implement additional_metrics_tags in libdd-trace-stats

Author: duncanpharvey

libdd-data-pipeline/src/trace_exporter/builder.rs

@@ -750,6 +750,7 @@ impl<R: SharedRuntime> TraceExporterBuilder<R> {
                 span_kinds,
                 self.peer_tags.clone(),
                 None,
+                vec![],
                 #[cfg(feature = "stats-obfuscation")]
                 None,
             )));

libdd-data-pipeline/src/trace_exporter/stats.rs

@@ -143,6 +143,7 @@ pub(crate) fn start_stats_computation<
             span_kinds,
             peer_tags,
             ctx.stats_cardinality_limit,
+            vec![],
             #[cfg(feature = "stats-obfuscation")]
             Some(client_side_stats.obfuscation_config.clone()),
         )));

libdd-trace-protobuf/src/pb_test.rs

@@ -72,7 +72,8 @@ mod tests {
                             ],
                             "HTTPMethod": "GET",
                             "HTTPEndpoint": "/test",
-                            "GRPCStatusCode": "0"
+                            "GRPCStatusCode": "0",
+                            "AdditionalMetricTags": []
                         }
                     ]
                 }

libdd-trace-stats/README.md

@@ -76,6 +76,7 @@ let mut concentrator = SpanConcentrator::new(
     SystemTime::now(),
     vec!["client".to_string(), "server".to_string()], // eligible span kinds
     vec!["peer.service".to_string()], // peer tag keys
+    vec!["example.key".to_string()], // additional metric tag keys
 );
 
 // Add spans

libdd-trace-stats/benches/span_concentrator_bench.rs

@@ -45,6 +45,7 @@ pub fn criterion_benchmark(c: &mut Criterion) {
         vec![],
         vec!["db_name".into(), "bucket_s3".into()],
         None,
+        vec![],
         #[cfg(feature = "stats-obfuscation")]
         None,
     );