TisonKun commented on a change in pull request #9832: [FLINK-11843] Bind lifespan of Dispatcher to leader session URL: https://github.com/apache/flink/pull/9832#discussion_r337829942
########## File path: flink-runtime/src/main/java/org/apache/flink/runtime/dispatcher/runner/AbstractDispatcherLeaderProcess.java ########## @@ -0,0 +1,254 @@ +/* + * 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.dispatcher.runner; + +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.api.common.JobID; +import org.apache.flink.runtime.clusterframework.ApplicationStatus; +import org.apache.flink.runtime.concurrent.FutureUtils; +import org.apache.flink.runtime.dispatcher.DispatcherGateway; +import org.apache.flink.runtime.dispatcher.DispatcherId; +import org.apache.flink.runtime.jobgraph.JobGraph; +import org.apache.flink.runtime.jobmanager.JobGraphWriter; +import org.apache.flink.runtime.rpc.FatalErrorHandler; +import org.apache.flink.runtime.webmonitor.RestfulGateway; +import org.apache.flink.util.AutoCloseableAsync; +import org.apache.flink.util.Preconditions; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import javax.annotation.Nullable; + +import java.util.Collection; +import java.util.Optional; +import java.util.UUID; +import java.util.concurrent.CompletableFuture; +import java.util.function.Predicate; +import java.util.function.Supplier; + +abstract class AbstractDispatcherLeaderProcess implements DispatcherLeaderProcess { + + protected final Logger log = LoggerFactory.getLogger(getClass()); + + private final Object lock = new Object(); + + private final UUID leaderSessionId; + + private final FatalErrorHandler fatalErrorHandler; + + private final CompletableFuture<DispatcherGateway> dispatcherGatewayFuture; + + private final CompletableFuture<String> leaderAddressFuture; + + private final CompletableFuture<Void> terminationFuture; + + private final CompletableFuture<ApplicationStatus> shutDownFuture; + + private State state; + + @Nullable + private DispatcherService dispatcherService; + + AbstractDispatcherLeaderProcess(UUID leaderSessionId, FatalErrorHandler fatalErrorHandler) { + this.leaderSessionId = leaderSessionId; + this.fatalErrorHandler = fatalErrorHandler; + + this.dispatcherGatewayFuture = new CompletableFuture<>(); + this.leaderAddressFuture = dispatcherGatewayFuture.thenApply(RestfulGateway::getAddress); + this.terminationFuture = new CompletableFuture<>(); + this.shutDownFuture = new CompletableFuture<>(); + + this.state = State.CREATED; + } + + @VisibleForTesting + State getState() { + synchronized (lock) { + return state; + } + } + + @Override + public final void start() { + runIfStateIs( + State.CREATED, + this::startInternal); + } + + private void startInternal() { + log.info("Start {}.", getClass().getSimpleName()); + state = State.RUNNING; + onStart(); + } + + @Override + public final UUID getLeaderSessionId() { + return leaderSessionId; + } + + @Override + public final CompletableFuture<DispatcherGateway> getDispatcherGateway() { + return dispatcherGatewayFuture; + } + + @Override + public final CompletableFuture<String> getLeaderAddressFuture() { + return leaderAddressFuture; + } + + @Override + public CompletableFuture<ApplicationStatus> getShutDownFuture() { + return shutDownFuture; + } + + protected final Optional<DispatcherService> getDispatcherService() { + return Optional.ofNullable(dispatcherService); + } + + @Override + public final CompletableFuture<Void> closeAsync() { + runIfStateIsNot( + State.STOPPED, + this::closeInternal); + + return terminationFuture; + } + + private void closeInternal() { + log.info("Stopping {}.", getClass().getSimpleName()); + + final CompletableFuture<Void> dispatcherServiceTerminationFuture = closeDispatcherService(); + + final CompletableFuture<Void> onCloseTerminationFuture = FutureUtils.composeAfterwards( + dispatcherServiceTerminationFuture, + this::onClose); + + FutureUtils.forward( + onCloseTerminationFuture, + this.terminationFuture); + + state = State.STOPPED; + } + + private CompletableFuture<Void> closeDispatcherService() { + if (dispatcherService != null) { + return dispatcherService.closeAsync(); + } else { + return FutureUtils.completedVoidFuture(); + } + } + + protected abstract void onStart(); + + protected CompletableFuture<Void> onClose() { + return FutureUtils.completedVoidFuture(); + } + + final void completeDispatcherSetup(DispatcherService dispatcherService) { + runIfStateIs( + State.RUNNING, + () -> completeDispatcherSetupInternal(dispatcherService)); + } + + private void completeDispatcherSetupInternal(DispatcherService createdDispatcherService) { + Preconditions.checkState(dispatcherService == null, "The DispatcherService can only be set once."); + dispatcherService = createdDispatcherService; + dispatcherGatewayFuture.complete(createdDispatcherService.getGateway()); + FutureUtils.forward(createdDispatcherService.getShutDownFuture(), shutDownFuture); + } + + final <V> Optional<V> supplyUnsynchronizedIfRunning(Supplier<V> supplier) { + synchronized (lock) { + if (state != State.RUNNING) { + return Optional.empty(); + } + } + + return Optional.of(supplier.get()); + } + + final <V> Optional<V> supplyIfRunning(Supplier<V> supplier) { + synchronized (lock) { + if (state != State.RUNNING) { + return Optional.empty(); + } + + return Optional.of(supplier.get()); + } + } + + final void runIfStateIs(State expectedState, Runnable action) { + runIfState(expectedState::equals, action); + } + + private void runIfStateIsNot(State notExpectedState, Runnable action) { + runIfState( + state -> !notExpectedState.equals(state), + action); + } + + private void runIfState(Predicate<State> actionPredicate, Runnable action) { + synchronized (lock) { + if (actionPredicate.test(state)) { + action.run(); + } + } + } + + final <T> Void onErrorIfRunning(T ignored, Throwable throwable) { + synchronized (lock) { + if (state != State.RUNNING) { + return null; + } + } + + if (throwable != null) { + closeAsync(); + fatalErrorHandler.onFatalError(throwable); + } + + return null; + } + + protected enum State { + CREATED, + RUNNING, + STOPPED + } + + // ------------------------------------------------------------ + // Internal classes + // ------------------------------------------------------------ + + interface DispatcherServiceFactory { + DispatcherService create( + DispatcherId fencingToken, + Collection<JobGraph> recoveredJobs, + JobGraphWriter jobGraphWriter); + } + + interface DispatcherService extends AutoCloseableAsync { Review comment: Shall we call this one `DispatcherContainer` since it is a thin wrapper of ``` Dispatcher dispatcher; DispatcherGateway dispatcherGateway; ``` and its methods don't like a service. What is more important is that I'm afraid it is a bit confusing the different between this `DispatcherService` and `DispatcherServices` which are totally different thing but share a similar name under the same scope. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
