From 2204c38125cf5079604ad250b1e0890c55ce758b Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Wed, 20 Apr 2016 12:15:10 -0400
Subject: [PATCH] Add trace moficiation notification handler interface
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---
 formats/ctf/ir/trace.c                     | 26 ++++++++++++++++++
 include/babeltrace/ctf-ir/trace-internal.h |  1 +
 include/babeltrace/ctf-ir/trace.h          | 31 ++++++++++++++++++++++
 3 files changed, 58 insertions(+)

diff --git a/formats/ctf/ir/trace.c b/formats/ctf/ir/trace.c
index 4d9e97f9..c4889b79 100644
--- a/formats/ctf/ir/trace.c
+++ b/formats/ctf/ir/trace.c
@@ -46,6 +46,11 @@
 #define DEFAULT_IDENTIFIER_SIZE 128
 #define DEFAULT_METADATA_STRING_SIZE 4096
 
+struct notification_handler {
+	bt_ctf_notification_cb func;
+	void *data;
+};
+
 static
 void bt_ctf_trace_destroy(struct bt_object *obj);
 static
@@ -1027,6 +1032,27 @@ end:
 	return ret;
 }
 
+int bt_ctf_trace_add_notification_handler_cb(struct bt_ctf_trace *trace,
+		bt_ctf_notification_cb handler, void *handler_data)
+{
+	int ret = 0;
+	struct notification_handler *handler_wrapper =
+			g_new0(struct notification_handler, 1);
+
+	if (!trace || !handler || !handler_wrapper) {
+		ret = -1;
+		goto error;
+	}
+
+	handler_wrapper->func = handler;
+	handler_wrapper->data = handler_data;
+	g_ptr_array_add(trace->notification_handlers, handler_wrapper);
+	return ret;
+error:
+	g_free(handler_wrapper);
+	return ret;
+}
+
 BT_HIDDEN
 struct bt_ctf_field_type *get_field_type(enum field_type_alias alias)
 {
diff --git a/include/babeltrace/ctf-ir/trace-internal.h b/include/babeltrace/ctf-ir/trace-internal.h
index f9091425..c631b97d 100644
--- a/include/babeltrace/ctf-ir/trace-internal.h
+++ b/include/babeltrace/ctf-ir/trace-internal.h
@@ -65,6 +65,7 @@ struct bt_ctf_trace {
 	 * trace is _always_ frozen.
 	 */
 	int valid;
+	GPtrArray *notification_handlers; /* Array of notification_handler */
 };
 
 struct metadata_context {
diff --git a/include/babeltrace/ctf-ir/trace.h b/include/babeltrace/ctf-ir/trace.h
index ee740039..ccbfe9ef 100644
--- a/include/babeltrace/ctf-ir/trace.h
+++ b/include/babeltrace/ctf-ir/trace.h
@@ -43,6 +43,18 @@ struct bt_ctf_stream;
 struct bt_ctf_stream_class;
 struct bt_ctf_clock;
 
+/**
+ * Notification handling function type.
+ *
+ * A reference must be taken on the notification if the handler has to
+ * keep ownership of the notification beyond the invocation of the callback.
+ *
+ * @param notification	Notification to handle
+ * @param data		Handler private data
+ */
+typedef void (*bt_ctf_notification_cb)(
+		struct bt_notification *notification, void *data);
+
 /*
  * bt_ctf_trace_create: create a trace instance.
  *
@@ -338,6 +350,25 @@ extern struct bt_ctf_field_type *bt_ctf_trace_get_packet_header_type(
 extern int bt_ctf_trace_set_packet_header_type(struct bt_ctf_trace *trace,
 		struct bt_ctf_field_type *packet_header_type);
 
+/*
+ * bt_ctf_trace_add_notification_handler_cb: set a notification callback
+ * which will be invoked whenever a trace's schema is modified.
+ *
+ * Register a notification handler to a trace.
+ *
+ * @param trace Trace instance.
+ * @param handler Notification handler to invoke on trace xmodification.
+ * @param handler_data Private data passed to the notification handler.
+ *
+ * Returns 0 on success, a negative value on error.
+ *
+ * Note: the notification handler will be used to serialize the trace's current
+ * state on registration. It will then be invoked on any change occuring within
+ * the trace's hierarchy.
+ */
+extern int bt_ctf_trace_add_notification_handler_cb(struct bt_ctf_trace *trace,
+		bt_ctf_notification_cb handler, void *handler_data);
+
 #ifdef __cplusplus
 }
 #endif
-- 
2.34.1