Add Netty Compression support

Reactor Netty 0.7.5 now supports all Compression options.
Unlike previous Reactor Netty versions, the minimum compression
threshold is now based on the content-length instead of
accumulating for a while the data.

See gh-12268

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/CompressionCustomizer.java

+/*
+ * Copyright 2012-2018 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.web.embedded.netty;
+
+import java.util.function.BiPredicate;
+
+import io.netty.handler.codec.http.HttpHeaderNames;
+import reactor.ipc.netty.http.server.HttpServerOptions;
+import reactor.ipc.netty.http.server.HttpServerRequest;
+import reactor.ipc.netty.http.server.HttpServerResponse;
+
+import org.springframework.boot.web.server.Compression;
+import org.springframework.util.MimeType;
+import org.springframework.util.MimeTypeUtils;
+
+/**
+ * Configure the HTTP compression on an Reactor Netty request/response handler.
+ *
+ * @author Stephane Maldini
+ */
+final class CompressionCustomizer implements NettyServerCustomizer {
+
+	private final Compression compression;
+
+	CompressionCustomizer(Compression compression) {
+		this.compression = compression;
+	}
+
+	@Override
+	public void customize(HttpServerOptions.Builder builder) {
+		if (compression.getMinResponseSize() >= 0) {
+			builder.compression(compression.getMinResponseSize());
+		}
+		
+		BiPredicate<HttpServerRequest, HttpServerResponse> compressPredicate = null;
+
+		if (compression.getMimeTypes() != null &&
+				compression.getMimeTypes().length > 0) {
+			compressPredicate = new CompressibleMimeTypePredicate(compression.getMimeTypes());
+		}
+
+		if (compression.getExcludedUserAgents() != null &&
+				compression.getExcludedUserAgents().length > 0 ) {
+			BiPredicate<HttpServerRequest, HttpServerResponse> agentCompressPredicate =
+					new CompressibleAgentPredicate(compression.getExcludedUserAgents());
+
+			compressPredicate = compressPredicate == null ?
+					agentCompressPredicate :
+					compressPredicate.and(agentCompressPredicate);
+		}
+
+		if (compressPredicate != null) {
+			builder.compression(compressPredicate);
+		}
+	}
+
+	private static class CompressibleAgentPredicate
+			implements BiPredicate<HttpServerRequest, HttpServerResponse> {
+
+		private final String[] excludedAgents;
+
+		CompressibleAgentPredicate(String[] excludedAgents) {
+			this.excludedAgents = new String[excludedAgents.length];
+			System.arraycopy(excludedAgents, 0, this.excludedAgents, 0, excludedAgents.length);
+		}
+
+		@Override
+		public boolean test(HttpServerRequest request, HttpServerResponse response) {
+			for(String excludedAgent : excludedAgents) {
+				if (request.requestHeaders()
+				           .contains(HttpHeaderNames.USER_AGENT, excludedAgent, true)) {
+					return false;
+				}
+			}
+			return true;
+		}
+	}
+
+	private static class CompressibleMimeTypePredicate
+			implements BiPredicate<HttpServerRequest, HttpServerResponse> {
+
+		private final MimeType[] mimeTypes;
+
+		CompressibleMimeTypePredicate(String[] mimeTypes) {
+			this.mimeTypes = new MimeType[mimeTypes.length];
+			for (int i = 0; i < mimeTypes.length; i++) {
+				this.mimeTypes[i] = MimeTypeUtils.parseMimeType(mimeTypes[i]);
+			}
+		}
+
+		@Override
+		public boolean test(HttpServerRequest request, HttpServerResponse response) {
+			String contentType = response.responseHeaders()
+			                             .get(HttpHeaderNames.CONTENT_TYPE);
+			if (contentType != null) {
+				for (MimeType mimeType : this.mimeTypes) {
+					if (mimeType.isCompatibleWith(MimeTypeUtils.parseMimeType(contentType))) {
+						return true;
+					}
+				}
+			}
+			return false;
+		}
+
+	}
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/embedded/netty/NettyReactiveWebServerFactory.java

@@ -106,8 +106,10 @@ public class NettyReactiveWebServerFactory extends AbstractReactiveWebServerFact
 						getSsl(), getSslStoreProvider());
 				sslServerCustomizer.customize(options);
 			}
-			if (getCompression() != null) {
-				options.compression(getCompression().getEnabled());
+			if (getCompression() != null && getCompression().getEnabled()) {
+				CompressionCustomizer compressionCustomizer = new CompressionCustomizer(
+						getCompression());
+				compressionCustomizer.customize(options);
 			}
 			applyCustomizers(options);
 		}).build();

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/reactive/server/AbstractReactiveWebServerFactoryTests.java

@@ -275,8 +275,6 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 
 	@Test
 	public void noCompressionForMimeType() throws Exception {
-		Assumptions.assumeThat(getFactory())
-				.isNotInstanceOf(NettyReactiveWebServerFactory.class);
 		Compression compression = new Compression();
 		compression.setMimeTypes(new String[] { "application/json" });
 		WebClient client = prepareCompressionTest(compression);
@@ -287,8 +285,6 @@ public abstract class AbstractReactiveWebServerFactoryTests {
 
 	@Test
 	public void noCompressionForUserAgent() throws Exception {
-		Assumptions.assumeThat(getFactory())
-				.isNotInstanceOf(NettyReactiveWebServerFactory.class);
 		Compression compression = new Compression();
 		compression.setEnabled(true);
 		compression.setExcludedUserAgents(new String[] { "testUserAgent" });