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+/*
+ * Copyright (c) 1994 by Xerox Corporation. All rights reserved.
+ * Copyright (c) 1996 by Silicon Graphics. All rights reserved.
+ * Copyright (c) 1998 by Fergus Henderson. All rights reserved.
+ * Copyright (c) 2000-2001 by Hewlett-Packard Company. All rights reserved.
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose, provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ */
+/*
+ * Support code for LinuxThreads, the clone()-based kernel
+ * thread package for Linux which is included in libc6.
+ *
+ * This code relies on implementation details of LinuxThreads,
+ * (i.e. properties not guaranteed by the Pthread standard),
+ * though this version now does less of that than the other Pthreads
+ * support code.
+ *
+ * Note that there is a lot of code duplication between linux_threads.c
+ * and thread support for some of the other Posix platforms; any changes
+ * made here may need to be reflected there too.
+ */
+ /* DG/UX ix86 support <takis@xfree86.org> */
+/*
+ * Linux_threads.c now also includes some code to support HPUX and
+ * OSF1 (Compaq Tru64 Unix, really). The OSF1 support is based on Eric Benson's
+ * patch.
+ *
+ * Eric also suggested an alternate basis for a lock implementation in
+ * his code:
+ * + #elif defined(OSF1)
+ * + unsigned long GC_allocate_lock = 0;
+ * + msemaphore GC_allocate_semaphore;
+ * + # define GC_TRY_LOCK() \
+ * + ((msem_lock(&GC_allocate_semaphore, MSEM_IF_NOWAIT) == 0) \
+ * + ? (GC_allocate_lock = 1) \
+ * + : 0)
+ * + # define GC_LOCK_TAKEN GC_allocate_lock
+ */
+
+/*#define DEBUG_THREADS 1*/
+/*#define GC_ASSERTIONS*/
+
+# include "private/pthread_support.h"
+
+# if defined(GC_PTHREADS) && !defined(GC_SOLARIS_THREADS) \
+ && !defined(GC_IRIX_THREADS) && !defined(GC_WIN32_THREADS) \
+ && !defined(GC_AIX_THREADS)
+
+# if defined(GC_HPUX_THREADS) && !defined(USE_PTHREAD_SPECIFIC) \
+ && !defined(USE_HPUX_TLS)
+# define USE_HPUX_TLS
+# endif
+
+# if (defined(GC_DGUX386_THREADS) || defined(GC_OSF1_THREADS) || \
+ defined(GC_DARWIN_THREADS)) && !defined(USE_PTHREAD_SPECIFIC)
+# define USE_PTHREAD_SPECIFIC
+# endif
+
+# if defined(GC_DGUX386_THREADS) && !defined(_POSIX4A_DRAFT10_SOURCE)
+# define _POSIX4A_DRAFT10_SOURCE 1
+# endif
+
+# if defined(GC_DGUX386_THREADS) && !defined(_USING_POSIX4A_DRAFT10)
+# define _USING_POSIX4A_DRAFT10 1
+# endif
+
+# ifdef THREAD_LOCAL_ALLOC
+# if !defined(USE_PTHREAD_SPECIFIC) && !defined(USE_HPUX_TLS)
+# include "private/specific.h"
+# endif
+# if defined(USE_PTHREAD_SPECIFIC)
+# define GC_getspecific pthread_getspecific
+# define GC_setspecific pthread_setspecific
+# define GC_key_create pthread_key_create
+ typedef pthread_key_t GC_key_t;
+# endif
+# if defined(USE_HPUX_TLS)
+# define GC_getspecific(x) (x)
+# define GC_setspecific(key, v) ((key) = (v), 0)
+# define GC_key_create(key, d) 0
+ typedef void * GC_key_t;
+# endif
+# endif
+# include <stdlib.h>
+# include <pthread.h>
+# include <sched.h>
+# include <time.h>
+# include <errno.h>
+# include <unistd.h>
+# include <sys/mman.h>
+# include <sys/time.h>
+# include <sys/types.h>
+# include <sys/stat.h>
+# include <fcntl.h>
+
+#if defined(GC_DARWIN_THREADS)
+# include "private/darwin_semaphore.h"
+#else
+# include <semaphore.h>
+#endif /* !GC_DARWIN_THREADS */
+
+#if defined(GC_DARWIN_THREADS)
+# include <sys/sysctl.h>
+#endif /* GC_DARWIN_THREADS */
+
+
+
+#if defined(GC_DGUX386_THREADS)
+# include <sys/dg_sys_info.h>
+# include <sys/_int_psem.h>
+ /* sem_t is an uint in DG/UX */
+ typedef unsigned int sem_t;
+#endif /* GC_DGUX386_THREADS */
+
+#ifndef __GNUC__
+# define __inline__
+#endif
+
+#ifdef GC_USE_LD_WRAP
+# define WRAP_FUNC(f) __wrap_##f
+# define REAL_FUNC(f) __real_##f
+#else
+# define WRAP_FUNC(f) GC_##f
+# if !defined(GC_DGUX386_THREADS)
+# define REAL_FUNC(f) f
+# else /* GC_DGUX386_THREADS */
+# define REAL_FUNC(f) __d10_##f
+# endif /* GC_DGUX386_THREADS */
+# undef pthread_create
+# if !defined(GC_DARWIN_THREADS)
+# undef pthread_sigmask
+# endif
+# undef pthread_join
+# undef pthread_detach
+#endif
+
+void GC_thr_init();
+
+static GC_bool parallel_initialized = FALSE;
+
+void GC_init_parallel();
+
+# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+
+/* We don't really support thread-local allocation with DBG_HDRS_ALL */
+
+#ifdef USE_HPUX_TLS
+ __thread
+#endif
+GC_key_t GC_thread_key;
+
+static GC_bool keys_initialized;
+
+/* Recover the contents of the freelist array fl into the global one gfl.*/
+/* Note that the indexing scheme differs, in that gfl has finer size */
+/* resolution, even if not all entries are used. */
+/* We hold the allocator lock. */
+static void return_freelists(ptr_t *fl, ptr_t *gfl)
+{
+ int i;
+ ptr_t q, *qptr;
+ size_t nwords;
+
+ for (i = 1; i < NFREELISTS; ++i) {
+ nwords = i * (GRANULARITY/sizeof(word));
+ qptr = fl + i;
+ q = *qptr;
+ if ((word)q >= HBLKSIZE) {
+ if (gfl[nwords] == 0) {
+ gfl[nwords] = q;
+ } else {
+ /* Concatenate: */
+ for (; (word)q >= HBLKSIZE; qptr = &(obj_link(q)), q = *qptr);
+ GC_ASSERT(0 == q);
+ *qptr = gfl[nwords];
+ gfl[nwords] = fl[i];
+ }
+ }
+ /* Clear fl[i], since the thread structure may hang around. */
+ /* Do it in a way that is likely to trap if we access it. */
+ fl[i] = (ptr_t)HBLKSIZE;
+ }
+}
+
+/* We statically allocate a single "size 0" object. It is linked to */
+/* itself, and is thus repeatedly reused for all size 0 allocation */
+/* requests. (Size 0 gcj allocation requests are incorrect, and */
+/* we arrange for those to fault asap.) */
+static ptr_t size_zero_object = (ptr_t)(&size_zero_object);
+
+/* Each thread structure must be initialized. */
+/* This call must be made from the new thread. */
+/* Caller holds allocation lock. */
+void GC_init_thread_local(GC_thread p)
+{
+ int i;
+
+ if (!keys_initialized) {
+ if (0 != GC_key_create(&GC_thread_key, 0)) {
+ ABORT("Failed to create key for local allocator");
+ }
+ keys_initialized = TRUE;
+ }
+ if (0 != GC_setspecific(GC_thread_key, p)) {
+ ABORT("Failed to set thread specific allocation pointers");
+ }
+ for (i = 1; i < NFREELISTS; ++i) {
+ p -> ptrfree_freelists[i] = (ptr_t)1;
+ p -> normal_freelists[i] = (ptr_t)1;
+# ifdef GC_GCJ_SUPPORT
+ p -> gcj_freelists[i] = (ptr_t)1;
+# endif
+ }
+ /* Set up the size 0 free lists. */
+ p -> ptrfree_freelists[0] = (ptr_t)(&size_zero_object);
+ p -> normal_freelists[0] = (ptr_t)(&size_zero_object);
+# ifdef GC_GCJ_SUPPORT
+ p -> gcj_freelists[0] = (ptr_t)(-1);
+# endif
+}
+
+#ifdef GC_GCJ_SUPPORT
+ extern ptr_t * GC_gcjobjfreelist;
+#endif
+
+/* We hold the allocator lock. */
+void GC_destroy_thread_local(GC_thread p)
+{
+ /* We currently only do this from the thread itself or from */
+ /* the fork handler for a child process. */
+# ifndef HANDLE_FORK
+ GC_ASSERT(GC_getspecific(GC_thread_key) == (void *)p);
+# endif
+ return_freelists(p -> ptrfree_freelists, GC_aobjfreelist);
+ return_freelists(p -> normal_freelists, GC_objfreelist);
+# ifdef GC_GCJ_SUPPORT
+ return_freelists(p -> gcj_freelists, GC_gcjobjfreelist);
+# endif
+}
+
+extern GC_PTR GC_generic_malloc_many();
+
+GC_PTR GC_local_malloc(size_t bytes)
+{
+ if (EXPECT(!SMALL_ENOUGH(bytes),0)) {
+ return(GC_malloc(bytes));
+ } else {
+ int index = INDEX_FROM_BYTES(bytes);
+ ptr_t * my_fl;
+ ptr_t my_entry;
+# if defined(REDIRECT_MALLOC) && !defined(USE_PTHREAD_SPECIFIC)
+ GC_key_t k = GC_thread_key;
+# endif
+ void * tsd;
+
+# if defined(REDIRECT_MALLOC) && !defined(USE_PTHREAD_SPECIFIC)
+ if (EXPECT(0 == k, 0)) {
+ /* This can happen if we get called when the world is */
+ /* being initialized. Whether we can actually complete */
+ /* the initialization then is unclear. */
+ GC_init_parallel();
+ k = GC_thread_key;
+ }
+# endif
+ tsd = GC_getspecific(GC_thread_key);
+# ifdef GC_ASSERTIONS
+ LOCK();
+ GC_ASSERT(tsd == (void *)GC_lookup_thread(pthread_self()));
+ UNLOCK();
+# endif
+ my_fl = ((GC_thread)tsd) -> normal_freelists + index;
+ my_entry = *my_fl;
+ if (EXPECT((word)my_entry >= HBLKSIZE, 1)) {
+ ptr_t next = obj_link(my_entry);
+ GC_PTR result = (GC_PTR)my_entry;
+ *my_fl = next;
+ obj_link(my_entry) = 0;
+ PREFETCH_FOR_WRITE(next);
+ return result;
+ } else if ((word)my_entry - 1 < DIRECT_GRANULES) {
+ *my_fl = my_entry + index + 1;
+ return GC_malloc(bytes);
+ } else {
+ GC_generic_malloc_many(BYTES_FROM_INDEX(index), NORMAL, my_fl);
+ if (*my_fl == 0) return GC_oom_fn(bytes);
+ return GC_local_malloc(bytes);
+ }
+ }
+}
+
+GC_PTR GC_local_malloc_atomic(size_t bytes)
+{
+ if (EXPECT(!SMALL_ENOUGH(bytes), 0)) {
+ return(GC_malloc_atomic(bytes));
+ } else {
+ int index = INDEX_FROM_BYTES(bytes);
+ ptr_t * my_fl = ((GC_thread)GC_getspecific(GC_thread_key))
+ -> ptrfree_freelists + index;
+ ptr_t my_entry = *my_fl;
+
+ if (EXPECT((word)my_entry >= HBLKSIZE, 1)) {
+ GC_PTR result = (GC_PTR)my_entry;
+ *my_fl = obj_link(my_entry);
+ return result;
+ } else if ((word)my_entry - 1 < DIRECT_GRANULES) {
+ *my_fl = my_entry + index + 1;
+ return GC_malloc_atomic(bytes);
+ } else {
+ GC_generic_malloc_many(BYTES_FROM_INDEX(index), PTRFREE, my_fl);
+ /* *my_fl is updated while the collector is excluded; */
+ /* the free list is always visible to the collector as */
+ /* such. */
+ if (*my_fl == 0) return GC_oom_fn(bytes);
+ return GC_local_malloc_atomic(bytes);
+ }
+ }
+}
+
+#ifdef GC_GCJ_SUPPORT
+
+#include "include/gc_gcj.h"
+
+#ifdef GC_ASSERTIONS
+ extern GC_bool GC_gcj_malloc_initialized;
+#endif
+
+extern int GC_gcj_kind;
+
+GC_PTR GC_local_gcj_malloc(size_t bytes,
+ void * ptr_to_struct_containing_descr)
+{
+ GC_ASSERT(GC_gcj_malloc_initialized);
+ if (EXPECT(!SMALL_ENOUGH(bytes), 0)) {
+ return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr);
+ } else {
+ int index = INDEX_FROM_BYTES(bytes);
+ ptr_t * my_fl = ((GC_thread)GC_getspecific(GC_thread_key))
+ -> gcj_freelists + index;
+ ptr_t my_entry = *my_fl;
+ if (EXPECT((word)my_entry >= HBLKSIZE, 1)) {
+ GC_PTR result = (GC_PTR)my_entry;
+ GC_ASSERT(!GC_incremental);
+ /* We assert that any concurrent marker will stop us. */
+ /* Thus it is impossible for a mark procedure to see the */
+ /* allocation of the next object, but to see this object */
+ /* still containing a free list pointer. Otherwise the */
+ /* marker might find a random "mark descriptor". */
+ *(volatile ptr_t *)my_fl = obj_link(my_entry);
+ /* We must update the freelist before we store the pointer. */
+ /* Otherwise a GC at this point would see a corrupted */
+ /* free list. */
+ /* A memory barrier is probably never needed, since the */
+ /* action of stopping this thread will cause prior writes */
+ /* to complete. */
+ GC_ASSERT(((void * volatile *)result)[1] == 0);
+ *(void * volatile *)result = ptr_to_struct_containing_descr;
+ return result;
+ } else if ((word)my_entry - 1 < DIRECT_GRANULES) {
+ if (!GC_incremental) *my_fl = my_entry + index + 1;
+ /* In the incremental case, we always have to take this */
+ /* path. Thus we leave the counter alone. */
+ return GC_gcj_malloc(bytes, ptr_to_struct_containing_descr);
+ } else {
+ GC_generic_malloc_many(BYTES_FROM_INDEX(index), GC_gcj_kind, my_fl);
+ if (*my_fl == 0) return GC_oom_fn(bytes);
+ return GC_local_gcj_malloc(bytes, ptr_to_struct_containing_descr);
+ }
+ }
+}
+
+#endif /* GC_GCJ_SUPPORT */
+
+# else /* !THREAD_LOCAL_ALLOC && !DBG_HDRS_ALL */
+
+# define GC_destroy_thread_local(t)
+
+# endif /* !THREAD_LOCAL_ALLOC */
+
+#if 0
+/*
+To make sure that we're using LinuxThreads and not some other thread
+package, we generate a dummy reference to `pthread_kill_other_threads_np'
+(was `__pthread_initial_thread_bos' but that disappeared),
+which is a symbol defined in LinuxThreads, but (hopefully) not in other
+thread packages.
+
+We no longer do this, since this code is now portable enough that it might
+actually work for something else.
+*/
+void (*dummy_var_to_force_linux_threads)() = pthread_kill_other_threads_np;
+#endif /* 0 */
+
+long GC_nprocs = 1; /* Number of processors. We may not have */
+ /* access to all of them, but this is as good */
+ /* a guess as any ... */
+
+#ifdef PARALLEL_MARK
+
+# ifndef MAX_MARKERS
+# define MAX_MARKERS 16
+# endif
+
+static ptr_t marker_sp[MAX_MARKERS] = {0};
+
+void * GC_mark_thread(void * id)
+{
+ word my_mark_no = 0;
+
+ marker_sp[(word)id] = GC_approx_sp();
+ for (;; ++my_mark_no) {
+ /* GC_mark_no is passed only to allow GC_help_marker to terminate */
+ /* promptly. This is important if it were called from the signal */
+ /* handler or from the GC lock acquisition code. Under Linux, it's */
+ /* not safe to call it from a signal handler, since it uses mutexes */
+ /* and condition variables. Since it is called only here, the */
+ /* argument is unnecessary. */
+ if (my_mark_no < GC_mark_no || my_mark_no > GC_mark_no + 2) {
+ /* resynchronize if we get far off, e.g. because GC_mark_no */
+ /* wrapped. */
+ my_mark_no = GC_mark_no;
+ }
+# ifdef DEBUG_THREADS
+ GC_printf1("Starting mark helper for mark number %ld\n", my_mark_no);
+# endif
+ GC_help_marker(my_mark_no);
+ }
+}
+
+extern long GC_markers; /* Number of mark threads we would */
+ /* like to have. Includes the */
+ /* initiating thread. */
+
+pthread_t GC_mark_threads[MAX_MARKERS];
+
+#define PTHREAD_CREATE REAL_FUNC(pthread_create)
+
+static void start_mark_threads()
+{
+ unsigned i;
+ pthread_attr_t attr;
+
+ if (GC_markers > MAX_MARKERS) {
+ WARN("Limiting number of mark threads\n", 0);
+ GC_markers = MAX_MARKERS;
+ }
+ if (0 != pthread_attr_init(&attr)) ABORT("pthread_attr_init failed");
+
+ if (0 != pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED))
+ ABORT("pthread_attr_setdetachstate failed");
+
+# if defined(HPUX) || defined(GC_DGUX386_THREADS)
+ /* Default stack size is usually too small: fix it. */
+ /* Otherwise marker threads or GC may run out of */
+ /* space. */
+# define MIN_STACK_SIZE (8*HBLKSIZE*sizeof(word))
+ {
+ size_t old_size;
+ int code;
+
+ if (pthread_attr_getstacksize(&attr, &old_size) != 0)
+ ABORT("pthread_attr_getstacksize failed\n");
+ if (old_size < MIN_STACK_SIZE) {
+ if (pthread_attr_setstacksize(&attr, MIN_STACK_SIZE) != 0)
+ ABORT("pthread_attr_setstacksize failed\n");
+ }
+ }
+# endif /* HPUX || GC_DGUX386_THREADS */
+# ifdef CONDPRINT
+ if (GC_print_stats) {
+ GC_printf1("Starting %ld marker threads\n", GC_markers - 1);
+ }
+# endif
+ for (i = 0; i < GC_markers - 1; ++i) {
+ if (0 != PTHREAD_CREATE(GC_mark_threads + i, &attr,
+ GC_mark_thread, (void *)(word)i)) {
+ WARN("Marker thread creation failed, errno = %ld.\n", errno);
+ }
+ }
+}
+
+#else /* !PARALLEL_MARK */
+
+static __inline__ void start_mark_threads()
+{
+}
+
+#endif /* !PARALLEL_MARK */
+
+/* Defining INSTALL_LOOPING_SEGV_HANDLER causes SIGSEGV and SIGBUS to */
+/* result in an infinite loop in a signal handler. This can be very */
+/* useful for debugging, since (as of RH7) gdb still seems to have */
+/* serious problems with threads. */
+#ifdef INSTALL_LOOPING_SEGV_HANDLER
+void GC_looping_handler(int sig)
+{
+ GC_printf3("Signal %ld in thread %lx, pid %ld\n",
+ sig, pthread_self(), getpid());
+ for (;;);
+}
+#endif
+
+GC_bool GC_thr_initialized = FALSE;
+
+volatile GC_thread GC_threads[THREAD_TABLE_SZ];
+
+void GC_push_thread_structures GC_PROTO((void))
+{
+ GC_push_all((ptr_t)(GC_threads), (ptr_t)(GC_threads)+sizeof(GC_threads));
+# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+ GC_push_all((ptr_t)(&GC_thread_key),
+ (ptr_t)(&GC_thread_key)+sizeof(&GC_thread_key));
+# endif
+}
+
+#ifdef THREAD_LOCAL_ALLOC
+/* We must explicitly mark ptrfree and gcj free lists, since the free */
+/* list links wouldn't otherwise be found. We also set them in the */
+/* normal free lists, since that involves touching less memory than if */
+/* we scanned them normally. */
+void GC_mark_thread_local_free_lists(void)
+{
+ int i, j;
+ GC_thread p;
+ ptr_t q;
+
+ for (i = 0; i < THREAD_TABLE_SZ; ++i) {
+ for (p = GC_threads[i]; 0 != p; p = p -> next) {
+ for (j = 1; j < NFREELISTS; ++j) {
+ q = p -> ptrfree_freelists[j];
+ if ((word)q > HBLKSIZE) GC_set_fl_marks(q);
+ q = p -> normal_freelists[j];
+ if ((word)q > HBLKSIZE) GC_set_fl_marks(q);
+# ifdef GC_GCJ_SUPPORT
+ q = p -> gcj_freelists[j];
+ if ((word)q > HBLKSIZE) GC_set_fl_marks(q);
+# endif /* GC_GCJ_SUPPORT */
+ }
+ }
+ }
+}
+#endif /* THREAD_LOCAL_ALLOC */
+
+static struct GC_Thread_Rep first_thread;
+
+/* Add a thread to GC_threads. We assume it wasn't already there. */
+/* Caller holds allocation lock. */
+GC_thread GC_new_thread(pthread_t id)
+{
+ int hv = ((word)id) % THREAD_TABLE_SZ;
+ GC_thread result;
+ static GC_bool first_thread_used = FALSE;
+
+ if (!first_thread_used) {
+ result = &first_thread;
+ first_thread_used = TRUE;
+ } else {
+ result = (struct GC_Thread_Rep *)
+ GC_INTERNAL_MALLOC(sizeof(struct GC_Thread_Rep), NORMAL);
+ }
+ if (result == 0) return(0);
+ result -> id = id;
+ result -> next = GC_threads[hv];
+ GC_threads[hv] = result;
+ GC_ASSERT(result -> flags == 0 && result -> thread_blocked == 0);
+ return(result);
+}
+
+/* Delete a thread from GC_threads. We assume it is there. */
+/* (The code intentionally traps if it wasn't.) */
+/* Caller holds allocation lock. */
+void GC_delete_thread(pthread_t id)
+{
+ int hv = ((word)id) % THREAD_TABLE_SZ;
+ register GC_thread p = GC_threads[hv];
+ register GC_thread prev = 0;
+
+ while (!pthread_equal(p -> id, id)) {
+ prev = p;
+ p = p -> next;
+ }
+ if (prev == 0) {
+ GC_threads[hv] = p -> next;
+ } else {
+ prev -> next = p -> next;
+ }
+ GC_INTERNAL_FREE(p);
+}
+
+/* If a thread has been joined, but we have not yet */
+/* been notified, then there may be more than one thread */
+/* in the table with the same pthread id. */
+/* This is OK, but we need a way to delete a specific one. */
+void GC_delete_gc_thread(pthread_t id, GC_thread gc_id)
+{
+ int hv = ((word)id) % THREAD_TABLE_SZ;
+ register GC_thread p = GC_threads[hv];
+ register GC_thread prev = 0;
+
+ while (p != gc_id) {
+ prev = p;
+ p = p -> next;
+ }
+ if (prev == 0) {
+ GC_threads[hv] = p -> next;
+ } else {
+ prev -> next = p -> next;
+ }
+ GC_INTERNAL_FREE(p);
+}
+
+/* Return a GC_thread corresponding to a given thread_t. */
+/* Returns 0 if it's not there. */
+/* Caller holds allocation lock or otherwise inhibits */
+/* updates. */
+/* If there is more than one thread with the given id we */
+/* return the most recent one. */
+GC_thread GC_lookup_thread(pthread_t id)
+{
+ int hv = ((word)id) % THREAD_TABLE_SZ;
+ register GC_thread p = GC_threads[hv];
+
+ while (p != 0 && !pthread_equal(p -> id, id)) p = p -> next;
+ return(p);
+}
+
+#ifdef HANDLE_FORK
+/* Remove all entries from the GC_threads table, except the */
+/* one for the current thread. We need to do this in the child */
+/* process after a fork(), since only the current thread */
+/* survives in the child. */
+void GC_remove_all_threads_but_me(void)
+{
+ pthread_t self = pthread_self();
+ int hv;
+ GC_thread p, next, me;
+
+ for (hv = 0; hv < THREAD_TABLE_SZ; ++hv) {
+ me = 0;
+ for (p = GC_threads[hv]; 0 != p; p = next) {
+ next = p -> next;
+ if (p -> id == self) {
+ me = p;
+ p -> next = 0;
+ } else {
+# ifdef THREAD_LOCAL_ALLOC
+ if (!(p -> flags & FINISHED)) {
+ GC_destroy_thread_local(p);
+ }
+# endif /* THREAD_LOCAL_ALLOC */
+ if (p != &first_thread) GC_INTERNAL_FREE(p);
+ }
+ }
+ GC_threads[hv] = me;
+ }
+}
+#endif /* HANDLE_FORK */
+
+#ifdef USE_PROC_FOR_LIBRARIES
+int GC_segment_is_thread_stack(ptr_t lo, ptr_t hi)
+{
+ int i;
+ GC_thread p;
+
+# ifdef PARALLEL_MARK
+ for (i = 0; i < GC_markers; ++i) {
+ if (marker_sp[i] > lo & marker_sp[i] < hi) return 1;
+ }
+# endif
+ for (i = 0; i < THREAD_TABLE_SZ; i++) {
+ for (p = GC_threads[i]; p != 0; p = p -> next) {
+ if (0 != p -> stack_end) {
+# ifdef STACK_GROWS_UP
+ if (p -> stack_end >= lo && p -> stack_end < hi) return 1;
+# else /* STACK_GROWS_DOWN */
+ if (p -> stack_end > lo && p -> stack_end <= hi) return 1;
+# endif
+ }
+ }
+ }
+ return 0;
+}
+#endif /* USE_PROC_FOR_LIBRARIES */
+
+#ifdef GC_LINUX_THREADS
+/* Return the number of processors, or i<= 0 if it can't be determined. */
+int GC_get_nprocs()
+{
+ /* Should be "return sysconf(_SC_NPROCESSORS_ONLN);" but that */
+ /* appears to be buggy in many cases. */
+ /* We look for lines "cpu<n>" in /proc/stat. */
+# define STAT_BUF_SIZE 4096
+# define STAT_READ read
+ /* If read is wrapped, this may need to be redefined to call */
+ /* the real one. */
+ char stat_buf[STAT_BUF_SIZE];
+ int f;
+ word result = 1;
+ /* Some old kernels only have a single "cpu nnnn ..." */
+ /* entry in /proc/stat. We identify those as */
+ /* uniprocessors. */
+ size_t i, len = 0;
+
+ f = open("/proc/stat", O_RDONLY);
+ if (f < 0 || (len = STAT_READ(f, stat_buf, STAT_BUF_SIZE)) < 100) {
+ WARN("Couldn't read /proc/stat\n", 0);
+ return -1;
+ }
+ for (i = 0; i < len - 100; ++i) {
+ if (stat_buf[i] == '\n' && stat_buf[i+1] == 'c'
+ && stat_buf[i+2] == 'p' && stat_buf[i+3] == 'u') {
+ int cpu_no = atoi(stat_buf + i + 4);
+ if (cpu_no >= result) result = cpu_no + 1;
+ }
+ }
+ close(f);
+ return result;
+}
+#endif /* GC_LINUX_THREADS */
+
+/* We hold the GC lock. Wait until an in-progress GC has finished. */
+/* Repeatedly RELEASES GC LOCK in order to wait. */
+/* If wait_for_all is true, then we exit with the GC lock held and no */
+/* collection in progress; otherwise we just wait for the current GC */
+/* to finish. */
+extern GC_bool GC_collection_in_progress();
+void GC_wait_for_gc_completion(GC_bool wait_for_all)
+{
+ if (GC_incremental && GC_collection_in_progress()) {
+ int old_gc_no = GC_gc_no;
+
+ /* Make sure that no part of our stack is still on the mark stack, */
+ /* since it's about to be unmapped. */
+ while (GC_incremental && GC_collection_in_progress()
+ && (wait_for_all || old_gc_no == GC_gc_no)) {
+ ENTER_GC();
+ GC_collect_a_little_inner(1);
+ EXIT_GC();
+ UNLOCK();
+ sched_yield();
+ LOCK();
+ }
+ }
+}
+
+#ifdef HANDLE_FORK
+/* Procedures called before and after a fork. The goal here is to make */
+/* it safe to call GC_malloc() in a forked child. It's unclear that is */
+/* attainable, since the single UNIX spec seems to imply that one */
+/* should only call async-signal-safe functions, and we probably can't */
+/* quite guarantee that. But we give it our best shot. (That same */
+/* spec also implies that it's not safe to call the system malloc */
+/* between fork() and exec(). Thus we're doing no worse than it. */
+
+/* Called before a fork() */
+void GC_fork_prepare_proc(void)
+{
+ /* Acquire all relevant locks, so that after releasing the locks */
+ /* the child will see a consistent state in which monitor */
+ /* invariants hold. Unfortunately, we can't acquire libc locks */
+ /* we might need, and there seems to be no guarantee that libc */
+ /* must install a suitable fork handler. */
+ /* Wait for an ongoing GC to finish, since we can't finish it in */
+ /* the (one remaining thread in) the child. */
+ LOCK();
+# if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
+ GC_wait_for_reclaim();
+# endif
+ GC_wait_for_gc_completion(TRUE);
+# if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
+ GC_acquire_mark_lock();
+# endif
+}
+
+/* Called in parent after a fork() */
+void GC_fork_parent_proc(void)
+{
+# if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
+ GC_release_mark_lock();
+# endif
+ UNLOCK();
+}
+
+/* Called in child after a fork() */
+void GC_fork_child_proc(void)
+{
+ /* Clean up the thread table, so that just our thread is left. */
+# if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
+ GC_release_mark_lock();
+# endif
+ GC_remove_all_threads_but_me();
+# ifdef PARALLEL_MARK
+ /* Turn off parallel marking in the child, since we are probably */
+ /* just going to exec, and we would have to restart mark threads. */
+ GC_markers = 1;
+ GC_parallel = FALSE;
+# endif /* PARALLEL_MARK */
+ UNLOCK();
+}
+#endif /* HANDLE_FORK */
+
+#if defined(GC_DGUX386_THREADS)
+/* Return the number of processors, or i<= 0 if it can't be determined. */
+int GC_get_nprocs()
+{
+ /* <takis@XFree86.Org> */
+ int numCpus;
+ struct dg_sys_info_pm_info pm_sysinfo;
+ int status =0;
+
+ status = dg_sys_info((long int *) &pm_sysinfo,
+ DG_SYS_INFO_PM_INFO_TYPE, DG_SYS_INFO_PM_CURRENT_VERSION);
+ if (status < 0)
+ /* set -1 for error */
+ numCpus = -1;
+ else
+ /* Active CPUs */
+ numCpus = pm_sysinfo.idle_vp_count;
+
+# ifdef DEBUG_THREADS
+ GC_printf1("Number of active CPUs in this system: %d\n", numCpus);
+# endif
+ return(numCpus);
+}
+#endif /* GC_DGUX386_THREADS */
+
+/* We hold the allocation lock. */
+void GC_thr_init()
+{
+# ifndef GC_DARWIN_THREADS
+ int dummy;
+# endif
+ GC_thread t;
+
+ if (GC_thr_initialized) return;
+ GC_thr_initialized = TRUE;
+
+# ifdef HANDLE_FORK
+ /* Prepare for a possible fork. */
+ pthread_atfork(GC_fork_prepare_proc, GC_fork_parent_proc,
+ GC_fork_child_proc);
+# endif /* HANDLE_FORK */
+ /* Add the initial thread, so we can stop it. */
+ t = GC_new_thread(pthread_self());
+# ifdef GC_DARWIN_THREADS
+ t -> stop_info.mach_thread = mach_thread_self();
+# else
+ t -> stop_info.stack_ptr = (ptr_t)(&dummy);
+# endif
+ t -> flags = DETACHED | MAIN_THREAD;
+
+ GC_stop_init();
+
+ /* Set GC_nprocs. */
+ {
+ char * nprocs_string = GETENV("GC_NPROCS");
+ GC_nprocs = -1;
+ if (nprocs_string != NULL) GC_nprocs = atoi(nprocs_string);
+ }
+ if (GC_nprocs <= 0) {
+# if defined(GC_HPUX_THREADS)
+ GC_nprocs = pthread_num_processors_np();
+# endif
+# if defined(GC_OSF1_THREADS)
+ GC_nprocs = sysconf(_SC_NPROCESSORS_ONLN);
+ if (GC_nprocs <= 0) GC_nprocs = 1;
+# endif
+# if defined(GC_FREEBSD_THREADS)
+ GC_nprocs = 1;
+# endif
+# if defined(GC_DARWIN_THREADS)
+ int ncpus = 1;
+ size_t len = sizeof(ncpus);
+ sysctl((int[2]) {CTL_HW, HW_NCPU}, 2, &ncpus, &len, NULL, 0);
+ GC_nprocs = ncpus;
+# endif
+# if defined(GC_LINUX_THREADS) || defined(GC_DGUX386_THREADS)
+ GC_nprocs = GC_get_nprocs();
+# endif
+ }
+ if (GC_nprocs <= 0) {
+ WARN("GC_get_nprocs() returned %ld\n", GC_nprocs);
+ GC_nprocs = 2;
+# ifdef PARALLEL_MARK
+ GC_markers = 1;
+# endif
+ } else {
+# ifdef PARALLEL_MARK
+ {
+ char * markers_string = GETENV("GC_MARKERS");
+ if (markers_string != NULL) {
+ GC_markers = atoi(markers_string);
+ } else {
+ GC_markers = GC_nprocs;
+ }
+ }
+# endif
+ }
+# ifdef PARALLEL_MARK
+# ifdef CONDPRINT
+ if (GC_print_stats) {
+ GC_printf2("Number of processors = %ld, "
+ "number of marker threads = %ld\n", GC_nprocs, GC_markers);
+ }
+# endif
+ if (GC_markers == 1) {
+ GC_parallel = FALSE;
+# ifdef CONDPRINT
+ if (GC_print_stats) {
+ GC_printf0("Single marker thread, turning off parallel marking\n");
+ }
+# endif
+ } else {
+ GC_parallel = TRUE;
+ /* Disable true incremental collection, but generational is OK. */
+ GC_time_limit = GC_TIME_UNLIMITED;
+ }
+# endif
+}
+
+
+/* Perform all initializations, including those that */
+/* may require allocation. */
+/* Called without allocation lock. */
+/* Must be called before a second thread is created. */
+/* Called without allocation lock. */
+void GC_init_parallel()
+{
+ if (parallel_initialized) return;
+ parallel_initialized = TRUE;
+
+ /* GC_init() calls us back, so set flag first. */
+ if (!GC_is_initialized) GC_init();
+ /* If we are using a parallel marker, start the helper threads. */
+# ifdef PARALLEL_MARK
+ if (GC_parallel) start_mark_threads();
+# endif
+ /* Initialize thread local free lists if used. */
+# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+ LOCK();
+ GC_init_thread_local(GC_lookup_thread(pthread_self()));
+ UNLOCK();
+# endif
+}
+
+
+#if !defined(GC_DARWIN_THREADS)
+int WRAP_FUNC(pthread_sigmask)(int how, const sigset_t *set, sigset_t *oset)
+{
+ sigset_t fudged_set;
+
+ if (set != NULL && (how == SIG_BLOCK || how == SIG_SETMASK)) {
+ fudged_set = *set;
+ sigdelset(&fudged_set, SIG_SUSPEND);
+ set = &fudged_set;
+ }
+ return(REAL_FUNC(pthread_sigmask)(how, set, oset));
+}
+#endif /* !GC_DARWIN_THREADS */
+
+/* Wrappers for functions that are likely to block for an appreciable */
+/* length of time. Must be called in pairs, if at all. */
+/* Nothing much beyond the system call itself should be executed */
+/* between these. */
+
+void GC_start_blocking(void) {
+# define SP_SLOP 128
+ GC_thread me;
+ LOCK();
+ me = GC_lookup_thread(pthread_self());
+ GC_ASSERT(!(me -> thread_blocked));
+# ifdef SPARC
+ me -> stop_info.stack_ptr = (ptr_t)GC_save_regs_in_stack();
+# else
+# ifndef GC_DARWIN_THREADS
+ me -> stop_info.stack_ptr = (ptr_t)GC_approx_sp();
+# endif
+# endif
+# ifdef IA64
+ me -> backing_store_ptr = (ptr_t)GC_save_regs_in_stack() + SP_SLOP;
+# endif
+ /* Add some slop to the stack pointer, since the wrapped call may */
+ /* end up pushing more callee-save registers. */
+# ifndef GC_DARWIN_THREADS
+# ifdef STACK_GROWS_UP
+ me -> stop_info.stack_ptr += SP_SLOP;
+# else
+ me -> stop_info.stack_ptr -= SP_SLOP;
+# endif
+# endif
+ me -> thread_blocked = TRUE;
+ UNLOCK();
+}
+
+void GC_end_blocking(void) {
+ GC_thread me;
+ LOCK(); /* This will block if the world is stopped. */
+ me = GC_lookup_thread(pthread_self());
+ GC_ASSERT(me -> thread_blocked);
+ me -> thread_blocked = FALSE;
+ UNLOCK();
+}
+
+#if defined(GC_DGUX386_THREADS)
+#define __d10_sleep sleep
+#endif /* GC_DGUX386_THREADS */
+
+/* A wrapper for the standard C sleep function */
+int WRAP_FUNC(sleep) (unsigned int seconds)
+{
+ int result;
+
+ GC_start_blocking();
+ result = REAL_FUNC(sleep)(seconds);
+ GC_end_blocking();
+ return result;
+}
+
+struct start_info {
+ void *(*start_routine)(void *);
+ void *arg;
+ word flags;
+ sem_t registered; /* 1 ==> in our thread table, but */
+ /* parent hasn't yet noticed. */
+};
+
+/* Called at thread exit. */
+/* Never called for main thread. That's OK, since it */
+/* results in at most a tiny one-time leak. And */
+/* linuxthreads doesn't reclaim the main threads */
+/* resources or id anyway. */
+void GC_thread_exit_proc(void *arg)
+{
+ GC_thread me;
+
+ LOCK();
+ me = GC_lookup_thread(pthread_self());
+ GC_destroy_thread_local(me);
+ if (me -> flags & DETACHED) {
+ GC_delete_thread(pthread_self());
+ } else {
+ me -> flags |= FINISHED;
+ }
+# if defined(THREAD_LOCAL_ALLOC) && !defined(USE_PTHREAD_SPECIFIC) \
+ && !defined(USE_HPUX_TLS) && !defined(DBG_HDRS_ALL)
+ GC_remove_specific(GC_thread_key);
+# endif
+ GC_wait_for_gc_completion(FALSE);
+ UNLOCK();
+}
+
+int WRAP_FUNC(pthread_join)(pthread_t thread, void **retval)
+{
+ int result;
+ GC_thread thread_gc_id;
+
+ LOCK();
+ thread_gc_id = GC_lookup_thread(thread);
+ /* This is guaranteed to be the intended one, since the thread id */
+ /* cant have been recycled by pthreads. */
+ UNLOCK();
+ result = REAL_FUNC(pthread_join)(thread, retval);
+# if defined (GC_FREEBSD_THREADS)
+ /* On FreeBSD, the wrapped pthread_join() sometimes returns (what
+ appears to be) a spurious EINTR which caused the test and real code
+ to gratuitously fail. Having looked at system pthread library source
+ code, I see how this return code may be generated. In one path of
+ code, pthread_join() just returns the errno setting of the thread
+ being joined. This does not match the POSIX specification or the
+ local man pages thus I have taken the liberty to catch this one
+ spurious return value properly conditionalized on GC_FREEBSD_THREADS. */
+ if (result == EINTR) result = 0;
+# endif
+ if (result == 0) {
+ LOCK();
+ /* Here the pthread thread id may have been recycled. */
+ GC_delete_gc_thread(thread, thread_gc_id);
+ UNLOCK();
+ }
+ return result;
+}
+
+int
+WRAP_FUNC(pthread_detach)(pthread_t thread)
+{
+ int result;
+ GC_thread thread_gc_id;
+
+ LOCK();
+ thread_gc_id = GC_lookup_thread(thread);
+ UNLOCK();
+ result = REAL_FUNC(pthread_detach)(thread);
+ if (result == 0) {
+ LOCK();
+ thread_gc_id -> flags |= DETACHED;
+ /* Here the pthread thread id may have been recycled. */
+ if (thread_gc_id -> flags & FINISHED) {
+ GC_delete_gc_thread(thread, thread_gc_id);
+ }
+ UNLOCK();
+ }
+ return result;
+}
+
+void * GC_start_routine(void * arg)
+{
+ int dummy;
+ struct start_info * si = arg;
+ void * result;
+ GC_thread me;
+ pthread_t my_pthread;
+ void *(*start)(void *);
+ void *start_arg;
+
+ my_pthread = pthread_self();
+# ifdef DEBUG_THREADS
+ GC_printf1("Starting thread 0x%lx\n", my_pthread);
+ GC_printf1("pid = %ld\n", (long) getpid());
+ GC_printf1("sp = 0x%lx\n", (long) &arg);
+# endif
+ LOCK();
+ me = GC_new_thread(my_pthread);
+#ifdef GC_DARWIN_THREADS
+ me -> stop_info.mach_thread = mach_thread_self();
+#else
+ me -> stop_info.stack_ptr = 0;
+#endif
+ me -> flags = si -> flags;
+ /* me -> stack_end = GC_linux_stack_base(); -- currently (11/99) */
+ /* doesn't work because the stack base in /proc/self/stat is the */
+ /* one for the main thread. There is a strong argument that that's */
+ /* a kernel bug, but a pervasive one. */
+# ifdef STACK_GROWS_DOWN
+ me -> stack_end = (ptr_t)(((word)(&dummy) + (GC_page_size - 1))
+ & ~(GC_page_size - 1));
+# ifndef GC_DARWIN_THREADS
+ me -> stop_info.stack_ptr = me -> stack_end - 0x10;
+# endif
+ /* Needs to be plausible, since an asynchronous stack mark */
+ /* should not crash. */
+# else
+ me -> stack_end = (ptr_t)((word)(&dummy) & ~(GC_page_size - 1));
+ me -> stop_info.stack_ptr = me -> stack_end + 0x10;
+# endif
+ /* This is dubious, since we may be more than a page into the stack, */
+ /* and hence skip some of it, though it's not clear that matters. */
+# ifdef IA64
+ me -> backing_store_end = (ptr_t)
+ (GC_save_regs_in_stack() & ~(GC_page_size - 1));
+ /* This is also < 100% convincing. We should also read this */
+ /* from /proc, but the hook to do so isn't there yet. */
+# endif /* IA64 */
+ UNLOCK();
+ start = si -> start_routine;
+# ifdef DEBUG_THREADS
+ GC_printf1("start_routine = 0x%lx\n", start);
+# endif
+ start_arg = si -> arg;
+ sem_post(&(si -> registered)); /* Last action on si. */
+ /* OK to deallocate. */
+ pthread_cleanup_push(GC_thread_exit_proc, 0);
+# if defined(THREAD_LOCAL_ALLOC) && !defined(DBG_HDRS_ALL)
+ LOCK();
+ GC_init_thread_local(me);
+ UNLOCK();
+# endif
+ result = (*start)(start_arg);
+#if DEBUG_THREADS
+ GC_printf1("Finishing thread 0x%x\n", pthread_self());
+#endif
+ me -> status = result;
+ pthread_cleanup_pop(1);
+ /* Cleanup acquires lock, ensuring that we can't exit */
+ /* while a collection that thinks we're alive is trying to stop */
+ /* us. */
+ return(result);
+}
+
+int
+WRAP_FUNC(pthread_create)(pthread_t *new_thread,
+ const pthread_attr_t *attr,
+ void *(*start_routine)(void *), void *arg)
+{
+ int result;
+ int detachstate;
+ word my_flags = 0;
+ struct start_info * si;
+ /* This is otherwise saved only in an area mmapped by the thread */
+ /* library, which isn't visible to the collector. */
+
+ /* We resist the temptation to muck with the stack size here, */
+ /* even if the default is unreasonably small. That's the client's */
+ /* responsibility. */
+
+ LOCK();
+ si = (struct start_info *)GC_INTERNAL_MALLOC(sizeof(struct start_info),
+ NORMAL);
+ UNLOCK();
+ if (!parallel_initialized) GC_init_parallel();
+ if (0 == si) return(ENOMEM);
+ sem_init(&(si -> registered), 0, 0);
+ si -> start_routine = start_routine;
+ si -> arg = arg;
+ LOCK();
+ if (!GC_thr_initialized) GC_thr_init();
+# ifdef GC_ASSERTIONS
+ {
+ int stack_size;
+ if (NULL == attr) {
+ pthread_attr_t my_attr;
+ pthread_attr_init(&my_attr);
+ pthread_attr_getstacksize(&my_attr, &stack_size);
+ } else {
+ pthread_attr_getstacksize(attr, &stack_size);
+ }
+ GC_ASSERT(stack_size >= (8*HBLKSIZE*sizeof(word)));
+ /* Our threads may need to do some work for the GC. */
+ /* Ridiculously small threads won't work, and they */
+ /* probably wouldn't work anyway. */
+ }
+# endif
+ if (NULL == attr) {
+ detachstate = PTHREAD_CREATE_JOINABLE;
+ } else {
+ pthread_attr_getdetachstate(attr, &detachstate);
+ }
+ if (PTHREAD_CREATE_DETACHED == detachstate) my_flags |= DETACHED;
+ si -> flags = my_flags;
+ UNLOCK();
+# ifdef DEBUG_THREADS
+ GC_printf1("About to start new thread from thread 0x%X\n",
+ pthread_self());
+# endif
+
+ result = REAL_FUNC(pthread_create)(new_thread, attr, GC_start_routine, si);
+
+# ifdef DEBUG_THREADS
+ GC_printf1("Started thread 0x%X\n", *new_thread);
+# endif
+ /* Wait until child has been added to the thread table. */
+ /* This also ensures that we hold onto si until the child is done */
+ /* with it. Thus it doesn't matter whether it is otherwise */
+ /* visible to the collector. */
+ while (0 != sem_wait(&(si -> registered))) {
+ if (EINTR != errno) ABORT("sem_wait failed");
+ }
+ sem_destroy(&(si -> registered));
+ LOCK();
+ GC_INTERNAL_FREE(si);
+ UNLOCK();
+
+ return(result);
+}
+
+#ifdef GENERIC_COMPARE_AND_SWAP
+ pthread_mutex_t GC_compare_and_swap_lock = PTHREAD_MUTEX_INITIALIZER;
+
+ GC_bool GC_compare_and_exchange(volatile GC_word *addr,
+ GC_word old, GC_word new_val)
+ {
+ GC_bool result;
+ pthread_mutex_lock(&GC_compare_and_swap_lock);
+ if (*addr == old) {
+ *addr = new_val;
+ result = TRUE;
+ } else {
+ result = FALSE;
+ }
+ pthread_mutex_unlock(&GC_compare_and_swap_lock);
+ return result;
+ }
+
+ GC_word GC_atomic_add(volatile GC_word *addr, GC_word how_much)
+ {
+ GC_word old;
+ pthread_mutex_lock(&GC_compare_and_swap_lock);
+ old = *addr;
+ *addr = old + how_much;
+ pthread_mutex_unlock(&GC_compare_and_swap_lock);
+ return old;
+ }
+
+#endif /* GENERIC_COMPARE_AND_SWAP */
+/* Spend a few cycles in a way that can't introduce contention with */
+/* othre threads. */
+void GC_pause()
+{
+ int i;
+# ifndef __GNUC__
+ volatile word dummy = 0;
+# endif
+
+ for (i = 0; i < 10; ++i) {
+# ifdef __GNUC__
+ __asm__ __volatile__ (" " : : : "memory");
+# else
+ /* Something that's unlikely to be optimized away. */
+ GC_noop(++dummy);
+# endif
+ }
+}
+
+#define SPIN_MAX 1024 /* Maximum number of calls to GC_pause before */
+ /* give up. */
+
+VOLATILE GC_bool GC_collecting = 0;
+ /* A hint that we're in the collector and */
+ /* holding the allocation lock for an */
+ /* extended period. */
+
+#if !defined(USE_SPIN_LOCK) || defined(PARALLEL_MARK)
+/* If we don't want to use the below spinlock implementation, either */
+/* because we don't have a GC_test_and_set implementation, or because */
+/* we don't want to risk sleeping, we can still try spinning on */
+/* pthread_mutex_trylock for a while. This appears to be very */
+/* beneficial in many cases. */
+/* I suspect that under high contention this is nearly always better */
+/* than the spin lock. But it's a bit slower on a uniprocessor. */
+/* Hence we still default to the spin lock. */
+/* This is also used to acquire the mark lock for the parallel */
+/* marker. */
+
+/* Here we use a strict exponential backoff scheme. I don't know */
+/* whether that's better or worse than the above. We eventually */
+/* yield by calling pthread_mutex_lock(); it never makes sense to */
+/* explicitly sleep. */
+
+void GC_generic_lock(pthread_mutex_t * lock)
+{
+#ifndef NO_PTHREAD_TRYLOCK
+ unsigned pause_length = 1;
+ unsigned i;
+
+ if (0 == pthread_mutex_trylock(lock)) return;
+ for (; pause_length <= SPIN_MAX; pause_length <<= 1) {
+ for (i = 0; i < pause_length; ++i) {
+ GC_pause();
+ }
+ switch(pthread_mutex_trylock(lock)) {
+ case 0:
+ return;
+ case EBUSY:
+ break;
+ default:
+ ABORT("Unexpected error from pthread_mutex_trylock");
+ }
+ }
+#endif /* !NO_PTHREAD_TRYLOCK */
+ pthread_mutex_lock(lock);
+}
+
+#endif /* !USE_SPIN_LOCK || PARALLEL_MARK */
+
+#if defined(USE_SPIN_LOCK)
+
+/* Reasonably fast spin locks. Basically the same implementation */
+/* as STL alloc.h. This isn't really the right way to do this. */
+/* but until the POSIX scheduling mess gets straightened out ... */
+
+volatile unsigned int GC_allocate_lock = 0;
+
+
+void GC_lock()
+{
+# define low_spin_max 30 /* spin cycles if we suspect uniprocessor */
+# define high_spin_max SPIN_MAX /* spin cycles for multiprocessor */
+ static unsigned spin_max = low_spin_max;
+ unsigned my_spin_max;
+ static unsigned last_spins = 0;
+ unsigned my_last_spins;
+ int i;
+
+ if (!GC_test_and_set(&GC_allocate_lock)) {
+ return;
+ }
+ my_spin_max = spin_max;
+ my_last_spins = last_spins;
+ for (i = 0; i < my_spin_max; i++) {
+ if (GC_collecting || GC_nprocs == 1) goto yield;
+ if (i < my_last_spins/2 || GC_allocate_lock) {
+ GC_pause();
+ continue;
+ }
+ if (!GC_test_and_set(&GC_allocate_lock)) {
+ /*
+ * got it!
+ * Spinning worked. Thus we're probably not being scheduled
+ * against the other process with which we were contending.
+ * Thus it makes sense to spin longer the next time.
+ */
+ last_spins = i;
+ spin_max = high_spin_max;
+ return;
+ }
+ }
+ /* We are probably being scheduled against the other process. Sleep. */
+ spin_max = low_spin_max;
+yield:
+ for (i = 0;; ++i) {
+ if (!GC_test_and_set(&GC_allocate_lock)) {
+ return;
+ }
+# define SLEEP_THRESHOLD 12
+ /* Under Linux very short sleeps tend to wait until */
+ /* the current time quantum expires. On old Linux */
+ /* kernels nanosleep(<= 2ms) just spins under Linux. */
+ /* (Under 2.4, this happens only for real-time */
+ /* processes.) We want to minimize both behaviors */
+ /* here. */
+ if (i < SLEEP_THRESHOLD) {
+ sched_yield();
+ } else {
+ struct timespec ts;
+
+ if (i > 24) i = 24;
+ /* Don't wait for more than about 15msecs, even */
+ /* under extreme contention. */
+ ts.tv_sec = 0;
+ ts.tv_nsec = 1 << i;
+ nanosleep(&ts, 0);
+ }
+ }
+}
+
+#else /* !USE_SPINLOCK */
+void GC_lock()
+{
+#ifndef NO_PTHREAD_TRYLOCK
+ if (1 == GC_nprocs || GC_collecting) {
+ pthread_mutex_lock(&GC_allocate_ml);
+ } else {
+ GC_generic_lock(&GC_allocate_ml);
+ }
+#else /* !NO_PTHREAD_TRYLOCK */
+ pthread_mutex_lock(&GC_allocate_ml);
+#endif /* !NO_PTHREAD_TRYLOCK */
+}
+
+#endif /* !USE_SPINLOCK */
+
+#if defined(PARALLEL_MARK) || defined(THREAD_LOCAL_ALLOC)
+
+#ifdef GC_ASSERTIONS
+ pthread_t GC_mark_lock_holder = NO_THREAD;
+#endif
+
+#if 0
+ /* Ugly workaround for a linux threads bug in the final versions */
+ /* of glibc2.1. Pthread_mutex_trylock sets the mutex owner */
+ /* field even when it fails to acquire the mutex. This causes */
+ /* pthread_cond_wait to die. Remove for glibc2.2. */
+ /* According to the man page, we should use */
+ /* PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP, but that isn't actually */
+ /* defined. */
+ static pthread_mutex_t mark_mutex =
+ {0, 0, 0, PTHREAD_MUTEX_ERRORCHECK_NP, {0, 0}};
+#else
+ static pthread_mutex_t mark_mutex = PTHREAD_MUTEX_INITIALIZER;
+#endif
+
+static pthread_cond_t builder_cv = PTHREAD_COND_INITIALIZER;
+
+void GC_acquire_mark_lock()
+{
+/*
+ if (pthread_mutex_lock(&mark_mutex) != 0) {
+ ABORT("pthread_mutex_lock failed");
+ }
+*/
+ GC_generic_lock(&mark_mutex);
+# ifdef GC_ASSERTIONS
+ GC_mark_lock_holder = pthread_self();
+# endif
+}
+
+void GC_release_mark_lock()
+{
+ GC_ASSERT(GC_mark_lock_holder == pthread_self());
+# ifdef GC_ASSERTIONS
+ GC_mark_lock_holder = NO_THREAD;
+# endif
+ if (pthread_mutex_unlock(&mark_mutex) != 0) {
+ ABORT("pthread_mutex_unlock failed");
+ }
+}
+
+/* Collector must wait for a freelist builders for 2 reasons: */
+/* 1) Mark bits may still be getting examined without lock. */
+/* 2) Partial free lists referenced only by locals may not be scanned */
+/* correctly, e.g. if they contain "pointer-free" objects, since the */
+/* free-list link may be ignored. */
+void GC_wait_builder()
+{
+ GC_ASSERT(GC_mark_lock_holder == pthread_self());
+# ifdef GC_ASSERTIONS
+ GC_mark_lock_holder = NO_THREAD;
+# endif
+ if (pthread_cond_wait(&builder_cv, &mark_mutex) != 0) {
+ ABORT("pthread_cond_wait failed");
+ }
+ GC_ASSERT(GC_mark_lock_holder == NO_THREAD);
+# ifdef GC_ASSERTIONS
+ GC_mark_lock_holder = pthread_self();
+# endif
+}
+
+void GC_wait_for_reclaim()
+{
+ GC_acquire_mark_lock();
+ while (GC_fl_builder_count > 0) {
+ GC_wait_builder();
+ }
+ GC_release_mark_lock();
+}
+
+void GC_notify_all_builder()
+{
+ GC_ASSERT(GC_mark_lock_holder == pthread_self());
+ if (pthread_cond_broadcast(&builder_cv) != 0) {
+ ABORT("pthread_cond_broadcast failed");
+ }
+}
+
+#endif /* PARALLEL_MARK || THREAD_LOCAL_ALLOC */
+
+#ifdef PARALLEL_MARK
+
+static pthread_cond_t mark_cv = PTHREAD_COND_INITIALIZER;
+
+void GC_wait_marker()
+{
+ GC_ASSERT(GC_mark_lock_holder == pthread_self());
+# ifdef GC_ASSERTIONS
+ GC_mark_lock_holder = NO_THREAD;
+# endif
+ if (pthread_cond_wait(&mark_cv, &mark_mutex) != 0) {
+ ABORT("pthread_cond_wait failed");
+ }
+ GC_ASSERT(GC_mark_lock_holder == NO_THREAD);
+# ifdef GC_ASSERTIONS
+ GC_mark_lock_holder = pthread_self();
+# endif
+}
+
+void GC_notify_all_marker()
+{
+ if (pthread_cond_broadcast(&mark_cv) != 0) {
+ ABORT("pthread_cond_broadcast failed");
+ }
+}
+
+#endif /* PARALLEL_MARK */
+
+# endif /* GC_LINUX_THREADS and friends */
+