Add retry mechanism for neural search inference.

src/main/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessor.java

@@ -25,6 +25,7 @@
 import org.opensearch.ml.common.output.model.ModelTensor;
 import org.opensearch.ml.common.output.model.ModelTensorOutput;
 import org.opensearch.ml.common.output.model.ModelTensors;
+import org.opensearch.neuralsearch.util.RetryUtil;
 
 /**
  * This class will act as an abstraction on the MLCommons client for accessing the ML Capabilities
@@ -98,13 +99,30 @@ public void inferenceSentences(
         @NonNull final String modelId,
         @NonNull final List<String> inputText,
         @NonNull final ActionListener<List<List<Float>>> listener
+    ) {
+        inferenceSentencesWithRetry(targetResponseFilters, modelId, inputText, 0, listener);
+    }
+
+    private void inferenceSentencesWithRetry(
+        final List<String> targetResponseFilters,
+        final String modelId,
+        final List<String> inputText,
+        final int retryTime,
+        final ActionListener<List<List<Float>>> listener
     ) {
         MLInput mlInput = createMLInput(targetResponseFilters, inputText);
         mlClient.predict(modelId, mlInput, ActionListener.wrap(mlOutput -> {
             final List<List<Float>> vector = buildVectorFromResponse(mlOutput);
             log.debug("Inference Response for input sentence {} is : {} ", inputText, vector);
             listener.onResponse(vector);
-        }, listener::onFailure));
+        }, e -> {
+            if (RetryUtil.shouldRetry(e, retryTime)) {
+                final int retryTimeAdd = retryTime + 1;
+                inferenceSentencesWithRetry(targetResponseFilters, modelId, inputText, retryTimeAdd, listener);
+            } else {
+                listener.onFailure(e);
+            }
+        }));
     }
 
     private MLInput createMLInput(final List<String> targetResponseFilters, List<String> inputText) {

src/main/java/org/opensearch/neuralsearch/util/RetryUtil.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.neuralsearch.util;
+
+import java.util.List;
+
+import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.opensearch.transport.NodeDisconnectedException;
+import org.opensearch.transport.NodeNotConnectedException;
+
+import com.google.common.collect.ImmutableList;
+
+public class RetryUtil {
+
+    private static final int MAX_RETRY = 3;
+
+    private static final List<Class<? extends Throwable>> RETRYABLE_EXCEPTIONS = ImmutableList.of(
+        NodeNotConnectedException.class,
+        NodeDisconnectedException.class
+    );
+
+    /**
+     *
+     * @param e {@link Exception} which is the exception received to check if retryable.
+     * @param retryTime {@link int} which is the current retried times.
+     * @return {@link boolean} which is the result of if current exception needs retry or not.
+     */
+    public static boolean shouldRetry(final Exception e, int retryTime) {
+        boolean hasRetryException = RETRYABLE_EXCEPTIONS.stream().anyMatch(x -> ExceptionUtils.indexOfThrowable(e, x) != -1);
+        return hasRetryException && retryTime < MAX_RETRY;
+    }
+
+}

src/test/java/org/opensearch/neuralsearch/ml/MLCommonsClientAccessorTests.java

@@ -5,6 +5,9 @@
 
 package org.opensearch.neuralsearch.ml;
 
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+
 import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -17,6 +20,7 @@
 import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
 import org.opensearch.action.ActionListener;
+import org.opensearch.cluster.node.DiscoveryNode;
 import org.opensearch.ml.client.MachineLearningNodeClient;
 import org.opensearch.ml.common.input.MLInput;
 import org.opensearch.ml.common.output.MLOutput;
@@ -26,6 +30,7 @@
 import org.opensearch.ml.common.output.model.ModelTensors;
 import org.opensearch.neuralsearch.constants.TestCommonConstants;
 import org.opensearch.test.OpenSearchTestCase;
+import org.opensearch.transport.NodeNotConnectedException;
 
 public class MLCommonsClientAccessorTests extends OpenSearchTestCase {
 
@@ -114,6 +119,47 @@ public void testInferenceSentences_whenExceptionFromMLClient_thenFailure() {
         Mockito.verifyNoMoreInteractions(resultListener);
     }
 
+    public void testInferenceSentences_whenNodeNotConnectedException_thenRetry_3Times() {
+        final NodeNotConnectedException nodeNodeConnectedException = new NodeNotConnectedException(
+            mock(DiscoveryNode.class),
+            "Node not connected"
+        );
+        Mockito.doAnswer(invocation -> {
+            final ActionListener<MLOutput> actionListener = invocation.getArgument(2);
+            actionListener.onFailure(nodeNodeConnectedException);
+            return null;
+        }).when(client).predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
+        accessor.inferenceSentences(
+            TestCommonConstants.TARGET_RESPONSE_FILTERS,
+            TestCommonConstants.MODEL_ID,
+            TestCommonConstants.SENTENCES_LIST,
+            resultListener
+        );
+
+        Mockito.verify(client, times(4))
+            .predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
+        Mockito.verify(resultListener).onFailure(nodeNodeConnectedException);
+    }
+
+    public void testInferenceSentences_whenNotConnectionException_thenNoRetry() {
+        final IllegalStateException illegalStateException = new IllegalStateException("Illegal state");
+        Mockito.doAnswer(invocation -> {
+            final ActionListener<MLOutput> actionListener = invocation.getArgument(2);
+            actionListener.onFailure(illegalStateException);
+            return null;
+        }).when(client).predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
+        accessor.inferenceSentences(
+            TestCommonConstants.TARGET_RESPONSE_FILTERS,
+            TestCommonConstants.MODEL_ID,
+            TestCommonConstants.SENTENCES_LIST,
+            resultListener
+        );
+
+        Mockito.verify(client, times(1))
+            .predict(Mockito.eq(TestCommonConstants.MODEL_ID), Mockito.isA(MLInput.class), Mockito.isA(ActionListener.class));
+        Mockito.verify(resultListener).onFailure(illegalStateException);
+    }
+
     private ModelTensorOutput createModelTensorOutput(final Float[] output) {
         final List<ModelTensors> tensorsList = new ArrayList<>();
         final List<ModelTensor> mlModelTensorList = new ArrayList<>();

src/test/java/org/opensearch/neuralsearch/processor/TextEmbeddingProcessorTests.java

@@ -17,6 +17,8 @@
 import java.util.function.BiConsumer;
 import java.util.function.Supplier;
 
+import lombok.SneakyThrows;
+
 import org.junit.Before;
 import org.mockito.InjectMocks;
 import org.mockito.Mock;
@@ -54,16 +56,17 @@ public void setup() {
         when(env.settings()).thenReturn(settings);
     }
 
-    private TextEmbeddingProcessor createInstance(List<List<Float>> vector) throws Exception {
+    @SneakyThrows
+    private TextEmbeddingProcessor createInstance(List<List<Float>> vector) {
         Map<String, Processor.Factory> registry = new HashMap<>();
         Map<String, Object> config = new HashMap<>();
         config.put(TextEmbeddingProcessor.MODEL_ID_FIELD, "mockModelId");
         config.put(TextEmbeddingProcessor.FIELD_MAP_FIELD, ImmutableMap.of("key1", "key1Mapped", "key2", "key2Mapped"));
-        TextEmbeddingProcessor processor = textEmbeddingProcessorFactory.create(registry, PROCESSOR_TAG, DESCRIPTION, config);
-        return processor;
+        return textEmbeddingProcessorFactory.create(registry, PROCESSOR_TAG, DESCRIPTION, config);
     }
 
-    public void testTextEmbeddingProcessConstructor_whenConfigMapError_throwIllegalArgumentException() throws Exception {
+    @SneakyThrows
+    public void testTextEmbeddingProcessConstructor_whenConfigMapError_throwIllegalArgumentException() {
         Map<String, Processor.Factory> registry = new HashMap<>();
         Map<String, Object> config = new HashMap<>();
         config.put(TextEmbeddingProcessor.MODEL_ID_FIELD, "mockModelId");
@@ -78,7 +81,8 @@ public void testTextEmbeddingProcessConstructor_whenConfigMapError_throwIllegalA
         }
     }
 
-    public void testTextEmbeddingProcessConstructor_whenConfigMapEmpty_throwIllegalArgumentException() throws Exception {
+    @SneakyThrows
+    public void testTextEmbeddingProcessConstructor_whenConfigMapEmpty_throwIllegalArgumentException() {
         Map<String, Processor.Factory> registry = new HashMap<>();
         Map<String, Object> config = new HashMap<>();
         config.put(TextEmbeddingProcessor.MODEL_ID_FIELD, "mockModelId");
@@ -89,7 +93,7 @@ public void testTextEmbeddingProcessConstructor_whenConfigMapEmpty_throwIllegalA
         }
     }
 
-    public void testExecute_successful() throws Exception {
+    public void testExecute_successful() {
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", "value1");
         sourceAndMetadata.put("key2", "value2");
@@ -108,7 +112,8 @@ public void testExecute_successful() throws Exception {
         verify(handler).accept(any(IngestDocument.class), isNull());
     }
 
-    public void testExecute_whenInferenceThrowInterruptedException_throwRuntimeException() throws Exception {
+    @SneakyThrows
+    public void testExecute_whenInferenceThrowInterruptedException_throwRuntimeException() {
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", "value1");
         sourceAndMetadata.put("key2", "value2");
@@ -127,7 +132,8 @@ public void testExecute_whenInferenceThrowInterruptedException_throwRuntimeExcep
         verify(handler).accept(isNull(), any(RuntimeException.class));
     }
 
-    public void testExecute_whenInferenceTextListEmpty_SuccessWithoutEmbedding() throws Exception {
+    @SneakyThrows
+    public void testExecute_whenInferenceTextListEmpty_SuccessWithoutEmbedding() {
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         IngestDocument ingestDocument = new IngestDocument(sourceAndMetadata, new HashMap<>());
         Map<String, Processor.Factory> registry = new HashMap<>();
@@ -144,7 +150,7 @@ public void testExecute_whenInferenceTextListEmpty_SuccessWithoutEmbedding() thr
         verify(handler).accept(any(IngestDocument.class), isNull());
     }
 
-    public void testExecute_withListTypeInput_successful() throws Exception {
+    public void testExecute_withListTypeInput_successful() {
         List<String> list1 = ImmutableList.of("test1", "test2", "test3");
         List<String> list2 = ImmutableList.of("test4", "test5", "test6");
         Map<String, Object> sourceAndMetadata = new HashMap<>();
@@ -165,7 +171,7 @@ public void testExecute_withListTypeInput_successful() throws Exception {
         verify(handler).accept(any(IngestDocument.class), isNull());
     }
 
-    public void testExecute_SimpleTypeWithEmptyStringValue_throwIllegalArgumentException() throws Exception {
+    public void testExecute_SimpleTypeWithEmptyStringValue_throwIllegalArgumentException() {
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", "    ");
         IngestDocument ingestDocument = new IngestDocument(sourceAndMetadata, new HashMap<>());
@@ -176,7 +182,7 @@ public void testExecute_SimpleTypeWithEmptyStringValue_throwIllegalArgumentExcep
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_listHasEmptyStringValue_throwIllegalArgumentException() throws Exception {
+    public void testExecute_listHasEmptyStringValue_throwIllegalArgumentException() {
         List<String> list1 = ImmutableList.of("", "test2", "test3");
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", list1);
@@ -188,7 +194,7 @@ public void testExecute_listHasEmptyStringValue_throwIllegalArgumentException()
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_listHasNonStringValue_throwIllegalArgumentException() throws Exception {
+    public void testExecute_listHasNonStringValue_throwIllegalArgumentException() {
         List<Integer> list2 = ImmutableList.of(1, 2, 3);
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key2", list2);
@@ -199,7 +205,7 @@ public void testExecute_listHasNonStringValue_throwIllegalArgumentException() th
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_listHasNull_throwIllegalArgumentException() throws Exception {
+    public void testExecute_listHasNull_throwIllegalArgumentException() {
         List<String> list = new ArrayList<>();
         list.add("hello");
         list.add(null);
@@ -213,7 +219,7 @@ public void testExecute_listHasNull_throwIllegalArgumentException() throws Excep
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_withMapTypeInput_successful() throws Exception {
+    public void testExecute_withMapTypeInput_successful() {
         Map<String, String> map1 = ImmutableMap.of("test1", "test2");
         Map<String, String> map2 = ImmutableMap.of("test4", "test5");
         Map<String, Object> sourceAndMetadata = new HashMap<>();
@@ -235,7 +241,7 @@ public void testExecute_withMapTypeInput_successful() throws Exception {
 
     }
 
-    public void testExecute_mapHasNonStringValue_throwIllegalArgumentException() throws Exception {
+    public void testExecute_mapHasNonStringValue_throwIllegalArgumentException() {
         Map<String, String> map1 = ImmutableMap.of("test1", "test2");
         Map<String, Double> map2 = ImmutableMap.of("test3", 209.3D);
         Map<String, Object> sourceAndMetadata = new HashMap<>();
@@ -248,7 +254,7 @@ public void testExecute_mapHasNonStringValue_throwIllegalArgumentException() thr
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_mapHasEmptyStringValue_throwIllegalArgumentException() throws Exception {
+    public void testExecute_mapHasEmptyStringValue_throwIllegalArgumentException() {
         Map<String, String> map1 = ImmutableMap.of("test1", "test2");
         Map<String, String> map2 = ImmutableMap.of("test3", "   ");
         Map<String, Object> sourceAndMetadata = new HashMap<>();
@@ -261,7 +267,7 @@ public void testExecute_mapHasEmptyStringValue_throwIllegalArgumentException() t
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_mapDepthReachLimit_throwIllegalArgumentException() throws Exception {
+    public void testExecute_mapDepthReachLimit_throwIllegalArgumentException() {
         Map<String, Object> ret = createMaxDepthLimitExceedMap(() -> 1);
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", "hello world");
@@ -273,7 +279,7 @@ public void testExecute_mapDepthReachLimit_throwIllegalArgumentException() throw
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testExecute_MLClientAccessorThrowFail_handlerFailure() throws Exception {
+    public void testExecute_MLClientAccessorThrowFail_handlerFailure() {
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", "value1");
         sourceAndMetadata.put("key2", "value2");
@@ -303,7 +309,7 @@ private Map<String, Object> createMaxDepthLimitExceedMap(Supplier<Integer> maxDe
         return innerMap;
     }
 
-    public void testExecute_hybridTypeInput_successful() throws Exception {
+    public void testExecute_hybridTypeInput_successful() {
         List<String> list1 = ImmutableList.of("test1", "test2");
         Map<String, List<String>> map1 = ImmutableMap.of("test3", list1);
         Map<String, Object> sourceAndMetadata = new HashMap<>();
@@ -314,7 +320,7 @@ public void testExecute_hybridTypeInput_successful() throws Exception {
         assert document.getSourceAndMetadata().containsKey("key2");
     }
 
-    public void testExecute_simpleTypeInputWithNonStringValue_handleIllegalArgumentException() throws Exception {
+    public void testExecute_simpleTypeInputWithNonStringValue_handleIllegalArgumentException() {
         Map<String, Object> sourceAndMetadata = new HashMap<>();
         sourceAndMetadata.put("key1", 100);
         sourceAndMetadata.put("key2", 100.232D);
@@ -331,7 +337,7 @@ public void testExecute_simpleTypeInputWithNonStringValue_handleIllegalArgumentE
         verify(handler).accept(isNull(), any(IllegalArgumentException.class));
     }
 
-    public void testGetType_successful() throws Exception {
+    public void testGetType_successful() {
         TextEmbeddingProcessor processor = createInstance(createMockVectorWithLength(2));
         assert processor.getType().equals(TextEmbeddingProcessor.TYPE);
     }
@@ -348,7 +354,8 @@ public void testProcessResponse_successful() throws Exception {
         assertEquals(12, ingestDocument.getSourceAndMetadata().size());
     }
 
-    public void testBuildVectorOutput_withPlainStringValue_successful() throws Exception {
+    @SneakyThrows
+    public void testBuildVectorOutput_withPlainStringValue_successful() {
         Map<String, Object> config = createPlainStringConfiguration();
         IngestDocument ingestDocument = createPlainIngestDocument();
         TextEmbeddingProcessor processor = createInstanceWithNestedMapConfiguration(config);
@@ -373,8 +380,9 @@ public void testBuildVectorOutput_withPlainStringValue_successful() throws Excep
         assertTrue(result.containsKey("oriKey6_knn"));
     }
 
+    @SneakyThrows
     @SuppressWarnings("unchecked")
-    public void testBuildVectorOutput_withNestedMap_successful() throws Exception {
+    public void testBuildVectorOutput_withNestedMap_successful() {
         Map<String, Object> config = createNestedMapConfiguration();
         IngestDocument ingestDocument = createNestedMapIngestDocument();
         TextEmbeddingProcessor processor = createInstanceWithNestedMapConfiguration(config);
@@ -421,7 +429,8 @@ private List<List<Float>> createMockVectorWithLength(int size) {
         return result;
     }
 
-    private TextEmbeddingProcessor createInstanceWithNestedMapConfiguration(Map<String, Object> fieldMap) throws Exception {
+    @SneakyThrows
+    private TextEmbeddingProcessor createInstanceWithNestedMapConfiguration(Map<String, Object> fieldMap) {
         Map<String, Processor.Factory> registry = new HashMap<>();
         Map<String, Object> config = new HashMap<>();
         config.put(TextEmbeddingProcessor.MODEL_ID_FIELD, "mockModelId");