From 1e4d8103c3bac7dfe6f9d966acadc4512b861ee6 Mon Sep 17 00:00:00 2001
From: Philippe Proulx <eeppeliteloop@gmail.com>
Date: Thu, 26 Jan 2017 04:29:52 -0500
Subject: [PATCH] Add bt_component_class_freeze()
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It is somewhat essential for a component class provider (plugin or
whatever else) to make sure that its created, shared component class is
not modified once properly configured.

The new bt_component_class_freeze() function freezes a component class
object so that it becomes immutable.

bt_component_create() also has the side effect of freezing its class.
This is analogous to bt_event_create() which freezes its class.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 .../component/component-class-internal.h      |  2 ++
 .../babeltrace/component/component-class.h    |  3 ++
 lib/component/component-class.c               | 31 +++++++++++++++----
 lib/component/component.c                     |  2 ++
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/include/babeltrace/component/component-class-internal.h b/include/babeltrace/component/component-class-internal.h
index 320a7d93..2dacc8f0 100644
--- a/include/babeltrace/component/component-class-internal.h
+++ b/include/babeltrace/component/component-class-internal.h
@@ -35,6 +35,7 @@
 #include <babeltrace/component/component-class-sink.h>
 #include <babeltrace/babeltrace-internal.h>
 #include <babeltrace/object-internal.h>
+#include <stdbool.h>
 #include <glib.h>
 
 struct bt_component_class;
@@ -58,6 +59,7 @@ struct bt_component_class {
 	} methods;
 	/* Array of struct bt_component_class_destroy_listener */
 	GArray *destroy_listeners;
+	bool frozen;
 };
 
 struct bt_component_class_source {
diff --git a/include/babeltrace/component/component-class.h b/include/babeltrace/component/component-class.h
index ad259b29..ccb776f0 100644
--- a/include/babeltrace/component/component-class.h
+++ b/include/babeltrace/component/component-class.h
@@ -66,6 +66,9 @@ extern int bt_component_class_set_description(
 		struct bt_component_class *component_class,
 		const char *description);
 
+extern int bt_component_class_freeze(
+		struct bt_component_class *component_class);
+
 /**
  * Get a component class' name.
  *
diff --git a/lib/component/component-class.c b/lib/component/component-class.c
index 22551f88..55f020d2 100644
--- a/lib/component/component-class.c
+++ b/lib/component/component-class.c
@@ -29,6 +29,7 @@
 #include <babeltrace/compiler.h>
 #include <babeltrace/component/component-class-internal.h>
 #include <babeltrace/ref.h>
+#include <stdbool.h>
 #include <glib.h>
 
 static
@@ -202,7 +203,7 @@ int bt_component_class_set_init_method(
 {
 	int ret = 0;
 
-	if (!component_class || !init_method) {
+	if (!component_class || component_class->frozen || !init_method) {
 		ret = -1;
 		goto end;
 	}
@@ -219,7 +220,7 @@ int bt_component_class_set_destroy_method(
 {
 	int ret = 0;
 
-	if (!component_class || !destroy_method) {
+	if (!component_class || component_class->frozen || !destroy_method) {
 		ret = -1;
 		goto end;
 	}
@@ -236,7 +237,7 @@ extern int bt_component_class_set_description(
 {
 	int ret = 0;
 
-	if (!component_class || !description) {
+	if (!component_class || component_class->frozen || !description) {
 		ret = -1;
 		goto end;
 	}
@@ -274,7 +275,7 @@ int bt_component_class_add_destroy_listener(struct bt_component_class *class,
 	int ret = 0;
 	struct bt_component_class_destroy_listener listener;
 
-	if (!class || !func) {
+	if (!class || class->frozen || !func) {
 		ret = -1;
 		goto end;
 	}
@@ -294,7 +295,8 @@ extern int bt_component_class_sink_set_add_iterator_method(
 	struct bt_component_class_sink *sink_class;
 	int ret = 0;
 
-	if (!component_class || !add_iterator_method ||
+	if (!component_class || component_class->frozen ||
+			!add_iterator_method ||
 			component_class->type != BT_COMPONENT_CLASS_TYPE_SINK) {
 		ret = -1;
 		goto end;
@@ -315,7 +317,8 @@ extern int bt_component_class_filter_set_add_iterator_method(
 	struct bt_component_class_filter *filter_class;
 	int ret = 0;
 
-	if (!component_class || !add_iterator_method ||
+	if (!component_class || component_class->frozen ||
+			!add_iterator_method ||
 			component_class->type !=
 			BT_COMPONENT_CLASS_TYPE_FILTER) {
 		ret = -1;
@@ -329,3 +332,19 @@ extern int bt_component_class_filter_set_add_iterator_method(
 end:
 	return ret;
 }
+
+int bt_component_class_freeze(
+		struct bt_component_class *component_class)
+{
+	int ret = 0;
+
+	if (!component_class) {
+		ret = -1;
+		goto end;
+	}
+
+	component_class->frozen = true;
+
+end:
+	return ret;
+}
diff --git a/lib/component/component.c b/lib/component/component.c
index fe1179c2..c188261c 100644
--- a/lib/component/component.c
+++ b/lib/component/component.c
@@ -225,6 +225,8 @@ struct bt_component *bt_component_create(
 		BT_PUT(component);
 		goto end;
 	}
+
+	bt_component_class_freeze(component->class);
 end:
 	return component;
 }
-- 
2.34.1