lib: graph API: return borrowed references when adding to an object

Before this patch, the following functions return a new reference when
their last parameter is not `NULL`:

* bt_graph_add_filter_component()
* bt_graph_add_filter_component_with_initialize_method_data()
* bt_graph_add_simple_sink_component()
* bt_graph_add_sink_component()
* bt_graph_add_sink_component_with_initialize_method_data()
* bt_graph_add_source_component()
* bt_graph_add_source_component_with_initialize_method_data()
* bt_graph_connect_ports()
* bt_self_component_filter_add_input_port()
* bt_self_component_filter_add_output_port()
* bt_self_component_sink_add_input_port()
* bt_self_component_source_add_output_port()

I'm changing this so that they return a borrowed reference instead. This
is more in line with other non-creating functions which always return
borrowed references.

It's okay to borrow here because the object to which you add an object
becomes its owner anyway.

Most sites are updated by removing the *_put_ref() call as the reference
is now borrowed.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I71a5e18760504d8f8610162e3f6d7bd8d87474f9
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2762
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>

src/bindings/python/bt2/bt2/component.py

@@ -845,7 +845,9 @@ def _add_output_port(self, name, user_data=None):
             comp_status, 'cannot add output port to source component object'
         )
         assert self_port_ptr is not None
-        return bt2_port._UserComponentOutputPort._create_from_ptr(self_port_ptr)
+        return bt2_port._UserComponentOutputPort._create_from_ptr_and_get_ref(
+            self_port_ptr
+        )
 
 
 class _UserFilterComponent(_UserComponent, _FilterComponentConst):
@@ -893,7 +895,9 @@ def _add_output_port(self, name, user_data=None):
             comp_status, 'cannot add output port to filter component object'
         )
         assert self_port_ptr
-        return bt2_port._UserComponentOutputPort._create_from_ptr(self_port_ptr)
+        return bt2_port._UserComponentOutputPort._create_from_ptr_and_get_ref(
+            self_port_ptr
+        )
 
     def _add_input_port(self, name, user_data=None):
         utils._check_str(name)
@@ -903,7 +907,9 @@ def _add_input_port(self, name, user_data=None):
             comp_status, 'cannot add input port to filter component object'
         )
         assert self_port_ptr
-        return bt2_port._UserComponentInputPort._create_from_ptr(self_port_ptr)
+        return bt2_port._UserComponentInputPort._create_from_ptr_and_get_ref(
+            self_port_ptr
+        )
 
 
 class _UserSinkComponent(_UserComponent, _SinkComponentConst):
@@ -943,7 +949,9 @@ def _add_input_port(self, name, user_data=None):
             comp_status, 'cannot add input port to sink component object'
         )
         assert self_port_ptr
-        return bt2_port._UserComponentInputPort._create_from_ptr(self_port_ptr)
+        return bt2_port._UserComponentInputPort._create_from_ptr_and_get_ref(
+            self_port_ptr
+        )
 
     def _create_message_iterator(self, input_port):
         utils._check_type(input_port, bt2_port._UserComponentInputPort)

src/bindings/python/bt2/bt2/graph.py

@@ -119,7 +119,9 @@ def add_component(
         )
         utils._handle_func_status(status, 'cannot add component to graph')
         assert comp_ptr
-        return bt2_component._create_component_from_const_ptr(comp_ptr, cc_type)
+        return bt2_component._create_component_from_const_ptr_and_get_ref(
+            comp_ptr, cc_type
+        )
 
     def connect_ports(self, upstream_port, downstream_port):
         utils._check_type(upstream_port, bt2_port._OutputPortConst)
@@ -129,7 +131,7 @@ def connect_ports(self, upstream_port, downstream_port):
         )
         utils._handle_func_status(status, 'cannot connect component ports within graph')
         assert conn_ptr
-        return bt2_connection._ConnectionConst._create_from_ptr(conn_ptr)
+        return bt2_connection._ConnectionConst._create_from_ptr_and_get_ref(conn_ptr)
 
     def add_port_added_listener(self, listener):
         if not callable(listener):

src/cli/babeltrace2.c

@@ -1442,6 +1442,7 @@ int cmd_run_ctx_connect_upstream_port_to_downstream_component(
 				ctx->graph, trimmer_class, trimmer_name,
 				trimmer_params, ctx->cfg->log_level,
 				&trimmer);
+			bt_component_filter_get_ref(trimmer);
 			free(trimmer_name);
 			if (add_comp_status !=
 					BT_GRAPH_ADD_COMPONENT_STATUS_OK) {
@@ -2270,18 +2271,21 @@ int cmd_run_ctx_create_components_from_config_components(
 				comp_cls, cfg_comp->instance_name->str,
 				cfg_comp->params, cfg_comp->log_level,
 				(void *) &comp);
+			bt_component_source_get_ref(comp);
 			break;
 		case BT_COMPONENT_CLASS_TYPE_FILTER:
 			ret = bt_graph_add_filter_component(ctx->graph,
 				comp_cls, cfg_comp->instance_name->str,
 				cfg_comp->params, cfg_comp->log_level,
 				(void *) &comp);
+			bt_component_filter_get_ref(comp);
 			break;
 		case BT_COMPONENT_CLASS_TYPE_SINK:
 			ret = bt_graph_add_sink_component(ctx->graph,
 				comp_cls, cfg_comp->instance_name->str,
 				cfg_comp->params, cfg_comp->log_level,
 				(void *) &comp);
+			bt_component_sink_get_ref(comp);
 			break;
 		default:
 			bt_common_abort();

src/lib/graph/component-filter.c

@@ -135,7 +135,6 @@ enum bt_self_component_add_port_status bt_self_component_filter_add_output_port(
 	if (self_port) {
 		/* Move reference to user */
 		*self_port = (void *) port;
-		port = NULL;
 	}
 
 end:
@@ -205,7 +204,6 @@ enum bt_self_component_add_port_status bt_self_component_filter_add_input_port(
 	if (self_port) {
 		/* Move reference to user */
 		*self_port = (void *) port;
-		port = NULL;
 	}
 
 end:

src/lib/graph/component-sink.c

@@ -139,7 +139,6 @@ enum bt_self_component_add_port_status bt_self_component_sink_add_input_port(
 	if (self_port) {
 		/* Move reference to user */
 		*self_port = (void *) port;
-		port = NULL;
 	}
 
 end:

src/lib/graph/component-source.c

@@ -133,7 +133,6 @@ enum bt_self_component_add_port_status bt_self_component_source_add_output_port(
 	if (self_port) {
 		/* Move reference to user */
 		*self_port = (void *) port;
-		port = NULL;
 	}
 
 end:

src/lib/graph/graph.c

@@ -433,7 +433,6 @@ enum bt_graph_connect_ports_status bt_graph_connect_ports(
 	if (user_connection) {
 		/* Move reference to user */
 		*user_connection = connection;
-		connection = NULL;
 	}
 
 end:
@@ -1020,7 +1019,6 @@ int add_component_with_init_method_data(
 	if (user_component) {
 		/* Move reference to user */
 		*user_component = component;
-		component = NULL;
 	}
 
 end:

tests/lib/plugin.c

@@ -204,7 +204,6 @@ static void test_sfs(const char *plugin_dir)
 		"the-sink", NULL, BT_LOGGING_LEVEL_NONE, &sink_component);
 	ok(graph_ret == BT_GRAPH_ADD_COMPONENT_STATUS_OK && sink_component,
 		"bt_graph_add_sink_component() still works after the plugin object is destroyed");
-	BT_COMPONENT_SINK_PUT_REF_AND_RESET(sink_component);
 	bt_graph_put_ref(graph);
 
 	free(sfs_path);

tests/lib/test_graph_topo.c

@@ -505,8 +505,6 @@ void test_src_adds_port_in_port_connected(void)
 	ok(src_port_connected_pos < graph_port_added_src_pos,
 		"event order is good");
 
-	bt_component_source_put_ref(src);
-	bt_component_sink_put_ref(sink);
 	bt_graph_put_ref(graph);
 }
 
@@ -573,9 +571,7 @@ void test_simple(void)
 	event.data.sink_comp_input_port_connected.other_port = gsrc_def_port;
 	ok(has_event(&event), "got the expected sink's port connected event");
 
-	bt_component_sink_put_ref(sink);
 	bt_graph_put_ref(graph);
-	bt_component_source_put_ref(src);
 }
 
 static
@@ -639,9 +635,6 @@ void test_src_port_connected_error(void)
 	ok(has_event(&event), "got the expected source's port connected event");
 
 	bt_graph_put_ref(graph);
-	bt_component_sink_put_ref(sink);
-	bt_component_source_put_ref(src);
-	bt_connection_put_ref(conn);
 }
 
 static
@@ -711,10 +704,7 @@ void test_sink_port_connected_error(void)
 	event.data.sink_comp_input_port_connected.other_port = gsrc_def_port;
 	ok(has_event(&event), "got the expected sink's port connected event");
 
-	bt_connection_put_ref(conn);
 	bt_graph_put_ref(graph);
-	bt_component_sink_put_ref(sink);
-	bt_component_source_put_ref(src);
 }
 
 static

tests/lib/test_remove_destruction_listener_in_destruction_listener.c

@@ -278,7 +278,6 @@ int main(int argc, char **argv)
 		BT_LOGGING_LEVEL_WARNING, &source);
 	BT_ASSERT(add_component_status == BT_GRAPH_ADD_COMPONENT_STATUS_OK);
 
-	bt_component_source_put_ref(source);
 	bt_component_class_source_put_ref(source_cc);
 	bt_message_iterator_class_put_ref(msg_iter_cls);
 	bt_graph_put_ref(graph);

tests/lib/test_simple_sink.c

@@ -109,7 +109,6 @@ bt_graph *create_graph_with_source(const bt_port_output **out_port)
 	*out_port = bt_component_source_borrow_output_port_by_index_const(
 		src_comp, 0);
 	BT_ASSERT(*out_port);
-	bt_component_source_put_ref(src_comp);
 	bt_component_class_source_put_ref(src_comp_cls);
 	bt_message_iterator_class_put_ref(msg_iter_cls);
 	return graph;
@@ -163,7 +162,6 @@ void test_simple_expect_run_once_status(
 	ok((run_once_status < 0) == (err != NULL),
 		"Current thread error is set if bt_graph_run_once returned an error");
 
-	bt_component_sink_put_ref(sink_comp);
 	bt_graph_put_ref(graph);
 	if (err) {
 		bt_error_release(err);