Add query shape hash method (#64) (#78)

(cherry picked from commit 1f4c4c6)

Signed-off-by: David Zane <davizane@amazon.com>
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: opensearch-trigger-bot[bot]

src/main/java/org/opensearch/plugin/insights/core/service/categorizer/QueryShapeGenerator.java

@@ -14,6 +14,8 @@
 import java.util.List;
 import java.util.Map;
 import java.util.function.Function;
+import org.apache.lucene.util.BytesRef;
+import org.opensearch.common.hash.MurmurHash3;
 import org.opensearch.core.common.io.stream.NamedWriteable;
 import org.opensearch.index.query.AbstractGeometryQueryBuilder;
 import org.opensearch.index.query.CommonTermsQueryBuilder;
@@ -76,6 +78,18 @@ public class QueryShapeGenerator {
     static final Map<Class<?>, List<Function<Object, String>>> AGG_FIELD_DATA_MAP = FieldDataMapHelper.getAggFieldDataMap();
     static final Map<Class<?>, List<Function<Object, String>>> SORT_FIELD_DATA_MAP = FieldDataMapHelper.getSortFieldDataMap();
 
+    /**
+     * Method to get query shape hash code given a source
+     * @param source search request source
+     * @param showFields whether to include field data in query shape
+     * @return Hash code of query shape as a MurmurHash3.Hash128 object (128-bit)
+     */
+    public static MurmurHash3.Hash128 getShapeHashCode(SearchSourceBuilder source, Boolean showFields) {
+        final String shape = buildShape(source, showFields);
+        final BytesRef shapeBytes = new BytesRef(shape);
+        return MurmurHash3.hash128(shapeBytes.bytes, 0, shapeBytes.length, 0, new MurmurHash3.Hash128());
+    }
+
     /**
      * Method to build search query shape given a source
      * @param source search request source