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Re: [Qemu-devel] [PATCH v5 07/14] qapi: Utilize implicit struct visits
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH v5 07/14] qapi: Utilize implicit struct visits |
Date: |
Wed, 16 Mar 2016 15:45:08 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Here's how I'd rebase this on the simplified PATCH 06 I just posted as a
reply to yours:
>From e35449172828351f0acd85f236add45d3eb575a7 Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Wed, 9 Mar 2016 17:55:28 -0700
Subject: [PATCH 07/14] qapi: Utilize implicit struct visits
Rather than generate inline per-member visits, take advantage
of the 'visit_type_FOO_members()' function for both event and
command marshalling. This is possible now that implicit
structs can be visited like any other.
Generated code shrinks accordingly; events initialize a struct
based on parameters, through a new gen_param_var() helper, like:
|@@ -338,6 +250,9 @@ void qapi_event_send_block_job_error(con
| QMPEventFuncEmit emit = qmp_event_get_func_emit();
| QmpOutputVisitor *qov;
| Visitor *v;
|+ q_obj_BLOCK_JOB_ERROR_arg param = {
|+ (char *)device, operation, action
|+ };
|
| if (!emit) {
| return;
@@ -351,19 +266,7 @@ void qapi_event_send_block_job_error(con
| if (err) {
| goto out;
| }
|- visit_type_str(v, "device", (char **)&device, &err);
|- if (err) {
|- goto out_obj;
|- }
|- visit_type_IoOperationType(v, "operation", &operation, &err);
|- if (err) {
|- goto out_obj;
|- }
|- visit_type_BlockErrorAction(v, "action", &action, &err);
|- if (err) {
|- goto out_obj;
|- }
|-out_obj:
|+ visit_type_q_obj_BLOCK_JOB_ERROR_arg_members(v, ¶m, &err);
| visit_end_struct(v, err ? NULL : &err);
Notice that the initialization of 'param' has to cast away const
(just as the old gen_visit_members() had to do): we can't change
the signature of the user function (which uses 'const char *'), but
have to assign it to a non-const QAPI object (which requires
'char *').
Likewise, command marshalling generates call arguments from a
stack-allocated struct, rather than a list of local variables:
|@@ -57,26 +57,15 @@ void qmp_marshal_add_fd(QDict *args, QOb
| QmpInputVisitor *qiv = qmp_input_visitor_new_strict(QOBJECT(args));
| QapiDeallocVisitor *qdv;
| Visitor *v;
|- bool has_fdset_id = false;
|- int64_t fdset_id = 0;
|- bool has_opaque = false;
|- char *opaque = NULL;
|-
|- v = qmp_input_get_visitor(qiv);
|- if (visit_optional(v, "fdset-id", &has_fdset_id)) {
|- visit_type_int(v, "fdset-id", &fdset_id, &err);
|- if (err) {
|- goto out;
|- }
|- }
|- if (visit_optional(v, "opaque", &has_opaque)) {
|- visit_type_str(v, "opaque", &opaque, &err);
|- if (err) {
|- goto out;
|- }
|+ q_obj_add_fd_arg qapi = {0};
|+
|+ v = qmp_input_get_visitor(qiv);
|+ visit_type_q_obj_add_fd_arg_members(v, &qapi, &err);
|+ if (err) {
|+ goto out;
| }
|
|- retval = qmp_add_fd(has_fdset_id, fdset_id, has_opaque, opaque, &err);
|+ retval = qmp_add_fd(qapi.has_fdset_id, qapi.fdset_id, qapi.has_opaque,
qapi.opaque, &err);
| if (err) {
| goto out;
| }
|@@ -88,12 +77,7 @@ out:
| qmp_input_visitor_cleanup(qiv);
| qdv = qapi_dealloc_visitor_new();
| v = qapi_dealloc_get_visitor(qdv);
|- if (visit_optional(v, "fdset-id", &has_fdset_id)) {
|- visit_type_int(v, "fdset-id", &fdset_id, NULL);
|- }
|- if (visit_optional(v, "opaque", &has_opaque)) {
|- visit_type_str(v, "opaque", &opaque, NULL);
|- }
|+ visit_type_q_obj_add_fd_arg_members(v, &qapi, NULL);
| qapi_dealloc_visitor_cleanup(qdv);
| }
For the marshaller, it has the nice side effect of eliminating a
chance of collision between argument QMP names and local variables.
A similar collision still exists in the qapi_event_send_FOO().
Document it with a FIXME comment.
This patch also paves the way for some followup simplifications
in the generator, in subsequent patches.
Signed-off-by: Eric Blake <address@hidden>
Message-Id: <address@hidden>
---
scripts/qapi-commands.py | 28 ++++++++++++----------------
scripts/qapi-event.py | 48 ++++++++++++++++++++++++++++++++++++++----------
2 files changed, 50 insertions(+), 26 deletions(-)
diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 3784f33..5ffc381 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -33,8 +33,8 @@ def gen_call(name, arg_type, ret_type):
assert not arg_type.variants
for memb in arg_type.members:
if memb.optional:
- argstr += 'has_%s, ' % c_name(memb.name)
- argstr += '%s, ' % c_name(memb.name)
+ argstr += 'qapi.has_%s, ' % c_name(memb.name)
+ argstr += 'qapi.%s, ' % c_name(memb.name)
lhs = ''
if ret_type:
@@ -71,21 +71,10 @@ def gen_marshal_vars(arg_type, ret_type):
QmpInputVisitor *qiv = qmp_input_visitor_new_strict(QOBJECT(args));
QapiDeallocVisitor *qdv;
Visitor *v;
-''')
+ %(c_name)s qapi = {0};
- for memb in arg_type.members:
- if memb.optional:
- ret += mcgen('''
- bool has_%(c_name)s = false;
''',
- c_name=c_name(memb.name))
- ret += mcgen('''
- %(c_type)s %(c_name)s = %(c_null)s;
-''',
- c_name=c_name(memb.name),
- c_type=memb.type.c_type(),
- c_null=memb.type.c_null())
- ret += '\n'
+ c_name=arg_type.c_name())
else:
ret += mcgen('''
@@ -107,17 +96,24 @@ def gen_marshal_input_visit(arg_type, dealloc=False):
qdv = qapi_dealloc_visitor_new();
v = qapi_dealloc_get_visitor(qdv);
''')
+ errp = 'NULL'
else:
ret += mcgen('''
v = qmp_input_get_visitor(qiv);
''')
+ errp = '&err'
- ret += gen_visit_members(arg_type.members, skiperr=dealloc)
+ ret += mcgen('''
+ visit_type_%(c_name)s_members(v, &qapi, %(errp)s);
+''',
+ c_name=arg_type.c_name(), errp=errp)
if dealloc:
ret += mcgen('''
qapi_dealloc_visitor_cleanup(qdv);
''')
+ else:
+ ret += gen_err_check()
return ret
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 27af206..9b5c5b5 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -28,7 +28,37 @@ def gen_event_send_decl(name, arg_type):
proto=gen_event_send_proto(name, arg_type))
+# Declare and initialize an object 'qapi' using parameters from gen_params()
+def gen_param_var(typ):
+ assert not typ.variants
+ ret = mcgen('''
+ %(c_name)s param = {
+''',
+ c_name=typ.c_name())
+ sep = ' '
+ for memb in typ.members:
+ ret += sep
+ sep = ', '
+ if memb.optional:
+ ret += 'has_' + c_name(memb.name) + sep
+ if memb.type.name == 'str':
+ # Cast away const added in gen_params()
+ ret += '(char *)'
+ ret += c_name(memb.name)
+ ret += mcgen('''
+
+ };
+''')
+ return ret
+
+
def gen_event_send(name, arg_type):
+ # FIXME: Our declaration of local variables (and of 'errp' in the
+ # parameter list) can collide with exploded members of the event's
+ # data type passed in as parameters. If this collision ever hits in
+ # practice, we can rename our local variables with a leading _ prefix,
+ # or split the code into a wrapper function that creates a boxed
+ # 'param' object then calls another to do the real work.
ret = mcgen('''
%(proto)s
@@ -43,10 +73,11 @@ def gen_event_send(name, arg_type):
ret += mcgen('''
QmpOutputVisitor *qov;
Visitor *v;
-
''')
+ ret += gen_param_var(arg_type)
ret += mcgen('''
+
emit = qmp_event_get_func_emit();
if (!emit) {
return;
@@ -58,26 +89,23 @@ def gen_event_send(name, arg_type):
name=name)
if arg_type and arg_type.members:
- assert not arg_type.variants
ret += mcgen('''
qov = qmp_output_visitor_new();
v = qmp_output_get_visitor(qov);
visit_start_struct(v, "%(name)s", NULL, 0, &err);
-''',
- name=name)
- ret += gen_err_check()
- ret += gen_visit_members(arg_type.members, need_cast=True,
- label='out_obj')
- ret += mcgen('''
-out_obj:
+ if (err) {
+ goto out;
+ }
+ visit_type_%(c_name)s_members(v, ¶m, &err);
visit_end_struct(v, err ? NULL : &err);
if (err) {
goto out;
}
qdict_put_obj(qmp, "data", qmp_output_get_qobject(qov));
-''')
+''',
+ name=name, c_name=arg_type.c_name())
ret += mcgen('''
emit(%(c_enum)s, qmp, &err);
--
2.4.3
- [Qemu-devel] [PATCH v5 03/14] qapi: Make c_type() more OO-like, (continued)
- [Qemu-devel] [PATCH v5 03/14] qapi: Make c_type() more OO-like, Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 08/14] qapi-commands: Inline single-use helpers of gen_marshal(), Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 10/14] qapi: Drop unused c_null(), Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 06/14] qapi-event: Slightly shrink generated code, Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 07/14] qapi: Utilize implicit struct visits, Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 12/14] qapi: Make BlockdevOptions doc example closer to reality, Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 09/14] qapi: Inline gen_visit_members() into lone caller, Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 05/14] qapi: Emit implicit structs in generated C, Eric Blake, 2016/03/09
- [Qemu-devel] [PATCH v5 04/14] qapi: Adjust names of implicit types, Eric Blake, 2016/03/09
[Qemu-devel] [PATCH v5 13/14] qapi: Allow anonymous base for flat union, Eric Blake, 2016/03/09