Added a runtime option to use a dummy threading implementation that uses

Original commit message from CVS:
Added a runtime option to use a dummy threading implementation that uses
NOPs for all synchronisation and threading operations.

gst/Makefile.am

@@ -74,6 +74,7 @@ libgstreamer_la_SOURCES =		\
 	gstscheduler.c		\
 	gstsystemclock.c	\
 	gstthread.c		\
+	gstthreaddummy.c	\
 	$(GST_TRACE_SRC)	\
 	gsttype.c		\
 	$(GST_TYPEFIND_SRC)	\

gst/gst.c

@@ -41,9 +41,13 @@ gboolean _gst_registry_auto_load = TRUE;
 static GstRegistry *_global_registry;
 static GstRegistry *_user_registry;
 static gboolean _gst_registry_fixed = FALSE;
+static gboolean _nothreads = FALSE;
 
 extern gint _gst_trace_on;
 
+extern GThreadFunctions gst_thread_dummy_functions;
+
+
 static void 		load_plugin_func 	(gpointer data, gpointer user_data);
 static void		init_popt_callback	(poptContext context, enum poptCallbackReason reason,
                                                  const struct poptOption *option, const char *arg, void *data);
@@ -76,6 +80,7 @@ enum {
   ARG_PLUGIN_PATH,
   ARG_PLUGIN_LOAD,
   ARG_SCHEDULER,
+  ARG_NOTHREADS,
   ARG_REGISTRY
 };
 
@@ -95,6 +100,7 @@ static const struct poptOption options[] = {
   {"gst-plugin-path",    NUL, POPT_ARG_STRING|POPT_ARGFLAG_STRIP, NULL, ARG_PLUGIN_PATH,    "'" G_SEARCHPATH_SEPARATOR_S "'--separated path list for loading plugins", "PATHS"},
   {"gst-plugin-load",    NUL, POPT_ARG_STRING|POPT_ARGFLAG_STRIP, NULL, ARG_PLUGIN_LOAD,    "comma-separated list of plugins to preload in addition to the list stored in env variable GST_PLUGIN_PATH", "PLUGINS"},
   {"gst-scheduler",      NUL, POPT_ARG_STRING|POPT_ARGFLAG_STRIP, NULL, ARG_SCHEDULER,      "scheduler to use ('standard' is the default)", "SCHEDULER"},
+  {"gst-nothreads",      NUL, POPT_ARG_NONE|POPT_ARGFLAG_STRIP,   NULL, ARG_NOTHREADS,      "use NOPs for all threading and locking operations", NULL},
   {"gst-registry",       NUL, POPT_ARG_STRING|POPT_ARGFLAG_STRIP, NULL, ARG_REGISTRY,       "registry to use" , "REGISTRY"},
   POPT_TABLEEND
 };
@@ -271,9 +277,6 @@ init_pre (void)
   const gchar *homedir;
   gchar *user_reg;
 
-  if (!g_thread_supported ())
-    g_thread_init (NULL);
-  
   g_type_init();
 
   _global_registry = gst_xml_registry_new ("global_registry", GLOBAL_REGISTRY_FILE);
@@ -334,12 +337,19 @@ init_post (void)
 #ifndef GST_DISABLE_TRACE
   GstTrace *gst_trace;
 #endif
+
+  if (!g_thread_supported ()) {
+    if (_nothreads)
+      g_thread_init (&gst_thread_dummy_functions);
+    else
+      g_thread_init (NULL);
+  }
   
   llf = G_LOG_LEVEL_CRITICAL | G_LOG_LEVEL_ERROR | G_LOG_FLAG_FATAL;
   g_log_set_handler(g_log_domain_gstreamer, llf, debug_log_handler, NULL);
   
-  GST_INFO (GST_CAT_GST_INIT, "Initializing GStreamer Core Library version %s",
-            GST_VERSION);
+  GST_INFO (GST_CAT_GST_INIT, "Initializing GStreamer Core Library version %s %s",
+            GST_VERSION, _nothreads?"(no threads)":"");
   
   gst_object_get_type ();
   gst_pad_get_type ();
@@ -482,6 +492,9 @@ init_popt_callback (poptContext context, enum poptCallbackReason reason,
     case ARG_SCHEDULER:
       gst_scheduler_factory_set_default_name (arg);
       break;
+    case ARG_NOTHREADS:
+      _nothreads = TRUE;
+      break;
     case ARG_REGISTRY:
       g_object_set (G_OBJECT (_user_registry), "location", arg, NULL);
       _gst_registry_fixed = TRUE;
@@ -497,6 +510,13 @@ init_popt_callback (poptContext context, enum poptCallbackReason reason,
   }
 }
 
+gboolean
+gst_with_threads (void)
+{
+  return !_nothreads;
+}
+
+
 static GSList *mainloops = NULL;
 
 /**

gst/gst.h

@@ -67,6 +67,8 @@ void 			 	gst_init_with_popt_table 	(int *argc, char **argv[],
 								 const struct poptOption *popt_options);
 const struct poptOption*	gst_init_get_popt_table 	(void);
 
+gboolean			gst_with_threads		(void);
+
 void 			 	gst_main		 	(void);
 void 			 	gst_main_quit		 	(void);
 

gst/gstthread.c

@@ -25,6 +25,7 @@
 /* #define GST_DEBUG_ENABLED */
 #include "gst_private.h"
 
+#include "gst.h"
 #include "gstthread.h"
 #include "gstscheduler.h"
 #include "gstqueue.h"
@@ -246,7 +247,8 @@ gst_thread_change_state (GstElement * element)
   void *stack;
   glong stacksize;
 
-  g_return_val_if_fail (GST_IS_THREAD (element), FALSE);
+  g_return_val_if_fail (GST_IS_THREAD (element), GST_STATE_FAILURE);
+  g_return_val_if_fail (gst_with_threads (), GST_STATE_FAILURE);
 
   thread = GST_THREAD (element);
 

gst/gstthreaddummy.c

+/* GStreamer
+ * Copyright (C) <1999> Erik Walthinsen <omega@cse.ogi.edu>
+ *
+ * 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., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <sys/time.h>
+#include <glib.h>
+#include "gstlog.h"
+
+static GMutex *mutex = NULL;
+static GCond  *cond = NULL;
+
+static GMutex*
+gst_mutex_new_dummy_impl (void) 
+{
+  if (!mutex)
+    mutex = g_malloc (8);
+
+  return mutex;
+}
+
+static void gst_mutex_dummy_impl (GMutex *mutex) { /* NOP */ }
+
+static gboolean
+gst_mutex_trylock_dummy_impl (GMutex *mutex)
+{
+  return TRUE;
+}
+
+static GCond*
+gst_cond_new_dummy_impl (void) 
+{
+  if (!cond)
+    cond = g_malloc (8);
+
+  return cond;
+}
+
+static void
+gst_cond_dummy_impl (GCond *cond) { /* NOP */ }
+
+static gboolean
+gst_cond_timed_wait_dummy_impl (GCond *cond, GMutex *mutex, GTimeVal *end_time)
+{
+  struct timeval tvtarget;
+  GTimeVal tvnow;
+  guint64 now, target;
+  gint64 diff;
+  
+  target = end_time->tv_sec * 1000000 + end_time->tv_usec;
+
+  g_get_current_time (&tvnow);
+  now = tvnow.tv_sec * 1000000 + tvnow.tv_usec;
+
+  diff = target - now;
+  if (diff > 1000) {
+    tvtarget.tv_usec = diff % 1000000;
+    tvtarget.tv_sec = diff / 1000000;
+
+    select(0, NULL, NULL, NULL, &tvtarget);
+  }
+  
+  return TRUE;
+}
+
+static GPrivate*
+gst_private_new_dummy_impl (GDestroyNotify destructor)
+{
+  gpointer data;
+
+  data = g_new0 (gpointer, 1);
+
+  return (GPrivate *) data;
+}
+
+static gpointer
+gst_private_get_dummy_impl (GPrivate *private_key)
+{
+  gpointer *data = (gpointer) private_key;
+  
+  return *data;
+}
+
+static void
+gst_private_set_dummy_impl (GPrivate *private_key, gpointer data)
+{
+  *((gpointer*)private_key) = data;
+}
+
+static void
+gst_thread_create_dummy_impl (GThreadFunc func, gpointer data, gulong stack_size,
+		              gboolean joinable, gboolean bound, GThreadPriority priority,
+			      gpointer thread, GError **error)
+{
+  g_warning ("GStreamer configured to not use threads");
+}
+
+static void
+gst_thread_dummy_impl (void) { /* NOP */ }
+
+static void
+gst_thread_dummy_impl_1 (gpointer thread) { /* NOP */ }
+
+static void
+gst_thread_set_priority_dummy_impl (gpointer thread, GThreadPriority priority) { /* NOP */ }
+
+static gboolean
+gst_thread_equal_dummy_impl (gpointer thread1, gpointer thread2)
+{
+  return (thread1 == thread2);
+}
+
+GThreadFunctions 
+gst_thread_dummy_functions =
+{
+  gst_mutex_new_dummy_impl,
+  (void (*)(GMutex *)) gst_mutex_dummy_impl,
+  gst_mutex_trylock_dummy_impl,
+  (void (*)(GMutex *)) gst_mutex_dummy_impl,
+  gst_mutex_dummy_impl,
+  gst_cond_new_dummy_impl,
+  (void (*)(GCond *)) gst_cond_dummy_impl,
+  (void (*)(GCond *)) gst_cond_dummy_impl,
+  (void (*)(GCond *, GMutex *)) gst_cond_dummy_impl,
+  gst_cond_timed_wait_dummy_impl,
+  gst_cond_dummy_impl,
+  gst_private_new_dummy_impl,
+  gst_private_get_dummy_impl,
+  gst_private_set_dummy_impl,
+  gst_thread_create_dummy_impl,
+  gst_thread_dummy_impl,
+  gst_thread_dummy_impl_1,
+  gst_thread_dummy_impl,
+  gst_thread_set_priority_dummy_impl,
+  gst_thread_dummy_impl_1,
+  gst_thread_equal_dummy_impl
+};
+