From c5fcc03bdfd50f2624ba0a3d39f0d5e5e856deef Mon Sep 17 00:00:00 2001
From: DENNIS <599166320@qq.com>
Date: Thu, 3 Nov 2022 18:50:27 +0800
Subject: [PATCH] PrometheusEmitter NullPointerException fix (#13286)

* PrometheusEmitter NullPointerException fix

* Improved null value judgment in pushMetric

* Delete meaningless judgments about namespace

* Delete unnecessary @Nullable above namespace attribute
---
 .../emitter/prometheus/PrometheusEmitter.java | 25 +++++++++----------
 .../prometheus/PrometheusEmitterConfig.java   |  1 -
 2 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitter.java b/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitter.java
index 8a9840191d6..c2909ec319f 100644
--- a/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitter.java
+++ b/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitter.java
@@ -57,7 +57,7 @@ public class PrometheusEmitter implements Emitter
 
   private HTTPServer server;
   private PushGateway pushGateway;
-  private String identifier;
+  private volatile String identifier;
   private ScheduledExecutorService exec;
 
   static PrometheusEmitter of(PrometheusEmitterConfig config)
@@ -170,27 +170,26 @@ public class PrometheusEmitter implements Emitter
 
   private void pushMetric()
   {
+    if (pushGateway == null || identifier == null) {
+      return;
+    }
     Map<String, DimensionsAndCollector> map = metrics.getRegisteredMetrics();
     CollectorRegistry metrics = new CollectorRegistry();
-    if (config.getNamespace() != null) {
-      try {
-        for (DimensionsAndCollector collector : map.values()) {
-          metrics.register(collector.getCollector());
-        }
-        pushGateway.push(metrics, config.getNamespace(), ImmutableMap.of(config.getNamespace(), identifier));
-      }
-      catch (IOException e) {
-        log.error(e, "Unable to push prometheus metrics to pushGateway");
+    try {
+      for (DimensionsAndCollector collector : map.values()) {
+        metrics.register(collector.getCollector());
       }
+      pushGateway.push(metrics, config.getNamespace(), ImmutableMap.of(config.getNamespace(), identifier));
+    }
+    catch (IOException e) {
+      log.error(e, "Unable to push prometheus metrics to pushGateway");
     }
   }
 
   @Override
   public void flush()
   {
-    if (pushGateway != null) {
-      pushMetric();
-    }
+    pushMetric();
   }
 
   @Override
diff --git a/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitterConfig.java b/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitterConfig.java
index ac4e15355ab..2dbbe5662bf 100644
--- a/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitterConfig.java
+++ b/extensions-contrib/prometheus-emitter/src/main/java/org/apache/druid/emitter/prometheus/PrometheusEmitterConfig.java
@@ -39,7 +39,6 @@ public class PrometheusEmitterConfig
   private final Strategy strategy;
 
   @JsonProperty
-  @Nullable
   private final String namespace;
 
   @JsonProperty