/*
* Copyright (C) 2003-2009, 2012-2013 by the gtk2-perl team (see the file
* AUTHORS for the full list)
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Library General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* This library is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
* License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
* $Id$
*/
=head2 GClosure / GPerlClosure
GPerlClosure is a wrapper around the gobject library's GClosure with
special handling for marshalling perl subroutines as callbacks.
This is specially tuned for use with GSignal and stuff like io watch,
timeout, and idle handlers.
For generic callback functions, which need parameters but do not get
registered with the type system, this is sometimes overkill. See
GPerlCallback, below.
=over
=cut
#include "gperl.h"
#include <gobject/gvaluecollector.h>
#include "gperl_marshal.h"
#include "gperl-private.h"
static void
gperl_closure_invalidate (gpointer data,
GClosure * closure)
{
GPerlClosure * pc = (GPerlClosure *)closure;
PERL_UNUSED_VAR (data);
#ifdef NOISY
warn ("Invalidating closure for %s\n", SvPV_nolen (pc->callback));
#endif
if (pc->callback) {
SvREFCNT_dec (pc->callback);
pc->callback = NULL;
}
if (pc->data) {
SvREFCNT_dec (pc->data);
pc->data = NULL;
}
}
#ifdef PERL_IMPLICIT_CONTEXT
# define INVOKED_FROM_FOREIGN_THREAD (!PERL_GET_CONTEXT)
#else
# define INVOKED_FROM_FOREIGN_THREAD \
(_gperl_get_main_tid () != g_thread_self ())
#endif
static void _closure_hand_to_main (GClosure * closure,
GValue * return_value,
guint n_param_values,
const GValue * param_values,
gpointer invocation_hint,
gpointer marshal_data);
static void
gperl_closure_marshal (GClosure * closure,
GValue * return_value,
guint n_param_values,
const GValue * param_values,
gpointer invocation_hint,
gpointer marshal_data)
{
gboolean want_return_value;
int flags;
guint i;
dGPERL_CLOSURE_MARSHAL_ARGS;
/* If the current thread doesn't have a Perl context associated with
* it, then we have no choice but to hand over everything to the main
* thread and let it handle marshalling.
*
* We cannot simply use the main thread's Perl context here because the
* Perl interpreter is not thread-safe. For the same reason, we cannot
* use perl_clone to create a new Perl interpreter from the main one.
*/
if (INVOKED_FROM_FOREIGN_THREAD) {
#ifdef NOISY
g_printerr ("*** GPerl asked to invoke callback from a foreign thread; "
"handing it over to the main loop\n");
#endif
_closure_hand_to_main (closure, return_value,
n_param_values, param_values,
invocation_hint, marshal_data);
return;
}
GPERL_CLOSURE_MARSHAL_INIT (closure, marshal_data);
PERL_UNUSED_VAR (invocation_hint);
ENTER;
SAVETMPS;
PUSHMARK (SP);
if (n_param_values == 0) {
data = SvREFCNT_inc (pc->data);
} else {
GPERL_CLOSURE_MARSHAL_PUSH_INSTANCE (param_values);
/* the rest of the params should be quite straightforward. */
for (i = 1; i < n_param_values; i++) {
SV * arg = SAVED_STACK_SV (
gperl_sv_from_value ((GValue*) param_values + i));
/* make these mortal as they go onto the stack */
XPUSHs (sv_2mortal (arg));
}
}
GPERL_CLOSURE_MARSHAL_PUSH_DATA;
PUTBACK;
want_return_value = return_value && G_VALUE_TYPE (return_value);
flags = want_return_value ? G_SCALAR : G_VOID|G_DISCARD;
SPAGAIN;
GPERL_CLOSURE_MARSHAL_CALL (flags);
PERL_UNUSED_VAR (count);
if (want_return_value) {
gperl_value_from_sv (return_value, POPs);
PUTBACK; /* vitally important */
}
/*
* clean up
*/
FREETMPS;
LEAVE;
}
typedef struct {
GClosure * closure;
GValue * return_value;
guint n_param_values;
const GValue * param_values;
gpointer invocation_hint;
gpointer marshal_data;
GCond * done_cond;
GMutex * done_mutex;
} MarshallerArgs;
static gboolean
_closure_remarshal (gpointer data)
{
MarshallerArgs *args = data;
g_mutex_lock (args->done_mutex);
gperl_closure_marshal (args->closure,
args->return_value,
args->n_param_values,
args->param_values,
args->invocation_hint,
args->marshal_data);
g_cond_signal (args->done_cond);
g_mutex_unlock (args->done_mutex);
return FALSE;
}
static void
_closure_hand_to_main (GClosure * closure,
GValue * return_value,
guint n_param_values,
const GValue * param_values,
gpointer invocation_hint,
gpointer marshal_data)
{
MarshallerArgs args;
args.closure = closure;
args.return_value = return_value;
args.n_param_values = n_param_values;
args.param_values = param_values;
args.invocation_hint = invocation_hint;
args.marshal_data = marshal_data;
/* We need to wait for the other thread to finish marshalling to avoid
* gperl_closure_marshal returning prematurely. */
#if GLIB_CHECK_VERSION (2, 32, 0)
/* FIXME: we should put these on the stack, but it gets real ugly real fast */
args.done_cond = g_slice_new (GCond);
g_cond_init (args.done_cond);
args.done_mutex = g_slice_new (GMutex);
g_mutex_init (args.done_mutex);
#else
args.done_cond = g_cond_new ();
args.done_mutex = g_mutex_new ();
#endif /* 2.32 */
g_mutex_lock (args.done_mutex);
/* FIXME: Should we use a higher priority? */
g_idle_add (_closure_remarshal, &args);
g_cond_wait (args.done_cond, args.done_mutex);
g_mutex_unlock (args.done_mutex);
#if GLIB_CHECK_VERSION (2, 32, 0)
g_cond_clear (args.done_cond);
g_slice_free (GCond, args.done_cond);
g_mutex_clear (args.done_mutex);
g_slice_free (GMutex, args.done_mutex);
#else
g_cond_free (args.done_cond);
g_mutex_free (args.done_mutex);
#endif /* 2.32 */
}
=item GClosure * gperl_closure_new (SV * callback, SV * data, gboolean swap)
Create and return a new GPerlClosure. I<callback> and I<data> will be copied
for storage; I<callback> must not be NULL. If I<swap> is TRUE, I<data> will be
swapped with the instance during invocation (this is used to implement
g_signal_connect_swapped()).
If compiled under a thread-enabled perl, the closure will be created and
marshaled in such a way as to ensure that the same interpreter which created
the closure will be used to invoke it.
=cut
GClosure *
gperl_closure_new (SV * callback,
SV * data,
gboolean swap)
{
return gperl_closure_new_with_marshaller (callback, data, swap, NULL);
}
=item GClosure * gperl_closure_new_with_marshaller (SV * callback, SV * data, gboolean swap, GClosureMarshal marshaller)
Like C<gperl_closure_new>, but uses a caller-supplied marshaller. This is
provided for use in those sticky circumstances when you just can't do it
any other way; in general, you want to use the default marshaller, which you
get if you provide NULL for I<marshaller>.
If you use you own marshaller, you need to take care of everything yourself,
including swapping the instance and data if C<GPERL_CLOSURE_SWAP_DATA
(closure)> is true, calling C<gperl_run_exception_handlers> if ERRSV is true
after invoking the perl sub, and ensuring that you properly use the
C<marshal_data> parameter as the perl interpreter when PERL_IMPLICIT_CONTEXT is
defined. See the implementation of the default marshaller,
C<gperl_closure_marshal>, in Glib/GClosure.xs for inspiration.
=cut
GClosure *
gperl_closure_new_with_marshaller (SV * callback,
SV * data,
gboolean swap,
GClosureMarshal marshaller)
{
GPerlClosure *closure;
g_return_val_if_fail (callback != NULL, NULL);
if (marshaller == NULL)
marshaller = gperl_closure_marshal;
closure = (GPerlClosure*) g_closure_new_simple (sizeof (GPerlClosure),
NULL);
g_closure_add_invalidate_notifier ((GClosure*) closure,
NULL, gperl_closure_invalidate);
#ifndef PERL_IMPLICIT_CONTEXT
g_closure_set_marshal ((GClosure*) closure, marshaller);
#else
/* make sure the closure gets executed by the same interpreter that's
* creating it now; gperl_closure_marshal will interpret the
* marshal_data as the proper aTHX. */
g_closure_set_meta_marshal ((GClosure*) closure, aTHX, marshaller);
#endif
/*
* we have to take full copies of these SVs, rather than just
* SvREFCNT_inc'ing them, to avoid some bizarre things that can
* happen in special cases. see the notes in perlcall section
* 'Using call_sv' for more info
*/
closure->callback = (callback && callback != &PL_sv_undef)
? newSVsv (callback)
: NULL;
closure->data = (data && data != &PL_sv_undef)
? newSVsv (data)
: NULL;
closure->swap = swap;
return (GClosure*)closure;
}
=back
=head2 GPerlCallback
generic callback functions usually get invoked directly, and are not passed
parameter lists as GValues. we could very easily wrap up such generic
callbacks with something that converts the parameters to GValues and then
channels everything through GClosure, but this has two problems: 1) the above
implementation of GClosure is tuned to marshalling signal handlers, which
always have an instance object, and 2) it's more work than is strictly
necessary.
additionally, generic callbacks aren't always kind to the GClosure paradigm.
so, here's GPerlCallback, which is designed specifically to run generic
callback functions. it reads parameters off the C stack and converts them into
parameters on the perl stack. (it uses the GValue to/from SV mechanism to do
so, but doesn't allocate any temps on the heap.) the callback object itself
stores the parameter type list.
unfortunately, since the data element is always last, but the number of
arguments is not known until we have the callback object, we can't pass
gperl_callback_invoke directly to functions requiring a callback; you'll have
to write a proxy callback which calls gperl_callback_invoke.
=over
=item GPerlCallback * gperl_callback_new (SV * func, SV * data, gint n_params, GType param_types[], GType return_type)
Create and return a new GPerlCallback; use gperl_callback_destroy when you are
finished with it.
I<func>: perl subroutine to call. this SV will be copied, so don't worry about
reference counts. must B<not> be #NULL.
I<data>: scalar to pass to I<func> in addition to all other arguments. the SV
will be copied, so don't worry about reference counts. may be #NULL.
I<n_params>: the number of elements in I<param_types>.
I<param_types>: the #GType of each argument that should be passed from the
invocation to I<func>. may be #NULL if I<n_params> is zero, otherwise it must
be I<n_params> elements long or nasty things will happen. this array will be
copied; see gperl_callback_invoke() for how it is used.
I<return_type>: the #GType of the return value, or 0 if the function has void
return.
=cut
GPerlCallback *
gperl_callback_new (SV * func,
SV * data,
gint n_params,
GType param_types[],
GType return_type)
{
GPerlCallback * callback;
callback = g_new0 (GPerlCallback, 1);
/* copy the scalars, so we still have them when the time comes to
* be invoked. see the perlcall manpage for more information. */
callback->func = newSVsv (func);
if (data)
callback->data = newSVsv (data);
callback->n_params = n_params;
if (callback->n_params) {
if (!param_types)
croak ("n_params is %d but param_types is NULL in gperl_callback_new", n_params);
callback->param_types = g_new (GType, n_params);
memcpy (callback->param_types, param_types,
n_params * sizeof (GType));
}
callback->return_type = return_type;
#ifdef PERL_IMPLICIT_CONTEXT
callback->priv = aTHX;
#endif
return callback;
}
=item void gperl_callback_destroy (GPerlCallback * callback)
Dispose of I<callback>.
=cut
void
gperl_callback_destroy (GPerlCallback * callback)
{
#ifdef NOISY
warn ("gperl_callback_destroy 0x%p", callback);
#endif
if (callback) {
if (callback->func) {
SvREFCNT_dec (callback->func);
callback->func = NULL;
}
if (callback->data) {
SvREFCNT_dec (callback->data);
callback->data = NULL;
}
if (callback->param_types) {
g_free (callback->param_types);
callback->n_params = 0;
callback->param_types = NULL;
}
g_free (callback);
}
}
=item void gperl_callback_invoke (GPerlCallback * callback, GValue * return_value, ...)
Marshall the variadic parameters according to I<callback>'s param_types, and
then invoke I<callback>'s subroutine in scalar context, or void context if the
return type is G_TYPE_VOID. If I<return_value> is not NULL, then value
returned (if any) will be copied into I<return_value>.
A typical callback handler would look like this:
static gint
real_c_callback (Foo * f, Bar * b, int a, gpointer data)
{
GPerlCallback * callback = (GPerlCallback*)data;
GValue return_value = {0,};
gint retval;
g_value_init (&return_value, callback->return_type);
gperl_callback_invoke (callback, &return_value,
f, b, a);
retval = g_value_get_int (&return_value);
g_value_unset (&return_value);
return retval;
}
=cut
void
gperl_callback_invoke (GPerlCallback * callback,
GValue * return_value,
...)
{
va_list var_args;
dGPERL_CALLBACK_MARSHAL_SP;
g_return_if_fail (callback != NULL);
GPERL_CALLBACK_MARSHAL_INIT (callback);
ENTER;
SAVETMPS;
PUSHMARK (SP);
va_start (var_args, return_value);
/* put args on the stack */
if (callback->n_params > 0) {
int i;
GValue v = {0, };
/* Crib note: must g_value_unset() even when asking for
* G_VALUE_NOCOPY_CONTENTS. A GObject is always
* g_object_ref()ed for storage in a GValue, even under
* G_VALUE_NOCOPY_CONTENTS (see code in
* g_value_object_collect_value()). Always reffing in
* G_VALUE_COLLECT is in fact the recommended behaviour for
* all ref-counted types (see the GTypeValueTable docs,
* apparently to ensure objects remain alive for the
* duration of a g_signal_emit_valist()).
*/
for (i = 0 ; i < callback->n_params ; i++) {
gchar * error = NULL;
SV * sv;
g_value_init (&v, callback->param_types[i]);
G_VALUE_COLLECT (&v, var_args, G_VALUE_NOCOPY_CONTENTS,
&error);
if (error) {
SV * errstr;
/* this should only happen if you've
* created the callback incorrectly */
/* we modified the stack -- we need to make
* sure perl sees that! */
PUTBACK;
errstr = newSVpvf ("error while collecting"
" varargs parameters: %s\n"
"is your GPerlCallback "
"created properly? "
" bailing out",
error);
g_free (error);
/* this won't return */
croak ("%s", SvPV_nolen (errstr));
}
sv = SAVED_STACK_SV (gperl_sv_from_value (&v));
g_value_unset (&v);
if (!sv) {
/* this should be very rare, too. */
PUTBACK;
croak ("failed to convert GValue to SV");
}
XPUSHs (sv_2mortal (sv));
}
}
/* Usual REFCNT_inc and 2mortal here for putting something on the
* stack. It's possible callback->func will disconnect itself, in
* which case gperl_callback_destroy() will REFCNT_dec the data.
* That's fine, it leaves the mortal ref on the stack as the only
* one remaining, and the next FREETMPS will decrement and destroy
* in the usual way.
*
* Being a plain push here means callback->func can modify its
* $_[-1] to modify the stored userdata. Slightly scary, but it's a
* cute way to get a free bit of per-connection data you can play
* with as a state variable or whatnot. And not making a copy saves
* a couple of bytes of memory :-).
*/
{
SV *data = callback->data;
if (data) {
XPUSHs (sv_2mortal (SvREFCNT_inc (data)));
}
}
va_end (var_args);
PUTBACK;
/* invoke the callback */
if (return_value && G_VALUE_TYPE (return_value)) {
if (1 != call_sv (callback->func, G_SCALAR))
croak ("callback returned more than one value in "
"scalar context --- something really bad "
"is happening");
SPAGAIN;
gperl_value_from_sv (return_value, POPs);
PUTBACK; /* we modified the stack pointer */
} else {
call_sv (callback->func, G_DISCARD);
}
/* clean up */
FREETMPS;
LEAVE;
}
#if 0
static const char *
dump_callback (GPerlCallback * c)
{
SV * sv = newSVpvf ("{%d, [", c->n_params);
int i;
for (i = 0 ; i < c->n_params ; i++)
sv_catpvf (sv, "%s%s", g_type_name (c->param_types[i]),
(i+1) == c->n_params ? "" : ", ");
sv_catpvf (sv, "], %s, %s[%d], %s[%d], 0x%p}",
g_type_name (c->return_type),
SvPV_nolen (c->func), SvREFCNT (c->func),
SvPV_nolen (c->data), SvREFCNT (c->data),
c->priv);
sv_2mortal (sv);
return SvPV_nolen (sv);
}
#endif
=back
=head2 Exception Handling
Like Event, Tk, and most other callback-using, event-based perl modules,
Glib traps exceptions that happen in callbacks. To enable your code to
do something about these exceptions, Glib stores a list of exception
handlers which will be called on the trapped exceptions. This is
completely distinct from the $SIG{__DIE__} mechanism provided by Perl
itself, for various reasons (not the least of which is that the Perl
docs and source code say that $SIG{__DIE__} is intended for running as
the program is about to exit, and other behaviors may be removed in the
future (apparently a source of much debate on p5p)).
=over
=cut
typedef struct {
gulong tag;
GClosure * closure;
} ExceptionHandler;
static GSList * exception_handlers = NULL;
G_LOCK_DEFINE_STATIC (exception_handlers);
/* this is modified only behind the exception_handlers lock. */
static gboolean in_exception_handler = FALSE;
=item int gperl_install_exception_handler (GClosure * closure)
Install a GClosure to be executed when gperl_closure_invoke() traps an
exception. The closure should return boolean (TRUE if the handler should
remain installed) and expect to receive a perl scalar. This scalar will be
a private copy of ERRSV ($@) which the handler can mangle to its heart's
content.
The return value is an integer id tag that may be passed to
gperl_removed_exception_handler().
=cut
int
gperl_install_exception_handler (GClosure * closure)
{
static int tag = 0;
ExceptionHandler * h;
h = g_new0 (ExceptionHandler, 1);
G_LOCK (exception_handlers);
h->tag = ++tag;
h->closure = g_closure_ref (closure);
g_closure_sink (closure);
exception_handlers = g_slist_append (exception_handlers, h);
G_UNLOCK (exception_handlers);
return h->tag;
}
void
exception_handler_free (ExceptionHandler * h)
{
g_closure_unref (h->closure);
g_free (h);
}
static void
remove_exception_handler_unlocked (guint tag)
{
GSList * i;
for (i = exception_handlers ; i != NULL ; i = i->next) {
ExceptionHandler * h = (ExceptionHandler*) i->data;
if (h->tag == tag) {
exception_handler_free (h);
exception_handlers =
g_slist_delete_link (exception_handlers, i);
break;
}
}
}
=item void gperl_remove_exception_handler (guint tag)
Remove the exception handler identified by I<tag>, as returned by
gperl_install_exception_handler(). If I<tag> cannot be found, this
does nothing.
WARNING: this function locks a global data structure, so do NOT call
it recursively. also, calling this from within an exception handler will
result in a deadlock situation. if you want to remove your handler just
have it return FALSE.
=cut
void
gperl_remove_exception_handler (guint tag)
{
G_LOCK (exception_handlers);
remove_exception_handler_unlocked (tag);
G_UNLOCK (exception_handlers);
}
static void
warn_of_ignored_exception (const char * message)
{
/* there's a bit of extra nastiness here to strip the trailing
* newline from the contents of ERRSV for printing.
*/
/*
* don't clobber $_. for some reason, SAVE_DEFSV doesn't work here.
* so we do it by hand.
*/
SV * saved_defsv = newSVsv (DEFSV);
ENTER;
SAVETMPS;
sv_setsv (DEFSV, ERRSV);
eval_pv ("s/^/*** /mg", FALSE);
eval_pv ("s/\n$//s", FALSE);
warn ("*** %s:\n"
"%s\n"
"*** ignoring",
message,
SvPV_nolen (DEFSV));
FREETMPS;
LEAVE;
sv_setsv (DEFSV, saved_defsv);
SvREFCNT_dec (saved_defsv);
}
=item void gperl_run_exception_handlers (void)
Invoke whatever exception handlers are installed. You will need this if
you have written a custom marshaler. Uses the value of the global ERRSV.
=cut
void
gperl_run_exception_handlers (void)
{
GSList * i, * this;
int n_run = 0;
/* to avoid problems with handlers that fiddle with the value of
* the global $@, we'll pass a copy of $@ to all the handlers
* on the stack. this way we know they all get the same one, and
* they can do whatever they want to it without actually affecting
* anyone else. */
SV * errsv = newSVsv (ERRSV);
if (in_exception_handler) {
warn_of_ignored_exception ("died in an exception handler");
return;
}
G_LOCK (exception_handlers);
++in_exception_handler;
/* call any registered handlers */
for (i = exception_handlers ; i != NULL ; /* in loop */) {
ExceptionHandler * h = (ExceptionHandler *) i->data;
GValue param_values = {0, };
GValue return_value = {0, };
g_value_init (¶m_values, GPERL_TYPE_SV);
g_value_init (&return_value, G_TYPE_BOOLEAN);
/* this will duplicate errsv each time, so that all
* callbacks get the same value. */
g_value_set_boxed (¶m_values, errsv);
g_closure_invoke (h->closure, &return_value,
1, ¶m_values, NULL);
this = i;
i = i->next;
g_assert (i != this);
if (!g_value_get_boolean (&return_value)) {
#ifdef NOISY
warn ("handler %d returned FALSE, removing\n", h->tag);
#endif
exception_handler_free (h);
exception_handlers =
g_slist_delete_link (exception_handlers, this);
}
g_value_unset (¶m_values);
g_value_unset (&return_value);
++n_run;
}
--in_exception_handler;
G_UNLOCK (exception_handlers);
if (n_run == 0)
warn_of_ignored_exception ("unhandled exception in callback");
/* and clear the error */
sv_setsv (ERRSV, &PL_sv_undef);
SvREFCNT_dec (errsv);
}
=back
=cut
MODULE = Glib::Closure PACKAGE = Glib PREFIX = gperl_
=for object Glib::Signal Object customization and general purpose notification
=cut
=for apidoc
=for arg func (subroutine)
Install a subroutine to be executed when a signal emission traps an exception
(a croak or die). I<$func> should return boolean (true if the handler should
remain installed) and expect to receive a single scalar. This scalar will be a
private copy of $@ which the handler can mangle to its heart's content.
Returns an identifier that may be used with C<remove_exception_handler>.
See C<gperl_install_exception_handler()> in L<Glib::xsapi>.
=cut
int
gperl_install_exception_handler (class, SV * func, SV * data=NULL)
C_ARGS:
gperl_closure_new (func, data, 0)
=for apidoc
Remove the exception handler identified by I<$tag>, as returned by
C<install_exception_handler>. If I<$tag> cannot be found, this
does nothing.
WARNING: Do not call this function from within an exception handler.
If you want to remove your handler during its execution just have it
return false.
See C<gperl_remove_exception_handler()> in L<Glib::xsapi>.
=cut
void
gperl_remove_exception_handler (class, guint tag)
C_ARGS:
tag
##
## end on the native package
##
MODULE = Glib::Closure PACKAGE = Glib::Closure PREFIX = g_closure_