Avoided repeated creation of ReadOnlyHttpHeaders wrapper

See gh-24680

spring-web/src/main/java/org/springframework/http/HttpHeaders.java

@@ -1769,7 +1769,9 @@ public String toString() {
 
 
 	/**
-	 * Apply a read-only {@code HttpHeaders} wrapper around the given headers.
+	 * Apply a read-only {@code HttpHeaders} wrapper around the given headers
+	 * that also caches the parsed representations of the "Accept" and
+	 * "Content-Type" headers.
 	 */
 	public static HttpHeaders readOnlyHttpHeaders(MultiValueMap<String, String> headers) {
 		Assert.notNull(headers, "HttpHeaders must not be null");

spring-web/src/main/java/org/springframework/http/client/AbstractClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -20,6 +20,7 @@
 import java.io.OutputStream;
 
 import org.springframework.http.HttpHeaders;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -35,10 +36,22 @@ public abstract class AbstractClientHttpRequest implements ClientHttpRequest {
 
 	private boolean executed = false;
 
+	@Nullable
+	private HttpHeaders readOnlyHeaders;
+
 
 	@Override
 	public final HttpHeaders getHeaders() {
-		return (this.executed ? HttpHeaders.readOnlyHttpHeaders(this.headers) : this.headers);
+		if (this.readOnlyHeaders != null) {
+			return this.readOnlyHeaders;
+		}
+		else if (this.executed) {
+			this.readOnlyHeaders = HttpHeaders.readOnlyHttpHeaders(this.headers);
+			return this.readOnlyHeaders;
+		}
+		else {
+			return this.headers;
+		}
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/http/client/reactive/AbstractClientHttpRequest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -60,6 +60,9 @@ private enum State {NEW, COMMITTING, COMMITTED}
 
 	private final List<Supplier<? extends Publisher<Void>>> commitActions = new ArrayList<>(4);
 
+	@Nullable
+	private HttpHeaders readOnlyHeaders;
+
 
 	public AbstractClientHttpRequest() {
 		this(new HttpHeaders());
@@ -74,10 +77,16 @@ public AbstractClientHttpRequest(HttpHeaders headers) {
 
 	@Override
 	public HttpHeaders getHeaders() {
-		if (State.COMMITTED.equals(this.state.get())) {
-			return HttpHeaders.readOnlyHttpHeaders(this.headers);
+		if (this.readOnlyHeaders != null) {
+			return this.readOnlyHeaders;
+		}
+		else if (State.COMMITTED.equals(this.state.get())) {
+			this.readOnlyHeaders = HttpHeaders.readOnlyHttpHeaders(this.headers);
+			return this.readOnlyHeaders;
+		}
+		else {
+			return this.headers;
 		}
-		return this.headers;
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/http/server/ServletServerHttpResponse.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -47,6 +47,9 @@ public class ServletServerHttpResponse implements ServerHttpResponse {
 
 	private boolean bodyUsed = false;
 
+	@Nullable
+	private HttpHeaders readOnlyHeaders;
+
 
 	/**
 	 * Construct a new instance of the ServletServerHttpResponse based on the given {@link HttpServletResponse}.
@@ -74,7 +77,16 @@ public void setStatusCode(HttpStatus status) {
 
 	@Override
 	public HttpHeaders getHeaders() {
-		return (this.headersWritten ? HttpHeaders.readOnlyHttpHeaders(this.headers) : this.headers);
+		if (this.readOnlyHeaders != null) {
+			return this.readOnlyHeaders;
+		}
+		else if (this.headersWritten) {
+			this.readOnlyHeaders = HttpHeaders.readOnlyHttpHeaders(this.headers);
+			return this.readOnlyHeaders;
+		}
+		else {
+			return this.headers;
+		}
 	}
 
 	@Override

spring-web/src/main/java/org/springframework/http/server/reactive/AbstractServerHttpResponse.java

@@ -75,6 +75,9 @@ private enum State {NEW, COMMITTING, COMMITTED}
 
 	private final List<Supplier<? extends Mono<Void>>> commitActions = new ArrayList<>(4);
 
+	@Nullable
+	private HttpHeaders readOnlyHeaders;
+
 
 	public AbstractServerHttpResponse(DataBufferFactory dataBufferFactory) {
 		this(dataBufferFactory, new HttpHeaders());
@@ -155,8 +158,16 @@ public Integer getStatusCodeValue() {
 
 	@Override
 	public HttpHeaders getHeaders() {
-		return (this.state.get() == State.COMMITTED ?
-				HttpHeaders.readOnlyHttpHeaders(this.headers) : this.headers);
+		if (this.readOnlyHeaders != null) {
+			return this.readOnlyHeaders;
+		}
+		else if (this.state.get() == State.COMMITTED) {
+			this.readOnlyHeaders = HttpHeaders.readOnlyHttpHeaders(this.headers);
+			return this.readOnlyHeaders;
+		}
+		else {
+			return this.headers;
+		}
 	}
 
 	@Override

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultClientResponse.java

@@ -234,29 +234,28 @@ HttpRequest request() {
 
 	private class DefaultHeaders implements Headers {
 
-		private HttpHeaders delegate() {
-			return response.getHeaders();
-		}
+		private final HttpHeaders httpHeaders =
+				HttpHeaders.readOnlyHttpHeaders(response.getHeaders());
 
 		@Override
 		public OptionalLong contentLength() {
-			return toOptionalLong(delegate().getContentLength());
+			return toOptionalLong(this.httpHeaders.getContentLength());
 		}
 
 		@Override
 		public Optional<MediaType> contentType() {
-			return Optional.ofNullable(delegate().getContentType());
+			return Optional.ofNullable(this.httpHeaders.getContentType());
 		}
 
 		@Override
 		public List<String> header(String headerName) {
-			List<String> headerValues = delegate().get(headerName);
+			List<String> headerValues = this.httpHeaders.get(headerName);
 			return (headerValues != null ? headerValues : Collections.emptyList());
 		}
 
 		@Override
 		public HttpHeaders asHttpHeaders() {
-			return HttpHeaders.readOnlyHttpHeaders(delegate());
+			return this.httpHeaders;
 		}
 
 		private OptionalLong toOptionalLong(long value) {

spring-webflux/src/main/java/org/springframework/web/reactive/function/client/DefaultWebClientBuilder.java

@@ -265,8 +265,8 @@ public WebClient build() {
 				.map(filter -> filter.apply(exchange))
 				.orElse(exchange) : exchange);
 		return new DefaultWebClient(filteredExchange, initUriBuilderFactory(),
-				this.defaultHeaders != null ? unmodifiableCopy(this.defaultHeaders) : null,
-				this.defaultCookies != null ? unmodifiableCopy(this.defaultCookies) : null,
+				this.defaultHeaders != null ? HttpHeaders.readOnlyHttpHeaders(this.defaultHeaders) : null,
+				this.defaultCookies != null ? HttpHeaders.readOnlyHttpHeaders(this.defaultCookies) : null,
 				this.defaultRequest, new DefaultWebClientBuilder(this));
 	}
 
@@ -308,10 +308,6 @@ private UriBuilderFactory initUriBuilderFactory() {
 		return factory;
 	}
 
-	private static HttpHeaders unmodifiableCopy(HttpHeaders headers) {
-		return HttpHeaders.readOnlyHttpHeaders(headers);
-	}
-
 	private static <K, V> MultiValueMap<K, V> unmodifiableCopy(MultiValueMap<K, V> map) {
 		return CollectionUtils.unmodifiableMultiValueMap(new LinkedMultiValueMap<>(map));
 	}

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequest.java

@@ -260,61 +260,60 @@ public String toString() {
 
 
 	private class DefaultHeaders implements Headers {
-
-		private HttpHeaders delegate() {
-			return request().getHeaders();
-		}
+
+		private final HttpHeaders httpHeaders =
+				HttpHeaders.readOnlyHttpHeaders(request().getHeaders());
 
 		@Override
 		public List<MediaType> accept() {
-			return delegate().getAccept();
+			return this.httpHeaders.getAccept();
 		}
 
 		@Override
 		public List<Charset> acceptCharset() {
-			return delegate().getAcceptCharset();
+			return this.httpHeaders.getAcceptCharset();
 		}
 
 		@Override
 		public List<Locale.LanguageRange> acceptLanguage() {
-			return delegate().getAcceptLanguage();
+			return this.httpHeaders.getAcceptLanguage();
 		}
 
 		@Override
 		public OptionalLong contentLength() {
-			long value = delegate().getContentLength();
+			long value = this.httpHeaders.getContentLength();
 			return (value != -1 ? OptionalLong.of(value) : OptionalLong.empty());
 		}
 
 		@Override
 		public Optional<MediaType> contentType() {
-			return Optional.ofNullable(delegate().getContentType());
+			return Optional.ofNullable(this.httpHeaders.getContentType());
 		}
 
 		@Override
 		public InetSocketAddress host() {
-			return delegate().getHost();
+			return this.httpHeaders.getHost();
 		}
 
 		@Override
 		public List<HttpRange> range() {
-			return delegate().getRange();
+			return this.httpHeaders.getRange();
 		}
 
 		@Override
 		public List<String> header(String headerName) {
-			List<String> headerValues = delegate().get(headerName);
+			List<String> headerValues = this.httpHeaders.get(headerName);
 			return (headerValues != null ? headerValues : Collections.emptyList());
 		}
 
 		@Override
 		public HttpHeaders asHttpHeaders() {
-			return HttpHeaders.readOnlyHttpHeaders(delegate());
+			return this.httpHeaders;
 		}
 
 		@Override
 		public String toString() {
-			return delegate().toString();
+			return this.httpHeaders.toString();
 		}
 	}
 

spring-webflux/src/test/java/org/springframework/web/reactive/function/client/DefaultClientResponseTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -60,6 +60,8 @@ public class DefaultClientResponseTests {
 
 	private ClientHttpResponse mockResponse;
 
+	private final HttpHeaders httpHeaders = new HttpHeaders();
+
 	private ExchangeStrategies mockExchangeStrategies;
 
 	private DefaultClientResponse defaultClientResponse;
@@ -68,6 +70,7 @@ public class DefaultClientResponseTests {
 	@BeforeEach
 	public void createMocks() {
 		mockResponse = mock(ClientHttpResponse.class);
+		given(mockResponse.getHeaders()).willReturn(this.httpHeaders);
 		mockExchangeStrategies = mock(ExchangeStrategies.class);
 		defaultClientResponse = new DefaultClientResponse(mockResponse, mockExchangeStrategies, "", "", () -> null);
 	}
@@ -91,7 +94,6 @@ public void rawStatusCode() {
 
 	@Test
 	public void header() {
-		HttpHeaders httpHeaders = new HttpHeaders();
 		long contentLength = 42L;
 		httpHeaders.setContentLength(contentLength);
 		MediaType contentType = MediaType.TEXT_PLAIN;
@@ -233,7 +235,6 @@ public void toEntityWithUnknownStatusCode() throws Exception {
 				= factory.wrap(ByteBuffer.wrap("foo".getBytes(StandardCharsets.UTF_8)));
 		Flux<DataBuffer> body = Flux.just(dataBuffer);
 
-		HttpHeaders httpHeaders = new HttpHeaders();
 		httpHeaders.setContentType(MediaType.TEXT_PLAIN);
 		given(mockResponse.getHeaders()).willReturn(httpHeaders);
 		given(mockResponse.getStatusCode()).willThrow(new IllegalArgumentException("999"));
@@ -293,13 +294,12 @@ public void toEntityList() {
 	}
 
 	@Test
-	public void toEntityListWithUnknownStatusCode() throws Exception {
+	public void toEntityListWithUnknownStatusCode() {
 		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
 		DefaultDataBuffer dataBuffer =
 				factory.wrap(ByteBuffer.wrap("foo".getBytes(StandardCharsets.UTF_8)));
 		Flux<DataBuffer> body = Flux.just(dataBuffer);
 
-		HttpHeaders httpHeaders = new HttpHeaders();
 		httpHeaders.setContentType(MediaType.TEXT_PLAIN);
 		given(mockResponse.getHeaders()).willReturn(httpHeaders);
 		given(mockResponse.getStatusCode()).willThrow(new IllegalArgumentException("999"));
@@ -321,8 +321,7 @@ public void toEntityListWithUnknownStatusCode() throws Exception {
 	@Test
 	public void toEntityListTypeReference() {
 		DefaultDataBufferFactory factory = new DefaultDataBufferFactory();
-		DefaultDataBuffer dataBuffer =
-				factory.wrap(ByteBuffer.wrap("foo".getBytes(StandardCharsets.UTF_8)));
+		DefaultDataBuffer dataBuffer = factory.wrap(ByteBuffer.wrap("foo".getBytes(StandardCharsets.UTF_8)));
 		Flux<DataBuffer> body = Flux.just(dataBuffer);
 
 		mockTextPlainResponse(body);
@@ -332,8 +331,7 @@ public void toEntityListTypeReference() {
 		given(mockExchangeStrategies.messageReaders()).willReturn(messageReaders);
 
 		ResponseEntity<List<String>> result = defaultClientResponse.toEntityList(
-				new ParameterizedTypeReference<String>() {
-				}).block();
+				new ParameterizedTypeReference<String>() {}).block();
 		assertThat(result.getBody()).isEqualTo(Collections.singletonList("foo"));
 		assertThat(result.getStatusCode()).isEqualTo(HttpStatus.OK);
 		assertThat(result.getStatusCodeValue()).isEqualTo(HttpStatus.OK.value());
@@ -342,9 +340,7 @@ public void toEntityListTypeReference() {
 
 
 	private void mockTextPlainResponse(Flux<DataBuffer> body) {
-		HttpHeaders httpHeaders = new HttpHeaders();
 		httpHeaders.setContentType(MediaType.TEXT_PLAIN);
-		given(mockResponse.getHeaders()).willReturn(httpHeaders);
 		given(mockResponse.getStatusCode()).willReturn(HttpStatus.OK);
 		given(mockResponse.getRawStatusCode()).willReturn(HttpStatus.OK.value());
 		given(mockResponse.getBody()).willReturn(body);