2 #include "private/gc_priv.h"
4 #if defined(GC_WIN32_THREADS)
11 /* Cygwin-specific forward decls */
12 # undef pthread_create
13 # undef pthread_sigmask
15 # undef pthread_detach
18 # define DEBUG_CYGWIN_THREADS 0
20 void * GC_start_routine(void * arg);
21 void GC_thread_exit_proc(void *arg);
25 /* The type of the first argument to InterlockedExchange. */
26 /* Documented to be LONG volatile *, but at least gcc likes */
31 # define MAX_THREADS 256
33 /* Things may get quite slow for large numbers of threads, */
34 /* since we look them up with sequential search. */
37 GC_bool GC_thr_initialized = FALSE;
39 DWORD GC_main_thread = 0;
41 struct GC_thread_Rep {
42 LONG in_use; /* Updated without lock. */
43 /* We assert that unused */
44 /* entries have invalid ids of */
45 /* zero and zero stack fields. */
48 ptr_t stack_base; /* The cold end of the stack. */
49 /* 0 ==> entry not valid. */
50 /* !in_use ==> stack_base == 0 */
54 void *status; /* hold exit value until join in case it's a pointer */
56 short flags; /* Protected by GC lock. */
57 # define FINISHED 1 /* Thread has exited. */
58 # define DETACHED 2 /* Thread is intended to be detached. */
62 typedef volatile struct GC_thread_Rep * GC_thread;
65 * We generally assume that volatile ==> memory ordering, at least among
69 volatile GC_bool GC_please_stop = FALSE;
71 volatile struct GC_thread_Rep thread_table[MAX_THREADS];
73 volatile LONG GC_max_thread_index = 0; /* Largest index in thread_table */
74 /* that was ever used. */
76 extern LONG WINAPI GC_write_fault_handler(struct _EXCEPTION_POINTERS *exc_info);
79 * This may be called from DllMain, and hence operates under unusual
82 static GC_thread GC_new_thread(void) {
84 /* It appears to be unsafe to acquire a lock here, since this */
85 /* code is apparently not preeemptible on some systems. */
86 /* (This is based on complaints, not on Microsoft's official */
87 /* documentation, which says this should perform "only simple */
88 /* initialization tasks".) */
89 /* Hence we make do with nonblocking synchronization. */
91 /* The following should be a noop according to the win32 */
92 /* documentation. There is empirical evidence that it */
94 # if defined(MPROTECT_VDB)
95 if (GC_incremental) SetUnhandledExceptionFilter(GC_write_fault_handler);
97 /* cast away volatile qualifier */
98 for (i = 0; InterlockedExchange((IE_t)&thread_table[i].in_use,1) != 0; i++) {
99 /* Compare-and-swap would make this cleaner, but that's not */
100 /* supported before Windows 98 and NT 4.0. In Windows 2000, */
101 /* InterlockedExchange is supposed to be replaced by */
102 /* InterlockedExchangePointer, but that's not really what I */
104 if (i == MAX_THREADS - 1)
105 ABORT("too many threads");
107 /* Update GC_max_thread_index if necessary. The following is safe, */
108 /* and unlike CompareExchange-based solutions seems to work on all */
109 /* Windows95 and later platforms. */
110 /* Unfortunately, GC_max_thread_index may be temporarily out of */
111 /* bounds, so readers have to compensate. */
112 while (i > GC_max_thread_index) {
113 InterlockedIncrement((IE_t)&GC_max_thread_index);
115 if (GC_max_thread_index >= MAX_THREADS) {
116 /* We overshot due to simultaneous increments. */
117 /* Setting it to MAX_THREADS-1 is always safe. */
118 GC_max_thread_index = MAX_THREADS - 1;
122 thread_table[i].pthread_id = pthread_self();
124 if (!DuplicateHandle(GetCurrentProcess(),
127 (HANDLE*)&thread_table[i].handle,
130 DUPLICATE_SAME_ACCESS)) {
131 DWORD last_error = GetLastError();
132 GC_printf1("Last error code: %lx\n", last_error);
133 ABORT("DuplicateHandle failed");
135 thread_table[i].stack_base = GC_get_stack_base();
136 /* Up until this point, GC_push_all_stacks considers this thread */
138 if (thread_table[i].stack_base == NULL)
139 ABORT("Failed to find stack base in GC_new_thread");
140 /* Up until this point, this entry is viewed as reserved but invalid */
141 /* by GC_delete_thread. */
142 thread_table[i].id = GetCurrentThreadId();
143 /* If this thread is being created while we are trying to stop */
144 /* the world, wait here. Hopefully this can't happen on any */
145 /* systems that don't allow us to block here. */
146 while (GC_please_stop) Sleep(20);
147 return thread_table + i;
151 * GC_max_thread_index may temporarily be larger than MAX_THREADS.
152 * To avoid subscript errors, we check on access.
157 LONG GC_get_max_thread_index()
159 LONG my_max = GC_max_thread_index;
161 if (my_max >= MAX_THREADS) return MAX_THREADS-1;
165 /* This is intended to be lock-free, though that */
166 /* assumes that the CloseHandle becomes visible before the */
167 /* in_use assignment. */
168 static void GC_delete_gc_thread(GC_thread thr)
170 CloseHandle(thr->handle);
171 /* cast away volatile qualifier */
176 # endif /* CYGWIN32 */
180 static void GC_delete_thread(DWORD thread_id) {
182 LONG my_max = GC_get_max_thread_index();
186 (!thread_table[i].in_use || thread_table[i].id != thread_id);
187 /* Must still be in_use, since nobody else can store our thread_id. */
190 WARN("Removing nonexistent thread %ld\n", (GC_word)thread_id);
192 GC_delete_gc_thread(thread_table+i);
199 /* Return a GC_thread corresponding to a given pthread_t. */
200 /* Returns 0 if it's not there. */
201 /* We assume that this is only called for pthread ids that */
202 /* have not yet terminated or are still joinable. */
203 static GC_thread GC_lookup_thread(pthread_t id)
206 LONG my_max = GC_get_max_thread_index();
210 (!thread_table[i].in_use || thread_table[i].pthread_id != id
211 || !thread_table[i].in_use);
212 /* Must still be in_use, since nobody else can store our thread_id. */
214 if (i > my_max) return 0;
215 return thread_table + i;
218 #endif /* CYGWIN32 */
220 void GC_push_thread_structures GC_PROTO((void))
222 /* Unlike the other threads implementations, the thread table here */
223 /* contains no pointers to the collectable heap. Thus we have */
224 /* no private structures we need to preserve. */
226 { int i; /* pthreads may keep a pointer in the thread exit value */
227 LONG my_max = GC_get_max_thread_index();
229 for (i = 0; i <= my_max; i++)
230 if (thread_table[i].in_use)
231 GC_push_all((ptr_t)&(thread_table[i].status),
232 (ptr_t)(&(thread_table[i].status)+1));
237 /* Defined in misc.c */
238 extern CRITICAL_SECTION GC_write_cs;
242 DWORD thread_id = GetCurrentThreadId();
245 if (!GC_thr_initialized) ABORT("GC_stop_world() called before GC_thr_init()");
247 GC_please_stop = TRUE;
249 EnterCriticalSection(&GC_write_cs);
250 # endif /* !CYGWIN32 */
251 for (i = 0; i <= GC_get_max_thread_index(); i++)
252 if (thread_table[i].stack_base != 0
253 && thread_table[i].id != thread_id) {
255 /* SuspendThread will fail if thread is running kernel code */
256 while (SuspendThread(thread_table[i].handle) == (DWORD)-1)
259 /* Apparently the Windows 95 GetOpenFileName call creates */
260 /* a thread that does not properly get cleaned up, and */
261 /* SuspendThread on its descriptor may provoke a crash. */
262 /* This reduces the probability of that event, though it still */
263 /* appears there's a race here. */
265 if (GetExitCodeThread(thread_table[i].handle,&exitCode) &&
266 exitCode != STILL_ACTIVE) {
267 thread_table[i].stack_base = 0; /* prevent stack from being pushed */
269 /* this breaks pthread_join on Cygwin, which is guaranteed to */
270 /* only see user pthreads */
271 thread_table[i].in_use = FALSE;
272 CloseHandle(thread_table[i].handle);
276 if (SuspendThread(thread_table[i].handle) == (DWORD)-1)
277 ABORT("SuspendThread failed");
279 thread_table[i].suspended = TRUE;
282 LeaveCriticalSection(&GC_write_cs);
283 # endif /* !CYGWIN32 */
286 void GC_start_world()
288 DWORD thread_id = GetCurrentThreadId();
290 LONG my_max = GC_get_max_thread_index();
292 for (i = 0; i <= my_max; i++)
293 if (thread_table[i].stack_base != 0 && thread_table[i].suspended
294 && thread_table[i].id != thread_id) {
295 if (ResumeThread(thread_table[i].handle) == (DWORD)-1)
296 ABORT("ResumeThread failed");
297 thread_table[i].suspended = FALSE;
299 GC_please_stop = FALSE;
303 # pragma warning(disable:4715)
305 ptr_t GC_current_stackbottom()
307 DWORD thread_id = GetCurrentThreadId();
309 LONG my_max = GC_get_max_thread_index();
311 for (i = 0; i <= my_max; i++)
312 if (thread_table[i].stack_base && thread_table[i].id == thread_id)
313 return thread_table[i].stack_base;
314 ABORT("no thread table entry for current thread");
317 # pragma warning(default:4715)
321 /* The VirtualQuery calls below won't work properly on WinCE, but */
322 /* since each stack is restricted to an aligned 64K region of */
323 /* virtual memory we can just take the next lowest multiple of 64K. */
324 # define GC_get_stack_min(s) \
325 ((ptr_t)(((DWORD)(s) - 1) & 0xFFFF0000))
327 static ptr_t GC_get_stack_min(ptr_t s)
330 MEMORY_BASIC_INFORMATION info;
331 VirtualQuery(s, &info, sizeof(info));
333 bottom = info.BaseAddress;
334 VirtualQuery(bottom - 1, &info, sizeof(info));
335 } while ((info.Protect & PAGE_READWRITE)
336 && !(info.Protect & PAGE_GUARD));
341 void GC_push_all_stacks()
343 DWORD thread_id = GetCurrentThreadId();
344 GC_bool found_me = FALSE;
349 LONG my_max = GC_get_max_thread_index();
351 for (i = 0; i <= my_max; i++) {
352 thread = thread_table + i;
353 if (thread -> in_use && thread -> stack_base) {
354 if (thread -> id == thread_id) {
359 context.ContextFlags = CONTEXT_INTEGER|CONTEXT_CONTROL;
360 if (!GetThreadContext(thread_table[i].handle, &context))
361 ABORT("GetThreadContext failed");
363 /* Push all registers that might point into the heap. Frame */
364 /* pointer registers are included in case client code was */
365 /* compiled with the 'omit frame pointer' optimisation. */
366 # define PUSH1(reg) GC_push_one((word)context.reg)
367 # define PUSH2(r1,r2) PUSH1(r1), PUSH1(r2)
368 # define PUSH4(r1,r2,r3,r4) PUSH2(r1,r2), PUSH2(r3,r4)
370 PUSH4(Edi,Esi,Ebx,Edx), PUSH2(Ecx,Eax), PUSH1(Ebp);
371 sp = (ptr_t)context.Esp;
372 # elif defined(ARM32)
373 PUSH4(R0,R1,R2,R3),PUSH4(R4,R5,R6,R7),PUSH4(R8,R9,R10,R11),PUSH1(R12);
374 sp = (ptr_t)context.Sp;
376 PUSH4(R0,R1,R2,R3), PUSH4(R4,R5,R6,R7), PUSH4(R8,R9,R10,R11);
377 PUSH2(R12,R13), PUSH1(R14);
378 sp = (ptr_t)context.R15;
380 PUSH4(IntAt,IntV0,IntV1,IntA0), PUSH4(IntA1,IntA2,IntA3,IntT0);
381 PUSH4(IntT1,IntT2,IntT3,IntT4), PUSH4(IntT5,IntT6,IntT7,IntS0);
382 PUSH4(IntS1,IntS2,IntS3,IntS4), PUSH4(IntS5,IntS6,IntS7,IntT8);
383 PUSH4(IntT9,IntK0,IntK1,IntS8);
384 sp = (ptr_t)context.IntSp;
386 PUSH4(Gpr0, Gpr3, Gpr4, Gpr5), PUSH4(Gpr6, Gpr7, Gpr8, Gpr9);
387 PUSH4(Gpr10,Gpr11,Gpr12,Gpr14), PUSH4(Gpr15,Gpr16,Gpr17,Gpr18);
388 PUSH4(Gpr19,Gpr20,Gpr21,Gpr22), PUSH4(Gpr23,Gpr24,Gpr25,Gpr26);
389 PUSH4(Gpr27,Gpr28,Gpr29,Gpr30), PUSH1(Gpr31);
390 sp = (ptr_t)context.Gpr1;
391 # elif defined(ALPHA)
392 PUSH4(IntV0,IntT0,IntT1,IntT2), PUSH4(IntT3,IntT4,IntT5,IntT6);
393 PUSH4(IntT7,IntS0,IntS1,IntS2), PUSH4(IntS3,IntS4,IntS5,IntFp);
394 PUSH4(IntA0,IntA1,IntA2,IntA3), PUSH4(IntA4,IntA5,IntT8,IntT9);
395 PUSH4(IntT10,IntT11,IntT12,IntAt);
396 sp = (ptr_t)context.IntSp;
398 # error "architecture is not supported"
402 stack_min = GC_get_stack_min(thread->stack_base);
404 if (sp >= stack_min && sp < thread->stack_base)
405 GC_push_all_stack(sp, thread->stack_base);
407 WARN("Thread stack pointer 0x%lx out of range, pushing everything\n",
409 GC_push_all_stack(stack_min, thread->stack_base);
413 if (!found_me) ABORT("Collecting from unknown thread.");
416 void GC_get_next_stack(char *start, char **lo, char **hi)
419 # define ADDR_LIMIT (char *)(-1L)
420 char * current_min = ADDR_LIMIT;
421 LONG my_max = GC_get_max_thread_index();
423 for (i = 0; i <= my_max; i++) {
424 char * s = (char *)thread_table[i].stack_base;
426 if (0 != s && s > start && s < current_min) {
431 if (current_min == ADDR_LIMIT) {
435 *lo = GC_get_stack_min(current_min);
436 if (*lo < start) *lo = start;
439 #if !defined(CYGWIN32)
441 #if !defined(MSWINCE) && defined(GC_DLL)
443 /* We register threads from DllMain */
445 GC_API HANDLE WINAPI GC_CreateThread(
446 LPSECURITY_ATTRIBUTES lpThreadAttributes,
447 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
448 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
450 return CreateThread(lpThreadAttributes, dwStackSize, lpStartAddress,
451 lpParameter, dwCreationFlags, lpThreadId);
454 #else /* defined(MSWINCE) || !defined(GC_DLL)) */
456 /* We have no DllMain to take care of new threads. Thus we */
457 /* must properly intercept thread creation. */
460 LPTHREAD_START_ROUTINE start;
464 static DWORD WINAPI thread_start(LPVOID arg);
466 GC_API HANDLE WINAPI GC_CreateThread(
467 LPSECURITY_ATTRIBUTES lpThreadAttributes,
468 DWORD dwStackSize, LPTHREAD_START_ROUTINE lpStartAddress,
469 LPVOID lpParameter, DWORD dwCreationFlags, LPDWORD lpThreadId )
471 HANDLE thread_h = NULL;
475 if (!GC_is_initialized) GC_init();
476 /* make sure GC is initialized (i.e. main thread is attached) */
478 args = GC_malloc_uncollectable(sizeof(thread_args));
479 /* Handed off to and deallocated by child thread. */
481 SetLastError(ERROR_NOT_ENOUGH_MEMORY);
485 /* set up thread arguments */
486 args -> start = lpStartAddress;
487 args -> param = lpParameter;
489 thread_h = CreateThread(lpThreadAttributes,
490 dwStackSize, thread_start,
491 args, dwCreationFlags,
497 static DWORD WINAPI thread_start(LPVOID arg)
500 thread_args *args = (thread_args *)arg;
504 /* Clear the thread entry even if we exit with an exception. */
505 /* This is probably pointless, since an uncaught exception is */
506 /* supposed to result in the process being killed. */
509 #endif /* __GNUC__ */
510 ret = args->start (args->param);
513 #endif /* __GNUC__ */
515 GC_delete_thread(GetCurrentThreadId());
518 #endif /* __GNUC__ */
522 #endif /* !defined(MSWINCE) && !(defined(__MINGW32__) && !defined(_DLL)) */
524 #endif /* !CYGWIN32 */
530 HINSTANCE hPrevInstance;
535 DWORD WINAPI main_thread_start(LPVOID arg);
537 int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
538 LPWSTR lpCmdLine, int nShowCmd)
542 main_thread_args args = {
543 hInstance, hPrevInstance, lpCmdLine, nShowCmd
548 /* initialize everything */
551 /* start the main thread */
552 thread_h = GC_CreateThread(
553 NULL, 0, main_thread_start, &args, 0, &thread_id);
555 if (thread_h != NULL)
557 WaitForSingleObject (thread_h, INFINITE);
558 GetExitCodeThread (thread_h, &exit_code);
559 CloseHandle (thread_h);
563 DeleteCriticalSection(&GC_allocate_ml);
565 return (int) exit_code;
568 DWORD WINAPI main_thread_start(LPVOID arg)
570 main_thread_args * args = (main_thread_args *) arg;
572 return (DWORD) GC_WinMain (args->hInstance, args->hPrevInstance,
573 args->lpCmdLine, args->nShowCmd);
576 # else /* !MSWINCE */
578 /* Called by GC_init() - we hold the allocation lock. */
580 if (GC_thr_initialized) return;
581 GC_main_thread = GetCurrentThreadId();
582 GC_thr_initialized = TRUE;
584 /* Add the initial thread, so we can stop it. */
591 void *(*start_routine)(void *);
596 int GC_pthread_join(pthread_t pthread_id, void **retval) {
601 # if DEBUG_CYGWIN_THREADS
602 GC_printf3("thread 0x%x(0x%x) is joining thread 0x%x.\n",
603 (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
606 /* Thread being joined might not have registered itself yet. */
607 /* After the join,thread id may have been recycled. */
608 /* FIXME: It would be better if this worked more like */
609 /* pthread_support.c. */
611 while ((me = GC_lookup_thread(pthread_id)) == 0) Sleep(10);
613 result = pthread_join(pthread_id, retval);
615 GC_delete_gc_thread(me);
617 # if DEBUG_CYGWIN_THREADS
618 GC_printf3("thread 0x%x(0x%x) completed join with thread 0x%x.\n",
619 (int)pthread_self(), GetCurrentThreadId(), (int)pthread_id);
625 /* Cygwin-pthreads calls CreateThread internally, but it's not
626 * easily interceptible by us..
627 * so intercept pthread_create instead
630 GC_pthread_create(pthread_t *new_thread,
631 const pthread_attr_t *attr,
632 void *(*start_routine)(void *), void *arg) {
634 struct start_info * si;
636 if (!GC_is_initialized) GC_init();
637 /* make sure GC is initialized (i.e. main thread is attached) */
639 /* This is otherwise saved only in an area mmapped by the thread */
640 /* library, which isn't visible to the collector. */
641 si = GC_malloc_uncollectable(sizeof(struct start_info));
642 if (0 == si) return(EAGAIN);
644 si -> start_routine = start_routine;
647 pthread_attr_getdetachstate(attr, &si->detached)
648 == PTHREAD_CREATE_DETACHED) {
652 # if DEBUG_CYGWIN_THREADS
653 GC_printf2("About to create a thread from 0x%x(0x%x)\n",
654 (int)pthread_self(), GetCurrentThreadId);
656 result = pthread_create(new_thread, attr, GC_start_routine, si);
658 if (result) { /* failure */
665 void * GC_start_routine(void * arg)
667 struct start_info * si = arg;
669 void *(*start)(void *);
671 pthread_t pthread_id;
676 # if DEBUG_CYGWIN_THREADS
677 GC_printf2("thread 0x%x(0x%x) starting...\n",(int)pthread_self(),
678 GetCurrentThreadId());
681 /* If a GC occurs before the thread is registered, that GC will */
682 /* ignore this thread. That's fine, since it will block trying to */
683 /* acquire the allocation lock, and won't yet hold interesting */
686 /* We register the thread here instead of in the parent, so that */
687 /* we don't need to hold the allocation lock during pthread_create. */
688 me = GC_new_thread();
691 start = si -> start_routine;
692 start_arg = si -> arg;
693 if (si-> detached) me -> flags |= DETACHED;
694 me -> pthread_id = pthread_id = pthread_self();
696 GC_free(si); /* was allocated uncollectable */
698 pthread_cleanup_push(GC_thread_exit_proc, (void *)me);
699 result = (*start)(start_arg);
700 me -> status = result;
701 pthread_cleanup_pop(0);
703 # if DEBUG_CYGWIN_THREADS
704 GC_printf2("thread 0x%x(0x%x) returned from start routine.\n",
705 (int)pthread_self(),GetCurrentThreadId());
711 void GC_thread_exit_proc(void *arg)
713 GC_thread me = (GC_thread)arg;
716 # if DEBUG_CYGWIN_THREADS
717 GC_printf2("thread 0x%x(0x%x) called pthread_exit().\n",
718 (int)pthread_self(),GetCurrentThreadId());
722 if (me -> flags & DETACHED) {
723 GC_delete_thread(GetCurrentThreadId());
725 /* deallocate it as part of join */
726 me -> flags |= FINISHED;
731 /* nothing required here... */
732 int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) {
733 return pthread_sigmask(how, set, oset);
736 int GC_pthread_detach(pthread_t thread)
739 GC_thread thread_gc_id;
742 thread_gc_id = GC_lookup_thread(thread);
744 result = pthread_detach(thread);
747 thread_gc_id -> flags |= DETACHED;
748 /* Here the pthread thread id may have been recycled. */
749 if (thread_gc_id -> flags & FINISHED) {
750 GC_delete_gc_thread(thread_gc_id);
757 #else /* !CYGWIN32 */
760 * We avoid acquiring locks here, since this doesn't seem to be preemptable.
761 * Pontus Rydin suggests wrapping the thread start routine instead.
764 BOOL WINAPI DllMain(HINSTANCE inst, ULONG reason, LPVOID reserved)
767 case DLL_PROCESS_ATTACH:
768 GC_init(); /* Force initialization before thread attach. */
770 case DLL_THREAD_ATTACH:
771 GC_ASSERT(GC_thr_initialized);
772 if (GC_main_thread != GetCurrentThreadId()) {
774 } /* o.w. we already did it during GC_thr_init(), called by GC_init() */
777 case DLL_THREAD_DETACH:
778 GC_delete_thread(GetCurrentThreadId());
781 case DLL_PROCESS_DETACH:
786 for (i = 0; i <= GC_get_max_thread_index(); ++i)
788 if (thread_table[i].in_use)
789 GC_delete_gc_thread(thread_table + i);
794 DeleteCriticalSection(&GC_allocate_ml);
802 #endif /* !CYGWIN32 */
804 # endif /* !MSWINCE */
806 #endif /* GC_WIN32_THREADS */