[Qemu-devel] [PATCH v4 05/10] qapi: Utilize implicit struct visits

[Eric Blake]

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, such as:

|@@ -381,6 +293,9 @@ void qapi_event_send_block_job_error(con
|     QmpOutputVisitor *qov;
|     Visitor *v;
|     QObject *obj;
|+    _obj_BLOCK_JOB_ERROR_arg qapi = {
|+        (char *)device, operation, action
|+    };
|
|     emit = qmp_event_get_func_emit();
|     if (!emit) {
|@@ -396,19 +311,7 @@ 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__obj_BLOCK_JOB_ERROR_arg_members(v, &qapi, &err);
|     visit_end_struct(v, err ? NULL : &err);

And command marshalling generates call arguments from a stack-allocated
struct:

|@@ -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;
|-        }
|+    _obj_add_fd_arg qapi = {0};
|+
|+    v = qmp_input_get_visitor(qiv);
|+    visit_type__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__obj_add_fd_arg_members(v, &qapi, NULL);
|     qapi_dealloc_visitor_cleanup(qdv);
| }

Signed-off-by: Eric Blake <address@hidden>

---
v4: new patch
---
 scripts/qapi.py          | 25 +++++++++++++++++++++++++
 scripts/qapi-commands.py | 28 ++++++++++++----------------
 scripts/qapi-event.py    | 16 +++++++---------
 3 files changed, 44 insertions(+), 25 deletions(-)

diff --git a/scripts/qapi.py b/scripts/qapi.py
index 6cf0a75..797ac7a 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1640,6 +1640,7 @@ extern const char *const %(c_name)s_lookup[];
     return ret


+# Explode arg_type into a parameter list, along with extra parameters
 def gen_params(arg_type, extra):
     if not arg_type:
         return extra
@@ -1657,6 +1658,30 @@ def gen_params(arg_type, extra):
     return ret


+# Declare and initialize an object 'qapi' using parameters from gen_params()
+def gen_struct_init(typ):
+    assert not typ.variants
+    ret = mcgen('''
+    %(c_name)s qapi = {
+''',
+                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_err_check(label='out', skiperr=False):
     if skiperr:
         return ''
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 c03cb78..627e9a0 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -44,8 +44,8 @@ def gen_event_send(name, arg_type):
     QmpOutputVisitor *qov;
     Visitor *v;
     QObject *obj;
-
 ''')
+        ret += gen_struct_init(arg_type) + '\n'

     ret += mcgen('''
     emit = qmp_event_get_func_emit();
@@ -65,13 +65,10 @@ def gen_event_send(name, arg_type):
     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, &qapi, &err);
     visit_end_struct(v, err ? NULL : &err);
     if (err) {
         goto out;
@@ -81,7 +78,8 @@ out_obj:
     g_assert(obj);

     qdict_put_obj(qmp, "data", obj);
-''')
+''',
+                     name=name, c_name=arg_type.c_name())

     ret += mcgen('''
     emit(%(c_enum)s, qmp, &err);
-- 
2.5.0