ref(grouping): Improve message parameterization metrics

src/sentry/grouping/context.py

@@ -60,6 +60,11 @@ def __init__(self, strategy_config: StrategyConfiguration, event: Event):
         self.canonical_event_message = event_message
         self.canonical_message_parameterized = parameterizer.parameterize(event_message)
 
+        # Track use of the cached values for metrics purposes. Any use past the first one signifies
+        # a reuse of the value, thus proving caching worthwhile.
+        self.cached_parameterizer_used = False
+        self.cached_param_result_used = False
+
         self._push_context_layer()
 
     def __setitem__(self, key: str, value: Any) -> None:

src/sentry/grouping/fingerprinting/utils.py

@@ -10,6 +10,7 @@
 from sentry.stacktraces.functions import get_function_name_for_frame
 from sentry.stacktraces.platform import get_behavior_family_for_platform
 from sentry.stacktraces.processing import get_crash_frame_from_event_data
+from sentry.utils import metrics
 from sentry.utils.event_frames import find_stack_frames
 from sentry.utils.safe import get_path
 from sentry.utils.tag_normalization import normalized_sdk_tag_from_event
@@ -340,6 +341,9 @@ def expand_title_template(
 ) -> str:
     def _handle_match(match: re.Match[str]) -> str:
         variable_key = match.group(1)
+        if variable_key == "message":
+            metrics.incr("grouping.message_used", tags={"reason": "custom_title"})
+
         # TODO: Once we have fully transitioned off of the `newstyle:2023-01-11` grouping config, we
         # can remove `use_legacy_unknown_variable_handling` and just return the value given by
         # `resolve_fingerprint_variable`

src/sentry/grouping/parameterization.py

@@ -312,6 +312,11 @@ def _handle_regex_match(match: re.Match[str]) -> str:
 
         parameterized = self._parameterization_regex.sub(_handle_regex_match, input_str)
 
+        metrics.incr(
+            "grouping.parameterizer_called",
+            tags={"changed": parameterized != input_str, "experimental": self._experimental},
+        )
+
         for key, value in matches_counter.items():
             # Track the kinds of replacements being made
             metrics.incr("grouping.value_parameterized", amount=value, tags={"key": key})

src/sentry/grouping/utils.py

@@ -63,13 +63,29 @@ def normalize_message_for_grouping(
     """
     if message == context.canonical_event_message:
         parameterized = context.canonical_message_parameterized
+
+        # Before we mark the value as having been used, check if it's already marked that way. If
+        # so, that means our use of the value here is at least the second use, thus proving the
+        # caching worthwhile.
+        if context.cached_param_result_used:
+            # This represents a saved call to `parameterizer.parameterize`
+            metrics.incr("grouping.cached_param_result_used")
+
+        context.cached_param_result_used = True
     else:
         parameterized = context.parameterizer.parameterize(message)
 
-    message_parameterized = parameterized != message
+        # Before we mark the parameterizer as having been used, check if it's already marked that
+        # way. If so, that means our use of it here is at least the second use, thus proving the
+        # caching worthwhile.
+        if context.cached_parameterizer_used:
+            # This represents a saved call to `in_rollout_group` on the project vis-à-vis
+            # experimental parameterization
+            metrics.incr("grouping.cached_parameterizer_used")
+
+        context.cached_parameterizer_used = True
 
-    if message_parameterized:
-        metrics.incr("grouping.message_parameterized", tags={"source": reason})
+    metrics.incr("grouping.message_used", tags={"reason": reason})
 
     return _trim_extra_lines(parameterized) if trim_message else parameterized