-/* Copyright (C) 1995,1996,1997,1998,2000,2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
+/* Copyright (C) 1995,1996,1997,1998,2000,2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define _GNU_SOURCE
+#include "libguile/boehm-gc.h"
#include "libguile/_scm.h"
#if HAVE_UNISTD_H
#endif
#include <stdio.h>
#include <assert.h>
+
+#ifdef HAVE_STRING_H
+#include <string.h> /* for memset used by FD_ZERO on Solaris 10 */
+#endif
+
#if HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include "libguile/iselect.h"
#include "libguile/fluids.h"
#include "libguile/continuations.h"
+#include "libguile/gc.h"
#include "libguile/init.h"
+#ifdef __MINGW32__
+#ifndef ETIMEDOUT
+# define ETIMEDOUT WSAETIMEDOUT
+#endif
+# include <fcntl.h>
+# include <process.h>
+# define pipe(fd) _pipe (fd, 256, O_BINARY)
+#endif /* __MINGW32__ */
+
/*** Queues */
/* Make an empty queue data structure.
/*** Thread smob routines */
-static SCM
-thread_mark (SCM obj)
-{
- scm_i_thread *t = SCM_I_THREAD_DATA (obj);
- scm_gc_mark (t->result);
- scm_gc_mark (t->join_queue);
- scm_gc_mark (t->dynwinds);
- scm_gc_mark (t->active_asyncs);
- scm_gc_mark (t->continuation_root);
- return t->dynamic_state;
-}
static int
thread_print (SCM exp, SCM port, scm_print_state *pstate SCM_UNUSED)
/* Getting into and out of guile mode.
*/
+/* Ken Raeburn observes that the implementation of suspend and resume
+ (and the things that build on top of them) are very likely not
+ correct (see below). We will need fix this eventually, and that's
+ why scm_leave_guile/scm_enter_guile are not exported in the API.
+
+ Ken writes:
+
+ Consider this sequence:
+
+ Function foo, called in Guile mode, calls suspend (maybe indirectly
+ through scm_leave_guile), which does this:
+
+ // record top of stack for the GC
+ t->top = SCM_STACK_PTR (&t); // just takes address of automatic
+ var 't'
+ // save registers.
+ SCM_FLUSH_REGISTER_WINDOWS; // sparc only
+ setjmp (t->regs); // here's most of the magic
+
+ ... and returns.
+
+ Function foo has a SCM value X, a handle on a non-immediate object, in
+ a caller-saved register R, and it's the only reference to the object
+ currently.
+
+ The compiler wants to use R in suspend, so it pushes the current
+ value, X, into a stack slot which will be reloaded on exit from
+ suspend; then it loads stuff into R and goes about its business. The
+ setjmp call saves (some of) the current registers, including R, which
+ no longer contains X. (This isn't a problem for a normal
+ setjmp/longjmp situation, where longjmp would be called before
+ setjmp's caller returns; the old value for X would be loaded back from
+ the stack after the longjmp, before the function returned.)
+
+ So, suspend returns, loading X back into R (and invalidating the jump
+ buffer) in the process. The caller foo then goes off and calls a
+ bunch of other functions out of Guile mode, occasionally storing X on
+ the stack again, but, say, much deeper on the stack than suspend's
+ stack frame went, and the stack slot where suspend had written X has
+ long since been overwritten with other values.
+
+ Okay, nothing actively broken so far. Now, let garbage collection
+ run, triggered by another thread.
+
+ The thread calling foo is out of Guile mode at the time, so the
+ garbage collector just scans a range of stack addresses. Too bad that
+ X isn't stored there. So the pointed-to storage goes onto the free
+ list, and I think you can see where things go from there.
+
+ Is there anything I'm missing that'll prevent this scenario from
+ happening? I mean, aside from, "well, suspend and scm_leave_guile
+ don't have many local variables, so they probably won't need to save
+ any registers on most systems, so we hope everything will wind up in
+ the jump buffer and we'll just get away with it"?
+
+ (And, going the other direction, if scm_leave_guile and suspend push
+ the stack pointer over onto a new page, and foo doesn't make further
+ function calls and thus the stack pointer no longer includes that
+ page, are we guaranteed that the kernel cannot release the now-unused
+ stack page that contains the top-of-stack pointer we just saved? I
+ don't know if any OS actually does that. If it does, we could get
+ faults in garbage collection.)
+
+ I don't think scm_without_guile has to have this problem, as it gets
+ more control over the stack handling -- but it should call setjmp
+ itself. I'd probably try something like:
+
+ // record top of stack for the GC
+ t->top = SCM_STACK_PTR (&t);
+ // save registers.
+ SCM_FLUSH_REGISTER_WINDOWS;
+ setjmp (t->regs);
+ res = func(data);
+ scm_enter_guile (t);
+
+ ... though even that's making some assumptions about the stack
+ ordering of local variables versus caller-saved registers.
+
+ For something like scm_leave_guile to work, I don't think it can just
+ rely on invalidated jump buffers. A valid jump buffer, and a handle
+ on the stack state at the point when the jump buffer was initialized,
+ together, would work fine, but I think then we're talking about macros
+ invoking setjmp in the caller's stack frame, and requiring that the
+ caller of scm_leave_guile also call scm_enter_guile before returning,
+ kind of like pthread_cleanup_push/pop calls that have to be paired up
+ in a function. (In fact, the pthread ones have to be paired up
+ syntactically, as if they might expand to a compound statement
+ incorporating the user's code, and invoking a compiler's
+ exception-handling primitives. Which might be something to think
+ about for cases where Guile is used with C++ exceptions or
+ pthread_cancel.)
+*/
+
scm_i_pthread_key_t scm_i_thread_key;
static void
}
}
-void
+typedef void* scm_t_guile_ticket;
+
+static void
scm_enter_guile (scm_t_guile_ticket ticket)
{
scm_i_thread *t = (scm_i_thread *)ticket;
return t;
}
-scm_t_guile_ticket
+static scm_t_guile_ticket
scm_leave_guile ()
{
scm_i_thread *t = suspend ();
static void
guilify_self_1 (SCM_STACKITEM *base)
{
- scm_i_thread *t = malloc (sizeof (scm_i_thread));
+ scm_i_thread *t = scm_gc_malloc (sizeof (scm_i_thread), "thread");
t->pthread = scm_i_pthread_self ();
t->handle = SCM_BOOL_F;
scm_i_pthread_mutex_init (&t->heap_mutex, NULL);
t->clear_freelists_p = 0;
t->gc_running_p = 0;
+ t->current_mark_stack_ptr = NULL;
+ t->current_mark_stack_limit = NULL;
t->exited = 0;
t->freelist = SCM_EOL;
scm_i_thread *t = SCM_I_CURRENT_THREAD;
SCM_NEWSMOB (t->handle, scm_tc16_thread, t);
- scm_gc_register_collectable_memory (t, sizeof (scm_i_thread), "thread");
+
t->continuation_root = scm_cons (t->handle, SCM_EOL);
t->continuation_base = t->base;
}
}
-#ifdef HAVE_LIBC_STACK_END
-
-extern void *__libc_stack_end;
-
#if SCM_USE_PTHREAD_THREADS
-#ifdef HAVE_PTHREAD_ATTR_GETSTACK
+/* pthread_getattr_np not available on MacOS X and Solaris 10. */
+#if HAVE_PTHREAD_ATTR_GETSTACK && HAVE_PTHREAD_GETATTR_NP
#define HAVE_GET_THREAD_STACK_BASE
void *start, *end;
size_t size;
- /* XXX - pthread_getattr_np from LinuxThreads does not seem to work
- for the main thread, but we can use __libc_stack_end in that
- case.
- */
-
pthread_getattr_np (pthread_self (), &attr);
pthread_attr_getstack (&attr, &start, &size);
end = (char *)start + size;
+ /* XXX - pthread_getattr_np from LinuxThreads does not seem to work
+ for the main thread, but we can use scm_get_stack_base in that
+ case.
+ */
+
+#ifndef PTHREAD_ATTR_GETSTACK_WORKS
if ((void *)&attr < start || (void *)&attr >= end)
- return __libc_stack_end;
+ return scm_get_stack_base ();
else
+#endif
{
#if SCM_STACK_GROWS_UP
return start;
}
}
-#endif /* HAVE_PTHREAD_ATTR_GETSTACK */
+#endif /* HAVE_PTHREAD_ATTR_GETSTACK && HAVE_PTHREAD_GETATTR_NP */
#else /* !SCM_USE_PTHREAD_THREADS */
static SCM_STACKITEM *
get_thread_stack_base ()
{
- return __libc_stack_end;
+ return scm_get_stack_base ();
}
#endif /* !SCM_USE_PTHREAD_THREADS */
-#endif /* HAVE_LIBC_STACK_END */
#ifdef HAVE_GET_THREAD_STACK_BASE
#define SCM_MUTEXP(x) SCM_SMOB_PREDICATE (scm_tc16_mutex, x)
#define SCM_MUTEX_DATA(x) ((fat_mutex *) SCM_SMOB_DATA (x))
-static SCM
-fat_mutex_mark (SCM mx)
-{
- fat_mutex *m = SCM_MUTEX_DATA (mx);
- scm_gc_mark (m->owner);
- return m->waiting;
-}
static size_t
fat_mutex_free (SCM mx)
"thread. That is, Guile's mutexes are @emph{recursive}. ")
#define FUNC_NAME s_scm_lock_mutex
{
- SCM_VALIDATE_MUTEX (1, mx);
char *msg;
+ SCM_VALIDATE_MUTEX (1, mx);
msg = fat_mutex_lock (mx);
if (msg)
scm_misc_error (NULL, msg, SCM_EOL);
#undef FUNC_NAME
void
-scm_frame_lock_mutex (SCM mutex)
+scm_dynwind_lock_mutex (SCM mutex)
{
- scm_frame_unwind_handler_with_scm ((void(*)(SCM))scm_unlock_mutex, mutex,
- SCM_F_WIND_EXPLICITLY);
- scm_frame_rewind_handler_with_scm ((void(*)(SCM))scm_lock_mutex, mutex,
- SCM_F_WIND_EXPLICITLY);
+ scm_dynwind_unwind_handler_with_scm ((void(*)(SCM))scm_unlock_mutex, mutex,
+ SCM_F_WIND_EXPLICITLY);
+ scm_dynwind_rewind_handler_with_scm ((void(*)(SCM))scm_lock_mutex, mutex,
+ SCM_F_WIND_EXPLICITLY);
}
static char *
#define SCM_CONDVARP(x) SCM_SMOB_PREDICATE (scm_tc16_condvar, x)
#define SCM_CONDVAR_DATA(x) ((fat_cond *) SCM_SMOB_DATA (x))
-static SCM
-fat_cond_mark (SCM cv)
-{
- fat_cond *c = SCM_CONDVAR_DATA (cv);
- return c->waiting;
-}
-
static size_t
fat_cond_free (SCM mx)
{
scm_mark_locations ((SCM_STACKITEM *) &ctx.uc_mcontext, \
((size_t) (sizeof (SCM_STACKITEM) - 1 + sizeof ctx.uc_mcontext) \
/ sizeof (SCM_STACKITEM))); \
- bot = (SCM_STACKITEM *) __libc_ia64_register_backing_store_base; \
- top = (SCM_STACKITEM *) ctx.uc_mcontext.sc_ar_bsp; \
+ bot = (SCM_STACKITEM *) scm_ia64_register_backing_store_base (); \
+ top = (SCM_STACKITEM *) scm_ia64_ar_bsp (&ctx); \
scm_mark_locations (bot, top - bot); } while (0)
#else
# define SCM_MARK_BACKING_STORE()
#endif
-void
-scm_threads_mark_stacks (void)
-{
- scm_i_thread *t;
- for (t = all_threads; t; t = t->next_thread)
- {
- /* Check that thread has indeed been suspended.
- */
- assert (t->top);
-
- scm_gc_mark (t->handle);
-
-#if SCM_STACK_GROWS_UP
- scm_mark_locations (t->base, t->top - t->base);
-#else
- scm_mark_locations (t->top, t->base - t->top);
-#endif
- scm_mark_locations ((SCM_STACKITEM *) t->regs,
- ((size_t) sizeof(t->regs)
- / sizeof (SCM_STACKITEM)));
- }
- SCM_MARK_BACKING_STORE ();
-}
/*** Select */
}
static void
-unlock (void *data)
+do_unlock (void *data)
{
scm_i_pthread_mutex_unlock ((scm_i_pthread_mutex_t *)data);
}
void
-scm_frame_pthread_mutex_lock (scm_i_pthread_mutex_t *mutex)
+scm_dynwind_pthread_mutex_lock (scm_i_pthread_mutex_t *mutex)
{
scm_i_scm_pthread_mutex_lock (mutex);
- scm_frame_unwind_handler (unlock, mutex, SCM_F_WIND_EXPLICITLY);
+ scm_dynwind_unwind_handler (do_unlock, mutex, SCM_F_WIND_EXPLICITLY);
}
int
/* This mutex is used by SCM_CRITICAL_SECTION_START/END.
*/
-scm_i_pthread_mutex_t scm_i_critical_section_mutex =
- SCM_I_PTHREAD_RECURSIVE_MUTEX_INITIALIZER;
+scm_i_pthread_mutex_t scm_i_critical_section_mutex;
int scm_i_critical_section_level = 0;
-static SCM framed_critical_section_mutex;
+static SCM dynwind_critical_section_mutex;
void
-scm_frame_critical_section (SCM mutex)
+scm_dynwind_critical_section (SCM mutex)
{
if (scm_is_false (mutex))
- mutex = framed_critical_section_mutex;
- scm_frame_lock_mutex (mutex);
- scm_frame_block_asyncs ();
+ mutex = dynwind_critical_section_mutex;
+ scm_dynwind_lock_mutex (mutex);
+ scm_dynwind_block_asyncs ();
}
/*** Initialization */
scm_i_pthread_key_t scm_i_freelist, scm_i_freelist2;
scm_i_pthread_mutex_t scm_i_misc_mutex;
+#if SCM_USE_PTHREAD_THREADS
+pthread_mutexattr_t scm_i_pthread_mutexattr_recursive[1];
+#endif
+
void
scm_threads_prehistory (SCM_STACKITEM *base)
{
+#if SCM_USE_PTHREAD_THREADS
+ pthread_mutexattr_init (scm_i_pthread_mutexattr_recursive);
+ pthread_mutexattr_settype (scm_i_pthread_mutexattr_recursive,
+ PTHREAD_MUTEX_RECURSIVE);
+#endif
+
+ scm_i_pthread_mutex_init (&scm_i_critical_section_mutex,
+ scm_i_pthread_mutexattr_recursive);
scm_i_pthread_mutex_init (&scm_i_misc_mutex, NULL);
scm_i_pthread_cond_init (&wake_up_cond, NULL);
scm_i_pthread_key_create (&scm_i_freelist, NULL);
scm_init_threads ()
{
scm_tc16_thread = scm_make_smob_type ("thread", sizeof (scm_i_thread));
- scm_set_smob_mark (scm_tc16_thread, thread_mark);
scm_set_smob_print (scm_tc16_thread, thread_print);
- scm_set_smob_free (scm_tc16_thread, thread_free);
+ scm_set_smob_free (scm_tc16_thread, thread_free); /* XXX: Could be removed */
scm_tc16_mutex = scm_make_smob_type ("mutex", sizeof (fat_mutex));
- scm_set_smob_mark (scm_tc16_mutex, fat_mutex_mark);
scm_set_smob_print (scm_tc16_mutex, fat_mutex_print);
scm_set_smob_free (scm_tc16_mutex, fat_mutex_free);
scm_tc16_condvar = scm_make_smob_type ("condition-variable",
sizeof (fat_cond));
- scm_set_smob_mark (scm_tc16_condvar, fat_cond_mark);
scm_set_smob_print (scm_tc16_condvar, fat_cond_print);
scm_set_smob_free (scm_tc16_condvar, fat_cond_free);
guilify_self_2 (SCM_BOOL_F);
threads_initialized_p = 1;
- framed_critical_section_mutex =
+ dynwind_critical_section_mutex =
scm_permanent_object (scm_make_recursive_mutex ());
}
HCoop / bpt / guile.git / blobdiff