Increase JavaDoc coverage and update PR based comments

Signed-off-by: Chenyang Ji <cyji@amazon.com>

gradle/missing-javadoc.gradle

@@ -141,7 +141,6 @@ configure([
   project(":plugins:mapper-annotated-text"),
   project(":plugins:mapper-murmur3"),
   project(":plugins:mapper-size"),
-  project(":plugins:query-insights"),
   project(":plugins:repository-azure"),
   project(":plugins:repository-gcs"),
   project(":plugins:repository-hdfs"),

plugins/query-insights/src/main/java/org/opensearch/plugin/insights/core/exporter/QueryInsightsExporter.java

@@ -20,11 +20,9 @@
  * @opensearch.internal
  */
 public abstract class QueryInsightsExporter<T extends SearchQueryRecord<?>> {
-    private QueryInsightsExporterType type;
-    private String identifier;
+    private final String identifier;
 
-    QueryInsightsExporter(QueryInsightsExporterType type, String identifier) {
-        this.type = type;
+    QueryInsightsExporter(String identifier) {
         this.identifier = identifier;
     }
 
@@ -35,18 +33,10 @@ public abstract class QueryInsightsExporter<T extends SearchQueryRecord<?>> {
      */
     public abstract void export(List<T> records) throws Exception;
 
-    public void setType(QueryInsightsExporterType type) {
-        this.type = type;
-    }
-
-    public QueryInsightsExporterType getType() {
-        return type;
-    }
-
-    public void setIdentifier(String identifier) {
-        this.identifier = identifier;
-    }
-
+    /**
+     * Get the identifier of this exporter
+     * @return identifier of this exporter
+     */
     public String getIdentifier() {
         return identifier;
     }

plugins/query-insights/src/main/java/org/opensearch/plugin/insights/core/exporter/QueryInsightsExporterType.java

@@ -16,15 +16,19 @@
  * @opensearch.internal
  */
 public enum QueryInsightsExporterType {
-    /* local index exporter */
-    LOCAL_INDEX("local_index");
+    /** local index exporter */
+    LOCAL_INDEX;
 
-    private final String type;
-
-    QueryInsightsExporterType(String type) {
-        this.type = type;
+    @Override
+    public String toString() {
+        return super.toString().toLowerCase(Locale.ROOT);
     }
 
+    /**
+     * Parse QueryInsightsExporterType from String
+     * @param type the String representation of the QueryInsightsExporterType
+     * @return QueryInsightsExporterType
+     */
     public static QueryInsightsExporterType parse(String type) {
         return valueOf(type.toUpperCase(Locale.ROOT));
     }

plugins/query-insights/src/main/java/org/opensearch/plugin/insights/core/exporter/QueryInsightsLocalIndexExporter.java

@@ -51,13 +51,20 @@ public class QueryInsightsLocalIndexExporter<T extends SearchQueryRecord<?>> ext
     /** The mapping for the local index that holds the data */
     private final InputStream localIndexMapping;
 
+    /**
+     * Create a QueryInsightsLocalIndexExporter Object
+     * @param clusterService The clusterService of the node
+     * @param client The OpenSearch Client to support index operations
+     * @param localIndexName The local index name to export the data to
+     * @param localIndexMapping The mapping for the local index
+     */
     public QueryInsightsLocalIndexExporter(
         ClusterService clusterService,
         Client client,
         String localIndexName,
         InputStream localIndexMapping
     ) {
-        super(QueryInsightsExporterType.LOCAL_INDEX, localIndexName);
+        super(localIndexName);
         this.clusterService = clusterService;
         this.client = client;
         this.localIndexMapping = localIndexMapping;
@@ -70,42 +77,35 @@ public QueryInsightsLocalIndexExporter(
      * @throws IOException if an error occurs
      */
     @Override
-    public synchronized void export(List<T> records) throws IOException {
+    public void export(List<T> records) throws IOException {
         if (records.size() == 0) {
             return;
         }
-        if (checkIfIndexExists()) {
-            bulkRecord(records);
-        } else {
-            // local index not exist
-            initLocalIndex(new ActionListener<>() {
-                @Override
-                public void onResponse(CreateIndexResponse response) {
-                    if (response.isAcknowledged()) {
-                        log.debug(
-                            String.format(Locale.ROOT, "successfully initialized local index %s for query insight.", getIdentifier())
-                        );
-                        try {
-                            bulkRecord(records);
-                        } catch (IOException e) {
-                            log.error(String.format(Locale.ROOT, "fail to ingest query insight data to local index, error: %s", e));
-                        }
-                    } else {
-                        log.error(
-                            String.format(
-                                Locale.ROOT,
-                                "request to created local index %s for query insight not acknowledged.",
-                                getIdentifier()
-                            )
-                        );
+        boolean indexExists = checkAndInitLocalIndex(new ActionListener<>() {
+            @Override
+            public void onResponse(CreateIndexResponse response) {
+                if (response.isAcknowledged()) {
+                    log.debug(String.format(Locale.ROOT, "successfully initialized local index %s for query insight.", getIdentifier()));
+                    try {
+                        bulkRecord(records);
+                    } catch (IOException e) {
+                        log.error(String.format(Locale.ROOT, "fail to ingest query insight data to local index, error: %s", e));
                     }
+                } else {
+                    log.error(
+                        String.format(Locale.ROOT, "request to created local index %s for query insight not acknowledged.", getIdentifier())
+                    );
                 }
+            }
 
-                @Override
-                public void onFailure(Exception e) {
-                    log.error(String.format(Locale.ROOT, "error creating local index for query insight: %s", e));
-                }
-            });
+            @Override
+            public void onFailure(Exception e) {
+                log.error(String.format(Locale.ROOT, "error creating local index for query insight: %s", e));
+            }
+        });
+
+        if (indexExists) {
+            bulkRecord(records);
         }
     }
 
@@ -120,15 +120,21 @@ private boolean checkIfIndexExists() {
     }
 
     /**
-     * Initialize the local OpenSearch Index for the exporter
+     * Check and initialize the local OpenSearch Index for the exporter
      *
      * @param listener the listener to be notified upon completion
+     * @return boolean to represent if the index has already been created before calling this function
      * @throws IOException if an error occurs
      */
-    private synchronized void initLocalIndex(ActionListener<CreateIndexResponse> listener) throws IOException {
-        CreateIndexRequest createIndexRequest = new CreateIndexRequest(this.getIdentifier()).mapping(getIndexMappings())
-            .settings(Settings.builder().put("index.hidden", false).build());
-        client.admin().indices().create(createIndexRequest, listener);
+    private synchronized boolean checkAndInitLocalIndex(ActionListener<CreateIndexResponse> listener) throws IOException {
+        if (!checkIfIndexExists()) {
+            CreateIndexRequest createIndexRequest = new CreateIndexRequest(this.getIdentifier()).mapping(getIndexMappings())
+                .settings(Settings.builder().put("index.hidden", false).build());
+            client.admin().indices().create(createIndexRequest, listener);
+            return false;
+        } else {
+            return true;
+        }
     }
 
     /**

plugins/query-insights/src/main/java/org/opensearch/plugin/insights/core/listener/SearchQueryLatencyListener.java

@@ -43,6 +43,12 @@ public final class SearchQueryLatencyListener extends SearchRequestOperationsLis
 
     private final TopQueriesByLatencyService topQueriesByLatencyService;
 
+    /**
+     * Constructor for SearchQueryLatencyListener
+     *
+     * @param clusterService The Node's cluster service.
+     * @param topQueriesByLatencyService The topQueriesByLatencyService associated with this listener
+     */
     @Inject
     public SearchQueryLatencyListener(ClusterService clusterService, TopQueriesByLatencyService topQueriesByLatencyService) {
         this.topQueriesByLatencyService = topQueriesByLatencyService;

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

@@ -46,7 +46,7 @@ public abstract class QueryInsightsService<R extends SearchQueryRecord<?>, S ext
     /** enable insight data export */
     private boolean enableExport;
 
-    /** The internal store that holds the query insight data */
+    /** The internal thread-safe store that holds the query insight data */
     @Nullable
     protected S store;
 
@@ -59,8 +59,19 @@ public abstract class QueryInsightsService<R extends SearchQueryRecord<?>, S ext
 
     /** The internal OpenSearch thread pool that execute async processing and exporting tasks*/
     protected final ThreadPool threadPool;
+
+    /**
+     * Holds a reference to delayed operation {@link Scheduler.Cancellable} so it can be cancelled when
+     * the service closed concurrently.
+     */
     protected volatile Scheduler.Cancellable scheduledFuture;
 
+    /**
+     * Create the Query Insights Service object
+     * @param threadPool The OpenSearch thread pool to run async tasks
+     * @param store The in memory store to keep the Query Insights data
+     * @param exporter The optional {@link QueryInsightsExporter} to export the Query Insights data
+     */
     @Inject
     public QueryInsightsService(ThreadPool threadPool, @Nullable S store, @Nullable E exporter) {
         this.threadPool = threadPool;
@@ -102,7 +113,13 @@ public List<R> getQueryData() throws IllegalArgumentException {
     public abstract void clearOutdatedData();
 
     /**
-     * Restart the exporter with new config
+     * Reset the exporter with new config
+     *
+     * This function can be used to enable/disable an exporter, change the type of the exporter,
+     * or change the identifier of the exporter.
+     * @param enabled the enable flag to set on the exporter
+     * @param type The QueryInsightsExporterType to set on the exporter
+     * @param identifier the Identifier to set on the exporter
      */
     public abstract void resetExporter(boolean enabled, QueryInsightsExporterType type, String identifier);
 
@@ -113,18 +130,34 @@ public void clearAllData() {
         store.clear();
     }
 
+    /**
+     * Set flag to enable or disable Query Insights data collection
+     * @param enableCollect Flag to enable or disable Query Insights data collection
+     */
     public void setEnableCollect(boolean enableCollect) {
         this.enableCollect = enableCollect;
     }
 
+    /**
+     * Get if the Query Insights data collection is enabled
+     * @return if the Query Insights data collection is enabled
+     */
     public boolean getEnableCollect() {
         return this.enableCollect;
     }
 
+    /**
+     * Set flag to enable or disable Query Insights data export
+     * @param enableExport
+     */
     public void setEnableExport(boolean enableExport) {
         this.enableExport = enableExport;
     }
 
+    /**
+     * Get if the Query Insights data export is enabled
+     * @return if the Query Insights data export is enabled
+     */
     public boolean getEnableExport() {
         return this.enableExport;
     }
@@ -156,7 +189,6 @@ private void doExport() {
         List<R> storedData = getQueryData();
         try {
             exporter.export(storedData);
-            log.debug(String.format(Locale.ROOT, "finish exporting query insight data to sink %s", storedData));
         } catch (Exception e) {
             throw new RuntimeException(String.format(Locale.ROOT, "failed to export query insight data to sink, error: %s", e));
         }
@@ -165,6 +197,10 @@ private void doExport() {
     @Override
     protected void doClose() {}
 
+    /**
+     * Get the export interval set for the {@link QueryInsightsExporter}
+     * @return export interval
+     */
     public TimeValue getExportInterval() {
         return exportInterval;
     }