[Qemu-devel] [PATCH RFC v3 32/32] qapi-introspect: Hide type names

[Markus Armbruster <armbru@redhat.com>]

To eliminate the temptation for clients to look up types by name
(which are not ABI), replace all type names by meaningless strings.

Reduces output of query-schema by 13 out of 85KiB.

TODO Either generate comments with the true type names, or provide an
option to generate without type name hiding.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 docs/qapi-code-gen.txt     | 14 +++++++-------
 scripts/qapi-introspect.py | 24 +++++++++++++++++++++---
 2 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index ed04770..3a78cf4 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -868,13 +868,13 @@ Example:
 [Uninteresting stuff omitted...]
 
     const char example_qmp_schema_json[] = "["
-        "{ \"arg-type\": \":empty\", \"name\": \"MY_EVENT\", \"meta-type\": \"event\" }, "
-        "{ \"meta-type\": \"builtin\", \"name\": \"int\", \"json-type\": \"int\" }, "
-        "{ \"meta-type\": \"builtin\", \"name\": \"str\", \"json-type\": \"string\" }, "
-        "{ \"meta-type\": \"object\", \"name\": \":empty\", \"members\": [ ] }, "
-        "{ \"meta-type\": \"object\", \"name\": \":obj-my-command-arg\", \"members\": [{ \"type\": \"UserDefOne\", \"name\": \"arg1\" } ] }, "
-        "{ \"meta-type\": \"object\", \"name\": \"UserDefOne\", \"members\": [{ \"type\": \"int\", \"name\": \"integer\" }, { \"type\": \"str\", \"name\": \"string\" } ] }, "
-        "{ \"arg-type\": \":obj-my-command-arg\", \"ret-type\": \"UserDefOne\", \"name\": \"my-command\", \"meta-type\": \"command\" } ]";
+        "{ \"arg-type\": \"0\", \"meta-type\": \"event\", \"name\": \"MY_EVENT\" }, "
+        "{ \"arg-type\": \"1\", \"meta-type\": \"command\", \"name\": \"my-command\", \"ret-type\": \"2\" }, "
+        "{ \"members\": [ ], \"meta-type\": \"object\", \"name\": \"0\" }, "
+        "{ \"members\": [{ \"name\": \"arg1\", \"type\": \"2\" } ], \"meta-type\": \"object\", \"name\": \"1\" }, "
+        "{ \"members\": [{ \"name\": \"integer\", \"type\": \"int\" }, { \"name\": \"string\", \"type\": \"str\" } ], \"meta-type\": \"object\", \"name\": \"2\" }, "
+        "{ \"json-type\": \"int\", \"meta-type\": \"builtin\", \"name\": \"int\" }, "
+        "{ \"json-type\": \"string\", \"meta-type\": \"builtin\", \"name\": \"str\" } ]";
     $ cat qapi-generated/example-qmp-introspect.h
 [Uninteresting stuff omitted...]
 
diff --git a/scripts/qapi-introspect.py b/scripts/qapi-introspect.py
index 05d30e5..5e99d4b 100644
--- a/scripts/qapi-introspect.py
+++ b/scripts/qapi-introspect.py
@@ -42,25 +42,29 @@ class QAPISchemaGenIntrospectVisitor(QAPISchemaVisitor):
         self.schema = None
         self.jsons = None
         self.used_types = None
+        self.name_map = None
 
     def visit_begin(self, schema):
         self.schema = schema
         self.jsons = []
         self.used_types = []
+        self.name_map = {}
         return QAPISchemaType   # don't visit types for now
 
     def visit_end(self):
         # visit the types that are actually used
+        jsons = self.jsons
+        self.jsons = []
         for typ in self.used_types:
             typ.visit(self)
-        self.jsons.sort()
         # generate C
+        jsons.extend(self.jsons)
         name = prefix + 'qmp_schema_json'
         self.decl = mcgen('''
 extern const char %(c_name)s[];
 ''',
                           c_name=c_name(name))
-        lines = to_json(self.jsons).split('\n')
+        lines = to_json(jsons).split('\n')
         c_string = '\n    '.join([to_c_string(line) for line in lines])
         self.defn = mcgen('''
 const char %(c_name)s[] = %(c_string)s;
@@ -70,6 +74,13 @@ const char %(c_name)s[] = %(c_string)s;
         self.schema = None
         self.jsons = None
         self.used_types = None
+        self.name_map = None
+
+    def _name(self, name):
+        if name not in self.name_map:
+            n = len(self.name_map)
+            self.name_map[name] = '%s' % n
+        return self.name_map[name]
 
     def _use_type(self, typ):
         # Map the various integer types to plain int
@@ -81,9 +92,16 @@ const char %(c_name)s[] = %(c_string)s;
         # Add type to work queue if new
         if typ not in self.used_types:
             self.used_types.append(typ)
-        return typ.name
+        # Clients should examine commands and events, not types.  Hide
+        # type names to reduce the temptation.  Also saves a few
+        # characters.
+        if isinstance(typ, QAPISchemaBuiltinType):
+            return typ.name
+        return self._name(typ.name)
 
     def _gen_json(self, name, mtype, obj={}):
+        if mtype != 'command' and mtype != 'event' and mtype != 'builtin':
+            name = self._name(name)
         obj['name'] = name
         obj['meta-type'] = mtype
         self.jsons.append(obj)
-- 
2.4.3