Made restricted registries call collect() only on relevant collections.

prometheus_client/registry.py

@@ -135,10 +135,20 @@ def __init__(self, names, registry):
         self._registry = registry
 
     def collect(self):
-        for metric in self._registry.collect():
-            m = metric._restricted_metric(self._name_set)
-            if m:
-                yield m
+        names = copy.copy(self._name_set)
+        collectors = set()
+        with self._registry._lock:
+            if 'target_info' in names and self._registry._target_info:
+                yield self._registry._target_info_metric()
+                names.remove('target_info')
+            for name in names:
+                if name in self._registry._names_to_collectors:
+                    collectors.add(self._registry._names_to_collectors[name])
+        for collector in collectors:
+            for metric in collector.collect():
+                m = metric._restricted_metric(self._name_set)
+                if m:
+                    yield m
 
 
 REGISTRY = CollectorRegistry(auto_describe=True)

tests/test_core.py

@@ -2,6 +2,7 @@
 
 from concurrent.futures import ThreadPoolExecutor
 import time
+from unittest.mock import MagicMock
 
 import pytest
 
@@ -838,6 +839,18 @@ def test_target_info_restricted_registry(self):
         m.samples = [Sample('target_info', {'foo': 'bar'}, 1)]
         self.assertEqual([m], list(registry.restricted_registry(['target_info']).collect()))
 
+    def test_restricted_registry_does_not_call_extra(self):
+        registry = CollectorRegistry()
+        mock_collector = MagicMock()
+        mock_collector.describe.return_value = [Metric('foo', 'help', 'summary')]
+        registry.register(mock_collector)
+        Summary('s', 'help', registry=registry).observe(7)
+
+        m = Metric('s', 'help', 'summary')
+        m.samples = [Sample('s_sum', {}, 7)]
+        self.assertEqual([m], list(registry.restricted_registry(['s_sum']).collect()))
+        mock_collector.collect.assert_not_called()
+
 
 if __name__ == '__main__':
     unittest.main()