From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Mon, 23 Nov 2015 23:14:10 +0000 (-0500)
Subject: Add parented object memory management to the Object interface
X-Git-Url: http://git.efficios.com/?p=babeltrace.git;a=commitdiff_plain;h=5d2d9981bec06082e6148185830b8bcf0a10f4af

Add parented object memory management to the Object interface

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/include/babeltrace/object-internal.h b/include/babeltrace/object-internal.h
index afba4479..0b0fd0f7 100644
--- a/include/babeltrace/object-internal.h
+++ b/include/babeltrace/object-internal.h
@@ -28,6 +28,7 @@
  */
 
 #include <babeltrace/ref-internal.h>
+#include <babeltrace/ref.h>
 
 /**
  * All objects publicly exposed by Babeltrace APIs must contain this structure
@@ -37,12 +38,71 @@
  */
 struct bt_object {
 	struct bt_ref ref_count;
+	/* Class-specific release function. */
+	bt_object_release_func release;
+	/* @see doc/ref-counting.md */
+	struct bt_object *parent;
 };
 
 static inline
-void bt_object_init(void *obj, bt_object_release_func release)
+long bt_object_get_ref_count(const void *);
+static inline
+void bt_object_set_parent(void *, void *);
+
+static
+void bt_object_release(void *ptr)
+{
+	struct bt_object *obj = ptr;
+
+	if (obj && obj->release && !bt_object_get_ref_count(obj)) {
+		obj->release(obj);
+	}
+}
+
+static
+void generic_release(struct bt_object *obj)
+{
+	if (obj->parent) {
+		/* The release function will be invoked by the parent. */
+		bt_put(obj->parent);
+	} else {
+		bt_object_release(obj);
+	}
+}
+
+static inline
+struct bt_object *bt_object_get_parent(void *ptr)
+{
+	struct bt_object *obj = ptr;
+
+	return ptr ? bt_get(obj->parent) : NULL;
+}
+
+static inline
+void bt_object_set_parent(void *child_ptr, void *parent)
 {
-	bt_ref_init(&((struct bt_object *) obj)->ref_count, release);
+	struct bt_object *child = child_ptr;
+
+	if (!child) {
+		return;
+	}
+
+	/*
+	 * It is assumed that a "child" being "parented" is publicly reachable.
+	 * Therefore, a reference to its parent must be taken. The reference
+	 * to the parent will be released once the object's reference count
+	 * falls to zero.
+	 */
+	child->parent = bt_get(parent);
+}
+
+static inline
+void bt_object_init(void *ptr, bt_object_release_func release)
+{
+	struct bt_object *obj = ptr;
+
+	obj->release = release;
+	bt_ref_init(&obj->ref_count, generic_release);
 }
 
 #endif /* BABELTRACE_OBJECT_INTERNAL_H */