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From 3f94b11a943c0e4d29c96930ced238580dc18fc7 Mon Sep 17 00:00:00 2001
From: Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
Date: Wed, 28 Mar 2018 19:21:52 -0300
Subject: [PATCH 2/2] object: Queue a forced GC when toggling down
During a GC, the collector asks each object which other
objects that it wants to hold on to so if there's an entire
section of the heap graph that's not connected to anything
else, and not reachable from the root set, then it can be
trashed all at once.
GObjects, however, don't work like that, there's only a
reference count but no notion of who owns the reference so,
a JS object that's proxying a GObject is unconditionally held
alive as long as the GObject has >1 references.
Since we cannot know how many more wrapped GObjects are going
be marked for garbage collection after the owner is destroyed,
always queue a garbage collection when a toggle reference goes
down.
Issue: #140
---
gi/object.cpp | 22 ++++++++++++++++++++++
gjs/context-private.h | 2 +-
gjs/context.cpp | 14 ++++++++------
3 files changed, 31 insertions(+), 7 deletions(-)
diff --git a/gi/object.cpp b/gi/object.cpp
index b20d8b9..f9cf3cc 100644
--- a/gi/object.cpp
+++ b/gi/object.cpp
@@ -987,8 +987,30 @@ handle_toggle_down(GObject *gobj)
* collected by the GC
*/
if (priv->keep_alive.rooted()) {
+ GjsContext *context;
+
gjs_debug_lifecycle(GJS_DEBUG_GOBJECT, "Unrooting object");
priv->keep_alive.switch_to_unrooted();
+
+ /* During a GC, the collector asks each object which other
+ * objects that it wants to hold on to so if there's an entire
+ * section of the heap graph that's not connected to anything
+ * else, and not reachable from the root set, then it can be
+ * trashed all at once.
+ *
+ * GObjects, however, don't work like that, there's only a
+ * reference count but no notion of who owns the reference so,
+ * a JS object that's proxying a GObject is unconditionally held
+ * alive as long as the GObject has >1 references.
+ *
+ * Since we cannot know how many more wrapped GObjects are going
+ * be marked for garbage collection after the owner is destroyed,
+ * always queue a garbage collection when a toggle reference goes
+ * down.
+ */
+ context = gjs_context_get_current();
+ if (!_gjs_context_destroying(context))
+ _gjs_context_schedule_gc(context);
}
}
diff --git a/gjs/context-private.h b/gjs/context-private.h
index c45c8d0..49c0cf9 100644
--- a/gjs/context-private.h
+++ b/gjs/context-private.h
@@ -36,7 +36,7 @@ bool _gjs_context_destroying (GjsContext *js_context);
void _gjs_context_schedule_gc_if_needed (GjsContext *js_context);
-void _gjs_context_schedule_gc (GjsContext *js_context);
+void _gjs_context_schedule_gc(GjsContext *js_context);
void _gjs_context_exit(GjsContext *js_context,
uint8_t exit_code);
diff --git a/gjs/context.cpp b/gjs/context.cpp
index 77d7eaa..a2ce34a 100644
--- a/gjs/context.cpp
+++ b/gjs/context.cpp
@@ -599,31 +599,33 @@ trigger_gc_if_needed (gpointer user_data)
else
gjs_gc_if_needed(js_context->context);
+ js_context->force_gc = false;
+
return G_SOURCE_REMOVE;
}
static void
-_gjs_context_schedule_gc_internal (GjsContext *js_context,
- bool force_gc)
+_gjs_context_schedule_gc_internal(GjsContext *js_context,
+ bool force_gc)
{
if (js_context->auto_gc_id > 0)
- g_source_remove(js_context->auto_gc_id);
+ return;
- js_context->force_gc = force_gc;
+ js_context->force_gc |= force_gc;
js_context->auto_gc_id = g_idle_add_full(G_PRIORITY_LOW,
trigger_gc_if_needed,
js_context, NULL);
}
void
-_gjs_context_schedule_gc (GjsContext *js_context)
+_gjs_context_schedule_gc(GjsContext *js_context)
{
_gjs_context_schedule_gc_internal(js_context, true);
}
void
-_gjs_context_schedule_gc_if_needed (GjsContext *js_context)
+_gjs_context_schedule_gc_if_needed(GjsContext *js_context)
{
_gjs_context_schedule_gc_internal(js_context, false);
}
--
2.17.0
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