pulsar-broker/src/main/java/org/apache/pulsar/broker/MessagingServiceShutdownHook.java

/**
 * 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.pulsar.broker;

import io.netty.util.concurrent.DefaultThreadFactory;
import java.lang.reflect.Method;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.function.Consumer;
import org.apache.pulsar.zookeeper.ZooKeeperSessionWatcher.ShutdownService;
import org.apache.zookeeper.ZooKeeper.States;
import org.slf4j.ILoggerFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class MessagingServiceShutdownHook extends Thread implements ShutdownService {

    private static final Logger LOG = LoggerFactory.getLogger(MessagingServiceShutdownHook.class);
    private static final String LogbackLoggerContextClassName = "ch.qos.logback.classic.LoggerContext";

    private PulsarService service = null;
    private final Consumer<Integer> processTerminator;

    public MessagingServiceShutdownHook(PulsarService service, Consumer<Integer> processTerminator) {
        this.service = service;
        this.processTerminator = processTerminator;
    }

    @Override
    public void run() {
        if (service.getConfiguration() != null) {
            LOG.info("messaging service shutdown hook started, lookup webservice="
                    + service.getSafeWebServiceAddress() + ", broker url=" + service.getSafeBrokerServiceUrl());
        }

        ExecutorService executor = Executors.newSingleThreadExecutor(new DefaultThreadFactory("shutdown-thread"));

        try {
            CompletableFuture<Void> future = new CompletableFuture<>();

            executor.execute(() -> {
                try {
                    service.close();
                    future.complete(null);
                } catch (PulsarServerException e) {
                    future.completeExceptionally(e);
                }
            });

            future.get(service.getConfiguration().getBrokerShutdownTimeoutMs(), TimeUnit.MILLISECONDS);

            LOG.info("Completed graceful shutdown. Exiting");
        } catch (TimeoutException e) {
            LOG.warn("Graceful shutdown timeout expired. Closing now");
        } catch (Exception e) {
            LOG.error("Failed to perform graceful shutdown, Exiting anyway", e);
        } finally {

            immediateFlushBufferedLogs();

            // always put system to halt immediately
            processTerminator.accept(0);
        }
    }

    @Override
    public void shutdown(int exitCode) {
        try {
            // Try to close ZK session to ensure all ephemeral locks gets released immediately
            if (service != null) {
                if (service.getZkClient().getState() != States.CLOSED) {
                    service.getZkClient().close();
                }
            }
        } catch (Exception e) {
            LOG.warn(e.getMessage(), e);
        }

        LOG.info("Invoking Runtime.halt({})", exitCode);
        immediateFlushBufferedLogs();
        processTerminator.accept(exitCode);
    }

    public static void immediateFlushBufferedLogs() {
        ILoggerFactory loggerFactory = LoggerFactory.getILoggerFactory();

        if (loggerFactory.getClass().getName().equals(LogbackLoggerContextClassName)) {
            // Use reflection to force the flush on the logger
            try {
                Class<?> logbackLoggerContextClass = Class.forName(LogbackLoggerContextClassName);
                Method stop = logbackLoggerContextClass.getMethod("stop");
                stop.invoke(loggerFactory);
            } catch (Throwable t) {
                LOG.info("Failed to flush logs", t);
            }
        }
    }

}