3 #if defined(GC_WIN32_THREADS)
5 #include "private/gc_priv.h"
11 /* Cygwin-specific forward decls */
12 # undef pthread_create
13 # undef pthread_sigmask
17 # define DEBUG_CYGWIN_THREADS 0
19 void * GC_start_routine(void * arg);
20 void GC_thread_exit_proc(void *arg);
24 /* The type of the first argument to InterlockedExchange. */
25 /* Documented to be LONG volatile *, but at least gcc likes */
30 # define MAX_THREADS 256
32 /* Things may get quite slow for large numbers of threads, */
33 /* since we look them up with sequential search. */
36 GC_bool GC_thr_initialized = FALSE;
38 DWORD GC_main_thread = 0;
40 struct GC_thread_Rep {
41 LONG in_use; /* Updated without lock. */
42 /* We assert that unused */
43 /* entries have invalid ids of */
44 /* zero and zero stack fields. */
47 ptr_t stack_base; /* The cold end of the stack. */
48 /* 0 ==> entry not valid. */
49 /* !in_use ==> stack_base == 0 */
53 void *status; /* hold exit value until join in case it's a pointer */
55 short flags; /* Protected by GC lock. */
56 # define FINISHED 1 /* Thread has exited. */
57 # define DETACHED 2 /* Thread is intended to be detached. */
61 typedef volatile struct GC_thread_Rep * GC_thread;
64 * We generally assume that volatile ==> memory ordering, at least among
68 volatile GC_bool GC_please_stop = FALSE;
70 volatile struct GC_thread_Rep thread_table[MAX_THREADS];
72 volatile LONG GC_max_thread_index = 0; /* Largest index in thread_table */
73 /* that was ever used. */
75 extern LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
78 * This may be called from DllMain, and hence operates under unusual
81 static GC_thread GC_new_thread(void) {
83 /* It appears to be unsafe to acquire a lock here, since this */
84 /* code is apparently not preeemptible on some systems. */
85 /* (This is based on complaints, not on Microsoft's official */
86 /* documentation, which says this should perform "only simple */
87 /* initialization tasks".) */
88 /* Hence we make do with nonblocking synchronization. */
90 /* The following should be a noop according to the win32 */
91 /* documentation. There is empirical evidence that it */
93 # if defined(MPROTECT_VDB)
94 if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
96 /* cast away volatile qualifier */
97 for (i = 0; InterlockedExchange((IE_t)&thread_table[i].in_use,1) != 0; i++) {
98 /* Compare-and-swap would make this cleaner, but that's not */
99 /* supported before Windows 98 and NT 4.0. In Windows 2000, */
100 /* InterlockedExchange is supposed to be replaced by */
101 /* InterlockedExchangePointer, but that's not really what I */
103 if (i == MAX_THREADS - 1)
104 ABORT("too many threads");
106 /* Update GC_max_thread_index if necessary. The following is safe, */
107 /* and unlike CompareExchange-based solutions seems to work on all */
108 /* Windows95 and later platforms. */
109 /* Unfortunately, GC_max_thread_index may be temporarily out of */
110 /* bounds, so readers have to compensate. */
111 while (i > GC_max_thread_index) {
112 InterlockedIncrement((IE_t)&GC_max_thread_index);
114 if (GC_max_thread_index >= MAX_THREADS) {
115 /* We overshot due to simultaneous increments. */
116 /* Setting it to MAX_THREADS-1 is always safe. */
117 GC_max_thread_index = MAX_THREADS - 1;
121 thread_table[i].pthread_id = pthread_self();
123 if (!DuplicateHandle(GetCurrentProcess(),
126 (HANDLE*)&thread_table[i].handle,
129 DUPLICATE_SAME_ACCESS)) {
130 DWORD last_error = GetLastError();
131 GC_printf1("Last error code: %lx\n", last_error);
132 ABORT("DuplicateHandle failed");
134 thread_table[i].stack_base = GC_get_stack_base();
135 /* Up until this point, GC_push_all_stacks considers this thread */
137 if (thread_table[i].stack_base == NULL)
138 ABORT("Failed to find stack base in GC_new_thread");
139 /* Up until this point, this entry is viewed as reserved but invalid */
140 /* by GC_delete_thread. */
141 thread_table[i].id = GetCurrentThreadId();
142 /* If this thread is being created while we are trying to stop */
143 /* the world, wait here. Hopefully this can't happen on any */
144 /* systems that don't allow us to block here. */
145 while (GC_please_stop) Sleep(20);
146 return thread_table + i;
150 * GC_max_thread_index may temporarily be larger than MAX_THREADS.
151 * To avoid subscript errors, we check on access.
156 LONG GC_get_max_thread_index()
158 LONG my_max = GC_max_thread_index;
160 if (my_max >= MAX_THREADS) return MAX_THREADS-1;
164 /* This is intended to be lock-free, though that */
165 /* assumes that the CloseHandle becomes visible before the */
166 /* in_use assignment. */
167 static void GC_delete_gc_thread(GC_thread thr)
169 CloseHandle(thr->handle);
170 /* cast away volatile qualifier */
175 # endif /* CYGWIN32 */
179 static void GC_delete_thread(DWORD thread_id) {
181 LONG my_max = GC_get_max_thread_index();
185 (!thread_table[i].in_use || thread_table[i].id != thread_id);
186 /* Must still be in_use, since nobody else can store our thread_id. */
189 WARN("Removing nonexisiting thread %ld\n", (GC_word)thread_id);
191 GC_delete_gc_thread(thread_table+i);
198 /* Return a GC_thread corresponding to a given pthread_t. */
199 /* Returns 0 if it's not there. */
200 /* We assume that this is only called for pthread ids that */
201 /* have not yet terminated or are still joinable. */
202 static GC_thread GC_lookup_thread(pthread_t id)
205 LONG my_max = GC_get_max_thread_index();
209 (!thread_table[i].in_use || thread_table[i].pthread_id != id
210 || !thread_table[i].in_use);
211 /* Must still be in_use, since nobody else can store our thread_id. */
213 if (i > my_max) return 0;
214 return thread_table + i;
217 #endif /* CYGWIN32 */
219 void GC_push_thread_structures GC_PROTO((void))
221 /* Unlike the other threads implementations, the thread table here */
222 /* contains no pointers to the collectable heap. Thus we have */
223 /* no private structures we need to preserve. */
225 { int i; /* pthreads may keep a pointer in the thread exit value */
226 LONG my_max = GC_get_max_thread_index();
228 for (i = 0; i <= my_max; i++)
229 if (thread_table[i].in_use)
230 GC_push_all((ptr_t)&(thread_table[i].status),
231 (ptr_t)(&(thread_table[i].status)+1));
238 DWORD thread_id = GetCurrentThreadId();
241 if (!GC_thr_initialized) ABORT("GC_stop_world() called before GC_thr_init()");
243 GC_please_stop = TRUE;
244 for (i = 0; i <= GC_get_max_thread_index(); i++)
245 if (thread_table[i].stack_base != 0
246 && thread_table[i].id != thread_id) {
248 /* SuspendThread will fail if thread is running kernel code */
249 while (SuspendThread(thread_table[i].handle) == (DWORD)-1)
252 /* Apparently the Windows 95 GetOpenFileName call creates */
253 /* a thread that does not properly get cleaned up, and */
254 /* SuspendThread on its descriptor may provoke a crash. */
255 /* This reduces the probability of that event, though it still */
256 /* appears there's a race here. */
258 if (GetExitCodeThread(thread_table[i].handle,&exitCode) &&
259 exitCode != STILL_ACTIVE) {
260 thread_table[i].stack_base = 0; /* prevent stack from being pushed */
262 /* this breaks pthread_join on Cygwin, which is guaranteed to */
263 /* only see user pthreads */
264 thread_table[i].in_use = FALSE;
265 CloseHandle(thread_table[i].handle);
269 if (SuspendThread(thread_table[i].handle) == (DWORD)-1)
270 ABORT("SuspendThread failed");
272 thread_table[i].suspended = TRUE;
276 void GC_start_world()
278 DWORD thread_id = GetCurrentThreadId();
280 LONG my_max = GC_get_max_thread_index();
282 for (i = 0; i <= my_max; i++)
283 if (thread_table[i].stack_base != 0 && thread_table[i].suspended
284 && thread_table[i].id != thread_id) {
285 if (ResumeThread(thread_table[i].handle) == (DWORD)-1)
286 ABORT("ResumeThread failed");
287 thread_table[i].suspended = FALSE;
289 GC_please_stop = FALSE;
293 # pragma warning(disable:4715)
295 ptr_t GC_current_stackbottom()
297 DWORD thread_id = GetCurrentThreadId();
299 LONG my_max = GC_get_max_thread_index();
301 for (i = 0; i <= my_max; i++)
302 if (thread_table[i].stack_base && thread_table[i].id == thread_id)
303 return thread_table[i].stack_base;
304 ABORT("no thread table entry for current thread");
307 # pragma warning(default:4715)
311 /* The VirtualQuery calls below won't work properly on WinCE, but */
312 /* since each stack is restricted to an aligned 64K region of */
313 /* virtual memory we can just take the next lowest multiple of 64K. */
314 # define GC_get_stack_min(s) \
315 ((ptr_t)(((DWORD)(s) - 1) & 0xFFFF0000))
317 static ptr_t GC_get_stack_min(ptr_t s)
320 MEMORY_BASIC_INFORMATION info;
321 VirtualQuery(s, &info, sizeof(info));
323 bottom = info.BaseAddress;
324 VirtualQuery(bottom - 1, &info, sizeof(info));
325 } while ((info.Protect & PAGE_READWRITE)
326 && !(info.Protect & PAGE_GUARD));
331 void GC_push_all_stacks()
333 DWORD thread_id = GetCurrentThreadId();
334 GC_bool found_me = FALSE;
339 LONG my_max = GC_get_max_thread_index();
341 for (i = 0; i <= my_max; i++) {
342 thread = thread_table + i;
343 if (thread -> in_use && thread -> stack_base) {
344 if (thread -> id == thread_id) {
349 context.ContextFlags = CONTEXT_INTEGER|CONTEXT_CONTROL;
350 if (!GetThreadContext(thread_table[i].handle, &context))
351 ABORT("GetThreadContext failed");
353 /* Push all registers that might point into the heap. Frame */
354 /* pointer registers are included in case client code was */
355 /* compiled with the 'omit frame pointer' optimisation. */
356 # define PUSH1(reg) GC_push_one((word)context.reg)
357 # define PUSH2(r1,r2) PUSH1(r1), PUSH1(r2)
358 # define PUSH4(r1,r2,r3,r4) PUSH2(r1,r2), PUSH2(r3,r4)
360 PUSH4(Edi,Esi,Ebx,Edx), PUSH2(Ecx,Eax), PUSH1(Ebp);
361 sp = (ptr_t)context.Esp;
362 # elif defined(ARM32)
363 PUSH4(R0,R1,R2,R3),PUSH4(R4,R5,R6,R7),PUSH4(R8,R9,R10,R11),PUSH1(R12);
364 sp = (ptr_t)context.Sp;
366 PUSH4(R0,R1,R2,R3), PUSH4(R4,R5,R6,R7), PUSH4(R8,R9,R10,R11);
367 PUSH2(R12,R13), PUSH1(R14);
368 sp = (ptr_t)context.R15;
370 PUSH4(IntAt,IntV0,IntV1,IntA0), PUSH4(IntA1,IntA2,IntA3,IntT0);
371 PUSH4(IntT1,IntT2,IntT3,IntT4), PUSH4(IntT5,IntT6,IntT7,IntS0);
372 PUSH4(IntS1,IntS2,IntS3,IntS4), PUSH4(IntS5,IntS6,IntS7,IntT8);
373 PUSH4(IntT9,IntK0,IntK1,IntS8);
374 sp = (ptr_t)context.IntSp;
376 PUSH4(Gpr0, Gpr3, Gpr4, Gpr5), PUSH4(Gpr6, Gpr7, Gpr8, Gpr9);
377 PUSH4(Gpr10,Gpr11,Gpr12,Gpr14), PUSH4(Gpr15,Gpr16,Gpr17,Gpr18);
378 PUSH4(Gpr19,Gpr20,Gpr21,Gpr22), PUSH4(Gpr23,Gpr24,Gpr25,Gpr26);
379 PUSH4(Gpr27,Gpr28,Gpr29,Gpr30), PUSH1(Gpr31);
380 sp = (ptr_t)context.Gpr1;
381 # elif defined(ALPHA)
382 PUSH4(IntV0,IntT0,IntT1,IntT2), PUSH4(IntT3,IntT4,IntT5,IntT6);
383 PUSH4(IntT7,IntS0,IntS1,IntS2), PUSH4(IntS3,IntS4,IntS5,IntFp);
384 PUSH4(IntA0,IntA1,IntA2,IntA3), PUSH4(IntA4,IntA5,IntT8,IntT9);
385 PUSH4(IntT10,IntT11,IntT12,IntAt);
386 sp = (ptr_t)context.IntSp;
388 # error "architecture is not supported"
392 stack_min = GC_get_stack_min(thread->stack_base);
394 if (sp >= stack_min && sp < thread->stack_base)
395 GC_push_all_stack(sp, thread->stack_base);
397 WARN("Thread stack pointer 0x%lx out of range, pushing everything\n",
399 GC_push_all_stack(stack_min, thread->stack_base);
403 if (!found_me) ABORT("Collecting from unknown thread.");
406 void GC_get_next_stack(char *start, char **lo, char **hi)
409 # define ADDR_LIMIT (char *)(-1L)
410 char * current_min = ADDR_LIMIT;
411 LONG my_max = GC_get_max_thread_index();
413 for (i = 0; i <= my_max; i++) {
414 char * s = (char *)thread_table[i].stack_base;
416 if (0 != s && s > start && s < current_min) {
421 if (current_min == ADDR_LIMIT) {
425 *lo = GC_get_stack_min(current_min);
426 if (*lo < start) *lo = start;
429 #if !defined(CYGWIN32)
431 #if !defined(MSWINCE) && defined(GC_DLL)
433 /* We register threads from DllMain */
435 GC_API HANDLE WINAPI GC_CreateThread(
436 LPSECURITY_ATTRIBUTES lpThreadAttributes,
437 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
438 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
440 return CreateThread(lpThreadAttributes, dwStackSize, lpStartAddress,
441 lpParameter, dwCreationFlags, lpThreadId);
444 #else /* defined(MSWINCE) || !defined(GC_DLL)) */
446 /* We have no DllMain to take care of new threads. Thus we */
447 /* must properly intercept thread creation. */
450 LPTHREAD_START_ROUTINE start;
454 static DWORD WINAPI thread_start(LPVOID arg);
456 GC_API HANDLE WINAPI GC_CreateThread(
457 LPSECURITY_ATTRIBUTES lpThreadAttributes,
458 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
459 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
461 HANDLE thread_h = NULL;
465 if (!GC_is_initialized) GC_init();
466 /* make sure GC is initialized (i.e. main thread is attached) */
468 args = GC_malloc_uncollectable(sizeof(thread_args));
469 /* Handed off to and deallocated by child thread. */
471 SetLastError(ERROR_NOT_ENOUGH_MEMORY);
475 /* set up thread arguments */
476 args -> start = lpStartAddress;
477 args -> param = lpParameter;
479 thread_h = CreateThread(lpThreadAttributes,
480 dwStackSize, thread_start,
481 args, dwCreationFlags,
487 static DWORD WINAPI thread_start(LPVOID arg)
490 thread_args *args = (thread_args *)arg;
494 /* Clear the thread entry even if we exit with an exception. */
495 /* This is probably pointless, since an uncaught exception is */
496 /* supposed to result in the process being killed. */
499 #endif /* __GNUC__ */
500 ret = args->start (args->param);
503 #endif /* __GNUC__ */
505 GC_delete_thread(GetCurrentThreadId());
508 #endif /* __GNUC__ */
512 #endif /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL)) */
514 #endif /* !CYGWIN32 */
520 HINSTANCE hPrevInstance;
525 DWORD WINAPI main_thread_start(LPVOID arg);
527 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
528 LPWSTR lpCmdLine, int nShowCmd)
532 main_thread_args args = {
533 hInstance, hPrevInstance, lpCmdLine, nShowCmd
538 /* initialize everything */
541 /* start the main thread */
542 thread_h = GC_CreateThread(
543 NULL, 0, main_thread_start, &args, 0, &thread_id);
545 if (thread_h != NULL)
547 WaitForSingleObject (thread_h, INFINITE);
548 GetExitCodeThread (thread_h, &exit_code);
549 CloseHandle (thread_h);
553 DeleteCriticalSection(&GC_allocate_ml);
555 return (int) exit_code;
558 DWORD WINAPI main_thread_start(LPVOID arg)
560 main_thread_args * args = (main_thread_args *) arg;
562 return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance,
563 args->lpCmdLine, args->nShowCmd);
566 # else /* !MSWINCE */
568 /* Called by GC_init() - we hold the allocation lock. */
570 if (GC_thr_initialized) return;
571 GC_main_thread = GetCurrentThreadId();
572 GC_thr_initialized = TRUE;
574 /* Add the initial thread, so we can stop it. */
581 void *(*start_routine)(void *);
586 int GC_pthread_join(pthread_t pthread_id, void **retval) {
591 # if DEBUG_CYGWIN_THREADS
592 GC_printf3("thread 0x%x(0x%x) is joining thread 0x%x.\n",
593 (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
596 /* Thread being joined might not have registered itself yet. */
597 /* After the join,thread id may have been recycled. */
598 /* FIXME: It would be better if this worked more like */
599 /* pthread_support.c. */
601 while ((me = GC_lookup_thread(pthread_id)) == 0) Sleep(10);
603 result = pthread_join(pthread_id, retval);
605 GC_delete_gc_thread(me);
607 # if DEBUG_CYGWIN_THREADS
608 GC_printf3("thread 0x%x(0x%x) completed join with thread 0x%x.\n",
609 (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
615 /* Cygwin-pthreads calls CreateThread internally, but it's not
616 * easily interceptible by us..
617 * so intercept pthread_create instead
620 GC_pthread_create(pthread_t *new_thread,
621 const pthread_attr_t *attr,
622 void *(*start_routine)(void *), void *arg) {
624 struct start_info * si;
626 if (!GC_is_initialized) GC_init();
627 /* make sure GC is initialized (i.e. main thread is attached) */
629 /* This is otherwise saved only in an area mmapped by the thread */
630 /* library, which isn't visible to the collector. */
631 si = GC_malloc_uncollectable(sizeof(struct start_info));
632 if (0 == si) return(EAGAIN);
634 si -> start_routine = start_routine;
637 pthread_attr_getdetachstate(attr, &si->detached)
638 == PTHREAD_CREATE_DETACHED) {
642 # if DEBUG_CYGWIN_THREADS
643 GC_printf2("About to create a thread from 0x%x(0x%x)\n",
644 (int)pthread_self(), GetCurrentThreadId);
646 result = pthread_create(new_thread, attr, GC_start_routine, si);
648 if (result) { /* failure */
655 void * GC_start_routine(void * arg)
657 struct start_info * si = arg;
659 void *(*start)(void *);
661 pthread_t pthread_id;
666 # if DEBUG_CYGWIN_THREADS
667 GC_printf2("thread 0x%x(0x%x) starting...\n",(int)pthread_self(),
668 GetCurrentThreadId());
671 /* If a GC occurs before the thread is registered, that GC will */
672 /* ignore this thread. That's fine, since it will block trying to */
673 /* acquire the allocation lock, and won't yet hold interesting */
676 /* We register the thread here instead of in the parent, so that */
677 /* we don't need to hold the allocation lock during pthread_create. */
678 me = GC_new_thread();
681 start = si -> start_routine;
682 start_arg = si -> arg;
683 if (si-> detached) me -> flags |= DETACHED;
684 me -> pthread_id = pthread_id = pthread_self();
686 GC_free(si); /* was allocated uncollectable */
688 pthread_cleanup_push(GC_thread_exit_proc, (void *)me);
689 result = (*start)(start_arg);
690 me -> status = result;
691 pthread_cleanup_pop(0);
693 # if DEBUG_CYGWIN_THREADS
694 GC_printf2("thread 0x%x(0x%x) returned from start routine.\n",
695 (int)pthread_self(),GetCurrentThreadId());
701 void GC_thread_exit_proc(void *arg)
703 GC_thread me = (GC_thread)arg;
706 # if DEBUG_CYGWIN_THREADS
707 GC_printf2("thread 0x%x(0x%x) called pthread_exit().\n",
708 (int)pthread_self(),GetCurrentThreadId());
712 if (me -> flags & DETACHED) {
713 GC_delete_thread(GetCurrentThreadId());
715 /* deallocate it as part of join */
716 me -> flags |= FINISHED;
721 /* nothing required here... */
722 int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) {
723 return pthread_sigmask(how, set, oset);
726 int GC_pthread_detach(pthread_t thread)
729 GC_thread thread_gc_id;
732 thread_gc_id = GC_lookup_thread(thread);
734 result = pthread_detach(thread);
737 thread_gc_id -> flags |= DETACHED;
738 /* Here the pthread thread id may have been recycled. */
739 if (thread_gc_id -> flags & FINISHED) {
740 GC_delete_gc_thread(thread_gc_id);
747 #else /* !CYGWIN32 */
750 * We avoid acquiring locks here, since this doesn't seem to be preemptable.
751 * Pontus Rydin suggests wrapping the thread start routine instead.
754 BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
757 case DLL_PROCESS_ATTACH:
758 GC_init(); /* Force initialization before thread attach. */
760 case DLL_THREAD_ATTACH:
761 GC_ASSERT(GC_thr_initialized);
762 if (GC_main_thread != GetCurrentThreadId()) {
764 } /* o.w. we already did it during GC_thr_init(), called by GC_init() */
767 case DLL_THREAD_DETACH:
768 GC_delete_thread(GetCurrentThreadId());
771 case DLL_PROCESS_DETACH:
776 for (i = 0; i <= GC_get_max_thread_index(); ++i)
778 if (thread_table[i].in_use)
779 GC_delete_gc_thread(thread_table + i);
784 DeleteCriticalSection(&GC_allocate_ml);
792 #endif /* !CYGWIN32 */
794 # endif /* !MSWINCE */
796 #endif /* GC_WIN32_THREADS */