Make translate_span a little faster (#132)

* Make translate_span a little faster

Using py-spy, it looks like the previous version spent some time doing

list(default_resource.attributes.keys()) every time it was called.

It seems this can be done once in the OTELWriter constructor instead.
Also, I think we can make it a set instead of a list (I believe `a in
my_set` is a bit quicker than `a in my_list`).

Does this commit include tests to verify the speed increase? Nah... 🤷

* isort

troncos/tracing/_span.py

@@ -15,13 +15,13 @@
 from opentelemetry.trace import SpanContext, SpanKind, Status, StatusCode
 from opentelemetry.trace.span import TraceFlags
 
-_dd_span_ignore_attr = [
+_dd_span_ignore_attr = {
     "runtime-id",
     "_sampling_priority_v1",
     "env",
     "version",
     "span.kind",
-]
+}
 
 
 def _span_context(span: DDSpan) -> SpanContext:
@@ -58,7 +58,7 @@ def _span_kind(dd_span: DDSpan) -> SpanKind:
 
 
 def _span_status_and_attributes(
-    dd_span: DDSpan, ignore_attrs: list[str]
+    dd_span: DDSpan, ignore_attrs: set[str]
 ) -> tuple[Status, list[Event], dict[str, Any]]:
     dd_span_err_attr_mapping = {
         "error.msg": "exception.message",
@@ -124,13 +124,18 @@ def _span_resource(dd_span: DDSpan, default_resource: Resource) -> Resource:
     return Resource(base_attributes)
 
 
-def translate_span(dd_span: DDSpan, default_resource: Resource) -> ReadableSpan:
+def default_ignore_attrs() -> set[str]:
+    return _dd_span_ignore_attr
+
+
+def translate_span(
+    dd_span: DDSpan, default_resource: Resource, ignore_attrs: set[str]
+) -> ReadableSpan:
     """Transelate a ddtrace span to an OTEL span."""
     assert dd_span.duration_ns, "Span not finished."
 
     status, events, attributes = _span_status_and_attributes(
-        dd_span,
-        ignore_attrs=_dd_span_ignore_attr + list(default_resource.attributes.keys()),
+        dd_span, ignore_attrs=ignore_attrs
     )
 
     otel_span = ReadableSpan(

troncos/tracing/_writer.py

@@ -6,7 +6,7 @@
 
 from ._enums import Exporter
 from ._otel import get_otel_span_processors
-from ._span import translate_span
+from ._span import default_ignore_attrs, translate_span
 
 
 class OTELWriter(TraceWriter):
@@ -28,6 +28,9 @@ def __init__(
         self.otel_default_resource = Resource.create(
             {"service.name": service_name, **(service_attributes or {})}
         )
+        self.otel_ignore_attrs = (
+            set(self.otel_default_resource.attributes.keys()) | default_ignore_attrs()
+        )
 
     def recreate(self) -> "OTELWriter":
         return self.__class__(
@@ -39,7 +42,11 @@ def recreate(self) -> "OTELWriter":
 
     def write(self, spans: list[Span] | None = None) -> None:
         transelated_spans = [
-            translate_span(span, default_resource=self.otel_default_resource)
+            translate_span(
+                span,
+                default_resource=self.otel_default_resource,
+                ignore_attrs=self.otel_ignore_attrs,
+            )
             for span in spans or []
         ]