Improves ServiceNameCollector

Author: amarziali

internal-api/src/main/java/datadog/trace/api/remoteconfig/ServiceNameCollector.java

@@ -4,8 +4,10 @@
 
 import datadog.trace.api.Config;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import javax.annotation.Nullable;
 import org.slf4j.Logger;
@@ -17,6 +19,9 @@ public class ServiceNameCollector {
 
   private static final int MAX_EXTRA_SERVICE = Config.get().getRemoteConfigMaxExtraServices();
 
+  private static final String SERVICE_NAME_LOWERCASE =
+      Config.get().getServiceName().toLowerCase(Locale.ROOT);
+
   // This is not final to allow mocking it on tests
   private static ServiceNameCollector INSTANCE = new ServiceNameCollector();
 
@@ -48,14 +53,30 @@ public void addService(final String serviceName) {
       }
       return;
     }
-    if (!Config.get().getServiceName().equalsIgnoreCase(serviceName)) {
-      services.put(serviceName.toLowerCase(Locale.ROOT), serviceName);
-    }
+    services.put(serviceName, serviceName);
   }
 
+  /**
+   * Get the list of unique services deduplicated by case. There is no locking on the addService map
+   * so, the method is not thread safe.
+   *
+   * @return
+   */
   @Nullable
   public List<String> getServices() {
-    return services.isEmpty() ? null : new ArrayList<>(services.values());
+    if (services.isEmpty()) {
+      return null;
+    }
+    final Set<String> uniques = new HashSet<>(services.size());
+    // avoids reiterating again to convert a set to a list
+    final ArrayList<String> ret = new ArrayList<>(services.size());
+    for (String current : services.keySet()) {
+      String lowerCase = current.toLowerCase(Locale.ROOT);
+      if (!SERVICE_NAME_LOWERCASE.equals(lowerCase) && uniques.add(lowerCase)) {
+        ret.add(current);
+      }
+    }
+    return ret.isEmpty() ? null : ret;
   }
 
   public void clear() {