[Backport 2.x] Make sure listener is started when query metrics enabled

src/main/java/org/opensearch/plugin/insights/QueryInsightsPlugin.java

@@ -81,7 +81,7 @@ public Collection<Object> createComponents(
             client,
             metricsRegistry
         );
-        return List.of(queryInsightsService, new QueryInsightsListener(clusterService, queryInsightsService));
+        return List.of(queryInsightsService, new QueryInsightsListener(clusterService, queryInsightsService, false));
     }
 
     @Override

src/main/java/org/opensearch/plugin/insights/core/exporter/QueryInsightsExporterFactory.java

@@ -118,6 +118,7 @@ public QueryInsightsExporter updateExporter(QueryInsightsExporter exporter, Stri
      * Close an exporter
      *
      * @param exporter the exporter to close
+     * @throws IOException exception
      */
     public void closeExporter(QueryInsightsExporter exporter) throws IOException {
         if (exporter != null) {

src/main/java/org/opensearch/plugin/insights/core/listener/QueryInsightsListener.java

@@ -8,6 +8,7 @@
 
 package org.opensearch.plugin.insights.core.listener;
 
+import static org.opensearch.plugin.insights.settings.QueryCategorizationSettings.SEARCH_QUERY_METRICS_ENABLED_SETTING;
 import static org.opensearch.plugin.insights.settings.QueryInsightsSettings.getTopNEnabledSetting;
 import static org.opensearch.plugin.insights.settings.QueryInsightsSettings.getTopNSizeSetting;
 import static org.opensearch.plugin.insights.settings.QueryInsightsSettings.getTopNWindowSizeSetting;
@@ -56,10 +57,27 @@ public final class QueryInsightsListener extends SearchRequestOperationsListener
      */
     @Inject
     public QueryInsightsListener(final ClusterService clusterService, final QueryInsightsService queryInsightsService) {
+        this(clusterService, queryInsightsService, false);
+    }
+
+    /**
+     * Constructor for QueryInsightsListener
+     *
+     * @param clusterService       The Node's cluster service.
+     * @param queryInsightsService The topQueriesByLatencyService associated with this listener
+     * @param initiallyEnabled Is the listener initially enabled/disabled
+     */
+    public QueryInsightsListener(
+        final ClusterService clusterService,
+        final QueryInsightsService queryInsightsService,
+        boolean initiallyEnabled
+    ) {
+        super(initiallyEnabled);
         this.clusterService = clusterService;
         this.queryInsightsService = queryInsightsService;
-        // Setting endpoints set up for top n queries, including enabling top n queries, window size and top n size
-        // Expected metricTypes are Latency, CPU and Memory.
+
+        // Setting endpoints set up for top n queries, including enabling top n queries, window size, and top n size
+        // Expected metricTypes are Latency, CPU, and Memory.
         for (MetricType type : MetricType.allMetricTypes()) {
             clusterService.getClusterSettings()
                 .addSettingsUpdateConsumer(getTopNEnabledSetting(type), v -> this.setEnableTopQueries(type, v));
@@ -82,31 +100,48 @@ public QueryInsightsListener(final ClusterService clusterService, final QueryIns
             this.queryInsightsService.validateWindowSize(type, clusterService.getClusterSettings().get(getTopNWindowSizeSetting(type)));
             this.queryInsightsService.setWindowSize(type, clusterService.getClusterSettings().get(getTopNWindowSizeSetting(type)));
         }
+
+        clusterService.getClusterSettings()
+            .addSettingsUpdateConsumer(SEARCH_QUERY_METRICS_ENABLED_SETTING, v -> setSearchQueryMetricsEnabled(v));
+        setSearchQueryMetricsEnabled(clusterService.getClusterSettings().get(SEARCH_QUERY_METRICS_ENABLED_SETTING));
     }
 
     /**
-     * Enable or disable top queries insights collection for {@link MetricType}
+     * Enable or disable top queries insights collection for {@link MetricType}.
      * This function will enable or disable the corresponding listeners
      * and query insights services.
      *
      * @param metricType {@link MetricType}
      * @param isCurrentMetricEnabled boolean
      */
     public void setEnableTopQueries(final MetricType metricType, final boolean isCurrentMetricEnabled) {
-        boolean isTopNFeaturePreviouslyDisabled = !queryInsightsService.isTopNFeatureEnabled();
         this.queryInsightsService.enableCollection(metricType, isCurrentMetricEnabled);
-        boolean isTopNFeatureCurrentlyDisabled = !queryInsightsService.isTopNFeatureEnabled();
+        updateQueryInsightsState();
+    }
 
-        if (isTopNFeatureCurrentlyDisabled) {
-            super.setEnabled(false);
-            if (!isTopNFeaturePreviouslyDisabled) {
-                queryInsightsService.checkAndStopQueryInsights();
-            }
-        } else {
+    /**
+     * Set search query metrics enabled to enable collection of search query categorization metrics.
+     * @param searchQueryMetricsEnabled boolean flag
+     */
+    public void setSearchQueryMetricsEnabled(boolean searchQueryMetricsEnabled) {
+        this.queryInsightsService.enableSearchQueryMetricsFeature(searchQueryMetricsEnabled);
+        updateQueryInsightsState();
+    }
+
+    /**
+     * Update the query insights service state based on the enabled features.
+     * If any feature is enabled, it starts the service. If no features are enabled, it stops the service.
+     */
+    private void updateQueryInsightsState() {
+        boolean anyFeatureEnabled = queryInsightsService.isAnyFeatureEnabled();
+
+        if (anyFeatureEnabled && !super.isEnabled()) {
             super.setEnabled(true);
-            if (isTopNFeaturePreviouslyDisabled) {
-                queryInsightsService.checkAndRestartQueryInsights();
-            }
+            queryInsightsService.stop(); // Ensures a clean restart
+            queryInsightsService.start();
+        } else if (!anyFeatureEnabled && super.isEnabled()) {
+            super.setEnabled(false);
+            queryInsightsService.stop();
         }
     }
 

src/main/java/org/opensearch/plugin/insights/core/service/QueryInsightsService.java

@@ -8,7 +8,6 @@
 
 package org.opensearch.plugin.insights.core.service;
 
-import static org.opensearch.plugin.insights.settings.QueryCategorizationSettings.SEARCH_QUERY_METRICS_ENABLED_SETTING;
 import static org.opensearch.plugin.insights.settings.QueryInsightsSettings.getExporterSettings;
 
 import java.io.IOException;
@@ -111,15 +110,15 @@ public QueryInsightsService(
             );
         }
 
-        this.searchQueryMetricsEnabled = clusterSettings.get(SEARCH_QUERY_METRICS_ENABLED_SETTING);
         this.searchQueryCategorizer = SearchQueryCategorizer.getInstance(metricsRegistry);
-        clusterSettings.addSettingsUpdateConsumer(SEARCH_QUERY_METRICS_ENABLED_SETTING, this::setSearchQueryMetricsEnabled);
+        this.enableSearchQueryMetricsFeature(false);
     }
 
     /**
      * Ingest the query data into in-memory stores
      *
      * @param record the record to ingest
+     * @return SearchQueryRecord
      */
     public boolean addRecord(final SearchQueryRecord record) {
         boolean shouldAdd = searchQueryMetricsEnabled;
@@ -228,22 +227,11 @@ public boolean isSearchQueryMetricsFeatureEnabled() {
     }
 
     /**
-     * Stops query insights service if no features enabled
+     * Enable/Disable search query metrics feature.
+     * @param enable enable/disable search query metrics feature
      */
-    public void checkAndStopQueryInsights() {
-        if (!isAnyFeatureEnabled()) {
-            this.stop();
-        }
-    }
-
-    /**
-     * Restarts query insights service if any feature enabled
-     */
-    public void checkAndRestartQueryInsights() {
-        if (isAnyFeatureEnabled()) {
-            this.stop();
-            this.start();
-        }
+    public void enableSearchQueryMetricsFeature(boolean enable) {
+        searchQueryMetricsEnabled = enable;
     }
 
     /**
@@ -306,24 +294,6 @@ public void setExporter(final MetricType type, final Settings settings) {
         }
     }
 
-    /**
-     * Set search query metrics enabled to enable collection of search query categorization metrics
-     * @param searchQueryMetricsEnabled boolean flag
-     */
-    public void setSearchQueryMetricsEnabled(boolean searchQueryMetricsEnabled) {
-        boolean oldSearchQueryMetricsEnabled = isSearchQueryMetricsFeatureEnabled();
-        this.searchQueryMetricsEnabled = searchQueryMetricsEnabled;
-        if (searchQueryMetricsEnabled) {
-            if (!oldSearchQueryMetricsEnabled) {
-                checkAndRestartQueryInsights();
-            }
-        } else {
-            if (oldSearchQueryMetricsEnabled) {
-                checkAndStopQueryInsights();
-            }
-        }
-    }
-
     /**
      * Get search query categorizer object
      * @return SearchQueryCategorizer object

src/main/java/org/opensearch/plugin/insights/core/service/TopQueriesService.java

@@ -363,6 +363,7 @@ public List<SearchQueryRecord> getTopQueriesCurrentSnapshot() {
 
     /**
      * Close the top n queries service
+     * @throws IOException exception
      */
     public void close() throws IOException {
         queryInsightsExporterFactory.closeExporter(this.exporter);

src/main/java/org/opensearch/plugin/insights/rules/action/top_queries/TopQueriesRequest.java

@@ -46,6 +46,7 @@ public TopQueriesRequest(final MetricType metricType, final String... nodesIds)
 
     /**
      * Get the type of requested metrics
+     * @return MetricType for current top query service
      */
     public MetricType getMetricType() {
         return metricType;

src/main/java/org/opensearch/plugin/insights/rules/model/Attribute.java

@@ -85,6 +85,7 @@ static void writeTo(final StreamOutput out, final Attribute attribute) throws IO
      *
      * @param out            the StreamOutput to write
      * @param attributeValue the Attribute value to write
+     * @throws IOException exception
      */
     @SuppressWarnings("unchecked")
     public static void writeValueTo(StreamOutput out, Object attributeValue) throws IOException {