Skip normalization & obfuscation and coalesce instead

Turns out the agent ignores the root_span_tags for v0.7 anyway.
This is useful to coalesce chunks with common data, allowing us to actually save us from doing redundant requests.
As it was currently, the agentful trace sender always sent one trace per request, instead of merging them.

We also skip normalization and rely on the agent to do it, for sake of consistency with other tracers and reduce the potentially duplicated work across tracer and agent. We may change that back in future, but for now we've determined it to be the easiest way to work, also with respect to normalization-unaware testing.

Signed-off-by: Bob Weinand <[email protected]>

data-pipeline/src/trace_exporter.rs

@@ -226,6 +226,7 @@ impl TraceExporter {
                     traces,
                     &header_tags,
                     |_chunk, _root_span_index| {},
+                    self.endpoint.api_key.is_some(),
                 );
 
                 let endpoint = Endpoint {

sidecar/src/service/sidecar_server.rs

@@ -309,8 +309,12 @@ impl SidecarServer {
             return;
         }
 
-        let payload =
-            trace_utils::collect_trace_chunks(traces, &headers, |_chunk, _root_span_index| {});
+        let payload = trace_utils::collect_trace_chunks(
+            traces,
+            &headers,
+            |_chunk, _root_span_index| {},
+            target.api_key.is_some(),
+        );
 
         // send trace payload to our trace flusher
         let data = SendData::new(size, payload, headers, target);

trace-mini-agent/src/trace_processor.rs

@@ -85,6 +85,7 @@ impl TraceProcessor for ServerlessTraceProcessor {
                     obfuscate_span(span, &config.obfuscation_config);
                 }
             },
+            true,
         );
 
         let send_data = SendData::new(body_size, payload, tracer_header_tags, &config.trace_intake);

trace-utils/Cargo.toml

@@ -23,12 +23,12 @@ datadog-trace-normalization = { path = "../trace-normalization" }
 tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
 rand = "0.8.5"
 bytes = "1.6.0"
-# This should only be used for testing. It isn't under dev-dependencies because test-utils can't be under #[cfg(test)].
-httpmock = {  version = "0.7.0", optional = true}
+httpmock = { version = "0.7.0", optional = true}
 
 [dev-dependencies]
 tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
 serde_json = "1.0"
+httpmock = { version = "0.7.0"}
 
 [features]
 test-utils = ["httpmock"]

trace-utils/src/trace_utils.rs

@@ -3,6 +3,7 @@
 
 use hyper::{body::Buf, Body};
 use log::{error, info};
+use std::cmp::Ordering;
 use std::collections::HashMap;
 
 pub use crate::send_data::SendData;
@@ -79,6 +80,18 @@ pub(crate) fn construct_tracer_payload(
     }
 }
 
+fn cmp_send_data_payloads(a: &pb::TracerPayload, b: &pb::TracerPayload) -> Ordering {
+    a.tracer_version
+        .cmp(&b.tracer_version)
+        .then(a.language_version.cmp(&b.language_version))
+        .then(a.language_name.cmp(&b.language_name))
+        .then(a.hostname.cmp(&b.hostname))
+        .then(a.container_id.cmp(&b.container_id))
+        .then(a.runtime_id.cmp(&b.runtime_id))
+        .then(a.env.cmp(&b.env))
+        .then(a.app_version.cmp(&b.app_version))
+}
+
 pub fn coalesce_send_data(mut data: Vec<SendData>) -> Vec<SendData> {
     // TODO trace payloads with identical data except for chunk could be merged?
 
@@ -103,6 +116,20 @@ pub fn coalesce_send_data(mut data: Vec<SendData>) -> Vec<SendData> {
         }
         false
     });
+    // Merge chunks with common properties. Reduces requests for agentful mode.
+    // And reduces a little bit of data for agentless.
+    for send_data in data.iter_mut() {
+        send_data
+            .tracer_payloads
+            .sort_unstable_by(cmp_send_data_payloads);
+        send_data.tracer_payloads.dedup_by(|a, b| {
+            if cmp_send_data_payloads(a, b) == Ordering::Equal {
+                b.chunks.append(&mut a.chunks);
+                return true;
+            }
+            false
+        })
+    }
     data
 }
 
@@ -288,10 +315,12 @@ pub fn collect_trace_chunks(
     mut traces: Vec<Vec<pb::Span>>,
     tracer_header_tags: &TracerHeaderTags,
     process_chunk: impl Fn(&mut TraceChunk, usize),
+    is_agentless: bool,
 ) -> pb::TracerPayload {
     let mut trace_chunks: Vec<pb::TraceChunk> = Vec::new();
 
-    let mut gathered_root_span_tags = false;
+    // We'll skip setting the global metadata and reply on the agent to unpack these
+    let mut gathered_root_span_tags = !is_agentless;
     let mut root_span_tags = RootSpanTags::default();
 
     for trace in traces.iter_mut() {
@@ -309,8 +338,10 @@ pub fn collect_trace_chunks(
             }
         };
 
-        if let Err(e) = normalizer::normalize_chunk(&mut chunk, root_span_index) {
-            error!("Error normalizing trace chunk: {e}");
+        if !is_agentless {
+            if let Err(e) = normalizer::normalize_chunk(&mut chunk, root_span_index) {
+                error!("Error normalizing trace chunk: {e}");
+            }
         }
 
         for span in chunk.spans.iter_mut() {
@@ -362,7 +393,7 @@ mod tests {
     use ddcommon::Endpoint;
 
     #[test]
-    fn test_coalescing_does_not_excced_max_size() {
+    fn test_coalescing_does_not_exceed_max_size() {
         let dummy = SendData::new(
             MAX_PAYLOAD_SIZE / 5 + 1,
             pb::TracerPayload {
@@ -371,7 +402,13 @@ mod tests {
                 language_version: "".to_string(),
                 tracer_version: "".to_string(),
                 runtime_id: "".to_string(),
-                chunks: vec![],
+                chunks: vec![pb::TraceChunk {
+                    priority: 0,
+                    origin: "".to_string(),
+                    spans: vec![],
+                    tags: Default::default(),
+                    dropped_trace: false,
+                }],
                 tags: Default::default(),
                 env: "".to_string(),
                 hostname: "".to_string(),
@@ -391,9 +428,27 @@ mod tests {
             5,
             coalesced
                 .iter()
-                .map(|s| s.tracer_payloads.len())
+                .map(|s| s
+                    .tracer_payloads
+                    .iter()
+                    .map(|p| p.chunks.len())
+                    .sum::<usize>())
                 .sum::<usize>()
         );
+        // assert some chunks are actually coalesced
+        assert!(
+            coalesced
+                .iter()
+                .map(|s| s
+                    .tracer_payloads
+                    .iter()
+                    .map(|p| p.chunks.len())
+                    .max()
+                    .unwrap())
+                .max()
+                .unwrap()
+                > 1
+        );
         assert!(coalesced.len() > 1 && coalesced.len() < 5);
     }