -> arg;
686 if (si-> detached) me -> flags |= DETACHED;
687 me -> pthread_id = pthread_id = pthread_self();
689 GC_free(si); /* was allocated uncollectable */
691 pthread_cleanup_push(GC_thread_exit_proc, (void *)me);
692 result = (*start)(start_arg);
693 me -> status = result;
694 pthread_cleanup_pop(0);
696 # if DEBUG_CYGWIN_THREADS
697 GC_printf2("thread 0x%x(0x%x) returned from start routine.\n",
698 (int)pthread_self(),GetCurrentThreadId());
704 void GC_thread_exit_proc(void *arg)
706 GC_thread me = (GC_thread)arg;
709 # if DEBUG_CYGWIN_THREADS
710 GC_printf2("thread 0x%x(0x%x) called pthread_exit().\n",
711 (int)pthread_self(),GetCurrentThreadId());
715 if (me -> flags & DETACHED) {
716 GC_delete_thread(GetCurrentThreadId());
718 /* deallocate it as part of join */
719 me -> flags |= FINISHED;
724 /* nothing required here... */
725 int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) {
726 return pthread_sigmask(how, set, oset);
729 int GC_pthread_detach(pthread_t thread)
732 GC_thread thread_gc_id;
735 thread_gc_id = GC_lookup_thread(thread);
737 result = pthread_detach(thread);
740 thread_gc_id -> flags |= DETACHED;
741 /* Here the pthread thread id may have been recycled. */
742 if (thread_gc_id -> flags & FINISHED) {
743 GC_delete_gc_thread(thread_gc_id);
750 #else /* !CYGWIN32 */
753 * We avoid acquiring locks here, since this doesn't seem to be preemptable.
754 * Pontus Rydin suggests wrapping the thread start routine instead.
757 BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
760 case DLL_PROCESS_ATTACH:
761 GC_init(); /* Force initialization before thread attach. */
763 case DLL_THREAD_ATTACH:
764 GC_ASSERT(GC_thr_initialized);
765 if (GC_main_thread != GetCurrentThreadId()) {
767 } /* o.w. we already did it during GC_thr_init(), called by GC_init() */
770 case DLL_THREAD_DETACH:
771 GC_delete_thread(GetCurrentThreadId());
774 case DLL_PROCESS_DETACH:
779 for (i = 0; i <= GC_get_max_thread_index(); ++i)
781 if (thread_table[i].in_use)
782 GC_delete_gc_thread(thread_table + i);
787 DeleteCriticalSection(&GC_allocate_ml);
795 #endif /* !CYGWIN32 */
797 # endif /* !MSWINCE */
799 #endif /* GC_WIN32_THREADS */