001/*
002 * Copyright 2002-2020 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.http.client.reactive;
018
019import java.net.URI;
020import java.util.concurrent.atomic.AtomicReference;
021import java.util.function.Function;
022
023import reactor.core.publisher.Mono;
024import reactor.netty.NettyOutbound;
025import reactor.netty.http.client.HttpClient;
026import reactor.netty.http.client.HttpClientRequest;
027import reactor.netty.resources.ConnectionProvider;
028import reactor.netty.resources.LoopResources;
029
030import org.springframework.http.HttpMethod;
031import org.springframework.util.Assert;
032
033/**
034 * Reactor-Netty implementation of {@link ClientHttpConnector}.
035 *
036 * @author Brian Clozel
037 * @author Rossen Stoyanchev
038 * @since 5.0
039 * @see reactor.netty.http.client.HttpClient
040 */
041public class ReactorClientHttpConnector implements ClientHttpConnector {
042
043        private final static Function<HttpClient, HttpClient> defaultInitializer = client -> client.compress(true);
044
045
046        private final HttpClient httpClient;
047
048
049        /**
050         * Default constructor. Initializes {@link HttpClient} via:
051         * <pre class="code">
052         * HttpClient.create().compress()
053         * </pre>
054         */
055        public ReactorClientHttpConnector() {
056                this.httpClient = defaultInitializer.apply(HttpClient.create());
057        }
058
059        /**
060         * Constructor with externally managed Reactor Netty resources, including
061         * {@link LoopResources} for event loop threads, and {@link ConnectionProvider}
062         * for the connection pool.
063         * <p>This constructor should be used only when you don't want the client
064         * to participate in the Reactor Netty global resources. By default the
065         * client participates in the Reactor Netty global resources held in
066         * {@link reactor.netty.http.HttpResources}, which is recommended since
067         * fixed, shared resources are favored for event loop concurrency. However,
068         * consider declaring a {@link ReactorResourceFactory} bean with
069         * {@code globalResources=true} in order to ensure the Reactor Netty global
070         * resources are shut down when the Spring ApplicationContext is closed.
071         * @param factory the resource factory to obtain the resources from
072         * @param mapper a mapper for further initialization of the created client
073         * @since 5.1
074         */
075        public ReactorClientHttpConnector(ReactorResourceFactory factory, Function<HttpClient, HttpClient> mapper) {
076                this.httpClient = defaultInitializer.andThen(mapper).apply(initHttpClient(factory));
077        }
078
079        private static HttpClient initHttpClient(ReactorResourceFactory resourceFactory) {
080                ConnectionProvider provider = resourceFactory.getConnectionProvider();
081                LoopResources resources = resourceFactory.getLoopResources();
082                Assert.notNull(provider, "No ConnectionProvider: is ReactorResourceFactory not initialized yet?");
083                Assert.notNull(resources, "No LoopResources: is ReactorResourceFactory not initialized yet?");
084                return HttpClient.create(provider).tcpConfiguration(tcpClient -> tcpClient.runOn(resources));
085        }
086
087        /**
088         * Constructor with a pre-configured {@code HttpClient} instance.
089         * @param httpClient the client to use
090         * @since 5.1
091         */
092        public ReactorClientHttpConnector(HttpClient httpClient) {
093                Assert.notNull(httpClient, "HttpClient is required");
094                this.httpClient = httpClient;
095        }
096
097
098        @Override
099        public Mono<ClientHttpResponse> connect(HttpMethod method, URI uri,
100                        Function<? super ClientHttpRequest, Mono<Void>> requestCallback) {
101
102                if (!uri.isAbsolute()) {
103                        return Mono.error(new IllegalArgumentException("URI is not absolute: " + uri));
104                }
105
106                AtomicReference<ReactorClientHttpResponse> responseRef = new AtomicReference<>();
107
108                return this.httpClient
109                                .request(io.netty.handler.codec.http.HttpMethod.valueOf(method.name()))
110                                .uri(uri.toString())
111                                .send((request, outbound) -> requestCallback.apply(adaptRequest(method, uri, request, outbound)))
112                                .responseConnection((response, connection) -> {
113                                        responseRef.set(new ReactorClientHttpResponse(response, connection));
114                                        return Mono.just((ClientHttpResponse) responseRef.get());
115                                })
116                                .next()
117                                .doOnCancel(() -> {
118                                        ReactorClientHttpResponse response = responseRef.get();
119                                        if (response != null) {
120                                                response.releaseAfterCancel(method);
121                                        }
122                                });
123        }
124
125        private ReactorClientHttpRequest adaptRequest(HttpMethod method, URI uri, HttpClientRequest request,
126                        NettyOutbound nettyOutbound) {
127
128                return new ReactorClientHttpRequest(method, uri, request, nettyOutbound);
129        }
130
131}