Allow creation of a 'subspace' within a Metrics object, returning another one

synapse/metrics/__init__.py

@@ -41,6 +41,9 @@ class Metrics(object):
     def __init__(self, name):
         self.name_prefix = name
 
+    def make_subspace(self, name):
+        return Metrics("%s_%s" % (self.name_prefix, name))
+
     def register_collector(self, func):
         all_collectors.append(func)