From a95291007b2478fcf32a2d71bf133b688bb4b675 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Tue, 18 Dec 2018 19:22:21 +0100 Subject: qapi: Eliminate indirection through qmp_event_get_func_emit() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The qapi_event_send_FOO() functions emit events like this: QMPEventFuncEmit emit; emit = qmp_event_get_func_emit(); if (!emit) { return; } qmp = qmp_event_build_dict("FOO"); [put event arguments into @qmp...] emit(QAPI_EVENT_FOO, qmp); The value of qmp_event_get_func_emit() depends only on the program: * In qemu-system-FOO, it's always monitor_qapi_event_queue. * In tests/test-qmp-event, it's always event_test_emit. * In all other programs, it's always null. This is exactly the kind of dependence the linker is supposed to resolve; we don't actually need an indirection. Note that things would fall apart if we linked more than one QAPI schema into a single program: each set of qapi_event_send_FOO() uses its own event enumeration, yet they share a single emit function. Which takes the event enumeration as an argument. Which one if there's more than one? More seriously: how does this work even now? qemu-system-FOO wants QAPIEvent, and passes a function taking that to qmp_event_set_func_emit(). test-qmp-event wants test_QAPIEvent, and passes a function taking that to qmp_event_set_func_emit(). It works by type trickery, of course: typedef void (*QMPEventFuncEmit)(unsigned event, QDict *dict); void qmp_event_set_func_emit(QMPEventFuncEmit emit); QMPEventFuncEmit qmp_event_get_func_emit(void); We use unsigned instead of the enumeration type. Relies on both enumerations boiling down to unsigned, which happens to be true for the compilers we use. Clean this up as follows: * Generate qapi_event_send_FOO() that call PREFIX_qapi_event_emit() instead of the value of qmp_event_set_func_emit(). * Generate a prototype for PREFIX_qapi_event_emit() into qapi-events.h. * PREFIX_ is empty for qapi/qapi-schema.json, and test_ for tests/qapi-schema/qapi-schema-test.json. It's qga_ for qga/qapi-schema.json, and doc-good- for tests/qapi-schema/doc-good.json, but those don't define any events. * Rename monitor_qapi_event_queue() to qapi_event_emit() instead of passing it to qmp_event_set_func_emit(). This takes care of qemu-system-FOO. * Rename event_test_emit() to test_qapi_event_emit() instead of passing it to qmp_event_set_func_emit(). This takes care of tests/test-qmp-event. * Add a qapi_event_emit() that does nothing to stubs/monitor.c. This takes care of all other programs that link code emitting QMP events. * Drop qmp_event_set_func_emit(), qmp_event_get_func_emit(). Signed-off-by: Markus Armbruster Message-Id: <20181218182234.28876-3-armbru@redhat.com> Reviewed-by: Marc-André Lureau [Commit message typos fixed] --- scripts/qapi/events.py | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'scripts') diff --git a/scripts/qapi/events.py b/scripts/qapi/events.py index 37ee5de..d86a2d2 100644 --- a/scripts/qapi/events.py +++ b/scripts/qapi/events.py @@ -58,7 +58,7 @@ def gen_param_var(typ): return ret -def gen_event_send(name, arg_type, boxed, event_enum_name): +def gen_event_send(name, arg_type, boxed, event_enum_name, event_emit): # 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 @@ -70,7 +70,6 @@ def gen_event_send(name, arg_type, boxed, event_enum_name): %(proto)s { QDict *qmp; - QMPEventFuncEmit emit; ''', proto=build_event_send_proto(name, arg_type, boxed)) @@ -86,11 +85,6 @@ def gen_event_send(name, arg_type, boxed, event_enum_name): ret += mcgen(''' - emit = qmp_event_get_func_emit(); - if (!emit) { - return; - } - qmp = qmp_event_build_dict("%(name)s"); ''', @@ -121,9 +115,10 @@ def gen_event_send(name, arg_type, boxed, event_enum_name): ''') ret += mcgen(''' - emit(%(c_enum)s, qmp); + %(event_emit)s(%(c_enum)s, qmp); ''', + event_emit=event_emit, c_enum=c_enum_const(event_enum_name, name)) if arg_type and not arg_type.is_empty(): @@ -145,6 +140,7 @@ class QAPISchemaGenEventVisitor(QAPISchemaModularCVisitor): ' * Schema-defined QAPI/QMP events', __doc__) self._event_enum_name = c_name(prefix + 'QAPIEvent', protect=False) self._event_enum_members = [] + self._event_emit_name = c_name(prefix + 'qapi_event_emit') def _begin_module(self, name): types = self._module_basename('qapi-types', name) @@ -170,15 +166,23 @@ class QAPISchemaGenEventVisitor(QAPISchemaModularCVisitor): def visit_end(self): (genc, genh) = self._module[self._main_module] - genh.add(gen_enum(self._event_enum_name, self._event_enum_members)) + genh.add(gen_enum(self._event_enum_name, + self._event_enum_members)) genc.add(gen_enum_lookup(self._event_enum_name, self._event_enum_members)) + genh.add(mcgen(''' + +void %(event_emit)s(%(event_enum)s event, QDict *qdict); +''', + event_emit=self._event_emit_name, + event_enum=self._event_enum_name)) def visit_event(self, name, info, ifcond, arg_type, boxed): with ifcontext(ifcond, self._genh, self._genc): self._genh.add(gen_event_send_decl(name, arg_type, boxed)) self._genc.add(gen_event_send(name, arg_type, boxed, - self._event_enum_name)) + self._event_enum_name, + self._event_emit_name)) self._event_enum_members.append(QAPISchemaMember(name, ifcond)) -- cgit v1.1