chore(llmobs): [MLOB-2064] add telemetry for custom vs. autoinstrumen…

…ted span creation (#11983)

Adds telemetry to track the number of LLMObs spans created either via
auto instrumentation or manual instrumentation.

## Checklist
- [x] PR author has checked that all the criteria below are met
- The PR description includes an overview of the change
- The PR description articulates the motivation for the change
- The change includes tests OR the PR description describes a testing
strategy
- The PR description notes risks associated with the change, if any
- Newly-added code is easy to change
- The change follows the [library release note
guidelines](https://ddtrace.readthedocs.io/en/stable/releasenotes.html)
- The change includes or references documentation updates if necessary
- Backport labels are set (if
[applicable](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting))

## Reviewer Checklist
- [x] Reviewer has checked that all the criteria below are met 
- Title is accurate
- All changes are related to the pull request's stated goal
- Avoids breaking
[API](https://ddtrace.readthedocs.io/en/stable/versioning.html#interfaces)
changes
- Testing strategy adequately addresses listed risks
- Newly-added code is easy to change
- Release note makes sense to a user of the library
- If necessary, author has acknowledged and discussed the performance
implications of this PR as reported in the benchmarks PR comment
- Backport labels are set in a manner that is consistent with the
[release branch maintenance
policy](https://ddtrace.readthedocs.io/en/latest/contributing.html#backporting)

ddtrace/llmobs/_integrations/base.py

@@ -16,6 +16,8 @@
 from ddtrace.internal.dogstatsd import get_dogstatsd_client
 from ddtrace.internal.hostname import get_hostname
 from ddtrace.internal.logger import get_logger
+from ddtrace.internal.telemetry import telemetry_writer
+from ddtrace.internal.telemetry.constants import TELEMETRY_NAMESPACE
 from ddtrace.internal.utils.formats import asbool
 from ddtrace.llmobs._constants import PARENT_ID_KEY
 from ddtrace.llmobs._constants import PROPAGATED_PARENT_ID_KEY
@@ -136,6 +138,15 @@ def trace(self, pin: Pin, operation_id: str, submit_to_llmobs: bool = False, **k
                 # in these cases to avoid conflicting with the later propagated tags.
                 parent_id = _get_llmobs_parent_id(span) or "undefined"
                 span._set_ctx_item(PARENT_ID_KEY, str(parent_id))
+        telemetry_writer.add_count_metric(
+            namespace=TELEMETRY_NAMESPACE.MLOBS,
+            name="span.start",
+            value=1,
+            tags=(
+                ("integration", self._integration_name),
+                ("autoinstrumented", "true"),
+            ),
+        )
         return span
 
     @classmethod

ddtrace/llmobs/_llmobs.py

@@ -27,6 +27,7 @@
 from ddtrace.internal.service import ServiceStatusError
 from ddtrace.internal.telemetry import telemetry_writer
 from ddtrace.internal.telemetry.constants import TELEMETRY_APM_PRODUCT
+from ddtrace.internal.telemetry.constants import TELEMETRY_NAMESPACE
 from ddtrace.internal.utils.formats import asbool
 from ddtrace.internal.utils.formats import parse_tags_str
 from ddtrace.llmobs import _constants as constants
@@ -520,6 +521,15 @@ def _start_span(
         model_provider: Optional[str] = None,
         ml_app: Optional[str] = None,
     ) -> Span:
+        telemetry_writer.add_count_metric(
+            namespace=TELEMETRY_NAMESPACE.MLOBS,
+            name="span.start",
+            value=1,
+            tags=(
+                ("autoinstrumented", "false"),
+                ("kind", operation_kind),
+            ),
+        )
         if name is None:
             name = operation_kind
         span = self.tracer.trace(name, resource=operation_kind, span_type=SpanTypes.LLM)