Add HttpClient factory support to ReactorHttpClientBuilder

Improve `ReactorHttpClientBuilder` support for creating the initial
`HttpClient`.

Fixes gh-45378

Author: philwebb

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/ReactorClientHttpRequestFactoryBuilder.java

@@ -20,12 +20,14 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.function.Consumer;
+import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 import reactor.netty.http.client.HttpClient;
 
 import org.springframework.boot.context.properties.PropertyMapper;
 import org.springframework.http.client.ReactorClientHttpRequestFactory;
+import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -63,6 +65,33 @@ public ReactorClientHttpRequestFactoryBuilder withCustomizers(
 		return new ReactorClientHttpRequestFactoryBuilder(mergedCustomizers(customizers), this.httpClientBuilder);
 	}
 
+	/**
+	 * Return a new {@link ReactorClientHttpRequestFactoryBuilder} that uses the given
+	 * {@link ReactorResourceFactory} to create the underlying {@link HttpClient}.
+	 * @param reactorResourceFactory the {@link ReactorResourceFactory} to use
+	 * @return a new {@link ReactorClientHttpRequestFactoryBuilder} instance
+	 * @since 3.5.0
+	 */
+	public ReactorClientHttpRequestFactoryBuilder withReactorResourceFactory(
+			ReactorResourceFactory reactorResourceFactory) {
+		Assert.notNull(reactorResourceFactory, "'reactorResourceFactory' must not be null");
+		return new ReactorClientHttpRequestFactoryBuilder(getCustomizers(),
+				this.httpClientBuilder.withReactorResourceFactory(reactorResourceFactory));
+	}
+
+	/**
+	 * Return a new {@link ReactorClientHttpRequestFactoryBuilder} that uses the given
+	 * factory to create the underlying {@link HttpClient}.
+	 * @param factory the factory to use
+	 * @return a new {@link ReactorClientHttpRequestFactoryBuilder} instance
+	 * @since 3.5.0
+	 */
+	public ReactorClientHttpRequestFactoryBuilder withHttpClientFactory(Supplier<HttpClient> factory) {
+		Assert.notNull(factory, "'factory' must not be null");
+		return new ReactorClientHttpRequestFactoryBuilder(getCustomizers(),
+				this.httpClientBuilder.withHttpClientFactory(factory));
+	}
+
 	/**
 	 * Return a new {@link ReactorClientHttpRequestFactoryBuilder} that applies additional
 	 * customization to the underlying {@link HttpClient}.

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/ReactorHttpClientBuilder.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.http.client;
 
 import java.time.Duration;
+import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 import javax.net.ssl.SSLException;
@@ -30,6 +31,7 @@
 import org.springframework.boot.ssl.SslBundle;
 import org.springframework.boot.ssl.SslManagerBundle;
 import org.springframework.boot.ssl.SslOptions;
+import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.util.Assert;
 import org.springframework.util.function.ThrowingConsumer;
 
@@ -43,16 +45,42 @@
  */
 public final class ReactorHttpClientBuilder {
 
+	private final Supplier<HttpClient> factory;
+
 	private final UnaryOperator<HttpClient> customizer;
 
 	public ReactorHttpClientBuilder() {
-		this(UnaryOperator.identity());
+		this(HttpClient::create, UnaryOperator.identity());
 	}
 
-	private ReactorHttpClientBuilder(UnaryOperator<HttpClient> customizer) {
+	private ReactorHttpClientBuilder(Supplier<HttpClient> httpClientFactory, UnaryOperator<HttpClient> customizer) {
+		this.factory = httpClientFactory;
 		this.customizer = customizer;
 	}
 
+	/**
+	 * Return a new {@link ReactorHttpClientBuilder} that uses the given
+	 * {@link ReactorResourceFactory} to create the {@link HttpClient}.
+	 * @param reactorResourceFactory the {@link ReactorResourceFactory} to use
+	 * @return a new {@link ReactorHttpClientBuilder} instance
+	 */
+	public ReactorHttpClientBuilder withReactorResourceFactory(ReactorResourceFactory reactorResourceFactory) {
+		Assert.notNull(reactorResourceFactory, "'reactorResourceFactory' must not be null");
+		return new ReactorHttpClientBuilder(() -> HttpClient.create(reactorResourceFactory.getConnectionProvider()),
+				(httpClient) -> this.customizer.apply(httpClient).runOn(reactorResourceFactory.getLoopResources()));
+	}
+
+	/**
+	 * Return a new {@link ReactorHttpClientBuilder} that uses the given factory to create
+	 * the {@link HttpClient}.
+	 * @param factory the factory to use
+	 * @return a new {@link ReactorHttpClientBuilder} instance
+	 */
+	public ReactorHttpClientBuilder withHttpClientFactory(Supplier<HttpClient> factory) {
+		Assert.notNull(factory, "'factory' must not be null");
+		return new ReactorHttpClientBuilder(factory, this.customizer);
+	}
+
 	/**
 	 * Return a new {@link ReactorHttpClientBuilder} that applies additional customization
 	 * to the underlying {@link HttpClient}.
@@ -72,7 +100,7 @@ public ReactorHttpClientBuilder withHttpClientCustomizer(UnaryOperator<HttpClien
 	 */
 	public HttpClient build(HttpClientSettings settings) {
 		settings = (settings != null) ? settings : HttpClientSettings.DEFAULTS;
-		HttpClient httpClient = applyDefaults(HttpClient.create());
+		HttpClient httpClient = applyDefaults(this.factory.get());
 		PropertyMapper map = PropertyMapper.get().alwaysApplyingWhenNonNull();
 		httpClient = map.from(settings::connectTimeout).to(httpClient, this::setConnectTimeout);
 		httpClient = map.from(settings::readTimeout).to(httpClient, HttpClient::responseTimeout);

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/http/client/reactive/ReactorClientHttpConnectorBuilder.java

@@ -19,11 +19,13 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.function.Consumer;
+import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 import reactor.netty.http.client.HttpClient;
 
 import org.springframework.boot.http.client.ReactorHttpClientBuilder;
+import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -60,6 +62,30 @@ public ReactorClientHttpConnectorBuilder withCustomizers(
 		return new ReactorClientHttpConnectorBuilder(mergedCustomizers(customizers), this.httpClientBuilder);
 	}
 
+	/**
+	 * Return a new {@link ReactorClientHttpConnectorBuilder} that uses the given
+	 * {@link ReactorResourceFactory} to create the underlying {@link HttpClient}.
+	 * @param reactorResourceFactory the {@link ReactorResourceFactory} to use
+	 * @return a new {@link ReactorClientHttpConnectorBuilder} instance
+	 */
+	public ReactorClientHttpConnectorBuilder withReactorResourceFactory(ReactorResourceFactory reactorResourceFactory) {
+		Assert.notNull(reactorResourceFactory, "'reactorResourceFactory' must not be null");
+		return new ReactorClientHttpConnectorBuilder(getCustomizers(),
+				this.httpClientBuilder.withReactorResourceFactory(reactorResourceFactory));
+	}
+
+	/**
+	 * Return a new {@link ReactorClientHttpConnectorBuilder} that uses the given factory
+	 * to create the underlying {@link HttpClient}.
+	 * @param factory the factory to use
+	 * @return a new {@link ReactorClientHttpConnectorBuilder} instance
+	 */
+	public ReactorClientHttpConnectorBuilder withHttpClientFactory(Supplier<HttpClient> factory) {
+		Assert.notNull(factory, "'factory' must not be null");
+		return new ReactorClientHttpConnectorBuilder(getCustomizers(),
+				this.httpClientBuilder.withHttpClientFactory(factory));
+	}
+
 	/**
 	 * Return a new {@link ReactorClientHttpConnectorBuilder} that applies additional
 	 * customization to the underlying {@link HttpClient}.

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/http/client/ReactorClientHttpRequestFactoryBuilderTests.java

@@ -19,16 +19,20 @@
 import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 import io.netty.channel.ChannelOption;
 import org.junit.jupiter.api.Test;
 import reactor.netty.http.client.HttpClient;
 
 import org.springframework.http.client.ReactorClientHttpRequestFactory;
+import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.then;
+import static org.mockito.Mockito.spy;
 
 /**
  * Tests for {@link ReactorClientHttpRequestFactoryBuilder} and
@@ -44,6 +48,25 @@ class ReactorClientHttpRequestFactoryBuilderTests
 		super(ReactorClientHttpRequestFactory.class, ClientHttpRequestFactoryBuilder.reactor());
 	}
 
+	@Test
+	void withwithHttpClientFactory() {
+		boolean[] called = new boolean[1];
+		Supplier<HttpClient> httpClientFactory = () -> {
+			called[0] = true;
+			return HttpClient.create();
+		};
+		ClientHttpRequestFactoryBuilder.reactor().withHttpClientFactory(httpClientFactory).build();
+		assertThat(called).containsExactly(true);
+	}
+
+	@Test
+	void withReactorResourceFactory() {
+		ReactorResourceFactory resourceFactory = spy(new ReactorResourceFactory());
+		ClientHttpRequestFactoryBuilder.reactor().withReactorResourceFactory(resourceFactory).build();
+		then(resourceFactory).should().getConnectionProvider();
+		then(resourceFactory).should().getLoopResources();
+	}
+
 	@Test
 	void withCustomizers() {
 		List<HttpClient> httpClients = new ArrayList<>();

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/http/client/reactive/ReactorClientHttpConnectorBuilderTests.java

@@ -18,18 +18,21 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 
 import io.netty.channel.ChannelOption;
 import org.junit.jupiter.api.Test;
 import reactor.netty.http.client.HttpClient;
 
-import org.springframework.boot.http.client.ClientHttpRequestFactoryBuilder;
 import org.springframework.boot.http.client.ReactorHttpClientBuilder;
+import org.springframework.http.client.ReactorResourceFactory;
 import org.springframework.http.client.reactive.ReactorClientHttpConnector;
 import org.springframework.test.util.ReflectionTestUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.then;
+import static org.mockito.Mockito.spy;
 
 /**
  * Tests for {@link ReactorClientHttpConnectorBuilder} and
@@ -44,6 +47,25 @@ class ReactorClientHttpConnectorBuilderTests
 		super(ReactorClientHttpConnector.class, ClientHttpConnectorBuilder.reactor());
 	}
 
+	@Test
+	void withwithHttpClientFactory() {
+		boolean[] called = new boolean[1];
+		Supplier<HttpClient> httpClientFactory = () -> {
+			called[0] = true;
+			return HttpClient.create();
+		};
+		ClientHttpConnectorBuilder.reactor().withHttpClientFactory(httpClientFactory).build();
+		assertThat(called).containsExactly(true);
+	}
+
+	@Test
+	void withReactorResourceFactory() {
+		ReactorResourceFactory resourceFactory = spy(new ReactorResourceFactory());
+		ClientHttpConnectorBuilder.reactor().withReactorResourceFactory(resourceFactory).build();
+		then(resourceFactory).should().getConnectionProvider();
+		then(resourceFactory).should().getLoopResources();
+	}
+
 	@Test
 	void withCustomizers() {
 		List<HttpClient> httpClients = new ArrayList<>();