pthread_support.c

linux下建立JAVA虚拟机的源码KAFFE

# 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 */

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 pthread_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_in_thread_creation = TRUE;
            GC_collect_a_little_inner(1);
	    GC_in_thread_creation = FALSE;
	    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)