refactor: Updated the reparenting logic for compact mode of partial traces to assign parent id to entry span

lib/transaction/trace/partial-trace.js

@@ -185,23 +185,26 @@ class PartialTrace {
   }
 
   /**
-   * Checks if span was the retained exit span for a given entity and it has other spans that talked to the same
-   * entity. It will then sort all timestamps for spans that got dropped and calculate the `nr.durations` and assign
-   * `nr.ids` for all dropped spans to same entity. It will also reparent the span links from dropped spans to the retained exit span.
+   * Checks if span had a parentId, if so it will reparent to entry span.
+   * If span was the retained exit span for a given entity and it has other spans that talked to the same entity, it will:
+   *  sort all timestamps for spans that got dropped and calculate the `nr.durations`
+   *  assign `nr.ids` for all dropped spans to same entity.
+   *  reparent the span links from dropped spans to the retained exit span.
    *
    * @param {SpanEvent} span to check if it has to calculate `nr.durations` and `nr.ids`
    */
   applyCompaction(span) {
+    if (span.parentId) {
+      logger.debug(`Partial trace is compact, reparenting span ${span.id} from parent ${span.parentId} to entry span ${this.transaction.baseSegment.name}${this.transaction.baseSegment.id}`)
+      span.addIntrinsicAttribute('parentId', this.transaction.baseSegment.id)
+    }
     const sameEntitySpans = this.compactSpanGroups[span.id]
 
     if (!sameEntitySpans) {
       logger.trace('Partial trace is compact, but not an exit span, not assigning `nr.ids` nor `nr.durations` to span %s', span.intrinsics.name)
       return
     }
 
-    logger.trace('Partial trace is compact, and an exit span, updating parentId(%s) to span %s', this.transaction.baseSegment.id, span.intrinsics.name)
-    span.addIntrinsicAttribute('parentId', this.transaction.baseSegment.id)
-
     if (sameEntitySpans?.length < 2) {
       logger.trace('Partial trace is compact, but no exit spans were dropped, not assigning `nr.ids` nor `nr.durations` to span %s', span.intrinsics.name)
       return

test/integration/distributed-tracing/core-tracing-assertions.js

@@ -80,7 +80,7 @@ function findSpan({ spans, name }) {
 function assertParentId({ parent, spans, span }) {
   if (parent) {
     const parentSpan = findSpan({ spans, name: parent })
-    assert.equal(span.parentId, parentSpan.id, `span ${span.intrinsics.name} should have parent ${parent}, got ${parentSpan.intrinsics.name}`)
+    assert.equal(span.parentId, parentSpan.id, `span ${span.intrinsics.name} should have parent ${parent}(${span.parentId}), got ${parentSpan.intrinsics.name}(${parentSpan.id})`)
   } else {
     assert.equal(span.parentId, parent)
   }

test/lib/cross_agent_tests/distributed_tracing/tracer_info_standard.json

@@ -65,20 +65,27 @@
         }
       },
       {
-        "name": "Llm/SOMETHING/function",
-        "timestamp": 1766435411000,
+        "name": "inprocess-2",
+        "timestamp": 1766435410020,
         "duration_millis": 200,
-        "agent_attrs": {
-          "http.url": "myllm"
-        },
         "children": [
           {
-            "name": "External/D",
-            "timestamp": 1766435411100,
-            "duration_millis": 250,
+            "name": "Llm/SOMETHING/function",
+            "timestamp": 1766435411000,
+            "duration_millis": 200,
             "agent_attrs": {
-              "http.url": "serviceD"
-            }
+              "http.url": "myllm"
+            },
+            "children": [
+              {
+                "name": "External/D",
+                "timestamp": 1766435411100,
+                "duration_millis": 250,
+                "agent_attrs": {
+                  "http.url": "serviceD"
+                }
+              }
+            ]
           }
         ]
       }

test/unit/transaction/trace/partial-trace.test.js

@@ -161,14 +161,15 @@ describe('applyCompaction', () => {
     transaction.baseSegment = { id: 100 }
     const now = Date.now()
     const span1 = {
+      parentId: 99,
       id: 1,
       intrinsics: { timestamp: now, duration: 5 },
       addIntrinsicAttribute: sinon.spy()
     }
-    const span2 = { id: 2, intrinsics: { timestamp: now, duration: 5 } } // duration is 5
-    const span3 = { id: 3, intrinsics: { timestamp: now, duration: 7 } } // duration is 7
-    const span4 = { id: 4, intrinsics: { timestamp: now + 5000, duration: 3 } } // duration is 8
-    const span5 = { id: 5, intrinsics: { timestamp: now + 10000, duration: 10 } } // duration is 18
+    const span2 = { parentId: 1, id: 2, intrinsics: { timestamp: now, duration: 5 } } // duration is 5
+    const span3 = { parentId: 1, id: 3, intrinsics: { timestamp: now, duration: 7 } } // duration is 7
+    const span4 = { parentId: 1, id: 4, intrinsics: { timestamp: now + 5000, duration: 3 } } // duration is 8
+    const span5 = { parentId: 1, id: 5, intrinsics: { timestamp: now + 10000, duration: 10 } } // duration is 18
     partialTrace.compactSpanGroups[1] = [span1, span5, span3, span4, span2]
     partialTrace.applyCompaction(span1)
     assert.ok(!transaction.metrics.unscoped['Supportability/Nodejs/PartialGranularity/NrIds/Dropped'])
@@ -184,7 +185,7 @@ describe('applyCompaction', () => {
     const { partialTrace, transaction } = t.nr
     transaction.baseSegment = { id: 100 }
     const now = Date.now()
-    const span1 = { id: 0, intrinsics: { timestamp: now, duration: 5 }, addIntrinsicAttribute: sinon.spy() }
+    const span1 = { parentId: 99, id: 0, intrinsics: { timestamp: now, duration: 5 }, addIntrinsicAttribute: sinon.spy() }
     partialTrace.compactSpanGroups[0] = []
     const nrIds = []
     for (let i = 1; i <= 100; i++) {
@@ -211,6 +212,7 @@ describe('applyCompaction', () => {
     transaction.baseSegment = { id: 100 }
     const now = Date.now()
     const span1 = {
+      parentId: 99,
       id: 1,
       intrinsics: { timestamp: now, duration: 5 },
       addIntrinsicAttribute: sinon.spy()