qemu/scripts
Eric Blake 3b098d5697 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 <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>
2016-07-06 10:52:04 +02:00
..
coccinelle coccinelle: Remove unnecessary variables for function return value 2016-06-20 16:38:13 +02:00
kvm kvm_stat: Remove 2016-05-29 09:11:10 +02:00
qemu-guest-agent qemu-ga: sample fsfreeze hooks 2013-01-08 16:38:12 -06:00
qemugdb scripts/gdb: Fix a python exception in mtree.py 2015-12-22 16:01:08 +08:00
qmp qmp-shell: fix pretty printing of JSON responses 2016-03-04 17:16:32 +01:00
tracetool qemu-common: push cpu.h inclusion out of qemu-common.h 2016-05-19 16:42:29 +02:00
analyse-9p-simpletrace.py scripts/analyse-9p-simpletrace.py: Add symbolic names for 9p operations. 2011-12-21 12:37:23 +05:30
analyze-inclusions scripts: add script to build QEMU and analyze inclusions 2016-05-19 12:09:28 +02:00
analyze-migration.py migration: fix analyze-migration.py script 2015-11-04 13:40:13 +01:00
check-qerror.sh qerror: add check-qerror.sh to verify alphabetical order 2012-01-18 10:23:39 -02:00
checkpatch.pl checkpatch: There is no qemu_strtod() 2016-06-30 15:24:36 +02:00
clean-includes os-posix: include sys/mman.h 2016-06-16 18:39:03 +02:00
cleanup-trace-events.pl cleanup-trace-events.pl: Tighten search for trace event call 2014-09-26 09:34:38 +01:00
cocci-macro-file.h coccinelle: add g_assert_cmp* to macro file 2016-05-23 16:53:46 +02:00
coverity-model.c coverity: Model g_memdup() 2015-12-17 17:33:49 +01:00
create_config * max-ram-below-4g improvement (Gerd) 2016-06-08 14:45:28 +01:00
disas-objdump.pl disas-objdump: Pass --adjust-vma to objdump 2013-08-24 07:26:45 +02:00
dump-guest-memory.py exec: hide mr->ram_addr from qemu_get_ram_ptr users 2016-05-29 09:11:12 +02:00
extract-vsssdk-headers Add a script to extract VSS SDK headers on POSIX system 2013-09-09 14:17:56 -05:00
feature_to_c.sh scripts: Use $(..) instead of deprecated `..` 2016-06-07 18:19:23 +03:00
get_maintainer.pl get_maintainer.pl: fall back to git if only lists are found 2016-02-09 17:07:55 +01:00
gtester-cat test makefile overhaul 2012-03-30 08:14:11 -05:00
hxtool vl.c: In qemu -h output, only print options for the arch we are running as 2011-12-19 10:27:33 -06:00
make-release make-release: Record SeaBIOS version 2014-03-31 15:02:04 +01:00
make_device_config.sh scripts: Use $(..) instead of deprecated `..` 2016-06-07 18:19:23 +03:00
ordereddict.py qapi: Clean up qapi.py per pep8 2015-10-12 18:44:54 +02:00
qapi-commands.py qapi: Add new visit_complete() function 2016-07-06 10:52:04 +02:00
qapi-event.py qapi: Add new visit_complete() function 2016-07-06 10:52:04 +02:00
qapi-introspect.py qapi: Clean up includes in generated files 2016-02-16 14:29:27 +00:00
qapi-types.py qapi: Add new visit_free() function 2016-07-06 10:52:04 +02:00
qapi-visit.py qapi: Add parameter to visit_end_* 2016-07-06 10:52:04 +02:00
qapi.py qapi: Use anonymous bases in QMP flat unions 2016-03-18 10:29:26 +01:00
qemu-binfmt-conf.sh scripts: Use $(..) instead of deprecated `..` 2016-06-07 18:19:23 +03:00
qemu-gdb.py gdb command: qemu handlers 2015-10-29 17:59:27 +00:00
qtest.py qtest: Add scripts/qtest.py 2015-02-16 15:07:18 +00:00
refresh-pxe-roms.sh roms: rewrite scripts/refresh-pxe-roms.sh 2013-09-30 09:44:35 +02:00
shaderinclude.pl opengl: add shader build infrastructure 2015-05-05 09:03:32 +02:00
signrom.py scripts/signrom.py: Check for magic in option ROMs. 2016-05-23 16:53:45 +02:00
simpletrace.py simpletrace: add simpletrace.py --no-header option 2014-08-12 14:26:11 +01:00
switch-timer-api misc: Fix case Qemu -> QEMU 2014-02-15 16:10:25 +04:00
texi2pod.pl scripts/text2pod.pl: Escape left brace 2015-11-02 14:50:27 +01:00
tracetool.py Revert "tracetool: use Python 2.4-compatible exception handling syntax" 2016-02-08 17:29:54 +01:00
update-linux-headers.sh scripts: Use $(..) instead of deprecated `..` 2016-06-07 18:19:23 +03:00
vmstate-static-checker.py vmstate-static-checker: fix size mismatch detection in unused fields 2016-06-17 18:24:33 +05:30