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https://gitlab.com/qemu-project/qemu
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3b098d5697
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 <eblake@redhat.com>
Message-Id: <1465490926-28625-13-git-send-email-eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
73 lines
1.6 KiB
C
73 lines
1.6 KiB
C
/*
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* QNull unit-tests.
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*
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* Copyright (C) 2016 Red Hat Inc.
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*
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* This work is licensed under the terms of the GNU LGPL, version 2.1 or later.
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* See the COPYING.LIB file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qapi/qmp/qobject.h"
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#include "qemu-common.h"
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#include "qapi/qmp-input-visitor.h"
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#include "qapi/qmp-output-visitor.h"
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#include "qapi/error.h"
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/*
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* Public Interface test-cases
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*
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* (with some violations to access 'private' data)
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*/
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static void qnull_ref_test(void)
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{
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QObject *obj;
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g_assert(qnull_.refcnt == 1);
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obj = qnull();
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g_assert(obj);
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g_assert(obj == &qnull_);
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g_assert(qnull_.refcnt == 2);
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g_assert(qobject_type(obj) == QTYPE_QNULL);
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qobject_decref(obj);
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g_assert(qnull_.refcnt == 1);
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}
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static void qnull_visit_test(void)
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{
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QObject *obj;
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Visitor *v;
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/*
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* Most tests of interactions between QObject and visitors are in
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* test-qmp-*-visitor; but these tests live here because they
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* depend on layering violations to check qnull_ refcnt.
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*/
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g_assert(qnull_.refcnt == 1);
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obj = qnull();
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v = qmp_input_visitor_new(obj, true);
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qobject_decref(obj);
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visit_type_null(v, NULL, &error_abort);
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visit_free(v);
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v = qmp_output_visitor_new(&obj);
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visit_type_null(v, NULL, &error_abort);
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visit_complete(v, &obj);
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g_assert(obj == &qnull_);
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qobject_decref(obj);
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visit_free(v);
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g_assert(qnull_.refcnt == 1);
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}
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int main(int argc, char **argv)
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{
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g_test_init(&argc, &argv, NULL);
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g_test_add_func("/public/qnull_ref", qnull_ref_test);
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g_test_add_func("/public/qnull_visit", qnull_visit_test);
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return g_test_run();
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}
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