Allow ExchangeStrategies customizations in WebClient

Prior to this commit, developers could configure their WebClient to use
their custom `ExchangeStrategies`, by providing it in the
`WebClient.Builder` chain.
Once created, an `ExchangeStrategies` instance is not mutable, which
makes it hard for further customizations by other components. In the
case of the reported issue, other components would override the default
configuration for the codecs maxInMemorySize.

This commit makes the `ExchangeStrategies` mutable and uses that fact to
further customize them with a new `WebClient.Builder#exchangeStrategies`
`Consumer` variant. This commit is also deprecating those mutating
variants in favor of a new `WebClient.Builder#exchangeStrategies` that
takes a `ExchangeStrategies#Builder` directly and avoids mutation issues
altogether.

Closes gh-24106

Author: bclozel

spring-test/src/main/java/org/springframework/test/web/reactive/server/DefaultWebTestClientBuilder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -137,11 +137,24 @@ public WebTestClient.Builder filters(Consumer<List<ExchangeFilterFunction>> filt
 	}
 
 	@Override
+	@Deprecated
 	public WebTestClient.Builder exchangeStrategies(ExchangeStrategies strategies) {
 		this.webClientBuilder.exchangeStrategies(strategies);
 		return this;
 	}
 
+	@Override
+	public WebTestClient.Builder exchangeStrategies(ExchangeStrategies.Builder strategies) {
+		this.webClientBuilder.exchangeStrategies(strategies);
+		return this;
+	}
+
+	@Override
+	public WebTestClient.Builder exchangeStrategies(Consumer<ExchangeStrategies.Builder> configurer) {
+		this.webClientBuilder.exchangeStrategies(configurer);
+		return this;
+	}
+
 	@Override
 	public WebTestClient.Builder responseTimeout(Duration timeout) {
 		this.responseTimeout = timeout;

spring-test/src/main/java/org/springframework/test/web/reactive/server/WebTestClient.java

@@ -77,6 +77,7 @@
  * and Spring Kotlin extensions to perform integration tests on an embedded WebFlux server.
  *
  * @author Rossen Stoyanchev
+ * @author Brian Clozel
  * @since 5.0
  * @see StatusAssertions
  * @see HeaderAssertions
@@ -436,11 +437,34 @@ interface Builder {
 
 		/**
 		 * Configure the {@link ExchangeStrategies} to use.
-		 * <p>By default {@link ExchangeStrategies#withDefaults()} is used.
+		 * <p>This is useful for changing the default settings, yet still allowing
+		 * further customizations via {@link #exchangeStrategies(Consumer)}.
+		 * By default {@link ExchangeStrategies#withDefaults()} is used.
 		 * @param strategies the strategies to use
+		 * @deprecated as of 5.1 in favor of {@link #exchangeStrategies(ExchangeStrategies.Builder)}
 		 */
+		@Deprecated
 		Builder exchangeStrategies(ExchangeStrategies strategies);
 
+		/**
+		 * Configure the {@link ExchangeStrategies.Builder} to use.
+		 * <p>This is useful for changing the default settings, yet still allowing
+		 * further customizations via {@link #exchangeStrategies(Consumer)}.
+		 * By default {@link ExchangeStrategies#builder()} is used.
+		 * @param strategies the strategies to use
+		 * @since 5.1.12
+		 */
+		Builder exchangeStrategies(ExchangeStrategies.Builder strategies);
+
+		/**
+		 * Customize the {@link ExchangeStrategies}.
+		 * <p>Allows further customization on {@link ExchangeStrategies},
+		 * mutating them if they were {@link #exchangeStrategies(ExchangeStrategies) set},
+		 * or starting from {@link ExchangeStrategies#withDefaults() defaults}.
+		 * @since 5.1.12
+		 */
+		Builder exchangeStrategies(Consumer<ExchangeStrategies.Builder> configurer);
+
 		/**
 		 * Max amount of time to wait for responses.
 		 * <p>By default 5 seconds.
@@ -877,7 +901,7 @@ interface BodyContentSpec {
 		 * @since 5.1
 		 * @see #xpath(String, Map, Object...)
 		 */
-		default XpathAssertions xpath(String expression, Object... args){
+		default XpathAssertions xpath(String expression, Object... args) {
 			return xpath(expression, null, args);
 		}
 
@@ -891,7 +915,7 @@ default XpathAssertions xpath(String expression, Object... args){
 		 * @param args arguments to parameterize the expression
 		 * @since 5.1
 		 */
-		XpathAssertions xpath(String expression, @Nullable  Map<String, String> namespaces, Object... args);
+		XpathAssertions xpath(String expression, @Nullable Map<String, String> namespaces, Object... args);
 
 		/**
 		 * Assert the response body content with the given {@link Consumer}.

spring-web/src/main/java/org/springframework/http/codec/ClientCodecConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -63,6 +63,11 @@ public interface ClientCodecConfigurer extends CodecConfigurer {
 	@Override
 	ClientDefaultCodecs defaultCodecs();
 
+	/**
+	 * Clone this {@link ClientCodecConfigurer}.
+	 */
+	@Override
+	ClientCodecConfigurer clone();
 
 	/**
 	 * Static factory method for a {@code ClientCodecConfigurer}.

spring-web/src/main/java/org/springframework/http/codec/CodecConfigurer.java

@@ -87,6 +87,12 @@ public interface CodecConfigurer {
 	 */
 	List<HttpMessageWriter<?>> getWriters();
 
+	/**
+	 * Clone this {@link CodecConfigurer}.
+	 * @since 5.1.12
+	 */
+	CodecConfigurer clone();
+
 
 	/**
 	 * Customize or replace the HTTP message readers and writers registered by

spring-web/src/main/java/org/springframework/http/codec/support/BaseCodecConfigurer.java

@@ -34,13 +34,14 @@
  * client and server specific variants.
  *
  * @author Rossen Stoyanchev
+ * @author Brian Clozel
  * @since 5.0
  */
 class BaseCodecConfigurer implements CodecConfigurer {
 
-	private final BaseDefaultCodecs defaultCodecs;
+	protected final BaseDefaultCodecs defaultCodecs;
 
-	private final DefaultCustomCodecs customCodecs = new DefaultCustomCodecs();
+	protected final DefaultCustomCodecs customCodecs;
 
 
 	/**
@@ -50,6 +51,16 @@ class BaseCodecConfigurer implements CodecConfigurer {
 	BaseCodecConfigurer(BaseDefaultCodecs defaultCodecs) {
 		Assert.notNull(defaultCodecs, "'defaultCodecs' is required");
 		this.defaultCodecs = defaultCodecs;
+		this.customCodecs = new DefaultCustomCodecs();
+	}
+
+	/**
+	 * Constructor with another {@link BaseCodecConfigurer} to copy
+	 * the configuration from.
+	 */
+	BaseCodecConfigurer(BaseCodecConfigurer other) {
+		this.defaultCodecs = other.cloneDefaultCodecs();
+		this.customCodecs = new DefaultCustomCodecs(other.customCodecs);
 	}
 
 
@@ -87,6 +98,17 @@ public List<HttpMessageWriter<?>> getWriters() {
 		return getWritersInternal(false);
 	}
 
+
+	@Override
+	public CodecConfigurer clone() {
+		return new BaseCodecConfigurer(this);
+	}
+
+	protected BaseDefaultCodecs cloneDefaultCodecs() {
+		return new BaseDefaultCodecs(this.defaultCodecs);
+	}
+
+
 	/**
 	 * Internal method that returns the configured writers.
 	 * @param forMultipart whether to returns writers for general use ("false"),
@@ -110,7 +132,7 @@ protected List<HttpMessageWriter<?>> getWritersInternal(boolean forMultipart) {
 	/**
 	 * Default implementation of {@code CustomCodecs}.
 	 */
-	private static final class DefaultCustomCodecs implements CustomCodecs {
+	protected static final class DefaultCustomCodecs implements CustomCodecs {
 
 		private final List<HttpMessageReader<?>> typedReaders = new ArrayList<>();
 
@@ -121,6 +143,16 @@ private static final class DefaultCustomCodecs implements CustomCodecs {
 		private final List<HttpMessageWriter<?>> objectWriters = new ArrayList<>();
 
 
+		DefaultCustomCodecs() {
+		}
+
+		DefaultCustomCodecs(DefaultCustomCodecs other) {
+			other.typedReaders.addAll(this.typedReaders);
+			other.typedWriters.addAll(this.typedWriters);
+			other.objectReaders.addAll(this.objectReaders);
+			other.objectWriters.addAll(this.objectWriters);
+		}
+
 		@Override
 		public void decoder(Decoder<?> decoder) {
 			reader(new DecoderHttpMessageReader<>(decoder));
@@ -143,7 +175,6 @@ public void writer(HttpMessageWriter<?> writer) {
 			(canWriteObject ? this.objectWriters : this.typedWriters).add(writer);
 		}
 
-
 		// Package private accessors...
 
 		List<HttpMessageReader<?>> getTypedReaders() {

spring-web/src/main/java/org/springframework/http/codec/support/BaseDefaultCodecs.java

@@ -105,6 +105,21 @@ class BaseDefaultCodecs implements CodecConfigurer.DefaultCodecs {
 	private boolean registerDefaults = true;
 
 
+	BaseDefaultCodecs() {
+	}
+
+	protected BaseDefaultCodecs(BaseDefaultCodecs other) {
+		this.jackson2JsonDecoder = other.jackson2JsonDecoder;
+		this.jackson2JsonEncoder = other.jackson2JsonEncoder;
+		this.protobufDecoder = other.protobufDecoder;
+		this.protobufEncoder = other.protobufEncoder;
+		this.jaxb2Decoder = other.jaxb2Decoder;
+		this.jaxb2Encoder = other.jaxb2Encoder;
+		this.maxInMemorySize = other.maxInMemorySize;
+		this.enableLoggingRequestDetails = other.enableLoggingRequestDetails;
+		this.registerDefaults = other.registerDefaults;
+	}
+
 	@Override
 	public void jackson2JsonDecoder(Decoder<?> decoder) {
 		this.jackson2JsonDecoder = decoder;

spring-web/src/main/java/org/springframework/http/codec/support/ClientDefaultCodecsImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,6 +49,17 @@ class ClientDefaultCodecsImpl extends BaseDefaultCodecs implements ClientCodecCo
 	private Supplier<List<HttpMessageWriter<?>>> partWritersSupplier;
 
 
+	ClientDefaultCodecsImpl() {
+	}
+
+	ClientDefaultCodecsImpl(ClientDefaultCodecsImpl other) {
+		super(other);
+		this.multipartCodecs = new DefaultMultipartCodecs(other.multipartCodecs);
+		this.sseDecoder = other.sseDecoder;
+		this.partWritersSupplier = other.partWritersSupplier;
+	}
+
+
 	/**
 	 * Set a supplier for part writers to use when
 	 * {@link #multipartCodecs()} are not explicitly configured.
@@ -73,6 +84,14 @@ public void serverSentEventDecoder(Decoder<?> decoder) {
 		this.sseDecoder = decoder;
 	}
 
+	@Override
+	public ClientDefaultCodecsImpl clone() {
+		ClientDefaultCodecsImpl codecs = new ClientDefaultCodecsImpl();
+		codecs.multipartCodecs = this.multipartCodecs;
+		codecs.sseDecoder = this.sseDecoder;
+		codecs.partWritersSupplier = this.partWritersSupplier;
+		return codecs;
+	}
 
 	@Override
 	protected void extendObjectReaders(List<HttpMessageReader<?>> objectReaders) {
@@ -116,6 +135,17 @@ private static class DefaultMultipartCodecs implements ClientCodecConfigurer.Mul
 
 		private final List<HttpMessageWriter<?>> writers = new ArrayList<>();
 
+
+		DefaultMultipartCodecs() {
+		}
+
+		DefaultMultipartCodecs(@Nullable DefaultMultipartCodecs other) {
+			if (other != null) {
+				this.writers.addAll(other.writers);
+			}
+		}
+
+
 		@Override
 		public ClientCodecConfigurer.MultipartCodecs encoder(Encoder<?> encoder) {
 			writer(new EncoderHttpMessageWriter<>(encoder));

spring-web/src/main/java/org/springframework/http/codec/support/DefaultClientCodecConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,14 +26,30 @@
  */
 public class DefaultClientCodecConfigurer extends BaseCodecConfigurer implements ClientCodecConfigurer {
 
+
 	public DefaultClientCodecConfigurer() {
 		super(new ClientDefaultCodecsImpl());
 		((ClientDefaultCodecsImpl) defaultCodecs()).setPartWritersSupplier(() -> getWritersInternal(true));
 	}
 
+	private DefaultClientCodecConfigurer(DefaultClientCodecConfigurer other) {
+		super(other);
+	}
+
+
 	@Override
 	public ClientDefaultCodecs defaultCodecs() {
 		return (ClientDefaultCodecs) super.defaultCodecs();
 	}
 
+	@Override
+	public DefaultClientCodecConfigurer clone() {
+		return new DefaultClientCodecConfigurer(this);
+	}
+
+	@Override
+	protected BaseDefaultCodecs cloneDefaultCodecs() {
+		return new ClientDefaultCodecsImpl((ClientDefaultCodecsImpl) defaultCodecs());
+	}
+
 }

spring-web/src/main/java/org/springframework/http/codec/support/DefaultServerCodecConfigurer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,13 +26,28 @@
  */
 public class DefaultServerCodecConfigurer extends BaseCodecConfigurer implements ServerCodecConfigurer {
 
+
 	public DefaultServerCodecConfigurer() {
 		super(new ServerDefaultCodecsImpl());
 	}
 
+	private DefaultServerCodecConfigurer(BaseCodecConfigurer other) {
+		super(other);
+	}
+
+
 	@Override
 	public ServerDefaultCodecs defaultCodecs() {
 		return (ServerDefaultCodecs) super.defaultCodecs();
 	}
 
+	@Override
+	public DefaultServerCodecConfigurer clone() {
+		return new DefaultServerCodecConfigurer(this);
+	}
+
+	@Override
+	protected BaseDefaultCodecs cloneDefaultCodecs() {
+		return new ServerDefaultCodecsImpl((ServerDefaultCodecsImpl) defaultCodecs());
+	}
 }

spring-web/src/main/java/org/springframework/http/codec/support/ServerDefaultCodecsImpl.java

@@ -46,6 +46,16 @@ class ServerDefaultCodecsImpl extends BaseDefaultCodecs implements ServerCodecCo
 	private Encoder<?> sseEncoder;
 
 
+	ServerDefaultCodecsImpl() {
+	}
+
+	ServerDefaultCodecsImpl(ServerDefaultCodecsImpl other) {
+		super(other);
+		this.multipartReader = other.multipartReader;
+		this.sseEncoder = other.sseEncoder;
+	}
+
+
 	@Override
 	public void multipartReader(HttpMessageReader<?> reader) {
 		this.multipartReader = reader;