tillrohrmann commented on a change in pull request #11683: [FLINK-15347] Add SupervisorActor which monitors the proper termination of AkkaRpcActors URL: https://github.com/apache/flink/pull/11683#discussion_r410182849
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/rpc/akka/SupervisorActor.java ########## @@ -0,0 +1,360 @@ +/* + * 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.rpc.akka; + +import org.apache.flink.runtime.concurrent.FutureUtils; +import org.apache.flink.runtime.rpc.RpcUtils; +import org.apache.flink.runtime.rpc.akka.exceptions.AkkaRpcException; +import org.apache.flink.runtime.rpc.akka.exceptions.AkkaUnknownMessageException; +import org.apache.flink.util.Preconditions; + +import akka.AkkaException; +import akka.actor.AbstractActor; +import akka.actor.ActorRef; +import akka.actor.ActorSystem; +import akka.actor.ChildRestartStats; +import akka.actor.Props; +import akka.actor.SupervisorStrategy; +import akka.japi.pf.DeciderBuilder; +import akka.pattern.Patterns; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; + +import java.util.HashMap; +import java.util.Map; +import java.util.Optional; +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.CompletionException; +import java.util.function.Function; + +import scala.PartialFunction; +import scala.collection.Iterable; + +/** + * Supervisor actor which is responsible for starting {@link AkkaRpcActor} instances and monitoring + * when the actors have terminated. + */ +class SupervisorActor extends AbstractActor { + + private static final Logger LOG = LoggerFactory.getLogger(SupervisorActor.class); + + private final Map<ActorRef, AkkaRpcActorRegistration> registeredAkkaRpcActors; + + SupervisorActor() { + this.registeredAkkaRpcActors = new HashMap<>(); + } + + @Override + public Receive createReceive() { + return receiveBuilder() + .match(StartAkkaRpcActor.class, this::createStartAkkaRpcActorMessage) + .matchAny(this::handleUnknownMessage) + .build(); + } + + @Override + public void postStop() throws Exception { + LOG.debug("Stopping supervisor actor."); + + super.postStop(); + + for (AkkaRpcActorRegistration actorRegistration : registeredAkkaRpcActors.values()) { + terminateAkkaRpcActorOnStop(actorRegistration); + } + + registeredAkkaRpcActors.clear(); + } + + @Override + public SupervisorActorSupervisorStrategy supervisorStrategy() { + return new SupervisorActorSupervisorStrategy(); + } + + private void terminateAkkaRpcActorOnStop(AkkaRpcActorRegistration akkaRpcActorRegistration) { + akkaRpcActorRegistration.terminateExceptionally(new AkkaRpcException( + String.format("Unexpected closing of %s with name %s.", getClass().getSimpleName(), akkaRpcActorRegistration.getEndpointId()))); + } + + private void createStartAkkaRpcActorMessage(StartAkkaRpcActor startAkkaRpcActor) { + final String endpointId = startAkkaRpcActor.getEndpointId(); + final AkkaRpcActorRegistration akkaRpcActorRegistration = new AkkaRpcActorRegistration(endpointId); + + final Props akkaRpcActorProps = startAkkaRpcActor.getPropsFactory().create(akkaRpcActorRegistration.getInternalTerminationFuture()); + + LOG.debug("Starting {} with name {}.", akkaRpcActorProps.actorClass().getSimpleName(), endpointId); + + try { + final ActorRef actorRef = getContext().actorOf(akkaRpcActorProps, endpointId); + + registeredAkkaRpcActors.put(actorRef, akkaRpcActorRegistration); + + getSender().tell(StartAkkaRpcActorResponse.success( + ActorRegistration.create( + actorRef, + akkaRpcActorRegistration.getExternalTerminationFuture())), + getSelf()); + } catch (AkkaException akkaException) { + getSender().tell(StartAkkaRpcActorResponse.failure(akkaException), getSelf()); + } + } + + private void akkaRpcActorTerminated(ActorRef actorRef) { + final AkkaRpcActorRegistration actorRegistration = removeAkkaRpcActor(actorRef); + + LOG.debug("AkkaRpcActor {} has terminated.", actorRef.path()); + actorRegistration.terminate(); + } + + private void akkaRpcActorFailed(ActorRef actorRef, Throwable cause) { + LOG.warn("AkkaRpcActor {} has failed. Shutting it down now.", actorRef.path(), cause); + + for (Map.Entry<ActorRef, AkkaRpcActorRegistration> registeredAkkaRpcActor : registeredAkkaRpcActors.entrySet()) { + final ActorRef otherActorRef = registeredAkkaRpcActor.getKey(); + if (otherActorRef.equals(actorRef)) { + final AkkaRpcException error = new AkkaRpcException(String.format("Stopping actor %s because it failed.", actorRef.path()), cause); + registeredAkkaRpcActor.getValue().markFailed(error); + } else { + final AkkaRpcException siblingException = new AkkaRpcException(String.format("Stopping actor %s because its sibling %s has failed.", otherActorRef.path(), actorRef.path())); + registeredAkkaRpcActor.getValue().markFailed(siblingException); + } + } + + getContext().getSystem().terminate(); + } + + private AkkaRpcActorRegistration removeAkkaRpcActor(ActorRef actorRef) { + return Optional.ofNullable(registeredAkkaRpcActors.remove(actorRef)) + .orElseThrow(() -> new IllegalStateException(String.format("Could not find actor %s.", actorRef.path()))); + } + + private void handleUnknownMessage(Object msg) { + final AkkaUnknownMessageException cause = new AkkaUnknownMessageException(String.format("Cannot handle unknown message %s.", msg)); + getSender().tell(new akka.actor.Status.Failure(cause), getSelf()); + throw cause; + } + + public static String getActorName() { + return AkkaRpcServiceUtils.SUPERVISOR_NAME; + } + + public static ActorRef startSupervisorActor(ActorSystem actorSystem) { + final Props supervisorProps = Props.create(SupervisorActor.class); + return actorSystem.actorOf(supervisorProps, getActorName()); + } + + public static StartAkkaRpcActorResponse startAkkaRpcActor( + ActorRef supervisor, + StartAkkaRpcActor.PropsFactory propsFactory, + String endpointId) { + return Patterns.ask( + supervisor, + createStartAkkaRpcActorMessage( + propsFactory, + endpointId), + RpcUtils.INF_DURATION).toCompletableFuture() + .thenApply(SupervisorActor.StartAkkaRpcActorResponse.class::cast) + .join(); + } + + public static StartAkkaRpcActor createStartAkkaRpcActorMessage( + StartAkkaRpcActor.PropsFactory propsFactory, + String endpointId) { + return StartAkkaRpcActor.create(propsFactory, endpointId); + } + + // ----------------------------------------------------------------------------- + // Internal classes + // ----------------------------------------------------------------------------- + + private final class SupervisorActorSupervisorStrategy extends SupervisorStrategy { + + @Override + public PartialFunction<Throwable, Directive> decider() { + return DeciderBuilder.match( + Exception.class, e -> SupervisorStrategy.stop() + ).build(); + } + + @Override + public boolean loggingEnabled() { + return false; + } + + @Override + public void handleChildTerminated(akka.actor.ActorContext context, ActorRef child, Iterable<ActorRef> children) { + akkaRpcActorTerminated(child); + } + + @Override + public void processFailure(akka.actor.ActorContext context, boolean restart, ActorRef child, Throwable cause, ChildRestartStats stats, Iterable<ChildRestartStats> children) { + Preconditions.checkArgument(!restart, "The supervisor strategy should never restart an actor."); + + akkaRpcActorFailed(child, cause); + } + } + + private static final class AkkaRpcActorRegistration { + private final String endpointId; + + private final CompletableFuture<Void> internalTerminationFuture; + + private final CompletableFuture<Void> externalTerminationFuture; + + @Nullable + private Throwable errorCause; + + private AkkaRpcActorRegistration(String endpointId) { + this.endpointId = endpointId; + internalTerminationFuture = new CompletableFuture<>(); + externalTerminationFuture = new CompletableFuture<>(); + errorCause = null; + } + + private CompletableFuture<Void> getInternalTerminationFuture() { + return internalTerminationFuture; + } + + private CompletableFuture<Void> getExternalTerminationFuture() { + return externalTerminationFuture; + } + + private String getEndpointId() { + return endpointId; + } + + private void terminate() { + CompletableFuture<Void> terminationFuture = internalTerminationFuture; + + if (errorCause != null) { + if (!internalTerminationFuture.completeExceptionally(errorCause)) { + // we have another failure reason -> let's add it + terminationFuture = internalTerminationFuture.<Void>handle( Review comment: I will remove it. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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