From 36a8e809253d95a84675700c6a62ffc912812383 Mon Sep 17 00:00:00 2001
From: brharrington <brharrington@gmail.com>
Date: Tue, 26 Mar 2024 12:18:46 -0500
Subject: [PATCH] core: support chaining child queries (#1628)

Update matcher to make it more convenient to chain together
child queries to indicate a path.
---
 .../atlas/core/model/TraceVocabulary.scala    |  8 ++++++-
 .../atlas/lwc/events/TraceMatcherSuite.scala  | 22 ++++++++++++++++++-
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/atlas-core/src/main/scala/com/netflix/atlas/core/model/TraceVocabulary.scala b/atlas-core/src/main/scala/com/netflix/atlas/core/model/TraceVocabulary.scala
index e0be14dbd..f4bf19fb9 100644
--- a/atlas-core/src/main/scala/com/netflix/atlas/core/model/TraceVocabulary.scala
+++ b/atlas-core/src/main/scala/com/netflix/atlas/core/model/TraceVocabulary.scala
@@ -86,12 +86,18 @@ object TraceVocabulary extends Vocabulary {
     override def name: String = "child"
 
     override protected def matcher: PartialFunction[List[Any], Boolean] = {
-      case (_: Query) :: (_: Query) :: _ => true
+      case (_: Query) :: (_: Query) :: _                                 => true
+      case (_: Query) :: (_: TraceQuery.Child) :: _                      => true
+      case (_: Query) :: TraceQuery.SpanAnd(_, _: TraceQuery.Child) :: _ => true
     }
 
     override protected def executor: PartialFunction[List[Any], List[Any]] = {
       case (q2: Query) :: (q1: Query) :: stack =>
         TraceQuery.Child(q1, q2) :: stack
+      case (q2: Query) :: (tq: TraceQuery.Child) :: stack =>
+        TraceQuery.SpanAnd(tq, TraceQuery.Child(tq.q2, q2)) :: stack
+      case (q2: Query) :: (s @ TraceQuery.SpanAnd(_, tq: TraceQuery.Child)) :: stack =>
+        TraceQuery.SpanAnd(s, TraceQuery.Child(tq.q2, q2)) :: stack
     }
 
     override def signature: String = "q1:TraceQuery q2:TraceQuery -- TraceQuery"
diff --git a/atlas-lwc-events/src/test/scala/com/netflix/atlas/lwc/events/TraceMatcherSuite.scala b/atlas-lwc-events/src/test/scala/com/netflix/atlas/lwc/events/TraceMatcherSuite.scala
index 268770591..32243e055 100644
--- a/atlas-lwc-events/src/test/scala/com/netflix/atlas/lwc/events/TraceMatcherSuite.scala
+++ b/atlas-lwc-events/src/test/scala/com/netflix/atlas/lwc/events/TraceMatcherSuite.scala
@@ -42,13 +42,20 @@ class TraceMatcherSuite extends FunSuite {
     )
   }
 
+  /**
+    *  a - b
+    *    - c - e - g
+    *        - f
+    *    - d
+    */
   private val sampleTrace = List(
     mkSpan("a", "1", null, 0L, 100L),
     mkSpan("b", "2", "1", 1L, 25L),
     mkSpan("c", "3", "1", 5L, 90L),
     mkSpan("d", "4", "1", 15L, 50L),
     mkSpan("e", "5", "3", 8L, 50L),
-    mkSpan("f", "6", "3", 55L, 20L)
+    mkSpan("f", "6", "3", 55L, 20L),
+    mkSpan("g", "7", "5", 4L, 5L)
   )
 
   private def checkMatch(query: TraceQuery, shouldMatch: Boolean): Unit = {
@@ -91,6 +98,19 @@ class TraceMatcherSuite extends FunSuite {
     val q3 = ExprUtils.parseTraceEventsQuery("app,a,:eq,app,e,:eq,:child").q
     checkMatch(q3, false)
   }
+
+  test("transitive child") {
+    val q1 = ExprUtils.parseTraceEventsQuery("app,a,:eq,app,c,:eq,:child,app,e,:eq,:child").q
+    checkMatch(q1, true)
+
+    val q2 = ExprUtils.parseTraceEventsQuery("app,a,:eq,app,b,:eq,:child,app,e,:eq,:child").q
+    checkMatch(q2, false)
+
+    val q3 = ExprUtils
+      .parseTraceEventsQuery("app,a,:eq,app,c,:eq,:child,app,e,:eq,:child,app,g,:eq,:child")
+      .q
+    checkMatch(q1, true)
+  }
 }
 
 object TraceMatcherSuite {