[glib] gmain: add GSourceIter

[Dan Winship <danw src gnome org>]

commit aaaaab91de10445a178e8183a95d98189249e868
Author: Dan Winship <danw gnome org>
Date:   Fri Jun 22 22:21:05 2012 -0400

    gmain: add GSourceIter
    
    add an explicit iterator for GMainContext sources
    
    https://bugzilla.gnome.org/show_bug.cgi?id=619329

 glib/gmain.c |  154 ++++++++++++++++++++++++++++++++++-----------------------
 1 files changed, 92 insertions(+), 62 deletions(-)
---
diff --git a/glib/gmain.c b/glib/gmain.c
index 21b3a72..dea2f3a 100644
--- a/glib/gmain.c
+++ b/glib/gmain.c
@@ -309,6 +309,13 @@ struct _GSourcePrivate
   GSource *parent_source;
 };
 
+typedef struct _GSourceIter
+{
+  GMainContext *context;
+  gboolean may_modify;
+  GSource *source;
+} GSourceIter;
+
 #define LOCK_CONTEXT(context) g_mutex_lock (&context->mutex)
 #define UNLOCK_CONTEXT(context) g_mutex_unlock (&context->mutex)
 #define G_THREAD_SELF g_thread_self ()
@@ -347,6 +354,13 @@ static void g_main_context_add_poll_unlocked    (GMainContext *context,
 static void g_main_context_remove_poll_unlocked (GMainContext *context,
 						 GPollFD      *fd);
 
+static void     g_source_iter_init  (GSourceIter   *iter,
+				     GMainContext  *context,
+				     gboolean       may_modify);
+static gboolean g_source_iter_next  (GSourceIter   *iter,
+				     GSource      **source);
+static void     g_source_iter_clear (GSourceIter   *iter);
+
 static gboolean g_timeout_prepare  (GSource     *source,
 				    gint        *timeout);
 static gboolean g_timeout_check    (GSource     *source);
@@ -472,7 +486,9 @@ poll_rec_list_free (GMainContext *context,
 void
 g_main_context_unref (GMainContext *context)
 {
+  GSourceIter iter;
   GSource *source;
+
   g_return_if_fail (context != NULL);
   g_return_if_fail (g_atomic_int_get (&context->ref_count) > 0); 
 
@@ -483,13 +499,9 @@ g_main_context_unref (GMainContext *context)
   main_context_list = g_slist_remove (main_context_list, context);
   G_UNLOCK (main_context_list);
 
-  source = context->source_list;
-  while (source)
-    {
-      GSource *next = source->next;
-      g_source_destroy_internal (source, context, FALSE);
-      source = next;
-    }
+  g_source_iter_init (&iter, context, TRUE);
+  while (g_source_iter_next (&iter, &source))
+    g_source_destroy_internal (source, context, FALSE);
 
   g_mutex_clear (&context->mutex);
 
@@ -804,6 +816,53 @@ g_source_new (GSourceFuncs *source_funcs,
   return source;
 }
 
+/* Holds context's lock */
+static void
+g_source_iter_init (GSourceIter  *iter,
+		    GMainContext *context,
+		    gboolean      may_modify)
+{
+  iter->context = context;
+  iter->source = NULL;
+  iter->may_modify = may_modify;
+}
+
+/* Holds context's lock */
+static gboolean
+g_source_iter_next (GSourceIter *iter, GSource **source)
+{
+  GSource *next_source;
+
+  if (iter->source)
+    {
+      next_source = iter->source->next;
+      if (iter->may_modify)
+	SOURCE_UNREF (iter->source, iter->context);
+    }
+  else
+    next_source = iter->context->source_list;
+
+  iter->source = next_source;
+  if (iter->source && iter->may_modify)
+    iter->source->ref_count++;
+
+  *source = iter->source;
+  return *source != NULL;
+}
+
+/* Holds context's lock. Only necessary to call if you broke out of
+ * the g_source_iter_next() loop early.
+ */
+static void
+g_source_iter_clear (GSourceIter *iter)
+{
+  if (iter->source && iter->may_modify)
+    {
+      SOURCE_UNREF (iter->source, iter->context);
+      iter->source = NULL;
+    }
+}
+
 /* Holds context's lock
  */
 static void
@@ -1702,6 +1761,7 @@ GSource *
 g_main_context_find_source_by_id (GMainContext *context,
 				  guint         source_id)
 {
+  GSourceIter iter;
   GSource *source;
   
   g_return_val_if_fail (source_id > 0, NULL);
@@ -1711,14 +1771,14 @@ g_main_context_find_source_by_id (GMainContext *context,
   
   LOCK_CONTEXT (context);
   
-  source = context->source_list;
-  while (source)
+  g_source_iter_init (&iter, context, FALSE);
+  while (g_source_iter_next (&iter, &source))
     {
       if (!SOURCE_DESTROYED (source) &&
 	  source->source_id == source_id)
 	break;
-      source = source->next;
     }
+  g_source_iter_clear (&iter);
 
   UNLOCK_CONTEXT (context);
 
@@ -1742,6 +1802,7 @@ g_main_context_find_source_by_funcs_user_data (GMainContext *context,
 					       GSourceFuncs *funcs,
 					       gpointer      user_data)
 {
+  GSourceIter iter;
   GSource *source;
   
   g_return_val_if_fail (funcs != NULL, NULL);
@@ -1751,8 +1812,8 @@ g_main_context_find_source_by_funcs_user_data (GMainContext *context,
   
   LOCK_CONTEXT (context);
 
-  source = context->source_list;
-  while (source)
+  g_source_iter_init (&iter, context, FALSE);
+  while (g_source_iter_next (&iter, &source))
     {
       if (!SOURCE_DESTROYED (source) &&
 	  source->source_funcs == funcs &&
@@ -1766,8 +1827,8 @@ g_main_context_find_source_by_funcs_user_data (GMainContext *context,
 	  if (callback_data == user_data)
 	    break;
 	}
-      source = source->next;
     }
+  g_source_iter_clear (&iter);
 
   UNLOCK_CONTEXT (context);
 
@@ -1789,6 +1850,7 @@ GSource *
 g_main_context_find_source_by_user_data (GMainContext *context,
 					 gpointer      user_data)
 {
+  GSourceIter iter;
   GSource *source;
   
   if (context == NULL)
@@ -1796,8 +1858,8 @@ g_main_context_find_source_by_user_data (GMainContext *context,
   
   LOCK_CONTEXT (context);
 
-  source = context->source_list;
-  while (source)
+  g_source_iter_init (&iter, context, FALSE);
+  while (g_source_iter_next (&iter, &source))
     {
       if (!SOURCE_DESTROYED (source) &&
 	  source->callback_funcs)
@@ -1810,8 +1872,8 @@ g_main_context_find_source_by_user_data (GMainContext *context,
 	  if (callback_data == user_data)
 	    break;
 	}
-      source = source->next;
     }
+  g_source_iter_clear (&iter);
 
   UNLOCK_CONTEXT (context);
 
@@ -2562,30 +2624,6 @@ g_main_dispatch (GMainContext *context)
   g_ptr_array_set_size (context->pending_dispatches, 0);
 }
 
-/* Holds context's lock */
-static inline GSource *
-next_valid_source (GMainContext *context,
-		   GSource      *source)
-{
-  GSource *new_source = source ? source->next : context->source_list;
-
-  while (new_source)
-    {
-      if (!SOURCE_DESTROYED (new_source))
-	{
-	  new_source->ref_count++;
-	  break;
-	}
-      
-      new_source = new_source->next;
-    }
-
-  if (source)
-    SOURCE_UNREF (source, context);
-	  
-  return new_source;
-}
-
 /**
  * g_main_context_acquire:
  * @context: a #GMainContext
@@ -2761,6 +2799,7 @@ g_main_context_prepare (GMainContext *context,
   gint n_ready = 0;
   gint current_priority = G_MAXINT;
   GSource *source;
+  GSourceIter iter;
 
   if (context == NULL)
     context = g_main_context_default ();
@@ -2802,18 +2841,15 @@ g_main_context_prepare (GMainContext *context,
 
   context->timeout = -1;
   
-  source = next_valid_source (context, NULL);
-  while (source)
+  g_source_iter_init (&iter, context, TRUE);
+  while (g_source_iter_next (&iter, &source))
     {
       gint source_timeout = -1;
 
+      if (SOURCE_DESTROYED (source) || SOURCE_BLOCKED (source))
+	continue;
       if ((n_ready > 0) && (source->priority > current_priority))
-	{
-	  SOURCE_UNREF (source, context);
-	  break;
-	}
-      if (SOURCE_BLOCKED (source))
-	goto next;
+	break;
 
       if (!(source->flags & G_SOURCE_READY))
 	{
@@ -2856,10 +2892,8 @@ g_main_context_prepare (GMainContext *context,
 	  else
 	    context->timeout = MIN (context->timeout, source_timeout);
 	}
-
-    next:
-      source = next_valid_source (context, source);
     }
+  g_source_iter_clear (&iter);
 
   UNLOCK_CONTEXT (context);
   
@@ -2954,6 +2988,7 @@ g_main_context_check (GMainContext *context,
 		      gint          n_fds)
 {
   GSource *source;
+  GSourceIter iter;
   GPollRec *pollrec;
   gint n_ready = 0;
   gint i;
@@ -2991,16 +3026,13 @@ g_main_context_check (GMainContext *context,
       i++;
     }
 
-  source = next_valid_source (context, NULL);
-  while (source)
+  g_source_iter_init (&iter, context, TRUE);
+  while (g_source_iter_next (&iter, &source))
     {
+      if (SOURCE_DESTROYED (source) || SOURCE_BLOCKED (source))
+	continue;
       if ((n_ready > 0) && (source->priority > max_priority))
-	{
-	  SOURCE_UNREF (source, context);
-	  break;
-	}
-      if (SOURCE_BLOCKED (source))
-	goto next;
+	break;
 
       if (!(source->flags & G_SOURCE_READY))
 	{
@@ -3041,10 +3073,8 @@ g_main_context_check (GMainContext *context,
            */
           max_priority = source->priority;
 	}
-
-    next:
-      source = next_valid_source (context, source);
     }
+  g_source_iter_clear (&iter);
 
   UNLOCK_CONTEXT (context);