From a177b2b46639f03315ec7d704acae45a1db94b22 Mon Sep 17 00:00:00 2001
From: "tim.quinn@oracle.com" <tim.quinn@oracle.com>
Date: Mon, 12 Apr 2021 06:01:07 -0500
Subject: [PATCH] Review comments: use common service loader with priority
 ordering

---
 metrics/metrics/pom.xml                           |  4 ++++
 .../helidon/metrics/ExemplarServiceManager.java   | 15 ++++-----------
 .../helidon/metrics/TestNearestValueSearch.java   | 14 +++++++-------
 3 files changed, 15 insertions(+), 18 deletions(-)

diff --git a/metrics/metrics/pom.xml b/metrics/metrics/pom.xml
index 04168c8aac1..44a4afafaad 100644
--- a/metrics/metrics/pom.xml
+++ b/metrics/metrics/pom.xml
@@ -46,6 +46,10 @@
             <groupId>io.helidon.config</groupId>
             <artifactId>helidon-config-mp</artifactId>
         </dependency>
+        <dependency>
+            <groupId>io.helidon.common</groupId>
+            <artifactId>helidon-common-service-loader</artifactId>
+        </dependency>
         <dependency>
             <groupId>org.eclipse.microprofile.metrics</groupId>
             <artifactId>microprofile-metrics-api</artifactId>
diff --git a/metrics/metrics/src/main/java/io/helidon/metrics/ExemplarServiceManager.java b/metrics/metrics/src/main/java/io/helidon/metrics/ExemplarServiceManager.java
index 80abaf907f1..d71d19e02fb 100644
--- a/metrics/metrics/src/main/java/io/helidon/metrics/ExemplarServiceManager.java
+++ b/metrics/metrics/src/main/java/io/helidon/metrics/ExemplarServiceManager.java
@@ -16,6 +16,8 @@
  */
 package io.helidon.metrics;
 
+import io.helidon.common.serviceloader.HelidonServiceLoader;
+
 import java.util.Comparator;
 import java.util.List;
 import java.util.ServiceLoader;
@@ -36,6 +38,7 @@ class ExemplarServiceManager {
 
     private static final List<ExemplarService> EXEMPLAR_SERVICES = collectExemplarServices();
 
+
     private static final Supplier<String> EXEMPLAR_SUPPLIER = EXEMPLAR_SERVICES.isEmpty()
             ? () -> ""
             : () -> EXEMPLAR_SERVICES.stream()
@@ -57,21 +60,11 @@ static String exemplarLabel() {
 
     private static List<ExemplarService> collectExemplarServices() {
         List<ExemplarService> exemplarServices =
-            ServiceLoader.load(ExemplarService.class)
-                .stream()
-                .sorted(Comparator.comparing(ExemplarServiceManager::priorityValue))
-                .map(ServiceLoader.Provider::get)
-                .collect(Collectors.toList());
-
+            HelidonServiceLoader.create(ServiceLoader.load(ExemplarService.class)).asList();
         if (!exemplarServices.isEmpty()) {
             LOGGER.log(Level.INFO, "Using metrics ExemplarServices " + exemplarServices.toString());
         }
 
         return exemplarServices;
     }
-
-    private static int priorityValue(ServiceLoader.Provider<ExemplarService> exemplarSupportProvider) {
-        Priority p = exemplarSupportProvider.type().getAnnotation(Priority.class);
-        return p == null ? ExemplarService.DEFAULT_PRIORITY : p.value();
-    }
 }
diff --git a/metrics/metrics/src/test/java/io/helidon/metrics/TestNearestValueSearch.java b/metrics/metrics/src/test/java/io/helidon/metrics/TestNearestValueSearch.java
index a14b6e84a2c..7a7f04a7e36 100644
--- a/metrics/metrics/src/test/java/io/helidon/metrics/TestNearestValueSearch.java
+++ b/metrics/metrics/src/test/java/io/helidon/metrics/TestNearestValueSearch.java
@@ -23,7 +23,7 @@
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 
-public class TestNearestValueSearch {
+class TestNearestValueSearch {
 
     private static final WeightedSample[] VALUES = new WeightedSample[] {
             new WeightedSample(1L),
@@ -32,37 +32,37 @@ public class TestNearestValueSearch {
             new WeightedSample(7L)};
 
     @Test
-    public void testExactMatch() {
+    void testExactMatch() {
         assertThat("Exact match of 1", WeightedSnapshot.slotNear(derived(1.0), VALUES), is(0));
         assertThat("Exact match of 3", WeightedSnapshot.slotNear(derived(3.0), VALUES), is(1));
         assertThat("Exact match of 5", WeightedSnapshot.slotNear(derived(5.0), VALUES), is(2));
     }
 
     @Test
-    public void testBeforeFirst() {
+    void testBeforeFirst() {
         assertThat("Approx match before first element", WeightedSnapshot.slotNear(derived(0.5), VALUES), is(0));
     }
 
     @Test
-    public void testAfterLast() {
+    void testAfterLast() {
         assertThat("Approx match after last element", WeightedSnapshot.slotNear(derived(9.0), VALUES),
                 is(VALUES.length - 1));
     }
 
     @Test
-    public void testCloserToLower() {
+    void testCloserToLower() {
         assertThat("Closer to lowest", WeightedSnapshot.slotNear(derived(1.2), VALUES), is(0));
         assertThat("Closer to inside", WeightedSnapshot.slotNear(derived(3.2), VALUES), is(1));
     }
 
     @Test
-    public void testCloserToHigher() {
+    void testCloserToHigher() {
         assertThat("Closer to highest", WeightedSnapshot.slotNear(derived(6.5), VALUES), is(3));
         assertThat("Closer to inside", WeightedSnapshot.slotNear(derived(2.5), VALUES), is(1));
     }
 
     @Test
-    public void testMidpoint() {
+    void testMidpoint() {
         assertThat("Midpoint", WeightedSnapshot.slotNear(derived(2.0), VALUES), is(0));
     }
 }