org.apache.flink.runtime.webmonitor.retriever.LeaderGatewayRetriever Maven / Gradle / Ivy
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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.webmonitor.retriever;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.runtime.highavailability.HighAvailabilityServices;
import org.apache.flink.runtime.rpc.RpcGateway;
import org.apache.flink.util.ExceptionUtils;
import java.util.UUID;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.atomic.AtomicReference;
/**
* Retrieves and stores the leading {@link RpcGateway}.
*
* @param type of the gateway to retrieve
*/
public abstract class LeaderGatewayRetriever extends LeaderRetriever implements GatewayRetriever {
private final AtomicReference> atomicGatewayFuture;
private volatile CompletableFuture initialGatewayFuture;
public LeaderGatewayRetriever() {
initialGatewayFuture = new CompletableFuture<>();
atomicGatewayFuture = new AtomicReference<>(initialGatewayFuture);
}
@Override
public CompletableFuture getFuture() {
final CompletableFuture currentGatewayFuture = atomicGatewayFuture.get();
if (currentGatewayFuture.isCompletedExceptionally()) {
try {
currentGatewayFuture.get();
} catch (ExecutionException | InterruptedException executionException) {
String leaderAddress;
try {
Tuple2 leaderAddressSessionId = getLeaderNow()
.orElse(Tuple2.of("unknown address", HighAvailabilityServices.DEFAULT_LEADER_ID));
leaderAddress = leaderAddressSessionId.f0;
} catch (Exception e) {
log.warn("Could not obtain the current leader.", e);
leaderAddress = "unknown leader address";
}
if (log.isDebugEnabled() || log.isTraceEnabled()) {
// only log exceptions on debug or trace level
log.warn(
"Error while retrieving the leader gateway. Retrying to connect to {}.",
leaderAddress,
ExceptionUtils.stripExecutionException(executionException));
} else {
log.warn(
"Error while retrieving the leader gateway. Retrying to connect to {}.",
leaderAddress);
}
}
// we couldn't resolve the gateway --> let's try again
final CompletableFuture newGatewayFuture = createGateway(getLeaderFuture());
// let's check if there was a concurrent createNewFuture call
if (atomicGatewayFuture.compareAndSet(currentGatewayFuture, newGatewayFuture)) {
return newGatewayFuture;
} else {
return atomicGatewayFuture.get();
}
} else {
return atomicGatewayFuture.get();
}
}
@Override
public void notifyNewLeaderAddress(CompletableFuture> newLeaderAddressFuture) {
final CompletableFuture newGatewayFuture = createGateway(newLeaderAddressFuture);
final CompletableFuture oldGatewayFuture = atomicGatewayFuture.getAndSet(newGatewayFuture);
newGatewayFuture.whenComplete(
(t, throwable) -> {
if (throwable != null) {
oldGatewayFuture.completeExceptionally(throwable);
} else {
oldGatewayFuture.complete(t);
}
});
}
protected abstract CompletableFuture createGateway(CompletableFuture> leaderFuture);
}