From 99f96b25b90a5abee2d4d9618785c8bd32f041a1 Mon Sep 17 00:00:00 2001
From: raymond zhao <raymond.zhao@datadoghq.com>
Date: Wed, 11 Oct 2023 16:09:03 -0400
Subject: [PATCH] Add warning for duplicate instance name

---
 src/main/java/org/datadog/jmxfetch/App.java | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/main/java/org/datadog/jmxfetch/App.java b/src/main/java/org/datadog/jmxfetch/App.java
index ddb6f1de8..c131791c3 100644
--- a/src/main/java/org/datadog/jmxfetch/App.java
+++ b/src/main/java/org/datadog/jmxfetch/App.java
@@ -29,11 +29,13 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Set;
 import java.util.concurrent.CancellationException;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
@@ -828,6 +830,8 @@ public void init(final boolean forceNewConnection) {
         this.brokenInstanceMap.clear();
 
         final List<Instance> newInstances = new ArrayList<>();
+        // used to track instance names already seen
+        Set<String> instanceNames = new HashSet<String>();
 
         log.info("Dealing with YAML config instances...");
         final Iterator<Entry<String, YamlParser>> it = this.configs.entrySet().iterator();
@@ -867,7 +871,11 @@ public void init(final boolean forceNewConnection) {
                             isDirectInstance(configInstance));
                     continue;
                 }
-
+                final String instanceName = (String) configInstance.get("name");
+                if (instanceNames.contains(instanceName)) {
+                    log.warn("Instance with name: {} already exists", instanceName);
+                }
+                instanceNames.add(instanceName);
                 // Create a new Instance object
                 log.info("Instantiating instance for: {}", name);
                 final Instance instance =
@@ -893,6 +901,11 @@ public void init(final boolean forceNewConnection) {
                 final String checkName = (String) checkConfig.get("check_name");
                 for (Map<String, Object> configInstance : configInstances) {
                     log.info("Instantiating instance for: " + checkName);
+                    final String instanceName = (String) configInstance.get("name");
+                    if (instanceNames.contains(instanceName)) {
+                        log.warn("Instance with name: {} already exists", instanceName);
+                    }
+                    instanceNames.add(instanceName);
                     final Instance instance =
                             instantiate(configInstance, initConfig, checkName, this.appConfig);
                     newInstances.add(instance);