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GMainContext: reorganize source list to avoid O(n) behavior

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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 2012-04-11 13:08:13 -04:00
parent aaaaab91de
commit 55bac5da0a
1 changed files with 128 additions and 30 deletions
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158
glib/gmain.c
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@ -195,6 +195,14 @@ typedef enum
G_SOURCE_BLOCKED = 1 << (G_HOOK_FLAG_USER_SHIFT + 2)
} GSourceFlags;
typedef struct _GSourceList GSourceList;
struct _GSourceList
{
GSource *head, *tail;
gint priority;
};
typedef struct _GMainWaiter GMainWaiter;
struct _GMainWaiter
@ -232,7 +240,7 @@ struct _GMainContext
gint timeout; /* Timeout for current iteration */
guint next_id;
GSource *source_list;
GList *source_lists;
gint in_check_or_prepare;
GPollRec *poll_records, *poll_records_tail;
@ -313,6 +321,7 @@ typedef struct _GSourceIter
{
GMainContext *context;
gboolean may_modify;
GList *current_list;
GSource *source;
} GSourceIter;
@ -551,7 +560,7 @@ g_main_context_new (void)
context->next_id = 1;
context->source_list = NULL;
context->source_lists = NULL;
context->poll_func = g_poll;
@ -823,6 +832,7 @@ g_source_iter_init (GSourceIter *iter,
gboolean may_modify)
{
iter->context = context;
iter->current_list = NULL;
iter->source = NULL;
iter->may_modify = may_modify;
}
@ -834,14 +844,33 @@ 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);
}
next_source = iter->source->next;
else
next_source = iter->context->source_list;
next_source = NULL;
if (!next_source)
{
if (iter->current_list)
iter->current_list = iter->current_list->next;
else
iter->current_list = iter->context->source_lists;
if (iter->current_list)
{
GSourceList *source_list = iter->current_list->data;
next_source = source_list->head;
}
}
/* Note: unreffing iter->source could potentially cause its
* GSourceList to be removed from source_lists (if iter->source is
* the only source in its list, and it is destroyed), so we have to
* keep it reffed until after we advance iter->current_list, above.
*/
if (iter->source && iter->may_modify)
SOURCE_UNREF (iter->source, iter->context);
iter->source = next_source;
if (iter->source && iter->may_modify)
iter->source->ref_count++;
@ -865,56 +894,121 @@ g_source_iter_clear (GSourceIter *iter)
/* Holds context's lock
*/
static void
g_source_list_add (GSource *source,
GMainContext *context)
static GSourceList *
find_source_list_for_priority (GMainContext *context,
gint priority,
gboolean create)
{
GList *iter, *last;
GSourceList *source_list;
last = NULL;
for (iter = context->source_lists; iter != NULL; last = iter, iter = iter->next)
{
source_list = iter->data;
if (source_list->priority == priority)
return source_list;
if (source_list->priority > priority)
{
if (!create)
return NULL;
source_list = g_slice_new0 (GSourceList);
source_list->priority = priority;
context->source_lists = g_list_insert_before (context->source_lists,
iter,
source_list);
return source_list;
}
}
if (!create)
return NULL;
source_list = g_slice_new0 (GSourceList);
source_list->priority = priority;
if (!last)
context->source_lists = g_list_append (NULL, source_list);
else
{
/* This just appends source_list to the end of
* context->source_lists without having to walk the list again.
*/
last = g_list_append (last, source_list);
}
return source_list;
}
/* Holds context's lock
*/
static void
source_add_to_context (GSource *source,
GMainContext *context)
{
GSourceList *source_list;
GSource *prev, *next;
source_list = find_source_list_for_priority (context, source->priority, TRUE);
if (source->priv->parent_source)
{
g_assert (source_list->head != NULL);
/* Put the source immediately before its parent */
prev = source->priv->parent_source->prev;
next = source->priv->parent_source;
}
else
{
prev = NULL;
next = context->source_list;
while (next && next->priority <= source->priority)
{
prev = next;
next = next->next;
}
prev = source_list->tail;
next = NULL;
}
source->next = next;
if (next)
next->prev = source;
else
source_list->tail = source;
source->prev = prev;
if (prev)
prev->next = source;
else
context->source_list = source;
source_list->head = source;
}
/* Holds context's lock
*/
static void
g_source_list_remove (GSource *source,
GMainContext *context)
source_remove_from_context (GSource *source,
GMainContext *context)
{
GSourceList *source_list;
source_list = find_source_list_for_priority (context, source->priority, FALSE);
g_return_if_fail (source_list != NULL);
if (source->prev)
source->prev->next = source->next;
else
context->source_list = source->next;
source_list->head = source->next;
if (source->next)
source->next->prev = source->prev;
else
source_list->tail = source->prev;
source->prev = NULL;
source->next = NULL;
if (source_list->head == NULL)
{
context->source_lists = g_list_remove (context->source_lists, source_list);
g_slice_free (GSourceList, source_list);
}
}
static guint
@ -928,7 +1022,7 @@ g_source_attach_unlocked (GSource *source,
result = source->source_id = context->next_id++;
source->ref_count++;
g_source_list_add (source, context);
source_add_to_context (source, context);
tmp_list = source->poll_fds;
while (tmp_list)
@ -1429,15 +1523,19 @@ g_source_set_priority_unlocked (GSource *source,
g_return_if_fail (source->priv->parent_source == NULL ||
source->priv->parent_source->priority == priority);
if (context)
{
/* Remove the source from the context's source and then
* add it back after so it is sorted in the correct place
*/
source_remove_from_context (source, source->context);
}
source->priority = priority;
if (context)
{
/* Remove the source from the context's source and then
* add it back so it is sorted in the correct place
*/
g_source_list_remove (source, source->context);
g_source_list_add (source, source->context);
source_add_to_context (source, source->context);
if (!SOURCE_BLOCKED (source))
{
@ -1693,7 +1791,7 @@ g_source_unref_internal (GSource *source,
{
if (!SOURCE_DESTROYED (source))
g_warning (G_STRLOC ": ref_count == 0, but source was still attached to a context!");
g_source_list_remove (source, context);
source_remove_from_context (source, context);
}
if (source->source_funcs->finalize)