From fbf4d7aea2867277465755d779ed93c564d99eea Mon Sep 17 00:00:00 2001
From: Georgios Andrianakis <geoand@gmail.com>
Date: Tue, 4 Jul 2023 10:46:37 +0300
Subject: [PATCH] Enhance OpenTelemetry's DropTargetsSampler

This allows us to move effectively drop traces
belonging to SwaggerUI and other framework endpoints

Fixes: #34376
---
 .../runtime/tracing/DropTargetsSampler.java   | 33 +++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/DropTargetsSampler.java b/extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/DropTargetsSampler.java
index 53966c5303204..b94709813e57c 100644
--- a/extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/DropTargetsSampler.java
+++ b/extensions/opentelemetry/runtime/src/main/java/io/quarkus/opentelemetry/runtime/tracing/DropTargetsSampler.java
@@ -25,8 +25,7 @@ public SamplingResult shouldSample(Context parentContext, String traceId, String
 
         if (spanKind.equals(SpanKind.SERVER)) {
             String target = attributes.get(SemanticAttributes.HTTP_TARGET);
-            // TODO - radcortez - Match /* endpoints
-            if (target != null && dropTargets.contains(target)) {
+            if (shouldDrop(target)) {
                 return SamplingResult.drop();
             }
         }
@@ -34,6 +33,36 @@ public SamplingResult shouldSample(Context parentContext, String traceId, String
         return sampler.shouldSample(parentContext, traceId, name, spanKind, attributes, parentLinks);
     }
 
+    /**
+     * Determines whether a path should be dropped
+     * TODO: this can certainly be optimized if we find that it's a hot-path
+     */
+    private boolean shouldDrop(String target) {
+        if ((target == null) || target.isEmpty()) {
+            return false;
+        }
+        if (safeContains(target)) {  // check exact match
+            return true;
+        }
+        if (target.charAt(target.length() - 1) == '/') { // check if the path without the ending slash matched
+            if (safeContains(target.substring(0, target.length() - 1))) {
+                return true;
+            }
+        }
+        int lastSlashIndex = target.lastIndexOf('/');
+        if (lastSlashIndex != -1) {
+            if (safeContains(target.substring(0, lastSlashIndex) + "*")
+                    || safeContains(target.substring(0, lastSlashIndex) + "/*")) { // check if a wildcard matches
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean safeContains(String target) {
+        return dropTargets.contains(target);
+    }
+
     @Override
     public String getDescription() {
         return sampler.getDescription();