[Streaming Indexing] Enhance RestAction with request / response streaming support

Signed-off-by: Andriy Redko <andriy.redko@aiven.io>

Author: reta

CHANGELOG.md

@@ -12,6 +12,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - [Remote Store] Add dynamic cluster settings to set timeout for segments upload to Remote Store ([#13679](https://github.com/opensearch-project/OpenSearch/pull/13679))
 - [Remote Store] Upload translog checkpoint as object metadata to translog.tlog([#13637](https://github.com/opensearch-project/OpenSearch/pull/13637))
 - Add getMetadataFields to MapperService ([#13819](https://github.com/opensearch-project/OpenSearch/pull/13819))
+- [Streaming Indexing] Enhance RestAction with request / response streaming support ([#13772](https://github.com/opensearch-project/OpenSearch/pull/13772))
 
 ### Dependencies
 - Bump `com.github.spullara.mustache.java:compiler` from 0.9.10 to 0.9.13 ([#13329](https://github.com/opensearch-project/OpenSearch/pull/13329), [#13559](https://github.com/opensearch-project/OpenSearch/pull/13559))

libs/core/src/main/java/org/opensearch/core/xcontent/XContentBuilder.java

@@ -64,6 +64,7 @@
  */
 @PublicApi(since = "1.0.0")
 public final class XContentBuilder implements Closeable, Flushable {
+    public static final XContentBuilder NO_CONTENT = new XContentBuilder();
 
     /**
      * Create a new {@link XContentBuilder} using the given {@link XContent} content.
@@ -230,6 +231,14 @@ public XContentBuilder(XContent xContent, OutputStream os, Set<String> includes,
         this.generator = xContent.createGenerator(bos, includes, excludes);
     }
 
+    /**
+     * Creates an instance of the {@link XContentBuilder} that has no content
+     */
+    private XContentBuilder() {
+        this.bos = null;
+        this.generator = null;
+    }
+
     public MediaType contentType() {
         return generator.contentType();
     }

plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/HttpContentSender.java

@@ -0,0 +1,21 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.http.reactor.netty4;
+
+import org.opensearch.core.action.ActionListener;
+
+import io.netty.handler.codec.http.HttpContent;
+import org.reactivestreams.Publisher;
+
+/**
+ * The generic interface for chunked {@link HttpContent} producers (response streaming).
+ */
+interface HttpContentSender extends Publisher<HttpContent> {
+    void send(HttpContent content, ActionListener<Void> listener, boolean isLast);
+}

plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/ReactorNetty4HttpChunk.java

@@ -0,0 +1,53 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.http.reactor.netty4;
+
+import org.opensearch.core.common.bytes.BytesReference;
+import org.opensearch.http.HttpChunk;
+import org.opensearch.transport.reactor.netty4.Netty4Utils;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import io.netty.buffer.ByteBuf;
+
+class ReactorNetty4HttpChunk implements HttpChunk {
+    private final AtomicBoolean released;
+    private final boolean pooled;
+    private final ByteBuf content;
+    private final boolean last;
+
+    ReactorNetty4HttpChunk(ByteBuf content, boolean last) {
+        this(new AtomicBoolean(false), true, content, last);
+    }
+
+    private ReactorNetty4HttpChunk(AtomicBoolean released, boolean pooled, ByteBuf content, boolean last) {
+        this.content = content;
+        this.pooled = pooled;
+        this.released = released;
+        this.last = last;
+    }
+
+    @Override
+    public BytesReference content() {
+        assert released.get() == false;
+        return Netty4Utils.toBytesReference(content);
+    }
+
+    @Override
+    public void release() {
+        if (pooled && released.compareAndSet(false, true)) {
+            content.release();
+        }
+    }
+
+    @Override
+    public boolean isLast() {
+        return last;
+    }
+}

plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/ReactorNetty4HttpServerTransport.java

@@ -26,6 +26,8 @@
 import org.opensearch.http.HttpServerChannel;
 import org.opensearch.http.reactor.netty4.ssl.SslUtils;
 import org.opensearch.plugins.SecureHttpTransportSettingsProvider;
+import org.opensearch.rest.RestHandler;
+import org.opensearch.rest.RestRequest.Method;
 import org.opensearch.telemetry.tracing.Tracer;
 import org.opensearch.threadpool.ThreadPool;
 import org.opensearch.transport.reactor.SharedGroupFactory;
@@ -40,6 +42,7 @@
 import java.time.Duration;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Optional;
 
 import io.netty.buffer.ByteBufAllocator;
 import io.netty.channel.ChannelOption;
@@ -351,24 +354,46 @@ public List<String> protocols() {
      * @return response publisher
      */
     protected Publisher<Void> incomingRequest(HttpServerRequest request, HttpServerResponse response) {
-        final NonStreamingRequestConsumer<HttpContent> consumer = new NonStreamingRequestConsumer<>(
-            this,
-            request,
-            response,
-            maxCompositeBufferComponents
+        final Method method = HttpConversionUtil.convertMethod(request.method());
+        final Optional<RestHandler> dispatchHandlerOpt = dispatcher.dispatchHandler(
+            request.uri(),
+            request.fullPath(),
+            method,
+            request.params()
         );
+        if (dispatchHandlerOpt.map(RestHandler::supportsStreaming).orElse(false)) {
+            final ReactorNetty4StreamingRequestConsumer<HttpContent> consumer = new ReactorNetty4StreamingRequestConsumer<>(
+                this,
+                request,
+                response
+            );
+
+            request.receiveContent()
+                .switchIfEmpty(Mono.just(DefaultLastHttpContent.EMPTY_LAST_CONTENT))
+                .subscribe(consumer, error -> {}, () -> consumer.accept(DefaultLastHttpContent.EMPTY_LAST_CONTENT));
+            consumer.start();
+
+            return response.sendObject(consumer);
+        } else {
+            final ReactorNetty4NonStreamingRequestConsumer<HttpContent> consumer = new ReactorNetty4NonStreamingRequestConsumer<>(
+                this,
+                request,
+                response,
+                maxCompositeBufferComponents
+            );
 
-        request.receiveContent().switchIfEmpty(Mono.just(DefaultLastHttpContent.EMPTY_LAST_CONTENT)).subscribe(consumer);
-
-        return Mono.from(consumer).flatMap(hc -> {
-            final FullHttpResponse r = (FullHttpResponse) hc;
-            response.status(r.status());
-            response.trailerHeaders(c -> r.trailingHeaders().forEach(h -> c.add(h.getKey(), h.getValue())));
-            response.chunkedTransfer(false);
-            response.compression(true);
-            r.headers().forEach(h -> response.addHeader(h.getKey(), h.getValue()));
-            return Mono.from(response.sendObject(r.content()));
-        });
+            request.receiveContent().switchIfEmpty(Mono.just(DefaultLastHttpContent.EMPTY_LAST_CONTENT)).subscribe(consumer);
+
+            return Mono.from(consumer).flatMap(hc -> {
+                final FullHttpResponse r = (FullHttpResponse) hc;
+                response.status(r.status());
+                response.trailerHeaders(c -> r.trailingHeaders().forEach(h -> c.add(h.getKey(), h.getValue())));
+                response.chunkedTransfer(false);
+                response.compression(true);
+                r.headers().forEach(h -> response.addHeader(h.getKey(), h.getValue()));
+                return Mono.from(response.sendObject(r.content()));
+            });
+        }
     }
 
     /**

plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/NonStreamingHttpChannel.java renamed to plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/ReactorNetty4NonStreamingHttpChannel.java

@@ -23,13 +23,13 @@
 import reactor.netty.http.server.HttpServerRequest;
 import reactor.netty.http.server.HttpServerResponse;
 
-class NonStreamingHttpChannel implements HttpChannel {
+class ReactorNetty4NonStreamingHttpChannel implements HttpChannel {
     private final HttpServerRequest request;
     private final HttpServerResponse response;
     private final CompletableContext<Void> closeContext = new CompletableContext<>();
     private final FluxSink<HttpContent> emitter;
 
-    NonStreamingHttpChannel(HttpServerRequest request, HttpServerResponse response, FluxSink<HttpContent> emitter) {
+    ReactorNetty4NonStreamingHttpChannel(HttpServerRequest request, HttpServerResponse response, FluxSink<HttpContent> emitter) {
         this.request = request;
         this.response = response;
         this.emitter = emitter;

plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/NonStreamingRequestConsumer.java renamed to plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/ReactorNetty4NonStreamingRequestConsumer.java

@@ -25,7 +25,7 @@
 import reactor.netty.http.server.HttpServerRequest;
 import reactor.netty.http.server.HttpServerResponse;
 
-class NonStreamingRequestConsumer<T extends HttpContent> implements Consumer<T>, Publisher<HttpContent>, Disposable {
+class ReactorNetty4NonStreamingRequestConsumer<T extends HttpContent> implements Consumer<T>, Publisher<HttpContent>, Disposable {
     private final HttpServerRequest request;
     private final HttpServerResponse response;
     private final CompositeByteBuf content;
@@ -34,7 +34,7 @@ class NonStreamingRequestConsumer<T extends HttpContent> implements Consumer<T>,
     private final AtomicBoolean disposed = new AtomicBoolean(false);
     private volatile FluxSink<HttpContent> emitter;
 
-    NonStreamingRequestConsumer(
+    ReactorNetty4NonStreamingRequestConsumer(
         AbstractHttpServerTransport transport,
         HttpServerRequest request,
         HttpServerResponse response,
@@ -64,12 +64,12 @@ public void accept(T message) {
         }
     }
 
-    public void process(HttpContent in, FluxSink<HttpContent> emitter) {
+    void process(HttpContent in, FluxSink<HttpContent> emitter) {
         // Consume request body in full before dispatching it
         content.addComponent(true, in.content().retain());
 
         if (in instanceof LastHttpContent) {
-            final NonStreamingHttpChannel channel = new NonStreamingHttpChannel(request, response, emitter);
+            final ReactorNetty4NonStreamingHttpChannel channel = new ReactorNetty4NonStreamingHttpChannel(request, response, emitter);
             final HttpRequest r = createRequest(request, content);
 
             try {

plugins/transport-reactor-netty4/src/main/java/org/opensearch/http/reactor/netty4/ReactorNetty4StreamingHttpChannel.java

@@ -0,0 +1,118 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.http.reactor.netty4;
+
+import org.opensearch.common.concurrent.CompletableContext;
+import org.opensearch.core.action.ActionListener;
+import org.opensearch.core.common.bytes.BytesReference;
+import org.opensearch.http.HttpChunk;
+import org.opensearch.http.HttpResponse;
+import org.opensearch.http.StreamingHttpChannel;
+import org.opensearch.transport.reactor.netty4.Netty4Utils;
+
+import java.net.InetSocketAddress;
+import java.util.List;
+import java.util.Map;
+
+import io.netty.buffer.Unpooled;
+import io.netty.handler.codec.http.DefaultHttpContent;
+import io.netty.handler.codec.http.FullHttpResponse;
+import io.netty.handler.codec.http.HttpContent;
+import org.reactivestreams.Publisher;
+import org.reactivestreams.Subscriber;
+import reactor.core.publisher.Flux;
+import reactor.core.publisher.FluxSink;
+import reactor.netty.http.server.HttpServerRequest;
+import reactor.netty.http.server.HttpServerResponse;
+
+class ReactorNetty4StreamingHttpChannel implements StreamingHttpChannel {
+    private final HttpServerRequest request;
+    private final HttpServerResponse response;
+    private final CompletableContext<Void> closeContext = new CompletableContext<>();
+    private final Publisher<HttpChunk> receiver;
+    private final HttpContentSender sender;
+    private volatile FluxSink<HttpChunk> producer;
+    private volatile boolean lastChunkReceived = false;
+
+    ReactorNetty4StreamingHttpChannel(HttpServerRequest request, HttpServerResponse response, HttpContentSender sender) {
+        this.request = request;
+        this.response = response;
+        this.sender = sender;
+        this.receiver = Flux.create(producer -> this.producer = producer);
+        this.request.withConnection(connection -> Netty4Utils.addListener(connection.channel().closeFuture(), closeContext));
+    }
+
+    @Override
+    public boolean isOpen() {
+        return true;
+    }
+
+    @Override
+    public void close() {
+        request.withConnection(connection -> connection.channel().close());
+    }
+
+    @Override
+    public void addCloseListener(ActionListener<Void> listener) {
+        closeContext.addListener(ActionListener.toBiConsumer(listener));
+    }
+
+    @Override
+    public void sendChunk(HttpChunk chunk, ActionListener<Void> listener) {
+        sender.send(createContent(chunk), listener, chunk.isLast());
+    }
+
+    @Override
+    public void sendResponse(HttpResponse response, ActionListener<Void> listener) {
+        sender.send(createContent(response), listener, true);
+    }
+
+    @Override
+    public void prepareResponse(int status, Map<String, List<String>> headers) {
+        this.response.status(status);
+        headers.forEach((k, vs) -> vs.forEach(v -> this.response.addHeader(k, v)));
+    }
+
+    @Override
+    public InetSocketAddress getRemoteAddress() {
+        return (InetSocketAddress) response.remoteAddress();
+    }
+
+    @Override
+    public InetSocketAddress getLocalAddress() {
+        return (InetSocketAddress) response.hostAddress();
+    }
+
+    @Override
+    public void receiveChunk(HttpChunk message) {
+        if (lastChunkReceived) {
+            return;
+        }
+
+        producer.next(message);
+        if (message.isLast()) {
+            lastChunkReceived = true;
+            producer.complete();
+        }
+    }
+
+    @Override
+    public void subscribe(Subscriber<? super HttpChunk> subscriber) {
+        receiver.subscribe(subscriber);
+    }
+
+    private static HttpContent createContent(HttpResponse response) {
+        final FullHttpResponse fullHttpResponse = (FullHttpResponse) response;
+        return new DefaultHttpContent(fullHttpResponse.content());
+    }
+
+    private static HttpContent createContent(HttpChunk chunk) {
+        return new DefaultHttpContent(Unpooled.copiedBuffer(BytesReference.toBytes(chunk.content())));
+    }
+}