org.apache.flink.runtime.rest.handler.LeaderRetrievalHandler Maven / Gradle / Ivy
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* distributed with this work for additional information
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* 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,
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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 type of the leader to retrieve
*/
@ChannelHandler.Sharable
public abstract class LeaderRetrievalHandler extends SimpleChannelInboundHandler {
protected final Logger logger = LoggerFactory.getLogger(getClass());
protected final GatewayRetriever leaderRetriever;
protected final Time timeout;
protected final Map responseHeaders;
protected LeaderRetrievalHandler(
@Nonnull GatewayRetriever leaderRetriever,
@Nonnull Time timeout,
@Nonnull Map 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 optLeaderConsumer = OptionalConsumer.of(leaderRetriever.getNow());
optLeaderConsumer.ifPresent(
gateway -> {
try {
respondAsLeader(channelHandlerContext, routedRequest, gateway);
} catch (Exception e) {
logger.error("Error while responding to the http request.", e);
HandlerUtils.sendErrorResponse(
channelHandlerContext,
request,
new ErrorResponseBody("Error while responding to the http request."),
HttpResponseStatus.INTERNAL_SERVER_ERROR,
responseHeaders);
}
}
).ifNotPresent(
() ->
HandlerUtils.sendErrorResponse(
channelHandlerContext,
request,
new ErrorResponseBody("Service temporarily unavailable due to an ongoing leader election. Please refresh."),
HttpResponseStatus.SERVICE_UNAVAILABLE,
responseHeaders));
}
protected abstract void respondAsLeader(ChannelHandlerContext channelHandlerContext, RoutedRequest request, T gateway) throws Exception;
}