gstreamer/plugins/tracers/gstleaks.c

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/* GStreamer
* Copyright (C) 2016 Collabora Ltd. <guillaume.desmottes@collabora.co.uk>
*
* gstleaks.c: tracing module detecting object leaks
*
* 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 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 St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
/**
* SECTION:gstleaks
* @short_description: detect GstObject and GstMiniObject leaks
*
* A tracing module tracking the lifetime of objects by logging those still
* alive when program is exiting and raising a warning.
* The type of objects tracked can be filtered using the parameters of the
* tracer, for example: GST_TRACERS="leaks(GstEvent,GstMessage)"
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef HAVE_UNWIND
/* No need for remote debugging so turn on the 'local only' optimizations in
* libunwind */
#define UNW_LOCAL_ONLY
#include <libunwind.h>
#endif /* HAVE_UNWIND */
#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#endif /* HAVE_BACKTRACE */
#include "gstleaks.h"
#ifdef G_OS_UNIX
#include <signal.h>
#endif /* G_OS_UNIX */
GST_DEBUG_CATEGORY_STATIC (gst_leaks_debug);
#define GST_CAT_DEFAULT gst_leaks_debug
#define _do_init \
GST_DEBUG_CATEGORY_INIT (gst_leaks_debug, "leaks", 0, "leaks tracer");
#define gst_leaks_tracer_parent_class parent_class
G_DEFINE_TYPE_WITH_CODE (GstLeaksTracer, gst_leaks_tracer,
GST_TYPE_TRACER, _do_init);
static GstTracerRecord *tr_alive;
#ifdef G_OS_UNIX
static GstTracerRecord *tr_added = NULL;
static GstTracerRecord *tr_removed = NULL;
#endif /* G_OS_UNIX */
static GQueue instances = G_QUEUE_INIT;
static void
set_filtering (GstLeaksTracer * self)
{
gchar *params;
GStrv tmp;
guint i;
g_object_get (self, "params", &params, NULL);
if (!params)
return;
tmp = g_strsplit (params, ",", -1);
self->filter = g_array_sized_new (FALSE, FALSE, sizeof (GType),
g_strv_length (tmp));
for (i = 0; tmp[i]; i++) {
GType type;
type = g_type_from_name (tmp[i]);
if (type == 0) {
/* The type may not yet be known by the type system, typically because
* the plugin implementing it as not yet be loaded. Save it for now as
* it will have another chance to be added to the filter later in
* should_handle_object_type() when/if the object type is actually
* used. */
if (!self->unhandled_filter)
self->unhandled_filter = g_hash_table_new (NULL, NULL);
g_hash_table_add (self->unhandled_filter,
GUINT_TO_POINTER (g_quark_from_string (tmp[i])));
g_atomic_int_inc (&self->unhandled_filter_count);
continue;
}
GST_DEBUG_OBJECT (self, "add filter on %s", tmp[i]);
g_array_append_val (self->filter, type);
}
g_strfreev (tmp);
g_free (params);
}
static gboolean
should_handle_object_type (GstLeaksTracer * self, GType object_type)
{
guint i, len;
if (!self->filter)
/* No filtering, handle all types */
return TRUE;
if (g_atomic_int_get (&self->unhandled_filter_count)) {
GST_OBJECT_LOCK (self);
if (self->unhandled_filter) {
GQuark q;
q = g_type_qname (object_type);
if (g_hash_table_contains (self->unhandled_filter, GUINT_TO_POINTER (q))) {
g_array_append_val (self->filter, object_type);
g_hash_table_remove (self->unhandled_filter, GUINT_TO_POINTER (q));
if (g_atomic_int_dec_and_test (&self->unhandled_filter_count))
g_clear_pointer (&self->unhandled_filter, g_hash_table_unref);
GST_OBJECT_UNLOCK (self);
return TRUE;
}
}
GST_OBJECT_UNLOCK (self);
}
len = self->filter->len;
for (i = 0; i < len; i++) {
GType type = g_array_index (self->filter, GType, i);
if (g_type_is_a (object_type, type))
return TRUE;
}
return FALSE;
}
#ifdef G_OS_UNIX
/* The object may be destroyed when we log it using the checkpointing system so
* we have to save its type name */
typedef struct
{
gpointer object;
const gchar *type_name;
} ObjectLog;
static ObjectLog *
object_log_new (gpointer obj)
{
ObjectLog *o = g_slice_new (ObjectLog);
o->object = obj;
if (G_IS_OBJECT (obj))
o->type_name = G_OBJECT_TYPE_NAME (obj);
else
o->type_name = g_type_name (GST_MINI_OBJECT_TYPE (obj));
return o;
}
static void
object_log_free (ObjectLog * obj)
{
g_slice_free (ObjectLog, obj);
}
#endif /* G_OS_UNIX */
static void
handle_object_destroyed (GstLeaksTracer * self, gpointer object)
{
GST_OBJECT_LOCK (self);
if (self->done) {
g_warning
("object %p destroyed while the leaks tracer was finalizing. Some threads are still running?",
object);
goto out;
}
g_hash_table_remove (self->objects, object);
#ifdef G_OS_UNIX
if (self->removed)
g_hash_table_add (self->removed, object_log_new (object));
#endif /* G_OS_UNIX */
out:
GST_OBJECT_UNLOCK (self);
}
static void
object_weak_cb (gpointer data, GObject * object)
{
GstLeaksTracer *self = data;
handle_object_destroyed (self, object);
}
static void
mini_object_weak_cb (gpointer data, GstMiniObject * object)
{
GstLeaksTracer *self = data;
handle_object_destroyed (self, object);
}
#ifdef HAVE_UNWIND
#define BT_NAME_SIZE 256
static gchar *
generate_unwind_trace (void)
{
unw_context_t ctx;
unw_cursor_t cursor;
GString *trace;
if (unw_getcontext (&ctx))
return NULL;
if (unw_init_local (&cursor, &ctx))
return NULL;
trace = g_string_new (NULL);
while (unw_step (&cursor) > 0) {
char name[BT_NAME_SIZE];
unw_word_t offp;
int ret;
ret = unw_get_proc_name (&cursor, name, BT_NAME_SIZE, &offp);
/* -UNW_ENOMEM is returned if name has been truncated */
if (ret != 0 && ret != -UNW_ENOMEM)
break;
g_string_append_printf (trace, "%s\n", name);
}
return g_string_free (trace, FALSE);
}
#endif /* HAVE_UNWIND */
#ifdef HAVE_BACKTRACE
#define BT_BUF_SIZE 100
static gchar *
generate_backtrace_trace (void)
{
int j, nptrs;
void *buffer[BT_BUF_SIZE];
char **strings;
GString *trace;
trace = g_string_new (NULL);
nptrs = backtrace (buffer, BT_BUF_SIZE);
strings = backtrace_symbols (buffer, nptrs);
if (!strings)
return NULL;
for (j = 0; j < nptrs; j++)
g_string_append_printf (trace, "%s\n", strings[j]);
return g_string_free (trace, FALSE);
}
#endif /* HAVE_BACKTRACE */
static gchar *
generate_trace (void)
{
gchar *trace = NULL;
#ifdef HAVE_UNWIND
trace = generate_unwind_trace ();
if (trace)
return trace;
#endif /* HAVE_UNWIND */
#ifdef HAVE_BACKTRACE
trace = generate_backtrace_trace ();
#endif /* HAVE_BACKTRACE */
return trace;
}
static void
handle_object_created (GstLeaksTracer * self, gpointer object, GType type,
gboolean gobject)
{
gchar *trace = NULL;
if (!should_handle_object_type (self, type))
return;
if (gobject)
g_object_weak_ref ((GObject *) object, object_weak_cb, self);
else
gst_mini_object_weak_ref (GST_MINI_OBJECT_CAST (object),
mini_object_weak_cb, self);
GST_OBJECT_LOCK (self);
if (self->log_stack_trace) {
trace = generate_trace ();
}
g_hash_table_insert (self->objects, object, trace);
#ifdef G_OS_UNIX
if (self->added)
g_hash_table_add (self->added, object_log_new (object));
#endif /* G_OS_UNIX */
GST_OBJECT_UNLOCK (self);
}
static void
mini_object_created_cb (GstTracer * tracer, GstClockTime ts,
GstMiniObject * object)
{
GstLeaksTracer *self = GST_LEAKS_TRACER_CAST (tracer);
handle_object_created (self, object, GST_MINI_OBJECT_TYPE (object), FALSE);
}
static void
object_created_cb (GstTracer * tracer, GstClockTime ts, GstObject * object)
{
GstLeaksTracer *self = GST_LEAKS_TRACER_CAST (tracer);
GType object_type = G_OBJECT_TYPE (object);
/* Can't track tracers as they may be disposed after the leak tracer itself */
if (g_type_is_a (object_type, GST_TYPE_TRACER))
return;
handle_object_created (self, object, object_type, TRUE);
}
static void
gst_leaks_tracer_init (GstLeaksTracer * self)
{
self->objects = g_hash_table_new_full (NULL, NULL, NULL, g_free);
if (g_getenv ("GST_LEAKS_TRACER_STACK_TRACE")) {
gchar *trace;
/* Test if we can retrieve backtrace */
trace = generate_trace ();
if (trace) {
self->log_stack_trace = TRUE;
g_free (trace);
} else {
g_warning ("Can't retrieve backtrace on this system");
}
}
g_queue_push_tail (&instances, self);
}
static void
gst_leaks_tracer_constructed (GObject * object)
{
GstLeaksTracer *self = GST_LEAKS_TRACER (object);
GstTracer *tracer = GST_TRACER (object);
set_filtering (self);
gst_tracing_register_hook (tracer, "mini-object-created",
G_CALLBACK (mini_object_created_cb));
gst_tracing_register_hook (tracer, "object-created",
G_CALLBACK (object_created_cb));
/* We rely on weak pointers rather than (mini-)object-destroyed hooks so we
* are notified of objects being destroyed even during the shuting down of
* the tracing system. */
((GObjectClass *) gst_leaks_tracer_parent_class)->constructed (object);
}
typedef struct
{
gpointer obj;
const gchar *type_name;
guint ref_count;
gchar *desc;
const gchar *trace;
} Leak;
/* The content of the returned Leak struct is valid until the self->objects
* hash table has been modified. */
static Leak *
leak_new (gpointer obj, GType type, guint ref_count, const gchar * trace)
{
Leak *leak = g_slice_new (Leak);
leak->obj = obj;
leak->type_name = g_type_name (type);
leak->ref_count = ref_count;
leak->desc = gst_info_strdup_printf ("%" GST_PTR_FORMAT, obj);
leak->trace = trace;
return leak;
}
static void
leak_free (Leak * leak)
{
g_free (leak->desc);
g_slice_free (Leak, leak);
}
static gint
sort_leaks (gconstpointer _a, gconstpointer _b)
{
const Leak *a = _a, *b = _b;
return g_strcmp0 (a->type_name, b->type_name);
}
static GList *
create_leaks_list (GstLeaksTracer * self)
{
GList *l = NULL;
GHashTableIter iter;
gpointer obj, trace;
g_hash_table_iter_init (&iter, self->objects);
while (g_hash_table_iter_next (&iter, &obj, &trace)) {
GType type;
guint ref_count;
if (GST_IS_OBJECT (obj)) {
if (GST_OBJECT_FLAG_IS_SET (obj, GST_OBJECT_FLAG_MAY_BE_LEAKED))
continue;
type = G_OBJECT_TYPE (obj);
ref_count = ((GObject *) obj)->ref_count;
} else {
if (GST_MINI_OBJECT_FLAG_IS_SET (obj, GST_MINI_OBJECT_FLAG_MAY_BE_LEAKED))
continue;
type = GST_MINI_OBJECT_TYPE (obj);
ref_count = ((GstMiniObject *) obj)->refcount;
}
l = g_list_prepend (l, leak_new (obj, type, ref_count, trace));
}
/* Sort leaks by type name so they are grouped together making the output
* easier to read */
l = g_list_sort (l, sort_leaks);
return l;
}
/* Return TRUE if at least one leaked object has been logged */
static gboolean
log_leaked (GstLeaksTracer * self)
{
GList *leaks, *l;
leaks = create_leaks_list (self);
if (!leaks)
return FALSE;
for (l = leaks; l != NULL; l = g_list_next (l)) {
Leak *leak = l->data;
gst_tracer_record_log (tr_alive, leak->type_name, leak->obj, leak->desc,
leak->ref_count, leak->trace ? leak->trace : "");
}
g_list_free_full (leaks, (GDestroyNotify) leak_free);
return TRUE;
}
static void
gst_leaks_tracer_finalize (GObject * object)
{
GstLeaksTracer *self = GST_LEAKS_TRACER (object);
gboolean leaks;
GHashTableIter iter;
gpointer obj;
self->done = TRUE;
/* Tracers are destroyed as part of gst_deinit() so now is a good time to
* report all the objects which are still alive. */
leaks = log_leaked (self);
/* Remove weak references */
g_hash_table_iter_init (&iter, self->objects);
while (g_hash_table_iter_next (&iter, &obj, NULL)) {
if (GST_IS_OBJECT (obj))
g_object_weak_unref (obj, object_weak_cb, self);
else
gst_mini_object_weak_unref (GST_MINI_OBJECT_CAST (obj),
mini_object_weak_cb, self);
}
g_clear_pointer (&self->objects, g_hash_table_unref);
if (self->filter)
g_array_free (self->filter, TRUE);
g_clear_pointer (&self->added, g_hash_table_unref);
g_clear_pointer (&self->removed, g_hash_table_unref);
g_clear_pointer (&self->unhandled_filter, g_hash_table_unref);
g_queue_remove (&instances, self);
if (leaks)
g_warning ("Leaks detected");
((GObjectClass *) gst_leaks_tracer_parent_class)->finalize (object);
}
#define RECORD_FIELD_TYPE_NAME \
"type-name", GST_TYPE_STRUCTURE, gst_structure_new ("value", \
"type", G_TYPE_GTYPE, G_TYPE_STRING, \
"related-to", GST_TYPE_TRACER_VALUE_SCOPE, GST_TRACER_VALUE_SCOPE_PROCESS, \
NULL)
#define RECORD_FIELD_ADDRESS \
"address", GST_TYPE_STRUCTURE, gst_structure_new ("value", \
"type", G_TYPE_GTYPE, G_TYPE_POINTER, \
"related-to", GST_TYPE_TRACER_VALUE_SCOPE, \
GST_TRACER_VALUE_SCOPE_PROCESS, \
NULL)
#define RECORD_FIELD_DESC \
"description", GST_TYPE_STRUCTURE, gst_structure_new ("value", \
"type", G_TYPE_GTYPE, G_TYPE_STRING, \
"related-to", GST_TYPE_TRACER_VALUE_SCOPE, GST_TRACER_VALUE_SCOPE_PROCESS, \
NULL)
#define RECORD_FIELD_REF_COUNT \
"ref-count", GST_TYPE_STRUCTURE, gst_structure_new ("value", \
"type", G_TYPE_GTYPE, G_TYPE_UINT, \
"related-to", GST_TYPE_TRACER_VALUE_SCOPE, GST_TRACER_VALUE_SCOPE_PROCESS, \
NULL)
#define RECORD_FIELD_TRACE \
"trace", GST_TYPE_STRUCTURE, gst_structure_new ("value", \
"type", G_TYPE_GTYPE, G_TYPE_STRING, \
"related-to", GST_TYPE_TRACER_VALUE_SCOPE, GST_TRACER_VALUE_SCOPE_PROCESS, \
NULL)
#ifdef G_OS_UNIX
static void
sig_usr1_handler_foreach (gpointer data, gpointer user_data)
{
GstLeaksTracer *tracer = data;
GST_OBJECT_LOCK (tracer);
GST_TRACE_OBJECT (tracer, "start listing currently alive objects");
log_leaked (tracer);
GST_TRACE_OBJECT (tracer, "done listing currently alive objects");
GST_OBJECT_UNLOCK (tracer);
}
static void
sig_usr1_handler (G_GNUC_UNUSED int signal)
{
g_queue_foreach (&instances, sig_usr1_handler_foreach, NULL);
}
static void
log_checkpoint (GHashTable * hash, GstTracerRecord * record)
{
GHashTableIter iter;
gpointer o;
g_hash_table_iter_init (&iter, hash);
while (g_hash_table_iter_next (&iter, &o, NULL)) {
ObjectLog *obj = o;
gst_tracer_record_log (record, obj->type_name, obj->object);
}
}
static void
do_checkpoint (GstLeaksTracer * self)
{
GST_TRACE_OBJECT (self, "listing objects created since last checkpoint");
log_checkpoint (self->added, tr_added);
GST_TRACE_OBJECT (self, "listing objects removed since last checkpoint");
log_checkpoint (self->removed, tr_removed);
g_hash_table_remove_all (self->added);
g_hash_table_remove_all (self->removed);
}
static void
sig_usr2_handler_foreach (gpointer data, gpointer user_data)
{
GstLeaksTracer *tracer = data;
GST_OBJECT_LOCK (tracer);
if (!tracer->added) {
GST_TRACE_OBJECT (tracer, "First checkpoint, start tracking objects");
tracer->added = g_hash_table_new_full (NULL, NULL,
(GDestroyNotify) object_log_free, NULL);
tracer->removed = g_hash_table_new_full (NULL, NULL,
(GDestroyNotify) object_log_free, NULL);
} else {
do_checkpoint (tracer);
}
GST_OBJECT_UNLOCK (tracer);
}
static void
sig_usr2_handler (G_GNUC_UNUSED int signal)
{
g_queue_foreach (&instances, sig_usr2_handler_foreach, NULL);
}
static void
setup_signals (void)
{
tr_added = gst_tracer_record_new ("object-added.class",
RECORD_FIELD_TYPE_NAME, RECORD_FIELD_ADDRESS, NULL);
GST_OBJECT_FLAG_SET (tr_added, GST_OBJECT_FLAG_MAY_BE_LEAKED);
tr_removed = gst_tracer_record_new ("object-removed.class",
RECORD_FIELD_TYPE_NAME, RECORD_FIELD_ADDRESS, NULL);
GST_OBJECT_FLAG_SET (tr_removed, GST_OBJECT_FLAG_MAY_BE_LEAKED);
signal (SIGUSR1, sig_usr1_handler);
signal (SIGUSR2, sig_usr2_handler);
}
#endif /* G_OS_UNIX */
static void
gst_leaks_tracer_class_init (GstLeaksTracerClass * klass)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
gobject_class->constructed = gst_leaks_tracer_constructed;
gobject_class->finalize = gst_leaks_tracer_finalize;
tr_alive = gst_tracer_record_new ("object-alive.class",
RECORD_FIELD_TYPE_NAME, RECORD_FIELD_ADDRESS, RECORD_FIELD_DESC,
RECORD_FIELD_REF_COUNT, RECORD_FIELD_TRACE, NULL);
GST_OBJECT_FLAG_SET (tr_alive, GST_OBJECT_FLAG_MAY_BE_LEAKED);
if (g_getenv ("GST_LEAKS_TRACER_SIG")) {
#ifdef G_OS_UNIX
setup_signals ();
#else
g_warning ("System doesn't support POSIX signals");
#endif /* G_OS_UNIX */
}
}