[ML] Fix loss of context in the inference API for streaming APIs (#118999) (#119222)

* Adding context preserving fix

* Update docs/changelog/118999.yaml

* Update docs/changelog/118999.yaml

* Using a setonce and adding a test

* Updating the changelog

(cherry picked from commit 7ba3cb9)

# Conflicts:
#	x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/InferenceBaseRestTest.java
#	x-pack/plugin/inference/qa/inference-service-tests/src/javaRestTest/java/org/elasticsearch/xpack/inference/InferenceCrudIT.java
#	x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferencePlugin.java
#	x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/rest/RestUnifiedCompletionInferenceAction.java
#	x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/rest/RestUnifiedCompletionInferenceActionTests.java

Author: jonathan-buttner

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

@@ -30,6 +30,7 @@
 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;
@@ -336,20 +337,34 @@ protected Map<String, Object> infer(String modelId, List<String> input) throws I
         return inferInternal(endpoint, input, 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);
     }
 
-    private Deque<ServerSentEvent> callAsync(String endpoint, List<String> input) throws Exception {
-        var responseConsumer = new AsyncInferenceResponseConsumer();
+    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));
+
+        return execAsyncCall(request, responseConsumerCallback);
+    }
+
+    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();
             }
 

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.settings.Settings;
 import org.elasticsearch.inference.TaskType;
@@ -19,6 +20,7 @@
 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;
@@ -28,9 +30,15 @@
 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++) {
@@ -282,7 +290,7 @@ public void testUnsupportedStream() throws Exception {
         assertEquals(TaskType.SPARSE_EMBEDDING.toString(), singleModel.get("task_type"));
 
         try {
-            var events = streamInferOnMockService(modelId, TaskType.SPARSE_EMBEDDING, List.of(randomAlphaOfLength(10)));
+            var events = streamInferOnMockService(modelId, TaskType.SPARSE_EMBEDDING, List.of(randomAlphaOfLength(10)), null);
             assertThat(events.size(), equalTo(2));
             events.forEach(event -> {
                 switch (event.name()) {
@@ -309,7 +317,7 @@ public void testSupportedStream() throws Exception {
 
         var input = IntStream.range(1, 2 + randomInt(8)).mapToObj(i -> randomAlphaOfLength(10)).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(String::toUpperCase).map(str -> "{\"completion\":[{\"delta\":\"" + str + "\"}]}"),

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

@@ -39,6 +39,7 @@
 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;
@@ -140,6 +141,9 @@ public class InferencePlugin extends Plugin implements ActionPlugin, ExtensibleP
     private final SetOnce<AmazonBedrockRequestSender.Factory> amazonBedrockFactory = new SetOnce<>();
     private final SetOnce<ServiceComponents> serviceComponents = new SetOnce<>();
     private final SetOnce<ElasticInferenceServiceComponents> eisComponents = 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<InferenceServiceRegistry> inferenceServiceRegistry = new SetOnce<>();
     private final SetOnce<ShardBulkInferenceActionFilter> shardBulkInferenceActionFilter = new SetOnce<>();
     private List<InferenceServiceExtension> inferenceServiceExtensions;
@@ -176,7 +180,7 @@ public List<RestHandler> getRestHandlers(
     ) {
         return List.of(
             new RestInferenceAction(),
-            new RestStreamInferenceAction(),
+            new RestStreamInferenceAction(threadPoolSetOnce),
             new RestGetInferenceModelAction(),
             new RestPutInferenceModelAction(),
             new RestUpdateInferenceModelAction(),
@@ -190,6 +194,7 @@ 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/ServerSentEventsRestActionListener.java

@@ -10,9 +10,11 @@
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.SetOnce;
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.ExceptionsHelper;
 import org.elasticsearch.action.ActionListener;
+import org.elasticsearch.action.support.ContextPreservingActionListener;
 import org.elasticsearch.common.bytes.ReleasableBytesReference;
 import org.elasticsearch.common.collect.Iterators;
 import org.elasticsearch.common.io.stream.BytesStream;
@@ -30,6 +32,7 @@
 import org.elasticsearch.rest.RestResponse;
 import org.elasticsearch.rest.RestStatus;
 import org.elasticsearch.tasks.TaskCancelledException;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xcontent.ToXContent;
 import org.elasticsearch.xcontent.XContentBuilder;
 import org.elasticsearch.xpack.core.inference.action.InferenceAction;
@@ -39,6 +42,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.Iterator;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.Flow;
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -55,6 +59,7 @@ public class ServerSentEventsRestActionListener implements ActionListener<Infere
     private final AtomicBoolean isLastPart = new AtomicBoolean(false);
     private final RestChannel channel;
     private final ToXContent.Params params;
+    private final SetOnce<ThreadPool> threadPool;
 
     /**
      * A listener for the first part of the next entry to become available for transmission.
@@ -66,13 +71,14 @@ public class ServerSentEventsRestActionListener implements ActionListener<Infere
      */
     private ActionListener<ChunkedRestResponseBodyPart> nextBodyPartListener;
 
-    public ServerSentEventsRestActionListener(RestChannel channel) {
-        this(channel, channel.request());
+    public ServerSentEventsRestActionListener(RestChannel channel, SetOnce<ThreadPool> threadPool) {
+        this(channel, channel.request(), threadPool);
     }
 
-    public ServerSentEventsRestActionListener(RestChannel channel, ToXContent.Params params) {
+    public ServerSentEventsRestActionListener(RestChannel channel, ToXContent.Params params, SetOnce<ThreadPool> threadPool) {
         this.channel = channel;
         this.params = params;
+        this.threadPool = Objects.requireNonNull(threadPool);
     }
 
     @Override
@@ -99,7 +105,7 @@ protected void ensureOpen() {
     }
 
     private void initializeStream(InferenceAction.Response response) {
-        nextBodyPartListener = ActionListener.wrap(bodyPart -> {
+        ActionListener<ChunkedRestResponseBodyPart> chunkedResponseBodyActionListener = ActionListener.wrap(bodyPart -> {
             // this is the first response, so we need to send the RestResponse to open the stream
             // all subsequent bytes will be delivered through the nextBodyPartListener
             channel.sendResponse(RestResponse.chunked(RestStatus.OK, bodyPart, this::release));
@@ -115,6 +121,12 @@ private void initializeStream(InferenceAction.Response response) {
                 )
             );
         });
+
+        nextBodyPartListener = ContextPreservingActionListener.wrapPreservingContext(
+            chunkedResponseBodyActionListener,
+            threadPool.get().getThreadContext()
+        );
+
         // subscribe will call onSubscribe, which requests the first chunk
         response.publisher().subscribe(subscriber);
     }

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/rest/RestStreamInferenceActionTests.java

@@ -12,8 +12,11 @@
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.test.rest.FakeRestRequest;
 import org.elasticsearch.test.rest.RestActionTestCase;
+import org.elasticsearch.threadpool.TestThreadPool;
+import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.xcontent.XContentType;
 import org.elasticsearch.xpack.core.inference.action.InferenceAction;
+import org.junit.After;
 import org.junit.Before;
 
 import static org.elasticsearch.xpack.inference.rest.BaseInferenceActionTests.createResponse;
@@ -22,10 +25,18 @@
 import static org.hamcrest.Matchers.instanceOf;
 
 public class RestStreamInferenceActionTests extends RestActionTestCase {
+    private final SetOnce<ThreadPool> threadPool = new SetOnce<>();
 
     @Before
     public void setUpAction() {
-        controller().registerHandler(new RestStreamInferenceAction());
+        threadPool.set(new TestThreadPool(getTestName()));
+        controller().registerHandler(new RestStreamInferenceAction(threadPool));
+    }
+
+    @After
+    public void tearDownAction() {
+        terminate(threadPool.get());
+
     }
 
     public void testStreamIsTrue() {