From 9b6389a5bf4506646329f3049406e33e72f06747 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20F=C4=85derski?= <daniel.faderski@allegro.pl>
Date: Tue, 29 Aug 2023 13:43:39 +0200
Subject: [PATCH] Add code refactor

---
 .../prometheus/PrometheusMetricsProvider.java |  9 ++----
 .../RestTemplatePrometheusClient.java         | 30 ++++++++++++-------
 2 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/PrometheusMetricsProvider.java b/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/PrometheusMetricsProvider.java
index 41f1cf6495..76ec258c2f 100644
--- a/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/PrometheusMetricsProvider.java
+++ b/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/PrometheusMetricsProvider.java
@@ -7,9 +7,6 @@
 import pl.allegro.tech.hermes.management.infrastructure.metrics.MonitoringTopicMetricsProvider;
 
 import java.util.List;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
 
 public class PrometheusMetricsProvider implements MonitoringSubscriptionMetricsProvider, MonitoringTopicMetricsProvider {
 
@@ -38,11 +35,9 @@ public PrometheusMetricsProvider(PrometheusClient prometheusClient, String consu
         this.prometheusClient = prometheusClient;
         this.consumersMetricsPrefix = consumersMetricsPrefix.isEmpty() ? "" : consumersMetricsPrefix + "_";
         this.frontendMetricsPrefix = frontendMetricsPrefix.isEmpty() ? "" : frontendMetricsPrefix + "_";
-        this.subscriptionMetricsToQuery = Stream.of(SUBSCRIPTION_DELIVERED, SUBSCRIPTION_TIMEOUTS,
+        this.subscriptionMetricsToQuery = String.join("|", List.of(SUBSCRIPTION_DELIVERED, SUBSCRIPTION_TIMEOUTS,
                         SUBSCRIPTION_THROUGHPUT, SUBSCRIPTION_OTHER_ERRORS, SUBSCRIPTION_BATCHES,
-                        SUBSCRIPTION_STATUS_CODES)
-                .map(this::consumerMetricName)
-                .collect(Collectors.joining("|"));
+                        SUBSCRIPTION_STATUS_CODES));
         this.topicMetricsToQuery = String.join("|", List.of(
                 frontendMetricName(TOPIC_RATE),
                 consumerMetricName(TOPIC_DELIVERY_RATE),
diff --git a/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/RestTemplatePrometheusClient.java b/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/RestTemplatePrometheusClient.java
index 6db0df643c..6dd658c699 100644
--- a/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/RestTemplatePrometheusClient.java
+++ b/hermes-management/src/main/java/pl/allegro/tech/hermes/management/infrastructure/prometheus/RestTemplatePrometheusClient.java
@@ -18,6 +18,7 @@
 import java.util.Map;
 import java.util.Optional;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import static java.net.URLEncoder.encode;
 
@@ -27,7 +28,6 @@ public class RestTemplatePrometheusClient implements PrometheusClient {
     private static final Logger logger = LoggerFactory.getLogger(RestTemplatePrometheusClient.class);
 
     private final URI prometheusUri;
-
     private final RestTemplate restTemplate;
 
     public RestTemplatePrometheusClient(RestTemplate restTemplate, URI prometheusUri) {
@@ -38,18 +38,11 @@ public RestTemplatePrometheusClient(RestTemplate restTemplate, URI prometheusUri
     @Override
     public MonitoringMetricsContainer readMetrics(String query) {
         try {
-            MonitoringMetricsContainer metricsContainer = MonitoringMetricsContainer.createEmpty();
             PrometheusResponse response = queryPrometheus(query);
             Preconditions.checkState(response.isSuccess(), "Prometheus response does not contain valid data");
 
-            Map<String, List<PrometheusResponse.Result>> metricsGroupedByName = response.data().results().stream()
-                    .map(RestTemplatePrometheusClient::remapNames)
-                    .collect(Collectors.groupingBy(r -> r.metricName().name()));
-            metricsGroupedByName.entrySet().stream()
-                    .map(RestTemplatePrometheusClient::sumResults)
-                    .forEach(pair -> metricsContainer.addMetricValue(pair.getKey(),
-                            MetricDecimalValue.of(pair.getValue().toString())));
-            return metricsContainer;
+            Map<String, List<PrometheusResponse.Result>> metricsGroupedByName = groupMetricsByName(response);
+            return produceMetricsContainer(metricsGroupedByName);
         } catch (Exception exception) {
             logger.warn("Unable to read from Prometheus...", exception);
             return MonitoringMetricsContainer.unavailable();
@@ -66,6 +59,23 @@ private PrometheusResponse queryPrometheus(String query) {
         return response.getBody();
     }
 
+    private static Map<String, List<PrometheusResponse.Result>> groupMetricsByName(PrometheusResponse response) {
+        return response.data().results().stream()
+                .map(RestTemplatePrometheusClient::remapNames)
+                .collect(Collectors.groupingBy(r -> r.metricName().name()));
+    }
+
+    private static MonitoringMetricsContainer produceMetricsContainer(Map<String, List<PrometheusResponse.Result>> metricsGroupedByName) {
+        MonitoringMetricsContainer metricsContainer = MonitoringMetricsContainer.createEmpty();
+
+        Stream<Pair<String, Double>> metricsSummedByName = metricsGroupedByName.entrySet().stream()
+                .map(RestTemplatePrometheusClient::sumResults);
+        metricsSummedByName.forEach(pair -> metricsContainer.addMetricValue(
+                pair.getKey(),
+                MetricDecimalValue.of(pair.getValue().toString())));
+        return metricsContainer;
+    }
+
     private static PrometheusResponse.Result remapNames(PrometheusResponse.Result r) {
         String suffix = "";
         if (r.metricName().is2xxStatusCode()) {