| /* |
| * 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.sling.distribution.journal.impl.shared; |
| |
| import static java.time.temporal.ChronoUnit.MINUTES; |
| import static java.time.temporal.ChronoUnit.SECONDS; |
| import static java.util.Objects.requireNonNull; |
| |
| import java.time.Duration; |
| import java.util.concurrent.atomic.AtomicInteger; |
| |
| import org.apache.commons.io.IOUtils; |
| import org.apache.sling.distribution.journal.ExceptionEventSender; |
| import org.apache.sling.distribution.journal.JournalAvailable; |
| import org.apache.sling.distribution.journal.MessagingProvider; |
| import org.apache.sling.distribution.journal.impl.shared.DistributionMetricsService.GaugeService; |
| import org.osgi.framework.BundleContext; |
| import org.osgi.framework.ServiceRegistration; |
| import org.osgi.service.component.annotations.Activate; |
| import org.osgi.service.component.annotations.Component; |
| import org.osgi.service.component.annotations.Deactivate; |
| import org.osgi.service.component.annotations.Reference; |
| import org.osgi.service.event.Event; |
| import org.osgi.service.event.EventConstants; |
| import org.osgi.service.event.EventHandler; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| @Component( |
| property = EventConstants.EVENT_TOPIC + "=" + ExceptionEventSender.ERROR_TOPIC |
| ) |
| public class JournalAvailableChecker implements JournalAvailable, EventHandler { |
| |
| private static final Duration INITIAL_RETRY_DELAY = Duration.of(1, SECONDS); |
| private static final Duration MAX_RETRY_DELAY = Duration.of(5, MINUTES); |
| |
| // Minimal number of errors before journal is considered unavailable |
| public static final int MIN_ERRORS = 2; |
| |
| private static final Logger LOG = LoggerFactory.getLogger(JournalAvailableChecker.class); |
| |
| @Reference |
| Topics topics; |
| |
| @Reference |
| MessagingProvider provider; |
| |
| @Reference |
| DistributionMetricsService metrics; |
| |
| private BundleContext context; |
| |
| private volatile ServiceRegistration<JournalAvailable> reg; |
| |
| private GaugeService<Boolean> gauge; |
| |
| private ExponentialBackOff backoffRetry; |
| |
| private AtomicInteger numErrors; |
| |
| @Activate |
| public void activate(BundleContext context) { |
| requireNonNull(provider); |
| requireNonNull(topics); |
| this.context = context; |
| this.numErrors = new AtomicInteger(); |
| gauge = metrics.createGauge(DistributionMetricsService.BASE_COMPONENT + ".journal_available", "", this::isAvailable); |
| LOG.info("Started Journal availability checker service"); |
| this.backoffRetry = new ExponentialBackOff(INITIAL_RETRY_DELAY, MAX_RETRY_DELAY, true, this::run); |
| this.backoffRetry.startChecks(); |
| } |
| |
| @Deactivate |
| public void deactivate() { |
| gauge.close(); |
| unRegister(); |
| IOUtils.closeQuietly(this.backoffRetry); |
| LOG.info("Stopped Journal availability checker service"); |
| } |
| |
| private void doChecks() { |
| provider.assertTopic(topics.getPackageTopic()); |
| provider.assertTopic(topics.getDiscoveryTopic()); |
| provider.assertTopic(topics.getStatusTopic()); |
| provider.assertTopic(topics.getCommandTopic()); |
| } |
| |
| private void available() { |
| LOG.info("Journal is available"); |
| if (this.reg == null) { |
| this.reg = context.registerService(JournalAvailable.class, this, null); |
| } |
| } |
| |
| private void unAvailable(Exception e) { |
| String msg = "Journal is still unavailable: " + e.getMessage(); |
| if (LOG.isDebugEnabled()) { |
| LOG.warn(msg, e); |
| } else { |
| LOG.warn(msg); |
| } |
| unRegister(); |
| } |
| |
| public boolean isAvailable() { |
| return reg != null; |
| } |
| |
| public void run() { |
| try { |
| LOG.debug("Journal checker is running"); |
| doChecks(); |
| available(); |
| } catch (Exception e) { |
| unAvailable(e); |
| throw e; |
| } |
| } |
| |
| private void unRegister() { |
| if (this.reg != null) { |
| this.reg.unregister(); |
| this.reg = null; |
| } |
| } |
| |
| @Override |
| public synchronized void handleEvent(Event event) { |
| String type = (String) event.getProperty(ExceptionEventSender.KEY_TYPE); |
| int curNumErrors = this.numErrors.incrementAndGet(); |
| if (curNumErrors >= MIN_ERRORS) { |
| LOG.warn("Received exception event {}. Journal is considered unavailable.", type); |
| unRegister(); |
| this.numErrors.set(0); |
| this.backoffRetry.startChecks(); |
| } else { |
| LOG.info("Received exception event {}. {} of {} errors occurred.", type, curNumErrors, MIN_ERRORS); |
| } |
| } |
| |
| } |