rest5client: cancel http request on interruption in the sync api

rest5-client/src/main/java/co/elastic/clients/transport/rest5_client/low_level/Rest5Client.java

@@ -298,11 +298,12 @@ private Response performRequest(final Iterator<Node> nodes, final InternalReques
         throws IOException {
         RequestContext context = request.createContextForNextAttempt(nodes.next());
         ClassicHttpResponse httpResponse;
+        Future<ClassicHttpResponse> future = null;
         try {
-            httpResponse = client.execute(context.requestProducer,
-                context.asyncResponseConsumer,
-                context.context, null).get();
+            future = client.execute(context.requestProducer, context.asyncResponseConsumer, context.context, null);
+            httpResponse = future.get();
         } catch (Exception e) {
+            if (future != null) future.cancel(true);
             RequestLogger.logFailedRequest(logger, request.httpRequest, context.node, e);
             onFailure(context.node);
             Exception cause = extractAndWrapCause(e);

rest5-client/src/test/java/co/elastic/clients/transport/rest5_client/low_level/RestClientInterruptTests.java

@@ -0,0 +1,126 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package co.elastic.clients.transport.rest5_client.low_level;
+
+import com.sun.net.httpserver.HttpServer;
+import org.apache.hc.core5.http.HttpHost;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.LockSupport;
+
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * Verifies that {@link Rest5Client#performRequest(Request)} cancels the underlying HTTP request
+ * when the calling thread is interrupted.
+ */
+public class RestClientInterruptTests {
+
+    private HttpServer httpServer;
+    private Rest5Client restClient;
+    private CountDownLatch requestArrived;
+    private CompletableFuture<Exception> serverException;
+
+    @BeforeEach
+    public void setUp() throws Exception {
+        requestArrived = new CountDownLatch(1);
+        serverException = new CompletableFuture<>();
+
+        httpServer = HttpServer.create(new InetSocketAddress(InetAddress.getLoopbackAddress(), 0), 0);
+        httpServer.createContext("/slow", exchange -> {
+            try (exchange; OutputStream out = exchange.getResponseBody()) {
+                exchange.sendResponseHeaders(200, 0);
+                requestArrived.countDown();
+
+                // Stream data slowly for 30 seconds. Throws IOException on client disconnect.
+                for (int i = 0; i < 30_000; i++) {
+                    out.write(' ');
+                    out.flush();
+                    LockSupport.parkNanos(1_000_000L);
+                }
+            } catch (IOException e) {
+                serverException.complete(e);
+            } finally {
+                serverException.complete(null);
+            }
+        });
+        httpServer.start();
+
+        InetSocketAddress address = httpServer.getAddress();
+        HttpHost host = new HttpHost("http", address.getHostName(), address.getPort());
+        restClient = Rest5Client.builder(host).build();
+    }
+
+    @AfterEach
+    public void tearDown() throws Exception {
+        restClient.close();
+        httpServer.stop(0);
+    }
+
+    @Test
+    @Timeout(10)
+    public void syncRequestShouldCancelOnThreadInterruption() throws Exception {
+        Thread clientThread = new Thread(() -> {
+            try { restClient.performRequest(new Request("GET", "/slow")); } catch (Exception e) { }
+        });
+        clientThread.start();
+
+        assertTrue(requestArrived.await(5, TimeUnit.SECONDS));
+        clientThread.interrupt();
+
+        // The server should get an IOException from writing to the closed connection.
+        assertInstanceOf(IOException.class, serverException.join(),
+            "HTTP connection should have been closed after thread interruption");
+    }
+
+    @Test
+    @Timeout(10)
+    public void asyncRequestShouldCancelOnFutureCancellation() throws Exception {
+        CompletableFuture<Response> responseFuture = new CompletableFuture<>();
+        Cancellable cancellable = restClient.performRequestAsync(new Request("GET", "/slow"), new ResponseListener() {
+            @Override
+            public void onSuccess(Response response) {
+                responseFuture.complete(response);
+            }
+
+            @Override
+            public void onFailure(Exception exception) {
+                responseFuture.completeExceptionally(exception);
+            }
+        });
+
+        assertTrue(requestArrived.await(5, TimeUnit.SECONDS));
+        cancellable.cancel();
+
+        assertInstanceOf(IOException.class, serverException.join(),
+            "HTTP connection should have been closed after future cancellation");
+    }
+}