do not override if using parent sampled

Author: sentrivana

sentry_sdk/integrations/opentelemetry/sampler.py

@@ -50,31 +50,33 @@ def get_parent_sampled(parent_context, trace_id):
     return None
 
 
+def _update_sample_rate(sample_rate: float, trace_state: TraceState) -> TraceState:
+    if TRACESTATE_SAMPLE_RATE_KEY in trace_state:
+        trace_state = trace_state.update(TRACESTATE_SAMPLE_RATE_KEY, str(sample_rate))
+    else:
+        trace_state = trace_state.add(TRACESTATE_SAMPLE_RATE_KEY, str(sample_rate))
+
+    return trace_state
+
+
 def dropped_result(parent_span_context, attributes, sample_rate=None):
     # type: (SpanContext, Attributes, Optional[float]) -> SamplingResult
     # these will only be added the first time in a root span sampling decision
+    # if sample_rate is provided, it'll be updated in trace state
     trace_state = parent_span_context.trace_state
 
     if TRACESTATE_SAMPLED_KEY not in trace_state:
         trace_state = trace_state.add(TRACESTATE_SAMPLED_KEY, "false")
     elif trace_state.get(TRACESTATE_SAMPLED_KEY) == "deferred":
         trace_state = trace_state.update(TRACESTATE_SAMPLED_KEY, "false")
 
+    if sample_rate is not None:
+        trace_state = _update_sample_rate(sample_rate, trace_state)
+
     is_root_span = not (
         parent_span_context.is_valid and not parent_span_context.is_remote
     )
     if is_root_span:
-        # Update the sample rate in the trace state
-        if sample_rate is not None:
-            if TRACESTATE_SAMPLE_RATE_KEY in trace_state:
-                trace_state = trace_state.update(
-                    TRACESTATE_SAMPLE_RATE_KEY, str(sample_rate)
-                )
-            else:
-                trace_state = trace_state.add(
-                    TRACESTATE_SAMPLE_RATE_KEY, str(sample_rate)
-                )
-
         # Tell Sentry why we dropped the transaction/root-span
         client = sentry_sdk.get_client()
         if client.monitor and client.monitor.downsample_factor > 0:
@@ -96,19 +98,18 @@ def dropped_result(parent_span_context, attributes, sample_rate=None):
 
 
 def sampled_result(span_context, attributes, sample_rate):
-    # type: (SpanContext, Attributes, float) -> SamplingResult
+    # type: (SpanContext, Attributes, Optional[float]) -> SamplingResult
     # these will only be added the first time in a root span sampling decision
+    # if sample_rate is provided, it'll be updated in trace state
     trace_state = span_context.trace_state
 
     if TRACESTATE_SAMPLED_KEY not in trace_state:
         trace_state = trace_state.add(TRACESTATE_SAMPLED_KEY, "true")
     elif trace_state.get(TRACESTATE_SAMPLED_KEY) == "deferred":
         trace_state = trace_state.update(TRACESTATE_SAMPLED_KEY, "true")
 
-    if TRACESTATE_SAMPLE_RATE_KEY in trace_state:
-        trace_state = trace_state.update(TRACESTATE_SAMPLE_RATE_KEY, str(sample_rate))
-    else:
-        trace_state = trace_state.add(TRACESTATE_SAMPLE_RATE_KEY, str(sample_rate))
+    if sample_rate is not None:
+        trace_state = _update_sample_rate(sample_rate, trace_state)
 
     return SamplingResult(
         Decision.RECORD_AND_SAMPLE,
@@ -152,9 +153,13 @@ def should_sample(
             if is_root_span:
                 sample_rate = float(custom_sampled)
                 if sample_rate > 0:
-                    return sampled_result(parent_span_context, attributes, sample_rate)
+                    return sampled_result(
+                        parent_span_context, attributes, sample_rate=sample_rate
+                    )
                 else:
-                    return dropped_result(parent_span_context, attributes, sample_rate)
+                    return dropped_result(
+                        parent_span_context, attributes, sample_rate=sample_rate
+                    )
             else:
                 logger.debug(
                     f"[Tracing] Ignoring sampled param for non-root span {name}"
@@ -163,6 +168,7 @@ def should_sample(
         # Check if there is a traces_sampler
         # Traces_sampler is responsible to check parent sampled to have full transactions.
         has_traces_sampler = callable(client.options.get("traces_sampler"))
+        inherited_parent_sampled = False
 
         if is_root_span and has_traces_sampler:
             sampling_context = create_sampling_context(
@@ -174,6 +180,7 @@ def should_sample(
             parent_sampled = get_parent_sampled(parent_span_context, trace_id)
             if parent_sampled is not None:
                 sample_rate = parent_sampled
+                inherited_parent_sampled = True
             else:
                 # Check if there is a traces_sample_rate
                 sample_rate = client.options.get("traces_sample_rate")
@@ -194,9 +201,17 @@ def should_sample(
         sampled = random.random() < sample_rate
 
         if sampled:
-            return sampled_result(parent_span_context, attributes, sample_rate)
+            return sampled_result(
+                parent_span_context,
+                attributes,
+                sample_rate=sample_rate if not inherited_parent_sampled else None,
+            )
         else:
-            return dropped_result(parent_span_context, attributes, sample_rate)
+            return dropped_result(
+                parent_span_context,
+                attributes,
+                sample_rate=sample_rate if not inherited_parent_sampled else None,
+            )
 
     def get_description(self) -> str:
         return self.__class__.__name__