fix bug on local index reader with generateLocalIndexDateHash

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

Author: ansjcy

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

@@ -207,7 +207,8 @@ public void close() {
      * @return A string representing the index name in the format "top_queries-YYYY.MM.dd-01234".
      */
     String buildLocalIndexName() {
-        return indexPattern.format(ZonedDateTime.now(ZoneOffset.UTC)) + "-" + generateLocalIndexDateHash();
+        ZonedDateTime currentTime = ZonedDateTime.now(ZoneOffset.UTC);
+        return indexPattern.format(currentTime) + "-" + generateLocalIndexDateHash(currentTime.toLocalDate());
     }
 
     /**

src/main/java/org/opensearch/plugin/insights/core/reader/LocalIndexReader.java

@@ -154,6 +154,6 @@ public void close() {
     }
 
     private String buildLocalIndexName(ZonedDateTime current) {
-        return current.format(indexPattern) + "-" + generateLocalIndexDateHash();
+        return current.format(indexPattern) + "-" + generateLocalIndexDateHash(current.toLocalDate());
     }
 }

src/main/java/org/opensearch/plugin/insights/core/utils/ExporterReaderUtils.java

@@ -8,8 +8,7 @@
 
 package org.opensearch.plugin.insights.core.utils;
 
-import java.time.Instant;
-import java.time.ZoneOffset;
+import java.time.LocalDate;
 import java.time.format.DateTimeFormatter;
 import java.util.Locale;
 
@@ -22,17 +21,16 @@ public class ExporterReaderUtils {
     private ExporterReaderUtils() {}
 
     /**
-     * Generates a consistent 5-digit numeric hash based on the current UTC date.
+     * Generates a consistent 5-digit numeric hash based on the given UTC date.
      * The generated hash is deterministic, meaning it will return the same result for the same date.
      *
      * @return A 5-digit numeric string representation of the current date's hash.
      */
-    public static String generateLocalIndexDateHash() {
-        // Get the current date in UTC (yyyy-MM-dd format)
-        String currentDate = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.ROOT)
-            .format(Instant.now().atOffset(ZoneOffset.UTC).toLocalDate());
+    public static String generateLocalIndexDateHash(LocalDate date) {
+        // Get the date string in UTC (yyyy-MM-dd format)
+        String dateString = DateTimeFormatter.ofPattern("yyyy-MM-dd", Locale.ROOT).format(date);
 
         // Generate a 5-digit numeric hash from the date's hashCode
-        return String.format(Locale.ROOT, "%05d", (currentDate.hashCode() % 100000 + 100000) % 100000);
+        return String.format(Locale.ROOT, "%05d", (dateString.hashCode() % 100000 + 100000) % 100000);
     }
 }

src/test/java/org/opensearch/plugin/insights/core/exporter/LocalIndexExporterTests.java

@@ -67,7 +67,9 @@ public class LocalIndexExporterTests extends OpenSearchTestCase {
 
     @Before
     public void setup() {
-        indexName = format.format(ZonedDateTime.now(ZoneOffset.UTC)) + "-" + generateLocalIndexDateHash();
+        indexName = format.format(ZonedDateTime.now(ZoneOffset.UTC))
+            + "-"
+            + generateLocalIndexDateHash(ZonedDateTime.now(ZoneOffset.UTC).toLocalDate());
         Settings.Builder settingsBuilder = Settings.builder();
         Settings settings = settingsBuilder.build();
         ClusterSettings clusterSettings = new ClusterSettings(settings, ClusterSettings.BUILT_IN_CLUSTER_SETTINGS);

src/test/java/org/opensearch/plugin/insights/core/service/QueryInsightsServiceTests.java

@@ -25,6 +25,8 @@
 import static org.opensearch.plugin.insights.core.utils.ExporterReaderUtils.generateLocalIndexDateHash;
 
 import java.time.Instant;
+import java.time.ZoneId;
+import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatter;
 import java.time.temporal.ChronoUnit;
 import java.util.HashMap;
@@ -257,7 +259,10 @@ public void testDeleteAllTopNIndices() {
         // Create 9 top_queries-* indices
         Map<String, IndexMetadata> indexMetadataMap = new HashMap<>();
         for (int i = 1; i < 10; i++) {
-            String indexName = "top_queries-2024.01.0" + i + "-" + generateLocalIndexDateHash();
+            String indexName = "top_queries-2024.01.0"
+                + i
+                + "-"
+                + generateLocalIndexDateHash(ZonedDateTime.of(2024, 1, i, 0, 0, 0, 0, ZoneId.of("UTC")).toLocalDate());
             long creationTime = Instant.now().minus(i, ChronoUnit.DAYS).toEpochMilli();
 
             IndexMetadata indexMetadata = IndexMetadata.builder(indexName)