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GMainContext: reorganize source list to avoid O(n) behavior
Rather than having a single priority-ordered list of GSources, store a list of queues of each priority level. This means that adding a source is now O(n) in the number of unique priority levels currently being used, rather than O(n) in the total number of sources. https://bugzilla.gnome.org/show_bug.cgi?id=619329
This commit is contained in:
Dan Winship
parent
aaaaab91de
commit
55bac5da0a
158
glib/gmain.c
158
glib/gmain.c
@ -195,6 +195,14 @@ typedef enum
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G_SOURCE_BLOCKED = 1 << (G_HOOK_FLAG_USER_SHIFT + 2)
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} GSourceFlags;
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typedef struct _GSourceList GSourceList;
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struct _GSourceList
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{
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GSource *head, *tail;
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gint priority;
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};
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typedef struct _GMainWaiter GMainWaiter;
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struct _GMainWaiter
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@ -232,7 +240,7 @@ struct _GMainContext
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gint timeout; /* Timeout for current iteration */
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guint next_id;
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GSource *source_list;
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GList *source_lists;
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gint in_check_or_prepare;
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GPollRec *poll_records, *poll_records_tail;
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@ -313,6 +321,7 @@ typedef struct _GSourceIter
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{
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GMainContext *context;
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gboolean may_modify;
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GList *current_list;
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GSource *source;
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} GSourceIter;
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@ -551,7 +560,7 @@ g_main_context_new (void)
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context->next_id = 1;
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context->source_list = NULL;
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context->source_lists = NULL;
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context->poll_func = g_poll;
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@ -823,6 +832,7 @@ g_source_iter_init (GSourceIter *iter,
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gboolean may_modify)
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{
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iter->context = context;
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iter->current_list = NULL;
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iter->source = NULL;
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iter->may_modify = may_modify;
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}
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@ -834,14 +844,33 @@ g_source_iter_next (GSourceIter *iter, GSource **source)
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GSource *next_source;
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if (iter->source)
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{
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next_source = iter->source->next;
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if (iter->may_modify)
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SOURCE_UNREF (iter->source, iter->context);
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}
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next_source = iter->source->next;
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else
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next_source = iter->context->source_list;
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next_source = NULL;
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if (!next_source)
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{
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if (iter->current_list)
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iter->current_list = iter->current_list->next;
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else
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iter->current_list = iter->context->source_lists;
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if (iter->current_list)
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{
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GSourceList *source_list = iter->current_list->data;
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next_source = source_list->head;
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}
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}
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/* Note: unreffing iter->source could potentially cause its
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* GSourceList to be removed from source_lists (if iter->source is
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* the only source in its list, and it is destroyed), so we have to
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* keep it reffed until after we advance iter->current_list, above.
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*/
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if (iter->source && iter->may_modify)
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SOURCE_UNREF (iter->source, iter->context);
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iter->source = next_source;
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if (iter->source && iter->may_modify)
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iter->source->ref_count++;
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@ -865,56 +894,121 @@ g_source_iter_clear (GSourceIter *iter)
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/* Holds context's lock
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*/
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static void
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g_source_list_add (GSource *source,
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GMainContext *context)
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static GSourceList *
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find_source_list_for_priority (GMainContext *context,
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gint priority,
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gboolean create)
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{
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GList *iter, *last;
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GSourceList *source_list;
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last = NULL;
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for (iter = context->source_lists; iter != NULL; last = iter, iter = iter->next)
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{
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source_list = iter->data;
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if (source_list->priority == priority)
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return source_list;
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if (source_list->priority > priority)
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{
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if (!create)
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return NULL;
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source_list = g_slice_new0 (GSourceList);
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source_list->priority = priority;
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context->source_lists = g_list_insert_before (context->source_lists,
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iter,
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source_list);
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return source_list;
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}
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}
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if (!create)
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return NULL;
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source_list = g_slice_new0 (GSourceList);
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source_list->priority = priority;
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if (!last)
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context->source_lists = g_list_append (NULL, source_list);
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else
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{
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/* This just appends source_list to the end of
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* context->source_lists without having to walk the list again.
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*/
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last = g_list_append (last, source_list);
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}
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return source_list;
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}
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/* Holds context's lock
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*/
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static void
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source_add_to_context (GSource *source,
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GMainContext *context)
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{
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GSourceList *source_list;
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GSource *prev, *next;
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source_list = find_source_list_for_priority (context, source->priority, TRUE);
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if (source->priv->parent_source)
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{
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g_assert (source_list->head != NULL);
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/* Put the source immediately before its parent */
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prev = source->priv->parent_source->prev;
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next = source->priv->parent_source;
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}
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else
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{
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prev = NULL;
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next = context->source_list;
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while (next && next->priority <= source->priority)
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{
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prev = next;
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next = next->next;
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}
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prev = source_list->tail;
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next = NULL;
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}
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source->next = next;
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if (next)
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next->prev = source;
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else
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source_list->tail = source;
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source->prev = prev;
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if (prev)
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prev->next = source;
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else
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context->source_list = source;
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source_list->head = source;
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}
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/* Holds context's lock
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*/
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static void
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g_source_list_remove (GSource *source,
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GMainContext *context)
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source_remove_from_context (GSource *source,
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GMainContext *context)
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{
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GSourceList *source_list;
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source_list = find_source_list_for_priority (context, source->priority, FALSE);
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g_return_if_fail (source_list != NULL);
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if (source->prev)
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source->prev->next = source->next;
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else
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context->source_list = source->next;
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source_list->head = source->next;
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if (source->next)
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source->next->prev = source->prev;
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else
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source_list->tail = source->prev;
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source->prev = NULL;
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source->next = NULL;
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if (source_list->head == NULL)
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{
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context->source_lists = g_list_remove (context->source_lists, source_list);
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g_slice_free (GSourceList, source_list);
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}
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}
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static guint
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@ -928,7 +1022,7 @@ g_source_attach_unlocked (GSource *source,
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result = source->source_id = context->next_id++;
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source->ref_count++;
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g_source_list_add (source, context);
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source_add_to_context (source, context);
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tmp_list = source->poll_fds;
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while (tmp_list)
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@ -1429,15 +1523,19 @@ g_source_set_priority_unlocked (GSource *source,
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g_return_if_fail (source->priv->parent_source == NULL ||
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source->priv->parent_source->priority == priority);
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if (context)
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{
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/* Remove the source from the context's source and then
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* add it back after so it is sorted in the correct place
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*/
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source_remove_from_context (source, source->context);
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}
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source->priority = priority;
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if (context)
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{
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/* Remove the source from the context's source and then
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* add it back so it is sorted in the correct place
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*/
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g_source_list_remove (source, source->context);
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g_source_list_add (source, source->context);
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source_add_to_context (source, source->context);
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if (!SOURCE_BLOCKED (source))
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{
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@ -1693,7 +1791,7 @@ g_source_unref_internal (GSource *source,
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{
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if (!SOURCE_DESTROYED (source))
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g_warning (G_STRLOC ": ref_count == 0, but source was still attached to a context!");
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g_source_list_remove (source, context);
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source_remove_from_context (source, context);
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}
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if (source->source_funcs->finalize)
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