From 3b098d56979d2f7fd707c5be85555d114353a28d Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Thu, 9 Jun 2016 10:48:43 -0600 Subject: qapi: Add new visit_complete() function Making each output visitor provide its own output collection function was the only remaining reason for exposing visitor sub-types to the rest of the code base. Add a polymorphic visit_complete() function which is a no-op for input visitors, and which populates an opaque pointer for output visitors. For maximum type-safety, also add a parameter to the output visitor constructors with a type-correct version of the output pointer, and assert that the two uses match. This approach was considered superior to either passing the output parameter only during construction (action at a distance during visit_free() feels awkward) or only during visit_complete() (defeating type safety makes it easier to use incorrectly). Most callers were function-local, and therefore a mechanical conversion; the testsuite was a bit trickier, but the previous cleanup patch minimized the churn here. The visit_complete() function may be called at most once; doing so lets us use transfer semantics rather than duplication or ref-count semantics to get the just-built output back to the caller, even though it means our behavior is not idempotent. Generated code is simplified as follows for events: |@@ -26,7 +26,7 @@ void qapi_event_send_acpi_device_ost(ACP | QDict *qmp; | Error *err = NULL; | QMPEventFuncEmit emit; |- QmpOutputVisitor *qov; |+ QObject *obj; | Visitor *v; | q_obj_ACPI_DEVICE_OST_arg param = { | info |@@ -39,8 +39,7 @@ void qapi_event_send_acpi_device_ost(ACP | | qmp = qmp_event_build_dict("ACPI_DEVICE_OST"); | |- qov = qmp_output_visitor_new(); |- v = qmp_output_get_visitor(qov); |+ v = qmp_output_visitor_new(&obj); | | visit_start_struct(v, "ACPI_DEVICE_OST", NULL, 0, &err); | if (err) { |@@ -55,7 +54,8 @@ void qapi_event_send_acpi_device_ost(ACP | goto out; | } | |- qdict_put_obj(qmp, "data", qmp_output_get_qobject(qov)); |+ visit_complete(v, &obj); |+ qdict_put_obj(qmp, "data", obj); | emit(QAPI_EVENT_ACPI_DEVICE_OST, qmp, &err); and for commands: | { | Error *err = NULL; |- QmpOutputVisitor *qov = qmp_output_visitor_new(); | Visitor *v; | |- v = qmp_output_get_visitor(qov); |+ v = qmp_output_visitor_new(ret_out); | visit_type_AddfdInfo(v, "unused", &ret_in, &err); |- if (err) { |- goto out; |+ if (!err) { |+ visit_complete(v, ret_out); | } |- *ret_out = qmp_output_get_qobject(qov); |- |-out: | error_propagate(errp, err); Signed-off-by: Eric Blake Message-Id: <1465490926-28625-13-git-send-email-eblake@redhat.com> Reviewed-by: Markus Armbruster Signed-off-by: Markus Armbruster --- qom/object.c | 28 ++++++++++++---------------- qom/qom-qobject.c | 10 +++++----- 2 files changed, 17 insertions(+), 21 deletions(-) (limited to 'qom') diff --git a/qom/object.c b/qom/object.c index 2407b667d9..8166b7dace 100644 --- a/qom/object.c +++ b/qom/object.c @@ -1221,7 +1221,6 @@ int object_property_get_enum(Object *obj, const char *name, const char *typename, Error **errp) { Error *err = NULL; - StringOutputVisitor *sov; Visitor *v; char *str; int ret; @@ -1241,15 +1240,14 @@ int object_property_get_enum(Object *obj, const char *name, enumprop = prop->opaque; - sov = string_output_visitor_new(false); - v = string_output_get_visitor(sov); + v = string_output_visitor_new(false, &str); object_property_get(obj, v, name, &err); if (err) { error_propagate(errp, err); visit_free(v); return 0; } - str = string_output_get_string(sov); + visit_complete(v, &str); visit_free(v); v = string_input_visitor_new(str); visit_type_enum(v, name, &ret, enumprop->strings, errp); @@ -1264,25 +1262,23 @@ void object_property_get_uint16List(Object *obj, const char *name, uint16List **list, Error **errp) { Error *err = NULL; - StringOutputVisitor *ov; Visitor *v; char *str; - ov = string_output_visitor_new(false); - object_property_get(obj, string_output_get_visitor(ov), - name, &err); + v = string_output_visitor_new(false, &str); + object_property_get(obj, v, name, &err); if (err) { error_propagate(errp, err); goto out; } - str = string_output_get_string(ov); + visit_complete(v, &str); + visit_free(v); v = string_input_visitor_new(str); visit_type_uint16List(v, NULL, list, errp); g_free(str); - visit_free(v); out: - visit_free(string_output_get_visitor(ov)); + visit_free(v); } void object_property_parse(Object *obj, const char *string, @@ -1296,21 +1292,21 @@ void object_property_parse(Object *obj, const char *string, char *object_property_print(Object *obj, const char *name, bool human, Error **errp) { - StringOutputVisitor *sov; + Visitor *v; char *string = NULL; Error *local_err = NULL; - sov = string_output_visitor_new(human); - object_property_get(obj, string_output_get_visitor(sov), name, &local_err); + v = string_output_visitor_new(human, &string); + object_property_get(obj, v, name, &local_err); if (local_err) { error_propagate(errp, local_err); goto out; } - string = string_output_get_string(sov); + visit_complete(v, &string); out: - visit_free(string_output_get_visitor(sov)); + visit_free(v); return string; } diff --git a/qom/qom-qobject.c b/qom/qom-qobject.c index 6714565f13..c225abcbad 100644 --- a/qom/qom-qobject.c +++ b/qom/qom-qobject.c @@ -33,14 +33,14 @@ QObject *object_property_get_qobject(Object *obj, const char *name, { QObject *ret = NULL; Error *local_err = NULL; - QmpOutputVisitor *qov; + Visitor *v; - qov = qmp_output_visitor_new(); - object_property_get(obj, qmp_output_get_visitor(qov), name, &local_err); + v = qmp_output_visitor_new(&ret); + object_property_get(obj, v, name, &local_err); if (!local_err) { - ret = qmp_output_get_qobject(qov); + visit_complete(v, &ret); } error_propagate(errp, local_err); - visit_free(qmp_output_get_visitor(qov)); + visit_free(v); return ret; } -- cgit v1.2.3