}

    /**
     * Safely registers a class with Kryo, logging any registration failures at WARN level.
     * <p>
     * This method catches exceptions for individual class registrations to ensure
     * that a failure to register one class doesn't prevent other classes from being registered.
     * Registration failures are logged at WARN level since they may cause serialization errors later.
     * </p>
     *

 */
public class RankFusionProcessorConcurrencyTest extends UnitFessTestCase {

    private static final String ID_FIELD = "_id";

    /**
     * Test concurrent registration of searchers from multiple threads.
     * Verifies that CopyOnWriteArrayList handles concurrent modifications safely.
     */
    @Test
    public void test_concurrentSearcherRegistration() throws Exception {

    }

    // ========== Security Tests ==========

    /**
     * Security test: Verify that unregistered classes are rejected during serialization.
     * This test ensures that the Kryo registration requirement is working correctly.
     * Unregistered classes should throw an exception to prevent potential RCE attacks.
     */
    @Test
    public void test_security_unregisteredClassRejected() {

        BoostQueryCommand newCommand = new BoostQueryCommand();
        newCommand.register();

        // Create a test BoostQuery to verify registration
        Term term = new Term("test", "register");
        TermQuery termQuery = new TermQuery(term);
        BoostQuery boostQuery = new BoostQuery(termQuery, 1.0f);

        assertSame(dataStore, dataStoreFactory.getDataStore("MYSTORE"));
        assertSame(dataStore, dataStoreFactory.getDataStore("mYsToRe"));
    }

    // Test multiple data store registration
    @Test
    public void test_multipleDataStores() {
        TestDataStore dataStore1 = new TestDataStore("Store1");
        TestDataStore2 dataStore2 = new TestDataStore2("Store2");

        for (final LlmClient client : clientList) {
            if (llmType.equals(client.getName())) {
                if (logger.isTraceEnabled()) {
                    logger.trace("[LLM] LlmClient found via registration. name={}", client.getName());
                }
                return client;
            }
        }
        logger.warn("[LLM] LlmClient not found. componentName={}", name);
        return null;
    }

import com.fasterxml.jackson.databind.ObjectMapper;

import jakarta.annotation.PostConstruct;
import jakarta.annotation.PreDestroy;

/**
 * Helper for inter-instance coordination via OpenSearch.
 * Provides heartbeat registration, distributed operation locking, and event notification
 * to prevent concurrent execution of maintenance operations across multiple Fess instances.
 */
public class CoordinatorHelper {