[ML] Fix loss of context in the inference API for streaming APIs

docs/changelog/118999.yaml

@@ -0,0 +1,6 @@
+pr: 118999
+summary: Fix loss of context in the inference API for streaming APIs
+area: Machine Learning
+type: bug
+issues:
+ - 119000

x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/InferenceBaseRestTest.java

@@ -34,6 +34,7 @@
 import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.function.Consumer;
 
 import static org.hamcrest.Matchers.anyOf;
 import static org.hamcrest.Matchers.equalTo;
@@ -341,31 +342,44 @@ protected Map<String, Object> infer(String modelId, List<String> input) throws I
         return inferInternal(endpoint, input, null, Map.of());
     }
 
-    protected Deque<ServerSentEvent> streamInferOnMockService(String modelId, TaskType taskType, List<String> input) throws Exception {
+    protected Deque<ServerSentEvent> streamInferOnMockService(
+        String modelId,
+        TaskType taskType,
+        List<String> input,
+        @Nullable Consumer<Response> responseConsumerCallback
+    ) throws Exception {
         var endpoint = Strings.format("_inference/%s/%s/_stream", taskType, modelId);
-        return callAsync(endpoint, input);
+        return callAsync(endpoint, input, responseConsumerCallback);
     }
 
-    protected Deque<ServerSentEvent> unifiedCompletionInferOnMockService(String modelId, TaskType taskType, List<String> input)
-        throws Exception {
+    protected Deque<ServerSentEvent> unifiedCompletionInferOnMockService(
+        String modelId,
+        TaskType taskType,
+        List<String> input,
+        @Nullable Consumer<Response> responseConsumerCallback
+    ) throws Exception {
         var endpoint = Strings.format("_inference/%s/%s/_unified", taskType, modelId);
-        return callAsyncUnified(endpoint, input, "user");
+        return callAsyncUnified(endpoint, input, "user", responseConsumerCallback);
     }
 
-    private Deque<ServerSentEvent> callAsync(String endpoint, List<String> input) throws Exception {
+    private Deque<ServerSentEvent> callAsync(String endpoint, List<String> input, @Nullable Consumer<Response> responseConsumerCallback)
+        throws Exception {
         var request = new Request("POST", endpoint);
         request.setJsonEntity(jsonBody(input, null));
 
-        return execAsyncCall(request);
+        return execAsyncCall(request, responseConsumerCallback);
     }
 
-    private Deque<ServerSentEvent> execAsyncCall(Request request) throws Exception {
+    private Deque<ServerSentEvent> execAsyncCall(Request request, @Nullable Consumer<Response> responseConsumerCallback) throws Exception {
         var responseConsumer = new AsyncInferenceResponseConsumer();
         request.setOptions(RequestOptions.DEFAULT.toBuilder().setHttpAsyncResponseConsumerFactory(() -> responseConsumer).build());
         var latch = new CountDownLatch(1);
         client().performRequestAsync(request, new ResponseListener() {
             @Override
             public void onSuccess(Response response) {
+                if (responseConsumerCallback != null) {
+                    responseConsumerCallback.accept(response);
+                }
                 latch.countDown();
             }
 
@@ -378,11 +392,16 @@ public void onFailure(Exception exception) {
         return responseConsumer.events();
     }
 
-    private Deque<ServerSentEvent> callAsyncUnified(String endpoint, List<String> input, String role) throws Exception {
+    private Deque<ServerSentEvent> callAsyncUnified(
+        String endpoint,
+        List<String> input,
+        String role,
+        @Nullable Consumer<Response> responseConsumerCallback
+    ) throws Exception {
         var request = new Request("POST", endpoint);
 
         request.setJsonEntity(createUnifiedJsonBody(input, role));
-        return execAsyncCall(request);
+        return execAsyncCall(request, responseConsumerCallback);
     }
 
     private String createUnifiedJsonBody(List<String> input, String role) throws IOException {

x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/InferenceCrudIT.java

@@ -10,6 +10,7 @@
 package org.elasticsearch.xpack.inference;
 
 import org.apache.http.util.EntityUtils;
+import org.elasticsearch.client.Response;
 import org.elasticsearch.client.ResponseException;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.settings.Settings;
@@ -28,6 +29,7 @@
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
+import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
@@ -37,9 +39,15 @@
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.equalToIgnoringCase;
 import static org.hamcrest.Matchers.hasSize;
+import static org.hamcrest.Matchers.is;
 
 public class InferenceCrudIT extends InferenceBaseRestTest {
 
+    private static final Consumer<Response> VALIDATE_ELASTIC_PRODUCT_HEADER_CONSUMER = (r) -> assertThat(
+        r.getHeader("X-elastic-product"),
+        is("Elasticsearch")
+    );
+
     @SuppressWarnings("unchecked")
     public void testCRUD() throws IOException {
         for (int i = 0; i < 5; i++) {
@@ -442,7 +450,7 @@ public void testUnsupportedStream() throws Exception {
         assertEquals(TaskType.SPARSE_EMBEDDING.toString(), singleModel.get("task_type"));
 
         try {
-            var events = streamInferOnMockService(modelId, TaskType.SPARSE_EMBEDDING, List.of(randomUUID()));
+            var events = streamInferOnMockService(modelId, TaskType.SPARSE_EMBEDDING, List.of(randomUUID()), null);
             assertThat(events.size(), equalTo(2));
             events.forEach(event -> {
                 switch (event.name()) {
@@ -469,7 +477,7 @@ public void testSupportedStream() throws Exception {
 
         var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomAlphanumericOfLength(5)).toList();
         try {
-            var events = streamInferOnMockService(modelId, TaskType.COMPLETION, input);
+            var events = streamInferOnMockService(modelId, TaskType.COMPLETION, input, VALIDATE_ELASTIC_PRODUCT_HEADER_CONSUMER);
 
             var expectedResponses = Stream.concat(
                 input.stream().map(s -> s.toUpperCase(Locale.ROOT)).map(str -> "{\"completion\":[{\"delta\":\"" + str + "\"}]}"),
@@ -496,7 +504,7 @@ public void testUnifiedCompletionInference() throws Exception {
 
         var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomAlphanumericOfLength(5)).toList();
         try {
-            var events = unifiedCompletionInferOnMockService(modelId, TaskType.COMPLETION, input);
+            var events = unifiedCompletionInferOnMockService(modelId, TaskType.COMPLETION, input, VALIDATE_ELASTIC_PRODUCT_HEADER_CONSUMER);
             var expectedResponses = expectedResultsIterator(input);
             assertThat(events.size(), equalTo((input.size() + 1) * 2));
             events.forEach(event -> {

x-pack/plugin/inference/src/internalClusterTest/java/org/elasticsearch/xpack/inference/rest/ServerSentEventsRestActionListenerTests.java

@@ -17,6 +17,7 @@
 import org.apache.http.nio.util.SimpleInputBuffer;
 import org.apache.http.protocol.HttpContext;
 import org.apache.http.util.EntityUtils;
+import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.RequestOptions;
 import org.elasticsearch.client.Response;
@@ -43,6 +44,7 @@
 import org.elasticsearch.rest.RestHandler;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.test.ESIntegTestCase;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xcontent.ToXContent;
 import org.elasticsearch.xpack.core.inference.action.InferenceAction;
 import org.elasticsearch.xpack.inference.external.response.streaming.ServerSentEvent;
@@ -52,6 +54,7 @@
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.Deque;
 import java.util.Iterator;
 import java.util.List;
@@ -96,6 +99,14 @@ protected Collection<Class<? extends Plugin>> nodePlugins() {
     }
 
     public static class StreamingPlugin extends Plugin implements ActionPlugin {
+        private final SetOnce<ThreadPool> threadPool = new SetOnce<>();
+
+        @Override
+        public Collection<?> createComponents(PluginServices services) {
+            threadPool.set(services.threadPool());
+            return Collections.emptyList();
+        }
+
         @Override
         public Collection<RestHandler> getRestHandlers(
             Settings settings,
@@ -122,7 +133,7 @@ public void handleRequest(RestRequest request, RestChannel channel, NodeClient c
                     var publisher = new RandomPublisher(requestCount, withError);
                     var inferenceServiceResults = new StreamingInferenceServiceResults(publisher);
                     var inferenceResponse = new InferenceAction.Response(inferenceServiceResults, inferenceServiceResults.publisher());
-                    new ServerSentEventsRestActionListener(channel).onResponse(inferenceResponse);
+                    new ServerSentEventsRestActionListener(channel, threadPool).onResponse(inferenceResponse);
                 }
             }, new RestHandler() {
                 @Override
@@ -132,7 +143,7 @@ public List<Route> routes() {
 
                 @Override
                 public void handleRequest(RestRequest request, RestChannel channel, NodeClient client) {
-                    new ServerSentEventsRestActionListener(channel).onFailure(expectedException);
+                    new ServerSentEventsRestActionListener(channel, threadPool).onFailure(expectedException);
                 }
             }, new RestHandler() {
                 @Override
@@ -143,7 +154,7 @@ public List<Route> routes() {
                 @Override
                 public void handleRequest(RestRequest request, RestChannel channel, NodeClient client) {
                     var inferenceResponse = new InferenceAction.Response(new SingleInferenceServiceResults());
-                    new ServerSentEventsRestActionListener(channel).onResponse(inferenceResponse);
+                    new ServerSentEventsRestActionListener(channel, threadPool).onResponse(inferenceResponse);
                 }
             });
         }

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferencePlugin.java

@@ -43,6 +43,7 @@
 import org.elasticsearch.search.rank.RankDoc;
 import org.elasticsearch.threadpool.ExecutorBuilder;
 import org.elasticsearch.threadpool.ScalingExecutorBuilder;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xcontent.ParseField;
 import org.elasticsearch.xpack.core.ClientHelper;
 import org.elasticsearch.xpack.core.action.XPackUsageFeatureAction;
@@ -154,6 +155,9 @@ public class InferencePlugin extends Plugin implements ActionPlugin, ExtensibleP
     private final SetOnce<HttpRequestSender.Factory> httpFactory = new SetOnce<>();
     private final SetOnce<AmazonBedrockRequestSender.Factory> amazonBedrockFactory = new SetOnce<>();
     private final SetOnce<ServiceComponents> serviceComponents = new SetOnce<>();
+    // This is mainly so that the rest handlers can access the ThreadPool in a way that avoids potential null pointers from it
+    // not being initialized yet
+    private final SetOnce<ThreadPool> threadPoolSetOnce = new SetOnce<>();
     private final SetOnce<ElasticInferenceServiceComponents> elasticInferenceServiceComponents = new SetOnce<>();
     private final SetOnce<InferenceServiceRegistry> inferenceServiceRegistry = new SetOnce<>();
     private final SetOnce<ShardBulkInferenceActionFilter> shardBulkInferenceActionFilter = new SetOnce<>();
@@ -197,9 +201,11 @@ public List<RestHandler> getRestHandlers(
         Supplier<DiscoveryNodes> nodesInCluster,
         Predicate<NodeFeature> clusterSupportsFeature
     ) {
+        assert serviceComponents.get() != null : "serviceComponents must be set before retrieving the rest handlers";
+
         var availableRestActions = List.of(
             new RestInferenceAction(),
-            new RestStreamInferenceAction(),
+            new RestStreamInferenceAction(threadPoolSetOnce),
             new RestGetInferenceModelAction(),
             new RestPutInferenceModelAction(),
             new RestUpdateInferenceModelAction(),
@@ -208,7 +214,7 @@ public List<RestHandler> getRestHandlers(
             new RestGetInferenceServicesAction()
         );
         List<RestHandler> conditionalRestActions = UnifiedCompletionFeature.UNIFIED_COMPLETION_FEATURE_FLAG.isEnabled()
-            ? List.of(new RestUnifiedCompletionInferenceAction())
+            ? List.of(new RestUnifiedCompletionInferenceAction(threadPoolSetOnce))
             : List.of();
 
         return Stream.concat(availableRestActions.stream(), conditionalRestActions.stream()).toList();
@@ -219,6 +225,7 @@ public Collection<?> createComponents(PluginServices services) {
         var throttlerManager = new ThrottlerManager(settings, services.threadPool(), services.clusterService());
         var truncator = new Truncator(settings, services.clusterService());
         serviceComponents.set(new ServiceComponents(services.threadPool(), throttlerManager, settings, truncator));
+        threadPoolSetOnce.set(services.threadPool());
 
         var httpClientManager = HttpClientManager.create(settings, services.threadPool(), services.clusterService(), throttlerManager);
         var httpRequestSenderFactory = new HttpRequestSender.Factory(serviceComponents.get(), httpClientManager, services.clusterService());

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/rest/RestStreamInferenceAction.java

@@ -7,20 +7,30 @@
 
 package org.elasticsearch.xpack.inference.rest;
 
+import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.rest.RestChannel;
 import org.elasticsearch.rest.Scope;
 import org.elasticsearch.rest.ServerlessScope;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xpack.core.inference.action.InferenceAction;
 
 import java.util.List;
+import java.util.Objects;
 
 import static org.elasticsearch.rest.RestRequest.Method.POST;
 import static org.elasticsearch.xpack.inference.rest.Paths.STREAM_INFERENCE_ID_PATH;
 import static org.elasticsearch.xpack.inference.rest.Paths.STREAM_TASK_TYPE_INFERENCE_ID_PATH;
 
 @ServerlessScope(Scope.PUBLIC)
 public class RestStreamInferenceAction extends BaseInferenceAction {
+    private final SetOnce<ThreadPool> threadPool;
+
+    public RestStreamInferenceAction(SetOnce<ThreadPool> threadPool) {
+        super();
+        this.threadPool = Objects.requireNonNull(threadPool);
+    }
+
     @Override
     public String getName() {
         return "stream_inference_action";
@@ -38,6 +48,6 @@ protected InferenceAction.Request prepareInferenceRequest(InferenceAction.Reques
 
     @Override
     protected ActionListener<InferenceAction.Response> listener(RestChannel channel) {
-        return new ServerSentEventsRestActionListener(channel);
+        return new ServerSentEventsRestActionListener(channel, threadPool);
     }
 }

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/rest/RestUnifiedCompletionInferenceAction.java

@@ -7,22 +7,32 @@
 
 package org.elasticsearch.xpack.inference.rest;
 
+import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.client.internal.node.NodeClient;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.Scope;
 import org.elasticsearch.rest.ServerlessScope;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xpack.core.inference.action.UnifiedCompletionAction;
 
 import java.io.IOException;
 import java.util.List;
+import java.util.Objects;
 
 import static org.elasticsearch.rest.RestRequest.Method.POST;
 import static org.elasticsearch.xpack.inference.rest.Paths.UNIFIED_INFERENCE_ID_PATH;
 import static org.elasticsearch.xpack.inference.rest.Paths.UNIFIED_TASK_TYPE_INFERENCE_ID_PATH;
 
 @ServerlessScope(Scope.PUBLIC)
 public class RestUnifiedCompletionInferenceAction extends BaseRestHandler {
+    private final SetOnce<ThreadPool> threadPool;
+
+    public RestUnifiedCompletionInferenceAction(SetOnce<ThreadPool> threadPool) {
+        super();
+        this.threadPool = Objects.requireNonNull(threadPool);
+    }
+
     @Override
     public String getName() {
         return "unified_inference_action";
@@ -44,6 +54,10 @@ protected RestChannelConsumer prepareRequest(RestRequest restRequest, NodeClient
             request = UnifiedCompletionAction.Request.parseRequest(params.inferenceEntityId(), params.taskType(), inferTimeout, parser);
         }
 
-        return channel -> client.execute(UnifiedCompletionAction.INSTANCE, request, new ServerSentEventsRestActionListener(channel));
+        return channel -> client.execute(
+            UnifiedCompletionAction.INSTANCE,
+            request,
+            new ServerSentEventsRestActionListener(channel, threadPool)
+        );
     }
 }