zentol commented on a change in pull request #7295: [FLINK-10748] Decouple RestServerEndpoint from Dispatcher URL: https://github.com/apache/flink/pull/7295#discussion_r241389144
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/LeaderRetrievalHandler.java ########## @@ -0,0 +1,103 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.flink.runtime.rest.handler; + +import org.apache.flink.api.common.time.Time; +import org.apache.flink.runtime.rest.handler.router.RoutedRequest; +import org.apache.flink.runtime.rest.handler.util.HandlerUtils; +import org.apache.flink.runtime.rest.messages.ErrorResponseBody; +import org.apache.flink.runtime.webmonitor.RestfulGateway; +import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever; +import org.apache.flink.util.OptionalConsumer; +import org.apache.flink.util.Preconditions; + +import org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandler; +import org.apache.flink.shaded.netty4.io.netty.channel.ChannelHandlerContext; +import org.apache.flink.shaded.netty4.io.netty.channel.SimpleChannelInboundHandler; +import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpRequest; +import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nonnull; + +import java.util.Map; + +/** + * {@link SimpleChannelInboundHandler} which encapsulates the leader retrieval logic for the + * REST endpoints. + * + * @param <T> type of the leader to retrieve + */ [email protected] +public abstract class LeaderRetrievalHandler<T extends RestfulGateway> extends SimpleChannelInboundHandler<RoutedRequest> { + + protected final Logger logger = LoggerFactory.getLogger(getClass()); + + protected final GatewayRetriever<? extends T> leaderRetriever; + + protected final Time timeout; + + protected final Map<String, String> responseHeaders; + + protected LeaderRetrievalHandler( + @Nonnull GatewayRetriever<? extends T> leaderRetriever, + @Nonnull Time timeout, + @Nonnull Map<String, String> responseHeaders) { + this.leaderRetriever = Preconditions.checkNotNull(leaderRetriever); + this.timeout = Preconditions.checkNotNull(timeout); + this.responseHeaders = Preconditions.checkNotNull(responseHeaders); + } + + @Override + protected void channelRead0( + ChannelHandlerContext channelHandlerContext, + RoutedRequest routedRequest) { + + HttpRequest request = routedRequest.getRequest(); + + OptionalConsumer<? extends T> optLeaderConsumer = OptionalConsumer.of(leaderRetriever.getNow()); + + optLeaderConsumer.ifPresent( + gateway -> { + try { + respondAsLeader(channelHandlerContext, routedRequest, gateway); + } catch (Exception e) { + logger.error("Error while responding as leader.", e); Review comment: I'd prefer that. It's a bit....well we just aren't _really_ the leader (in a way this concept no longer exists on the REST handler level), so it seems a bid misleading. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
