Use a response callback instead

tests/unit/legacy/api/xmlrpc/test_xmlrpc.py

@@ -812,8 +812,18 @@ def test_multicall(self, monkeypatch):
         body = pretend.stub()
         response = pretend.stub(body=body)
 
-        invoke_subrequest = pretend.call_recorder(lambda *a, **kw: response)
-        request = pretend.stub(invoke_subrequest=invoke_subrequest)
+        request = pretend.stub(
+            invoke_subrequest=pretend.call_recorder(lambda *a, **kw: response),
+            add_response_callback=pretend.call_recorder(
+                lambda *a, **kw: response),
+        )
+
+        callback = pretend.stub()
+        monkeypatch.setattr(
+            xmlrpc,
+            'response_callback',
+            pretend.call_recorder(lambda metric_name: callback)
+        )
 
         args = [
             {'methodName': 'search', 'params': [{'name': 'foo'}]},
@@ -827,10 +837,13 @@ def test_multicall(self, monkeypatch):
             pretend.call('/RPC2', headers={'Content-Type': 'text/xml'}),
             pretend.call('/RPC2', headers={'Content-Type': 'text/xml'}),
         ]
-        assert invoke_subrequest.calls == [
+        assert request.invoke_subrequest.calls == [
             pretend.call(subreq, use_tweens=True),
             pretend.call(subreq, use_tweens=True),
         ]
+        assert request.add_response_callback.calls == [
+            pretend.call(callback),
+        ]
         assert dumps.calls == [
             pretend.call(({'name': 'foo'},), methodname='search'),
             pretend.call(({'classifiers': ['bar']},), methodname='browse'),
@@ -869,3 +882,22 @@ def test_too_many_multicalls_method(self):
         assert exc.value.faultString == (
             'ValueError: Multicall limit is 20 calls'
         )
+
+    def test_response_callback(self):
+        metric_name = 'some_metric_name'
+        callback = xmlrpc.response_callback(metric_name)
+
+        request = pretend.stub(
+            registry=pretend.stub(
+                datadog=pretend.stub(
+                    histogram=pretend.call_recorder(lambda *a: None)
+                )
+            )
+        )
+        response = pretend.stub(content_length=pretend.stub())
+
+        callback(request, response)
+
+        assert request.registry.datadog.histogram.calls == [
+            pretend.call(metric_name, response.content_length),
+        ]

tests/unit/test_config.py

@@ -402,7 +402,6 @@ def __init__(self):
             pretend.call("pyramid_retry"),
             pretend.call("pyramid_tm"),
             pretend.call("pyramid_services"),
-            pretend.call(".legacy.api.xmlrpc"),
             pretend.call(".legacy.api.xmlrpc.cache"),
             pretend.call("pyramid_rpc.xmlrpc"),
             pretend.call(".legacy.action_routing"),

warehouse/config.py

@@ -377,9 +377,6 @@ def configure(settings=None):
     # Register support for services
     config.include("pyramid_services")
 
-    # Register our XMLRPC API
-    config.include(".legacy.api.xmlrpc")
-
     # Register our XMLRPC cache
     config.include(".legacy.api.xmlrpc.cache")
 

warehouse/legacy/api/xmlrpc/__init__.py

@@ -10,21 +10,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from pyramid.events import NewResponse
-
 import warehouse.legacy.api.xmlrpc.views  # noqa
-
-
-def on_new_response(new_response_event):
-    request = new_response_event.request
-    if not hasattr(request, 'content_length_metric_name'):
-        return
-
-    request.registry.datadog.histogram(
-        request.content_length_metric_name,
-        new_response_event.response.content_length
-    )
-
-
-def includeme(config):
-    config.add_subscriber(on_new_response, NewResponse)

warehouse/legacy/api/xmlrpc/views.py

@@ -448,12 +448,18 @@ def browse(request, classifiers):
     return [(r.name, r.version) for r in releases]
 
 
+def response_callback(metric_name):
+
+    def _callback(request, response):
+        request.registry.datadog.histogram(
+            metric_name, response.content_length
+        )
+
+    return _callback
+
+
 @xmlrpc_method(method='system.multicall')
 def multicall(request, args):
-    request.content_length_metric_name = (
-        'warehouse.xmlrpc.system.multicall.content_length'
-    )
-
     if any(arg.get('methodName') == 'system.multicall' for arg in args):
         raise XMLRPCWrappedError(
             ValueError('Cannot use system.multicall inside a multicall')
@@ -478,4 +484,9 @@ def multicall(request, args):
         ).encode()
         response = request.invoke_subrequest(subreq, use_tweens=True)
         responses.append(xmlrpc.client.loads(response.body))
+
+    request.add_response_callback(
+        response_callback('warehouse.xmlrpc.system.multicall.content_length')
+    )
+
     return responses