Add metrics for multicall response size

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

@@ -0,0 +1,48 @@
+import pretend
+from pyramid.events import NewResponse
+
+from warehouse.legacy.api.xmlrpc import on_new_response, includeme
+
+
+def test_on_new_response_enabled():
+    metric_name = pretend.stub()
+    histogram = pretend.call_recorder(lambda metric_name, value: None)
+    content_length = pretend.stub()
+    new_response_event = pretend.stub(
+        request=pretend.stub(
+            content_length_metric_name=metric_name,
+            registry=pretend.stub(datadog=pretend.stub(histogram=histogram)),
+        ),
+        response=pretend.stub(content_length=content_length)
+    )
+
+    on_new_response(new_response_event)
+
+    assert histogram.calls == [
+        pretend.call(metric_name, content_length),
+    ]
+
+
+def test_on_new_response_disabled():
+    histogram = pretend.call_recorder(lambda metric_name, value: None)
+    new_response_event = pretend.stub(
+        request=pretend.stub(
+            registry=pretend.stub(datadog=pretend.stub(histogram=histogram)),
+        ),
+    )
+
+    on_new_response(new_response_event)
+
+    assert histogram.calls == []
+
+
+def test_includeme():
+    config = pretend.stub(
+        add_subscriber=pretend.call_recorder(lambda subscriber, iface: None),
+    )
+
+    includeme(config)
+
+    assert config.add_subscriber.calls == [
+        pretend.call(on_new_response, NewResponse),
+    ]

tests/unit/test_config.py

@@ -402,6 +402,7 @@ 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

@@ -377,6 +377,9 @@ 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

@@ -10,4 +10,21 @@
 # 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

@@ -450,6 +450,10 @@ def browse(request, classifiers):
 
 @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')