feat(grouping): Add helper to combine hints (#91833)

When a frame is affected by both an in-app rule and a contributes rule, the split enhancements allow us to get both hints, rather than having one clobber the other (as is the case now). That does not mean, however, that both hints are always relevant. This PR adds a helper, `_combine_hints`, to appropriately use or ignore each hint, and combine them when necessary. It's not yet used, but will be when we switch to actually using the split enhancements, rather than just running them alongside the non-split ones.

Note that `_combine_hints` needs the final `contributes` value to already be in place when it runs, so this also moves the setting of that value earlier in `assemble_stacktrace_component`.

Author: lobsterkatie

src/sentry/grouping/enhancer/__init__.py

@@ -257,6 +257,46 @@ def _split_rules(
     )
 
 
+def _combine_hints(
+    variant_name: str,
+    frame_component: FrameGroupingComponent,
+    in_app_hint: str | None,
+    contributes_hint: str | None,
+) -> str | None:
+    """
+    Given possible in-app and contributes hints, determine the frame's final hint.
+    """
+    frame_type = "in-app" if frame_component.in_app else "system"
+
+    # In-app hints never apply to the system stacktrace, so even if the contributes hint is `None`,
+    # it's the one we want
+    if variant_name == "system":
+        return contributes_hint
+
+    # From here on out everything we're doing is for the app variant
+
+    # System frames never contribute to the app stacktrace, so if they've already been marked out of
+    # app, we don't care whether or not they're ignored (or un-ignored), because they weren't going
+    # to count anyway.
+    if frame_type == "system":
+        return in_app_hint
+
+    # If only one hint exists, return that one
+    if in_app_hint and not contributes_hint:
+        return in_app_hint
+    if contributes_hint and not in_app_hint:
+        return contributes_hint
+
+    # If neither hint exists, return None
+    if not in_app_hint and not contributes_hint:
+        return None
+
+    # Combine the hints in such as way that we get "marked in-app by xxx AND un-ignored by yyy" and
+    # "marked in-app by xxx BUT ignored by yyy"
+    conjunction = "and" if frame_component.contributes else "but"
+    return f"{in_app_hint} {conjunction} {contributes_hint}"
+
+
 def is_valid_profiling_matcher(matchers: list[str]) -> bool:
     for matcher in matchers:
         if not matcher.startswith(VALID_PROFILING_MATCHER_PREFIXES):
@@ -683,6 +723,8 @@ def assemble_stacktrace_component(
             else:
                 contributes = rust_frame.contributes
 
+            frame_component.update(contributes=contributes)
+
             hint = get_hint_for_frame(variant_name, frame, frame_component, rust_frame)
             if self.run_split_enhancements:
                 split_in_app_hint = (
@@ -696,7 +738,7 @@ def assemble_stacktrace_component(
                     variant_name, frame, frame_component, contributes_rust_frame, "contributes"
                 )
 
-            frame_component.update(contributes=contributes, hint=hint)
+            frame_component.update(hint=hint)
 
             # Add this frame to our tally
             key = f"{"in_app" if frame_component.in_app else "system"}_{"contributing" if frame_component.contributes else "non_contributing"}_frames"

tests/sentry/grouping/enhancements/test_hints.py

@@ -6,7 +6,7 @@
 import pytest
 
 from sentry.grouping.component import FrameGroupingComponent
-from sentry.grouping.enhancer import get_hint_for_frame
+from sentry.grouping.enhancer import _combine_hints, get_hint_for_frame
 
 
 @dataclass
@@ -431,3 +431,35 @@ def test_get_hint_for_frame(
         get_hint_for_frame(variant_name, frame, frame_component, rust_frame, desired_hint_type)  # type: ignore[arg-type]
         == expected_result
     )
+
+
+@pytest.mark.parametrize(
+    ["variant_name", "in_app", "contributes", "in_app_hint", "contributes_hint", "expected_result"],
+    [
+        ("app", True, True, in_app_hint, None, in_app_hint),
+        ("app", True, True, in_app_hint, unignored_hint, f"{in_app_hint} and {unignored_hint}"),
+        ("app", True, False, in_app_hint, ignored_hint, f"{in_app_hint} but {ignored_hint}"),
+        ("app", False, True, out_of_app_hint, None, out_of_app_hint),
+        ("app", False, True, out_of_app_hint, unignored_hint, out_of_app_hint),
+        ("app", False, False, out_of_app_hint, ignored_hint, out_of_app_hint),
+        ("system", True, True, None, None, None),
+        ("system", True, True, None, unignored_hint, unignored_hint),
+        ("system", True, False, None, ignored_hint, ignored_hint),
+        ("system", False, True, None, None, None),
+        ("system", False, True, None, unignored_hint, unignored_hint),
+        ("system", False, False, None, ignored_hint, ignored_hint),
+    ],
+)
+def test_combining_hints(
+    variant_name,
+    in_app,
+    contributes,
+    in_app_hint,
+    contributes_hint,
+    expected_result,
+):
+    frame_component = FrameGroupingComponent(in_app=in_app, contributes=contributes, values=[])
+    assert (
+        _combine_hints(variant_name, frame_component, in_app_hint, contributes_hint)
+        == expected_result
+    )