Increment priority when only sampled is sent in headers

Author: hmstepanek

newrelic/api/transaction.py

@@ -1017,15 +1017,16 @@ def sampling_algo_compute_sampled_and_priority(self, priority, sampled, sampler_
         # or newrelic DT headers and may be overridden in _make_sampling_decision
         # based on the configuration. The only time they are set in here is when the
         # sampling decision must be made by the adaptive sampling algorithm.
+        adjust_priority = priority is None or sampled is None
         if priority is None:
             # Truncate priority field to 6 digits past the decimal.
             priority = float(f"{random.random():.6f}")  # noqa: S311
         if sampled is None:
             _logger.debug("No trusted account id found. Sampling decision will be made by adaptive sampling algorithm.")
             sampled = self._application.compute_sampled(**sampler_kwargs)
+        if adjust_priority and sampled:
             # Increment the priority + 2 for full and + 1 for partial granularity.
-            if sampled:
-                priority += 1 + int(sampler_kwargs.get("full_granularity"))
+            priority += 1 + int(sampler_kwargs.get("full_granularity"))
         return priority, sampled
 
     def _compute_sampled_and_priority(

tests/agent_features/test_distributed_tracing.py

@@ -1451,3 +1451,21 @@ def _test():
         pass
 
     _test()
+
+
+def test_distributed_trace_priority_set_when_only_sampled_set_in_headers(
+    monkeypatch,
+):
+    monkeypatch.setattr(random, 'random', lambda *args, **kwargs: 0.123)
+
+    @override_application_settings(_override_settings)
+    @validate_transaction_object_attributes({"sampled": True, "priority": 2.123})
+    @background_task()
+    def _test():
+        headers = {
+            "traceparent": f"00-0af7651916cd43dd8448eb211c80319c-00f067aa0ba902b7-01",
+            "tracestate": f"1@nr=0-0-1-2827902-0af7651916cd43dd-00f067aa0ba902b7-1--1518469636035"
+        }
+        accept_distributed_trace_headers(headers)
+
+    _test()