feat(spans): track and report spans that were dropped

sentry_sdk/_types.py

@@ -78,6 +78,7 @@ class SDKInfo(TypedDict):
             "check_in_id": str,
             "contexts": dict[str, dict[str, object]],
             "dist": str,
+            "dropped_spans": int,
             "duration": Optional[float],
             "environment": str,
             "errors": list[dict[str, Any]],  # TODO: We can expand on this type

sentry_sdk/client.py

@@ -10,6 +10,7 @@
 
 from sentry_sdk._compat import PY37, check_uwsgi_thread_support
 from sentry_sdk.utils import (
+    AnnotatedValue,
     ContextVar,
     capture_internal_exceptions,
     current_stacktrace,
@@ -483,6 +484,8 @@ def _prepare_event(
     ):
         # type: (...) -> Optional[Event]
 
+        previous_total_spans = None  # type: Optional[int]
+
         if event.get("timestamp") is None:
             event["timestamp"] = datetime.now(timezone.utc)
 
@@ -507,13 +510,16 @@ def _prepare_event(
                 return None
 
             event = event_
-
             spans_delta = spans_before - len(event.get("spans", []))
             if is_transaction and spans_delta > 0 and self.transport is not None:
                 self.transport.record_lost_event(
                     "event_processor", data_category="span", quantity=spans_delta
                 )
 
+            dropped_spans = event.pop("dropped_spans", 0) + spans_delta # type: int
+            if dropped_spans > 0 or spans_delta > 0:
+                previous_total_spans = spans_before + dropped_spans
+
         if (
             self.options["attach_stacktrace"]
             and "exception" not in event
@@ -561,6 +567,9 @@ def _prepare_event(
             if event_scrubber:
                 event_scrubber.scrub_event(event)
 
+        if previous_total_spans is not None:
+            event["spans"] = AnnotatedValue(event.get("spans", []), {"len": previous_total_spans})
+
         # Postprocess the event here so that annotated types do
         # generally not surface in before_send
         if event is not None:

sentry_sdk/tracing.py

@@ -193,7 +193,7 @@ def get_span_status_from_http_code(http_status_code):
 class _SpanRecorder:
     """Limits the number of spans recorded in a transaction."""
 
-    __slots__ = ("maxlen", "spans")
+    __slots__ = ("maxlen", "spans", "dropped_spans")
 
     def __init__(self, maxlen):
         # type: (int) -> None
@@ -204,11 +204,13 @@ def __init__(self, maxlen):
         # limits: either transaction+spans or only child spans.
         self.maxlen = maxlen - 1
         self.spans = []  # type: List[Span]
+        self.dropped_spans = 0 # type: int
 
     def add(self, span):
         # type: (Span) -> None
         if len(self.spans) > self.maxlen:
             span._span_recorder = None
+            self.dropped_spans += 1
         else:
             self.spans.append(span)
 
@@ -972,6 +974,9 @@ def finish(
             if span.timestamp is not None
         ]
 
+        len_diff = len(self._span_recorder.spans) - len(finished_spans)        
+        dropped_spans = len_diff + self._span_recorder.dropped_spans
+
         # we do this to break the circular reference of transaction -> span
         # recorder -> span -> containing transaction (which is where we started)
         # before either the spans or the transaction goes out of scope and has
@@ -996,6 +1001,9 @@ def finish(
             "spans": finished_spans,
         }  # type: Event
 
+        if dropped_spans > 0:
+            event["dropped_spans"] = dropped_spans
+
         if self._profile is not None and self._profile.valid():
             event["profile"] = self._profile
             self._profile = None

tests/tracing/test_misc.py

@@ -11,7 +11,7 @@
 from sentry_sdk.tracing import Span, Transaction
 from sentry_sdk.tracing_utils import should_propagate_trace
 from sentry_sdk.utils import Dsn
-
+from tests.conftest import ApproxDict
 
 def test_span_trimming(sentry_init, capture_events):
     sentry_init(traces_sample_rate=1.0, _experiments={"max_spans": 3})
@@ -31,6 +31,31 @@ def test_span_trimming(sentry_init, capture_events):
     assert span2["op"] == "foo1"
     assert span3["op"] == "foo2"
 
+    assert event["_meta"]["spans"][""]["len"] == 10
+
+
+def test_span_data_scrubbing_and_trimming(sentry_init, capture_events):
+    sentry_init(traces_sample_rate=1.0, _experiments={"max_spans": 3})
+    events = capture_events()
+
+    with start_transaction(name="hi"):
+        with start_span(op="foo", name="bar") as span:
+            span.set_data("password", "secret")
+            span.set_data("datafoo", "databar")
+
+        for i in range(10):
+            with start_span(op="foo{}".format(i)):
+                pass
+
+    (event,) = events
+    assert event["spans"][0]["data"] == ApproxDict(
+        {"password": "[Filtered]", "datafoo": "databar"}
+    )
+    assert event["_meta"]["spans"] == {
+        "0": {"data": {"password": {"": {"rem": [["!config", "s"]]}}}},
+        "": {"len": 11},
+    }
+
 
 def test_transaction_naming(sentry_init, capture_events):
     sentry_init(traces_sample_rate=1.0)